2002-08-12 21:17:25 +00:00
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//===- InstructionCombining.cpp - Combine multiple instructions -----------===//
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2001-12-14 16:52:21 +00:00
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//
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// InstructionCombining - Combine instructions to form fewer, simple
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2002-09-02 04:59:56 +00:00
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// instructions. This pass does not modify the CFG This pass is where algebraic
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// simplification happens.
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2001-12-14 16:52:21 +00:00
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//
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// This pass combines things like:
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// %Y = add int 1, %X
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// %Z = add int 1, %Y
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// into:
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// %Z = add int 2, %X
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//
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// This is a simple worklist driven algorithm.
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//
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//===----------------------------------------------------------------------===//
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2002-05-07 20:03:00 +00:00
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#include "llvm/Transforms/Scalar.h"
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2002-05-07 18:12:18 +00:00
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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2002-08-02 19:29:35 +00:00
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#include "llvm/Transforms/Utils/Local.h"
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2002-04-08 20:18:09 +00:00
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#include "llvm/ConstantHandling.h"
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2001-12-14 16:52:21 +00:00
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#include "llvm/iMemory.h"
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2002-04-15 19:45:29 +00:00
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#include "llvm/iOther.h"
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2002-05-06 18:06:38 +00:00
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#include "llvm/iPHINode.h"
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2002-04-18 17:39:14 +00:00
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#include "llvm/iOperators.h"
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2002-02-26 21:46:54 +00:00
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#include "llvm/Pass.h"
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2002-11-04 16:18:53 +00:00
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#include "llvm/DerivedTypes.h"
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2002-02-12 21:07:25 +00:00
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#include "llvm/Support/InstIterator.h"
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2002-04-18 17:39:14 +00:00
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#include "llvm/Support/InstVisitor.h"
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2002-10-01 22:38:41 +00:00
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#include "Support/Statistic.h"
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2002-05-14 15:24:07 +00:00
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#include <algorithm>
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2001-12-14 16:52:21 +00:00
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2002-04-18 17:39:14 +00:00
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namespace {
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2002-10-01 22:38:41 +00:00
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Statistic<> NumCombined ("instcombine", "Number of insts combined");
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Statistic<> NumConstProp("instcombine", "Number of constant folds");
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Statistic<> NumDeadInst ("instcombine", "Number of dead inst eliminated");
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2002-04-27 06:56:12 +00:00
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class InstCombiner : public FunctionPass,
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2002-04-18 17:39:14 +00:00
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public InstVisitor<InstCombiner, Instruction*> {
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// Worklist of all of the instructions that need to be simplified.
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std::vector<Instruction*> WorkList;
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2002-06-25 16:13:24 +00:00
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void AddUsesToWorkList(Instruction &I) {
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2002-04-18 17:39:14 +00:00
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// The instruction was simplified, add all users of the instruction to
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// the work lists because they might get more simplified now...
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//
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2002-06-25 16:13:24 +00:00
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for (Value::use_iterator UI = I.use_begin(), UE = I.use_end();
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2002-04-18 17:39:14 +00:00
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UI != UE; ++UI)
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WorkList.push_back(cast<Instruction>(*UI));
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}
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2002-09-02 04:59:56 +00:00
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// removeFromWorkList - remove all instances of I from the worklist.
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void removeFromWorkList(Instruction *I);
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2002-04-18 17:39:14 +00:00
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public:
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2002-06-25 16:13:24 +00:00
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virtual bool runOnFunction(Function &F);
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2002-04-18 17:39:14 +00:00
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2002-04-28 21:27:06 +00:00
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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2002-10-21 20:00:28 +00:00
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AU.setPreservesCFG();
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2002-04-28 21:27:06 +00:00
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}
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2002-04-18 17:39:14 +00:00
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// Visitation implementation - Implement instruction combining for different
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// instruction types. The semantics are as follows:
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// Return Value:
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// null - No change was made
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2002-08-12 21:17:25 +00:00
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// I - Change was made, I is still valid, I may be dead though
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2002-04-18 17:39:14 +00:00
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// otherwise - Change was made, replace I with returned instruction
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//
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2002-06-25 16:13:24 +00:00
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Instruction *visitAdd(BinaryOperator &I);
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Instruction *visitSub(BinaryOperator &I);
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Instruction *visitMul(BinaryOperator &I);
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Instruction *visitDiv(BinaryOperator &I);
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Instruction *visitRem(BinaryOperator &I);
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Instruction *visitAnd(BinaryOperator &I);
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Instruction *visitOr (BinaryOperator &I);
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Instruction *visitXor(BinaryOperator &I);
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Instruction *visitSetCondInst(BinaryOperator &I);
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2003-03-10 19:16:08 +00:00
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Instruction *visitShiftInst(ShiftInst &I);
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2002-06-25 16:13:24 +00:00
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Instruction *visitCastInst(CastInst &CI);
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Instruction *visitPHINode(PHINode &PN);
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Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
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2002-11-04 16:18:53 +00:00
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Instruction *visitAllocationInst(AllocationInst &AI);
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2002-04-18 17:39:14 +00:00
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// visitInstruction - Specify what to return for unhandled instructions...
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2002-06-25 16:13:24 +00:00
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Instruction *visitInstruction(Instruction &I) { return 0; }
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2002-08-09 23:47:40 +00:00
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// InsertNewInstBefore - insert an instruction New before instruction Old
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// in the program. Add the new instruction to the worklist.
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//
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void InsertNewInstBefore(Instruction *New, Instruction &Old) {
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2002-08-23 18:32:43 +00:00
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assert(New && New->getParent() == 0 &&
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"New instruction already inserted into a basic block!");
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2002-08-09 23:47:40 +00:00
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BasicBlock *BB = Old.getParent();
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BB->getInstList().insert(&Old, New); // Insert inst
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WorkList.push_back(New); // Add to worklist
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}
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// ReplaceInstUsesWith - This method is to be used when an instruction is
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// found to be dead, replacable with another preexisting expression. Here
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// we add all uses of I to the worklist, replace all uses of I with the new
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// value, then return I, so that the inst combiner will know that I was
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// modified.
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//
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Instruction *ReplaceInstUsesWith(Instruction &I, Value *V) {
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AddUsesToWorkList(I); // Add all modified instrs to worklist
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I.replaceAllUsesWith(V);
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return &I;
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}
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2002-04-18 17:39:14 +00:00
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};
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2002-07-23 18:06:35 +00:00
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2002-07-26 21:12:46 +00:00
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RegisterOpt<InstCombiner> X("instcombine", "Combine redundant instructions");
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2002-04-18 17:39:14 +00:00
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}
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2003-03-10 21:43:22 +00:00
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// getComplexity: Assign a complexity or rank value to LLVM Values...
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// 0 -> Constant, 1 -> Other, 2 -> Argument, 2 -> Unary, 3 -> OtherInst
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static unsigned getComplexity(Value *V) {
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if (isa<Instruction>(V)) {
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if (BinaryOperator::isNeg(V) || BinaryOperator::isNot(V))
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return 2;
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return 3;
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}
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if (isa<Argument>(V)) return 2;
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return isa<Constant>(V) ? 0 : 1;
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}
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2002-04-18 17:39:14 +00:00
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2003-03-10 21:43:22 +00:00
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// SimplifyCommutative - This performs a few simplifications for commutative
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// operators:
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//
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// 1. Order operands such that they are listed from right (least complex) to
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// left (most complex). This puts constants before unary operators before
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// binary operators.
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2002-04-18 17:39:14 +00:00
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//
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2003-03-10 21:43:22 +00:00
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// 2. Handle the case of (op (op V, C1), C2), changing it to:
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// (op V, (op C1, C2))
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//
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static bool SimplifyCommutative(BinaryOperator &I) {
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bool Changed = false;
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if (getComplexity(I.getOperand(0)) < getComplexity(I.getOperand(1)))
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Changed = !I.swapOperands();
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if (!I.isAssociative()) return Changed;
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Instruction::BinaryOps Opcode = I.getOpcode();
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if (BinaryOperator *Op = dyn_cast<BinaryOperator>(I.getOperand(0))) {
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if (Op->getOpcode() == Opcode && isa<Constant>(I.getOperand(1)) &&
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isa<Constant>(Op->getOperand(1))) {
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Instruction *New = BinaryOperator::create(I.getOpcode(), I.getOperand(1),
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Op->getOperand(1));
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Constant *Folded = ConstantFoldInstruction(New);
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delete New;
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assert(Folded && "Couldn't constant fold commutative operand?");
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I.setOperand(0, Op->getOperand(0));
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I.setOperand(1, Folded);
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return true;
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}
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}
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return Changed;
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2002-04-18 17:39:14 +00:00
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}
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2001-12-14 16:52:21 +00:00
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2003-03-10 23:06:50 +00:00
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// dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
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// if the LHS is a constant zero (which is the 'negate' form).
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2002-05-06 16:49:18 +00:00
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//
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2003-03-10 23:06:50 +00:00
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static inline Value *dyn_castNegVal(Value *V) {
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if (BinaryOperator::isNeg(V))
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return BinaryOperator::getNegArgument(cast<BinaryOperator>(V));
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// Constants can be considered to be negated values...
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if (Constant *C = dyn_cast<Constant>(V)) {
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Constant *NC = *Constant::getNullValue(V->getType()) - *C;
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assert(NC && "Couldn't constant fold a subtract!");
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return NC;
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}
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return 0;
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}
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static inline Value *dyn_castNotVal(Value *V) {
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if (BinaryOperator::isNot(V))
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return BinaryOperator::getNotArgument(cast<BinaryOperator>(V));
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// Constants can be considered to be not'ed values...
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if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(V)) {
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Constant *NC = *ConstantIntegral::getAllOnesValue(C->getType()) ^ *C;
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assert(NC && "Couldn't constant fold an exclusive or!");
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return NC;
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}
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return 0;
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2002-05-06 16:49:18 +00:00
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}
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2003-03-10 23:06:50 +00:00
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static bool isOnlyUse(Value *V) {
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return V->use_size() == 1 || isa<Constant>(V);
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2003-02-18 19:28:33 +00:00
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}
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2002-08-14 17:51:49 +00:00
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2003-02-18 19:28:33 +00:00
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// Log2 - Calculate the log base 2 for the specified value if it is exactly a
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// power of 2.
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static unsigned Log2(uint64_t Val) {
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assert(Val > 1 && "Values 0 and 1 should be handled elsewhere!");
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unsigned Count = 0;
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while (Val != 1) {
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if (Val & 1) return 0; // Multiple bits set?
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Val >>= 1;
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++Count;
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}
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return Count;
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2002-08-14 17:51:49 +00:00
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}
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2003-02-18 19:57:07 +00:00
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static inline Value *dyn_castFoldableMul(Value *V) {
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if (V->use_size() == 1 && V->getType()->isInteger())
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if (Instruction *I = dyn_cast<Instruction>(V))
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if (I->getOpcode() == Instruction::Mul)
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if (isa<Constant>(I->getOperand(1)))
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return I->getOperand(0);
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return 0;
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}
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2002-06-25 16:13:24 +00:00
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Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
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2003-03-10 21:43:22 +00:00
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bool Changed = SimplifyCommutative(I);
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2002-06-25 16:13:24 +00:00
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Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
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2002-05-06 16:49:18 +00:00
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// Eliminate 'add int %X, 0'
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2002-08-12 21:17:25 +00:00
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if (RHS == Constant::getNullValue(I.getType()))
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return ReplaceInstUsesWith(I, LHS);
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2002-05-06 16:49:18 +00:00
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2002-05-08 22:46:53 +00:00
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// -A + B --> B - A
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2003-03-10 23:06:50 +00:00
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if (Value *V = dyn_castNegVal(LHS))
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2002-05-08 22:46:53 +00:00
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return BinaryOperator::create(Instruction::Sub, RHS, V);
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2002-05-06 16:49:18 +00:00
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// A + -B --> A - B
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2003-03-10 23:06:50 +00:00
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if (!isa<Constant>(RHS))
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if (Value *V = dyn_castNegVal(RHS))
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return BinaryOperator::create(Instruction::Sub, LHS, V);
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2002-04-18 17:39:14 +00:00
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2003-02-18 19:57:07 +00:00
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// X*C + X --> X * (C+1)
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if (dyn_castFoldableMul(LHS) == RHS) {
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Constant *CP1 = *cast<Constant>(cast<Instruction>(LHS)->getOperand(1)) +
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*ConstantInt::get(I.getType(), 1);
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assert(CP1 && "Couldn't constant fold C + 1?");
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return BinaryOperator::create(Instruction::Mul, RHS, CP1);
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}
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// X + X*C --> X * (C+1)
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if (dyn_castFoldableMul(RHS) == LHS) {
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Constant *CP1 = *cast<Constant>(cast<Instruction>(RHS)->getOperand(1)) +
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*ConstantInt::get(I.getType(), 1);
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assert(CP1 && "Couldn't constant fold C + 1?");
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return BinaryOperator::create(Instruction::Mul, LHS, CP1);
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}
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2002-06-25 16:13:24 +00:00
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return Changed ? &I : 0;
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2002-04-18 17:39:14 +00:00
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}
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2002-02-26 21:46:54 +00:00
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2002-06-25 16:13:24 +00:00
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Instruction *InstCombiner::visitSub(BinaryOperator &I) {
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Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
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2002-05-06 16:14:14 +00:00
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2002-08-12 21:17:25 +00:00
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if (Op0 == Op1) // sub X, X -> 0
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return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
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2002-04-18 17:39:14 +00:00
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2002-08-12 21:17:25 +00:00
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// If this is a 'B = x-(-A)', change to B = x+A...
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2003-03-10 23:06:50 +00:00
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if (Value *V = dyn_castNegVal(Op1))
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2002-05-08 22:46:53 +00:00
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return BinaryOperator::create(Instruction::Add, Op0, V);
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2002-05-06 16:49:18 +00:00
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2003-02-18 19:28:33 +00:00
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// Replace (-1 - A) with (~A)...
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if (ConstantInt *C = dyn_cast<ConstantInt>(Op0))
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if (C->isAllOnesValue())
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return BinaryOperator::createNot(Op1);
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2002-05-09 01:29:19 +00:00
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if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1))
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2003-02-18 19:28:33 +00:00
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if (Op1I->use_size() == 1) {
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// Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
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// is not used by anyone else...
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//
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if (Op1I->getOpcode() == Instruction::Sub) {
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// Swap the two operands of the subexpr...
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Value *IIOp0 = Op1I->getOperand(0), *IIOp1 = Op1I->getOperand(1);
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Op1I->setOperand(0, IIOp1);
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Op1I->setOperand(1, IIOp0);
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// Create the new top level add instruction...
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return BinaryOperator::create(Instruction::Add, Op0, Op1);
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}
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// Replace (A - (A & B)) with (A & ~B) if this is the only use of (A&B)...
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//
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if (Op1I->getOpcode() == Instruction::And &&
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|
(Op1I->getOperand(0) == Op0 || Op1I->getOperand(1) == Op0)) {
|
|
|
|
Value *OtherOp = Op1I->getOperand(Op1I->getOperand(0) == Op0);
|
|
|
|
|
|
|
|
Instruction *NewNot = BinaryOperator::createNot(OtherOp, "B.not", &I);
|
|
|
|
return BinaryOperator::create(Instruction::And, Op0, NewNot);
|
|
|
|
}
|
2003-02-18 19:57:07 +00:00
|
|
|
|
|
|
|
// X - X*C --> X * (1-C)
|
|
|
|
if (dyn_castFoldableMul(Op1I) == Op0) {
|
|
|
|
Constant *CP1 = *ConstantInt::get(I.getType(), 1) -
|
|
|
|
*cast<Constant>(cast<Instruction>(Op1)->getOperand(1));
|
|
|
|
assert(CP1 && "Couldn't constant fold 1-C?");
|
|
|
|
return BinaryOperator::create(Instruction::Mul, Op0, CP1);
|
|
|
|
}
|
2002-05-09 01:29:19 +00:00
|
|
|
}
|
2003-02-18 19:28:33 +00:00
|
|
|
|
2003-02-18 19:57:07 +00:00
|
|
|
// X*C - X --> X * (C-1)
|
|
|
|
if (dyn_castFoldableMul(Op0) == Op1) {
|
|
|
|
Constant *CP1 = *cast<Constant>(cast<Instruction>(Op0)->getOperand(1)) -
|
|
|
|
*ConstantInt::get(I.getType(), 1);
|
|
|
|
assert(CP1 && "Couldn't constant fold C - 1?");
|
|
|
|
return BinaryOperator::create(Instruction::Mul, Op1, CP1);
|
|
|
|
}
|
|
|
|
|
2002-05-06 16:14:14 +00:00
|
|
|
return 0;
|
2002-04-18 17:39:14 +00:00
|
|
|
}
|
|
|
|
|
2002-06-25 16:13:24 +00:00
|
|
|
Instruction *InstCombiner::visitMul(BinaryOperator &I) {
|
2003-03-10 21:43:22 +00:00
|
|
|
bool Changed = SimplifyCommutative(I);
|
2003-02-18 19:28:33 +00:00
|
|
|
Value *Op0 = I.getOperand(0);
|
2002-04-18 17:39:14 +00:00
|
|
|
|
2002-08-12 21:17:25 +00:00
|
|
|
// Simplify mul instructions with a constant RHS...
|
2003-02-18 19:28:33 +00:00
|
|
|
if (Constant *Op1 = dyn_cast<Constant>(I.getOperand(1))) {
|
|
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
|
|
|
|
const Type *Ty = CI->getType();
|
|
|
|
uint64_t Val = Ty->isSigned() ?
|
|
|
|
(uint64_t)cast<ConstantSInt>(CI)->getValue() :
|
|
|
|
cast<ConstantUInt>(CI)->getValue();
|
|
|
|
switch (Val) {
|
|
|
|
case 0:
|
|
|
|
return ReplaceInstUsesWith(I, Op1); // Eliminate 'mul double %X, 0'
|
|
|
|
case 1:
|
|
|
|
return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul int %X, 1'
|
|
|
|
case 2: // Convert 'mul int %X, 2' to 'add int %X, %X'
|
|
|
|
return BinaryOperator::create(Instruction::Add, Op0, Op0, I.getName());
|
|
|
|
}
|
2002-04-29 22:24:47 +00:00
|
|
|
|
2003-02-18 19:28:33 +00:00
|
|
|
if (uint64_t C = Log2(Val)) // Replace X*(2^C) with X << C
|
|
|
|
return new ShiftInst(Instruction::Shl, Op0,
|
|
|
|
ConstantUInt::get(Type::UByteTy, C));
|
|
|
|
} else {
|
|
|
|
ConstantFP *Op1F = cast<ConstantFP>(Op1);
|
|
|
|
if (Op1F->isNullValue())
|
|
|
|
return ReplaceInstUsesWith(I, Op1);
|
|
|
|
|
|
|
|
// "In IEEE floating point, x*1 is not equivalent to x for nans. However,
|
|
|
|
// ANSI says we can drop signals, so we can do this anyway." (from GCC)
|
|
|
|
if (Op1F->getValue() == 1.0)
|
|
|
|
return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0'
|
|
|
|
}
|
2001-12-14 16:52:21 +00:00
|
|
|
}
|
|
|
|
|
2002-06-25 16:13:24 +00:00
|
|
|
return Changed ? &I : 0;
|
2002-04-18 17:39:14 +00:00
|
|
|
}
|
|
|
|
|
2002-06-25 16:13:24 +00:00
|
|
|
Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
|
2002-05-06 16:14:14 +00:00
|
|
|
// div X, 1 == X
|
2003-02-18 19:28:33 +00:00
|
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) {
|
2002-08-12 21:17:25 +00:00
|
|
|
if (RHS->equalsInt(1))
|
|
|
|
return ReplaceInstUsesWith(I, I.getOperand(0));
|
2003-02-18 19:28:33 +00:00
|
|
|
|
|
|
|
// Check to see if this is an unsigned division with an exact power of 2,
|
|
|
|
// if so, convert to a right shift.
|
|
|
|
if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
|
|
|
|
if (uint64_t Val = C->getValue()) // Don't break X / 0
|
|
|
|
if (uint64_t C = Log2(Val))
|
|
|
|
return new ShiftInst(Instruction::Shr, I.getOperand(0),
|
|
|
|
ConstantUInt::get(Type::UByteTy, C));
|
|
|
|
}
|
|
|
|
|
|
|
|
// 0 / X == 0, we don't need to preserve faults!
|
|
|
|
if (ConstantInt *LHS = dyn_cast<ConstantInt>(I.getOperand(0)))
|
|
|
|
if (LHS->equalsInt(0))
|
|
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
|
|
|
2002-05-06 16:14:14 +00:00
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
|
2002-06-25 16:13:24 +00:00
|
|
|
Instruction *InstCombiner::visitRem(BinaryOperator &I) {
|
2003-02-18 19:28:33 +00:00
|
|
|
if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) {
|
|
|
|
if (RHS->equalsInt(1)) // X % 1 == 0
|
|
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
|
|
|
|
|
|
|
// Check to see if this is an unsigned remainder with an exact power of 2,
|
|
|
|
// if so, convert to a bitwise and.
|
|
|
|
if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS))
|
|
|
|
if (uint64_t Val = C->getValue()) // Don't break X % 0 (divide by zero)
|
|
|
|
if (Log2(Val))
|
|
|
|
return BinaryOperator::create(Instruction::And, I.getOperand(0),
|
|
|
|
ConstantUInt::get(I.getType(), Val-1));
|
|
|
|
}
|
|
|
|
|
|
|
|
// 0 % X == 0, we don't need to preserve faults!
|
|
|
|
if (ConstantInt *LHS = dyn_cast<ConstantInt>(I.getOperand(0)))
|
|
|
|
if (LHS->equalsInt(0))
|
2002-08-12 21:17:25 +00:00
|
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
2002-08-09 23:47:40 +00:00
|
|
|
|
2002-08-12 21:17:25 +00:00
|
|
|
return 0;
|
2002-08-09 23:47:40 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
// isMaxValueMinusOne - return true if this is Max-1
|
2002-08-12 21:17:25 +00:00
|
|
|
static bool isMaxValueMinusOne(const ConstantInt *C) {
|
2002-08-09 23:47:40 +00:00
|
|
|
if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C)) {
|
|
|
|
// Calculate -1 casted to the right type...
|
|
|
|
unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
|
|
|
|
uint64_t Val = ~0ULL; // All ones
|
|
|
|
Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
|
|
|
|
return CU->getValue() == Val-1;
|
|
|
|
}
|
|
|
|
|
|
|
|
const ConstantSInt *CS = cast<ConstantSInt>(C);
|
|
|
|
|
|
|
|
// Calculate 0111111111..11111
|
|
|
|
unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
|
|
|
|
int64_t Val = INT64_MAX; // All ones
|
|
|
|
Val >>= 64-TypeBits; // Shift out unwanted 1 bits...
|
|
|
|
return CS->getValue() == Val-1;
|
|
|
|
}
|
|
|
|
|
|
|
|
// isMinValuePlusOne - return true if this is Min+1
|
2002-08-12 21:17:25 +00:00
|
|
|
static bool isMinValuePlusOne(const ConstantInt *C) {
|
2002-08-09 23:47:40 +00:00
|
|
|
if (const ConstantUInt *CU = dyn_cast<ConstantUInt>(C))
|
|
|
|
return CU->getValue() == 1;
|
|
|
|
|
|
|
|
const ConstantSInt *CS = cast<ConstantSInt>(C);
|
|
|
|
|
|
|
|
// Calculate 1111111111000000000000
|
|
|
|
unsigned TypeBits = C->getType()->getPrimitiveSize()*8;
|
|
|
|
int64_t Val = -1; // All ones
|
|
|
|
Val <<= TypeBits-1; // Shift over to the right spot
|
|
|
|
return CS->getValue() == Val+1;
|
2002-05-06 16:14:14 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
|
2002-06-25 16:13:24 +00:00
|
|
|
Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
|
2003-03-10 21:43:22 +00:00
|
|
|
bool Changed = SimplifyCommutative(I);
|
2002-06-25 16:13:24 +00:00
|
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
2002-05-06 16:14:14 +00:00
|
|
|
|
|
|
|
// and X, X = X and X, 0 == 0
|
2002-08-12 21:17:25 +00:00
|
|
|
if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
|
|
|
|
return ReplaceInstUsesWith(I, Op1);
|
2002-05-06 16:14:14 +00:00
|
|
|
|
|
|
|
// and X, -1 == X
|
2002-08-13 17:50:24 +00:00
|
|
|
if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1))
|
2002-08-12 21:17:25 +00:00
|
|
|
if (RHS->isAllOnesValue())
|
|
|
|
return ReplaceInstUsesWith(I, Op0);
|
2002-05-06 16:14:14 +00:00
|
|
|
|
2003-03-10 23:06:50 +00:00
|
|
|
Value *Op0NotVal = dyn_castNotVal(Op0);
|
|
|
|
Value *Op1NotVal = dyn_castNotVal(Op1);
|
2003-02-18 19:28:33 +00:00
|
|
|
|
|
|
|
// (~A & ~B) == (~(A | B)) - Demorgan's Law
|
2003-03-10 23:06:50 +00:00
|
|
|
if (Op0NotVal && Op1NotVal && isOnlyUse(Op0) && isOnlyUse(Op1)) {
|
2003-02-18 19:28:33 +00:00
|
|
|
Instruction *Or = BinaryOperator::create(Instruction::Or, Op0NotVal,
|
|
|
|
Op1NotVal,I.getName()+".demorgan",
|
|
|
|
&I);
|
|
|
|
return BinaryOperator::createNot(Or);
|
|
|
|
}
|
|
|
|
|
|
|
|
if (Op0NotVal == Op1 || Op1NotVal == Op0) // A & ~A == ~A & A == 0
|
|
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
2002-08-23 18:32:43 +00:00
|
|
|
|
2002-06-25 16:13:24 +00:00
|
|
|
return Changed ? &I : 0;
|
2002-05-06 16:14:14 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
2002-06-25 16:13:24 +00:00
|
|
|
Instruction *InstCombiner::visitOr(BinaryOperator &I) {
|
2003-03-10 21:43:22 +00:00
|
|
|
bool Changed = SimplifyCommutative(I);
|
2002-06-25 16:13:24 +00:00
|
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
2002-05-06 16:14:14 +00:00
|
|
|
|
|
|
|
// or X, X = X or X, 0 == X
|
2002-08-12 21:17:25 +00:00
|
|
|
if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
|
|
|
|
return ReplaceInstUsesWith(I, Op0);
|
2002-05-06 16:14:14 +00:00
|
|
|
|
|
|
|
// or X, -1 == -1
|
2002-08-13 17:50:24 +00:00
|
|
|
if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1))
|
2002-08-12 21:17:25 +00:00
|
|
|
if (RHS->isAllOnesValue())
|
|
|
|
return ReplaceInstUsesWith(I, Op1);
|
2002-05-06 16:14:14 +00:00
|
|
|
|
2003-03-10 23:06:50 +00:00
|
|
|
if (Value *X = dyn_castNotVal(Op0)) // ~A | A == -1
|
2003-02-18 19:28:33 +00:00
|
|
|
if (X == Op1)
|
|
|
|
return ReplaceInstUsesWith(I,
|
|
|
|
ConstantIntegral::getAllOnesValue(I.getType()));
|
|
|
|
|
2003-03-10 23:06:50 +00:00
|
|
|
if (Value *X = dyn_castNotVal(Op1)) // A | ~A == -1
|
2003-02-18 19:28:33 +00:00
|
|
|
if (X == Op0)
|
|
|
|
return ReplaceInstUsesWith(I,
|
|
|
|
ConstantIntegral::getAllOnesValue(I.getType()));
|
|
|
|
|
2002-06-25 16:13:24 +00:00
|
|
|
return Changed ? &I : 0;
|
2002-05-06 16:14:14 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
2002-06-25 16:13:24 +00:00
|
|
|
Instruction *InstCombiner::visitXor(BinaryOperator &I) {
|
2003-03-10 21:43:22 +00:00
|
|
|
bool Changed = SimplifyCommutative(I);
|
2002-06-25 16:13:24 +00:00
|
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
2002-05-06 16:14:14 +00:00
|
|
|
|
|
|
|
// xor X, X = 0
|
2002-08-12 21:17:25 +00:00
|
|
|
if (Op0 == Op1)
|
|
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
|
2002-05-06 16:14:14 +00:00
|
|
|
|
2002-08-13 17:50:24 +00:00
|
|
|
if (ConstantIntegral *Op1C = dyn_cast<ConstantIntegral>(Op1)) {
|
2002-08-09 23:47:40 +00:00
|
|
|
// xor X, 0 == X
|
2002-08-12 21:17:25 +00:00
|
|
|
if (Op1C->isNullValue())
|
|
|
|
return ReplaceInstUsesWith(I, Op0);
|
2002-08-09 23:47:40 +00:00
|
|
|
|
2002-08-20 18:24:26 +00:00
|
|
|
// Is this a "NOT" instruction?
|
|
|
|
if (Op1C->isAllOnesValue()) {
|
|
|
|
// xor (xor X, -1), -1 = not (not X) = X
|
2003-03-10 23:06:50 +00:00
|
|
|
if (Value *X = dyn_castNotVal(Op0))
|
2002-08-14 17:51:49 +00:00
|
|
|
return ReplaceInstUsesWith(I, X);
|
2002-08-20 18:24:26 +00:00
|
|
|
|
|
|
|
// xor (setcc A, B), true = not (setcc A, B) = setncc A, B
|
|
|
|
if (SetCondInst *SCI = dyn_cast<SetCondInst>(Op0))
|
|
|
|
if (SCI->use_size() == 1)
|
|
|
|
return new SetCondInst(SCI->getInverseCondition(),
|
|
|
|
SCI->getOperand(0), SCI->getOperand(1));
|
|
|
|
}
|
2002-05-06 16:14:14 +00:00
|
|
|
}
|
|
|
|
|
2003-03-10 23:06:50 +00:00
|
|
|
if (Value *X = dyn_castNotVal(Op0)) // ~A ^ A == -1
|
2003-02-18 19:28:33 +00:00
|
|
|
if (X == Op1)
|
|
|
|
return ReplaceInstUsesWith(I,
|
|
|
|
ConstantIntegral::getAllOnesValue(I.getType()));
|
|
|
|
|
2003-03-10 23:06:50 +00:00
|
|
|
if (Value *X = dyn_castNotVal(Op1)) // A ^ ~A == -1
|
2003-02-18 19:28:33 +00:00
|
|
|
if (X == Op0)
|
|
|
|
return ReplaceInstUsesWith(I,
|
|
|
|
ConstantIntegral::getAllOnesValue(I.getType()));
|
|
|
|
|
2003-03-10 18:24:17 +00:00
|
|
|
|
|
|
|
|
|
|
|
if (Instruction *Op1I = dyn_cast<Instruction>(Op1))
|
|
|
|
if (Op1I->getOpcode() == Instruction::Or)
|
|
|
|
if (Op1I->getOperand(0) == Op0) { // B^(B|A) == (A|B)^B
|
|
|
|
cast<BinaryOperator>(Op1I)->swapOperands();
|
|
|
|
I.swapOperands();
|
|
|
|
std::swap(Op0, Op1);
|
|
|
|
} else if (Op1I->getOperand(1) == Op0) { // B^(A|B) == (A|B)^B
|
|
|
|
I.swapOperands();
|
|
|
|
std::swap(Op0, Op1);
|
|
|
|
}
|
|
|
|
|
|
|
|
if (Instruction *Op0I = dyn_cast<Instruction>(Op0))
|
|
|
|
if (Op0I->getOpcode() == Instruction::Or && Op0I->use_size() == 1) {
|
|
|
|
if (Op0I->getOperand(0) == Op1) // (B|A)^B == (A|B)^B
|
|
|
|
cast<BinaryOperator>(Op0I)->swapOperands();
|
2003-03-10 21:43:22 +00:00
|
|
|
if (Op0I->getOperand(1) == Op1) { // (A|B)^B == A & ~B
|
2003-03-10 18:24:17 +00:00
|
|
|
Value *NotB = BinaryOperator::createNot(Op1, Op1->getName()+".not", &I);
|
|
|
|
WorkList.push_back(cast<Instruction>(NotB));
|
2003-03-10 21:43:22 +00:00
|
|
|
return BinaryOperator::create(Instruction::And, Op0I->getOperand(0),
|
|
|
|
NotB);
|
2003-03-10 18:24:17 +00:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2002-06-25 16:13:24 +00:00
|
|
|
return Changed ? &I : 0;
|
2002-05-06 16:14:14 +00:00
|
|
|
}
|
|
|
|
|
2002-08-09 23:47:40 +00:00
|
|
|
// AddOne, SubOne - Add or subtract a constant one from an integer constant...
|
|
|
|
static Constant *AddOne(ConstantInt *C) {
|
|
|
|
Constant *Result = *C + *ConstantInt::get(C->getType(), 1);
|
|
|
|
assert(Result && "Constant folding integer addition failed!");
|
|
|
|
return Result;
|
|
|
|
}
|
|
|
|
static Constant *SubOne(ConstantInt *C) {
|
|
|
|
Constant *Result = *C - *ConstantInt::get(C->getType(), 1);
|
|
|
|
assert(Result && "Constant folding integer addition failed!");
|
|
|
|
return Result;
|
|
|
|
}
|
|
|
|
|
2002-05-09 20:11:54 +00:00
|
|
|
// isTrueWhenEqual - Return true if the specified setcondinst instruction is
|
|
|
|
// true when both operands are equal...
|
|
|
|
//
|
2002-06-25 16:13:24 +00:00
|
|
|
static bool isTrueWhenEqual(Instruction &I) {
|
|
|
|
return I.getOpcode() == Instruction::SetEQ ||
|
|
|
|
I.getOpcode() == Instruction::SetGE ||
|
|
|
|
I.getOpcode() == Instruction::SetLE;
|
2002-05-09 20:11:54 +00:00
|
|
|
}
|
|
|
|
|
2002-06-25 16:13:24 +00:00
|
|
|
Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
|
2003-03-10 21:43:22 +00:00
|
|
|
bool Changed = SimplifyCommutative(I);
|
2002-08-09 23:47:40 +00:00
|
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
|
|
|
const Type *Ty = Op0->getType();
|
2002-05-06 16:14:14 +00:00
|
|
|
|
|
|
|
// setcc X, X
|
2002-08-09 23:47:40 +00:00
|
|
|
if (Op0 == Op1)
|
|
|
|
return ReplaceInstUsesWith(I, ConstantBool::get(isTrueWhenEqual(I)));
|
2002-05-09 20:11:54 +00:00
|
|
|
|
|
|
|
// setcc <global*>, 0 - Global value addresses are never null!
|
2002-08-09 23:47:40 +00:00
|
|
|
if (isa<GlobalValue>(Op0) && isa<ConstantPointerNull>(Op1))
|
|
|
|
return ReplaceInstUsesWith(I, ConstantBool::get(!isTrueWhenEqual(I)));
|
|
|
|
|
|
|
|
// setcc's with boolean values can always be turned into bitwise operations
|
|
|
|
if (Ty == Type::BoolTy) {
|
|
|
|
// If this is <, >, or !=, we can change this into a simple xor instruction
|
|
|
|
if (!isTrueWhenEqual(I))
|
|
|
|
return BinaryOperator::create(Instruction::Xor, Op0, Op1, I.getName());
|
|
|
|
|
|
|
|
// Otherwise we need to make a temporary intermediate instruction and insert
|
|
|
|
// it into the instruction stream. This is what we are after:
|
|
|
|
//
|
|
|
|
// seteq bool %A, %B -> ~(A^B)
|
|
|
|
// setle bool %A, %B -> ~A | B
|
|
|
|
// setge bool %A, %B -> A | ~B
|
|
|
|
//
|
|
|
|
if (I.getOpcode() == Instruction::SetEQ) { // seteq case
|
|
|
|
Instruction *Xor = BinaryOperator::create(Instruction::Xor, Op0, Op1,
|
|
|
|
I.getName()+"tmp");
|
|
|
|
InsertNewInstBefore(Xor, I);
|
2002-08-14 17:51:49 +00:00
|
|
|
return BinaryOperator::createNot(Xor, I.getName());
|
2002-08-09 23:47:40 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
// Handle the setXe cases...
|
|
|
|
assert(I.getOpcode() == Instruction::SetGE ||
|
|
|
|
I.getOpcode() == Instruction::SetLE);
|
|
|
|
|
|
|
|
if (I.getOpcode() == Instruction::SetGE)
|
|
|
|
std::swap(Op0, Op1); // Change setge -> setle
|
|
|
|
|
|
|
|
// Now we just have the SetLE case.
|
2002-08-14 17:51:49 +00:00
|
|
|
Instruction *Not = BinaryOperator::createNot(Op0, I.getName()+"tmp");
|
2002-08-09 23:47:40 +00:00
|
|
|
InsertNewInstBefore(Not, I);
|
|
|
|
return BinaryOperator::create(Instruction::Or, Not, Op1, I.getName());
|
|
|
|
}
|
|
|
|
|
|
|
|
// Check to see if we are doing one of many comparisons against constant
|
|
|
|
// integers at the end of their ranges...
|
|
|
|
//
|
|
|
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
|
|
|
|
// Check to see if we are comparing against the minimum or maximum value...
|
2002-08-12 21:17:25 +00:00
|
|
|
if (CI->isMinValue()) {
|
2002-08-09 23:47:40 +00:00
|
|
|
if (I.getOpcode() == Instruction::SetLT) // A < MIN -> FALSE
|
|
|
|
return ReplaceInstUsesWith(I, ConstantBool::False);
|
|
|
|
if (I.getOpcode() == Instruction::SetGE) // A >= MIN -> TRUE
|
|
|
|
return ReplaceInstUsesWith(I, ConstantBool::True);
|
|
|
|
if (I.getOpcode() == Instruction::SetLE) // A <= MIN -> A == MIN
|
|
|
|
return BinaryOperator::create(Instruction::SetEQ, Op0,Op1, I.getName());
|
|
|
|
if (I.getOpcode() == Instruction::SetGT) // A > MIN -> A != MIN
|
|
|
|
return BinaryOperator::create(Instruction::SetNE, Op0,Op1, I.getName());
|
|
|
|
|
2002-08-12 21:17:25 +00:00
|
|
|
} else if (CI->isMaxValue()) {
|
2002-08-09 23:47:40 +00:00
|
|
|
if (I.getOpcode() == Instruction::SetGT) // A > MAX -> FALSE
|
|
|
|
return ReplaceInstUsesWith(I, ConstantBool::False);
|
|
|
|
if (I.getOpcode() == Instruction::SetLE) // A <= MAX -> TRUE
|
|
|
|
return ReplaceInstUsesWith(I, ConstantBool::True);
|
|
|
|
if (I.getOpcode() == Instruction::SetGE) // A >= MAX -> A == MAX
|
|
|
|
return BinaryOperator::create(Instruction::SetEQ, Op0,Op1, I.getName());
|
|
|
|
if (I.getOpcode() == Instruction::SetLT) // A < MAX -> A != MAX
|
|
|
|
return BinaryOperator::create(Instruction::SetNE, Op0,Op1, I.getName());
|
|
|
|
|
|
|
|
// Comparing against a value really close to min or max?
|
|
|
|
} else if (isMinValuePlusOne(CI)) {
|
|
|
|
if (I.getOpcode() == Instruction::SetLT) // A < MIN+1 -> A == MIN
|
|
|
|
return BinaryOperator::create(Instruction::SetEQ, Op0,
|
|
|
|
SubOne(CI), I.getName());
|
|
|
|
if (I.getOpcode() == Instruction::SetGE) // A >= MIN-1 -> A != MIN
|
|
|
|
return BinaryOperator::create(Instruction::SetNE, Op0,
|
|
|
|
SubOne(CI), I.getName());
|
|
|
|
|
|
|
|
} else if (isMaxValueMinusOne(CI)) {
|
|
|
|
if (I.getOpcode() == Instruction::SetGT) // A > MAX-1 -> A == MAX
|
|
|
|
return BinaryOperator::create(Instruction::SetEQ, Op0,
|
|
|
|
AddOne(CI), I.getName());
|
|
|
|
if (I.getOpcode() == Instruction::SetLE) // A <= MAX-1 -> A != MAX
|
|
|
|
return BinaryOperator::create(Instruction::SetNE, Op0,
|
|
|
|
AddOne(CI), I.getName());
|
|
|
|
}
|
2002-05-06 16:14:14 +00:00
|
|
|
}
|
|
|
|
|
2002-06-25 16:13:24 +00:00
|
|
|
return Changed ? &I : 0;
|
2002-05-06 16:14:14 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
2003-03-10 19:16:08 +00:00
|
|
|
Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
|
2002-06-25 16:13:24 +00:00
|
|
|
assert(I.getOperand(1)->getType() == Type::UByteTy);
|
|
|
|
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
|
2002-05-06 16:14:14 +00:00
|
|
|
|
|
|
|
// shl X, 0 == X and shr X, 0 == X
|
|
|
|
// shl 0, X == 0 and shr 0, X == 0
|
|
|
|
if (Op1 == Constant::getNullValue(Type::UByteTy) ||
|
2002-08-12 21:17:25 +00:00
|
|
|
Op0 == Constant::getNullValue(Op0->getType()))
|
|
|
|
return ReplaceInstUsesWith(I, Op0);
|
2002-05-06 16:14:14 +00:00
|
|
|
|
2003-03-10 19:16:08 +00:00
|
|
|
// If this is a shift of a shift, see if we can fold the two together...
|
|
|
|
if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0)) {
|
|
|
|
if (isa<Constant>(Op1) && isa<Constant>(Op0SI->getOperand(1))) {
|
|
|
|
ConstantUInt *ShiftAmt1C = cast<ConstantUInt>(Op0SI->getOperand(1));
|
|
|
|
unsigned ShiftAmt1 = ShiftAmt1C->getValue();
|
|
|
|
unsigned ShiftAmt2 = cast<ConstantUInt>(Op1)->getValue();
|
|
|
|
|
|
|
|
// Check for (A << c1) << c2 and (A >> c1) >> c2
|
|
|
|
if (I.getOpcode() == Op0SI->getOpcode()) {
|
|
|
|
unsigned Amt = ShiftAmt1+ShiftAmt2; // Fold into one big shift...
|
|
|
|
return new ShiftInst(I.getOpcode(), Op0SI->getOperand(0),
|
|
|
|
ConstantUInt::get(Type::UByteTy, Amt));
|
|
|
|
}
|
|
|
|
|
|
|
|
if (I.getType()->isUnsigned()) { // Check for (A << c1) >> c2 or visaversa
|
|
|
|
// Calculate bitmask for what gets shifted off the edge...
|
|
|
|
Constant *C = ConstantIntegral::getAllOnesValue(I.getType());
|
|
|
|
if (I.getOpcode() == Instruction::Shr)
|
|
|
|
C = *C >> *ShiftAmt1C;
|
|
|
|
else
|
|
|
|
C = *C << *ShiftAmt1C;
|
|
|
|
assert(C && "Couldn't constant fold shift expression?");
|
|
|
|
|
|
|
|
Instruction *Mask =
|
|
|
|
BinaryOperator::create(Instruction::And, Op0SI->getOperand(0),
|
|
|
|
C, Op0SI->getOperand(0)->getName()+".mask",&I);
|
|
|
|
WorkList.push_back(Mask);
|
|
|
|
|
|
|
|
// Figure out what flavor of shift we should use...
|
|
|
|
if (ShiftAmt1 == ShiftAmt2)
|
|
|
|
return ReplaceInstUsesWith(I, Mask); // (A << c) >> c === A & c2
|
|
|
|
else if (ShiftAmt1 < ShiftAmt2) {
|
|
|
|
return new ShiftInst(I.getOpcode(), Mask,
|
|
|
|
ConstantUInt::get(Type::UByteTy, ShiftAmt2-ShiftAmt1));
|
|
|
|
} else {
|
|
|
|
return new ShiftInst(Op0SI->getOpcode(), Mask,
|
|
|
|
ConstantUInt::get(Type::UByteTy, ShiftAmt1-ShiftAmt2));
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2002-08-12 21:17:25 +00:00
|
|
|
// shl uint X, 32 = 0 and shr ubyte Y, 9 = 0, ... just don't eliminate shr of
|
2002-05-06 16:14:14 +00:00
|
|
|
// a signed value.
|
|
|
|
//
|
|
|
|
if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) {
|
2003-03-10 19:16:08 +00:00
|
|
|
unsigned TypeBits = Op0->getType()->getPrimitiveSize()*8;
|
|
|
|
if (CUI->getValue() >= TypeBits &&
|
|
|
|
(!Op0->getType()->isSigned() || I.getOpcode() == Instruction::Shl))
|
|
|
|
return ReplaceInstUsesWith(I, Constant::getNullValue(Op0->getType()));
|
2002-09-10 23:04:09 +00:00
|
|
|
|
|
|
|
// Check to see if we are shifting left by 1. If so, turn it into an add
|
|
|
|
// instruction.
|
|
|
|
if (I.getOpcode() == Instruction::Shl && CUI->equalsInt(1))
|
2003-02-18 19:28:33 +00:00
|
|
|
// Convert 'shl int %X, 1' to 'add int %X, %X'
|
2002-09-10 23:04:09 +00:00
|
|
|
return BinaryOperator::create(Instruction::Add, Op0, Op0, I.getName());
|
|
|
|
|
2002-05-06 16:14:14 +00:00
|
|
|
}
|
2002-10-08 16:16:40 +00:00
|
|
|
|
|
|
|
// shr int -1, X = -1 (for any arithmetic shift rights of ~0)
|
|
|
|
if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(Op0))
|
|
|
|
if (I.getOpcode() == Instruction::Shr && CSI->isAllOnesValue())
|
|
|
|
return ReplaceInstUsesWith(I, CSI);
|
|
|
|
|
2002-05-06 16:14:14 +00:00
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
|
2002-05-02 17:06:02 +00:00
|
|
|
// isEliminableCastOfCast - Return true if it is valid to eliminate the CI
|
|
|
|
// instruction.
|
|
|
|
//
|
2002-06-25 16:13:24 +00:00
|
|
|
static inline bool isEliminableCastOfCast(const CastInst &CI,
|
2002-05-02 17:06:02 +00:00
|
|
|
const CastInst *CSrc) {
|
2002-06-25 16:13:24 +00:00
|
|
|
assert(CI.getOperand(0) == CSrc);
|
2002-05-02 17:06:02 +00:00
|
|
|
const Type *SrcTy = CSrc->getOperand(0)->getType();
|
|
|
|
const Type *MidTy = CSrc->getType();
|
2002-06-25 16:13:24 +00:00
|
|
|
const Type *DstTy = CI.getType();
|
2002-05-02 17:06:02 +00:00
|
|
|
|
2002-08-02 20:00:25 +00:00
|
|
|
// It is legal to eliminate the instruction if casting A->B->A if the sizes
|
|
|
|
// are identical and the bits don't get reinterpreted (for example
|
2002-08-14 23:21:10 +00:00
|
|
|
// int->float->int would not be allowed)
|
2002-08-02 20:00:25 +00:00
|
|
|
if (SrcTy == DstTy && SrcTy->isLosslesslyConvertableTo(MidTy))
|
|
|
|
return true;
|
2002-05-02 17:06:02 +00:00
|
|
|
|
|
|
|
// Allow free casting and conversion of sizes as long as the sign doesn't
|
|
|
|
// change...
|
2002-09-03 01:08:28 +00:00
|
|
|
if (SrcTy->isIntegral() && MidTy->isIntegral() && DstTy->isIntegral()) {
|
2002-08-02 20:00:25 +00:00
|
|
|
unsigned SrcSize = SrcTy->getPrimitiveSize();
|
|
|
|
unsigned MidSize = MidTy->getPrimitiveSize();
|
|
|
|
unsigned DstSize = DstTy->getPrimitiveSize();
|
|
|
|
|
2002-08-15 16:15:25 +00:00
|
|
|
// Cases where we are monotonically decreasing the size of the type are
|
|
|
|
// always ok, regardless of what sign changes are going on.
|
|
|
|
//
|
2002-08-14 23:21:10 +00:00
|
|
|
if (SrcSize >= MidSize && MidSize >= DstSize)
|
2002-08-02 20:00:25 +00:00
|
|
|
return true;
|
2002-08-15 16:15:25 +00:00
|
|
|
|
2002-09-23 23:39:43 +00:00
|
|
|
// Cases where the source and destination type are the same, but the middle
|
|
|
|
// type is bigger are noops.
|
|
|
|
//
|
|
|
|
if (SrcSize == DstSize && MidSize > SrcSize)
|
|
|
|
return true;
|
|
|
|
|
2002-08-15 16:15:25 +00:00
|
|
|
// If we are monotonically growing, things are more complex.
|
|
|
|
//
|
|
|
|
if (SrcSize <= MidSize && MidSize <= DstSize) {
|
|
|
|
// We have eight combinations of signedness to worry about. Here's the
|
|
|
|
// table:
|
|
|
|
static const int SignTable[8] = {
|
|
|
|
// CODE, SrcSigned, MidSigned, DstSigned, Comment
|
|
|
|
1, // U U U Always ok
|
|
|
|
1, // U U S Always ok
|
|
|
|
3, // U S U Ok iff SrcSize != MidSize
|
|
|
|
3, // U S S Ok iff SrcSize != MidSize
|
|
|
|
0, // S U U Never ok
|
|
|
|
2, // S U S Ok iff MidSize == DstSize
|
|
|
|
1, // S S U Always ok
|
|
|
|
1, // S S S Always ok
|
|
|
|
};
|
|
|
|
|
|
|
|
// Choose an action based on the current entry of the signtable that this
|
|
|
|
// cast of cast refers to...
|
|
|
|
unsigned Row = SrcTy->isSigned()*4+MidTy->isSigned()*2+DstTy->isSigned();
|
|
|
|
switch (SignTable[Row]) {
|
|
|
|
case 0: return false; // Never ok
|
|
|
|
case 1: return true; // Always ok
|
|
|
|
case 2: return MidSize == DstSize; // Ok iff MidSize == DstSize
|
|
|
|
case 3: // Ok iff SrcSize != MidSize
|
|
|
|
return SrcSize != MidSize || SrcTy == Type::BoolTy;
|
|
|
|
default: assert(0 && "Bad entry in sign table!");
|
|
|
|
}
|
|
|
|
}
|
2002-08-02 20:00:25 +00:00
|
|
|
}
|
2002-05-02 17:06:02 +00:00
|
|
|
|
|
|
|
// Otherwise, we cannot succeed. Specifically we do not want to allow things
|
|
|
|
// like: short -> ushort -> uint, because this can create wrong results if
|
|
|
|
// the input short is negative!
|
|
|
|
//
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
// CastInst simplification
|
2002-04-18 17:39:14 +00:00
|
|
|
//
|
2002-06-25 16:13:24 +00:00
|
|
|
Instruction *InstCombiner::visitCastInst(CastInst &CI) {
|
2002-05-02 17:06:02 +00:00
|
|
|
// If the user is casting a value to the same type, eliminate this cast
|
|
|
|
// instruction...
|
2002-08-12 21:17:25 +00:00
|
|
|
if (CI.getType() == CI.getOperand(0)->getType())
|
|
|
|
return ReplaceInstUsesWith(CI, CI.getOperand(0));
|
2002-05-02 17:06:02 +00:00
|
|
|
|
|
|
|
// If casting the result of another cast instruction, try to eliminate this
|
|
|
|
// one!
|
|
|
|
//
|
2002-08-02 20:00:25 +00:00
|
|
|
if (CastInst *CSrc = dyn_cast<CastInst>(CI.getOperand(0))) {
|
2002-05-02 17:06:02 +00:00
|
|
|
if (isEliminableCastOfCast(CI, CSrc)) {
|
|
|
|
// This instruction now refers directly to the cast's src operand. This
|
|
|
|
// has a good chance of making CSrc dead.
|
2002-06-25 16:13:24 +00:00
|
|
|
CI.setOperand(0, CSrc->getOperand(0));
|
|
|
|
return &CI;
|
2002-05-02 17:06:02 +00:00
|
|
|
}
|
|
|
|
|
2002-08-02 20:00:25 +00:00
|
|
|
// If this is an A->B->A cast, and we are dealing with integral types, try
|
|
|
|
// to convert this into a logical 'and' instruction.
|
|
|
|
//
|
|
|
|
if (CSrc->getOperand(0)->getType() == CI.getType() &&
|
2002-09-03 01:08:28 +00:00
|
|
|
CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
|
2002-08-02 20:00:25 +00:00
|
|
|
CI.getType()->isUnsigned() && CSrc->getType()->isUnsigned() &&
|
|
|
|
CSrc->getType()->getPrimitiveSize() < CI.getType()->getPrimitiveSize()){
|
|
|
|
assert(CSrc->getType() != Type::ULongTy &&
|
|
|
|
"Cannot have type bigger than ulong!");
|
|
|
|
unsigned AndValue = (1U << CSrc->getType()->getPrimitiveSize()*8)-1;
|
|
|
|
Constant *AndOp = ConstantUInt::get(CI.getType(), AndValue);
|
|
|
|
return BinaryOperator::create(Instruction::And, CSrc->getOperand(0),
|
|
|
|
AndOp);
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2002-04-18 17:39:14 +00:00
|
|
|
return 0;
|
2001-12-14 16:52:21 +00:00
|
|
|
}
|
|
|
|
|
2002-05-02 17:06:02 +00:00
|
|
|
|
2002-05-06 18:06:38 +00:00
|
|
|
// PHINode simplification
|
|
|
|
//
|
2002-06-25 16:13:24 +00:00
|
|
|
Instruction *InstCombiner::visitPHINode(PHINode &PN) {
|
2002-05-06 18:06:38 +00:00
|
|
|
// If the PHI node only has one incoming value, eliminate the PHI node...
|
2002-08-12 21:17:25 +00:00
|
|
|
if (PN.getNumIncomingValues() == 1)
|
|
|
|
return ReplaceInstUsesWith(PN, PN.getIncomingValue(0));
|
2002-08-20 15:35:35 +00:00
|
|
|
|
|
|
|
// Otherwise if all of the incoming values are the same for the PHI, replace
|
|
|
|
// the PHI node with the incoming value.
|
|
|
|
//
|
2002-08-22 20:22:01 +00:00
|
|
|
Value *InVal = 0;
|
|
|
|
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
|
|
|
|
if (PN.getIncomingValue(i) != &PN) // Not the PHI node itself...
|
|
|
|
if (InVal && PN.getIncomingValue(i) != InVal)
|
|
|
|
return 0; // Not the same, bail out.
|
|
|
|
else
|
|
|
|
InVal = PN.getIncomingValue(i);
|
|
|
|
|
|
|
|
// The only case that could cause InVal to be null is if we have a PHI node
|
|
|
|
// that only has entries for itself. In this case, there is no entry into the
|
|
|
|
// loop, so kill the PHI.
|
|
|
|
//
|
|
|
|
if (InVal == 0) InVal = Constant::getNullValue(PN.getType());
|
2002-05-06 18:06:38 +00:00
|
|
|
|
2002-08-20 15:35:35 +00:00
|
|
|
// All of the incoming values are the same, replace the PHI node now.
|
|
|
|
return ReplaceInstUsesWith(PN, InVal);
|
2002-05-06 18:06:38 +00:00
|
|
|
}
|
|
|
|
|
2002-05-02 17:06:02 +00:00
|
|
|
|
2002-06-25 16:13:24 +00:00
|
|
|
Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
|
2002-08-02 19:29:35 +00:00
|
|
|
// Is it 'getelementptr %P, uint 0' or 'getelementptr %P'
|
2002-06-25 16:13:24 +00:00
|
|
|
// If so, eliminate the noop.
|
2002-08-02 19:29:35 +00:00
|
|
|
if ((GEP.getNumOperands() == 2 &&
|
2002-09-11 01:21:33 +00:00
|
|
|
GEP.getOperand(1) == Constant::getNullValue(Type::LongTy)) ||
|
2002-08-12 21:17:25 +00:00
|
|
|
GEP.getNumOperands() == 1)
|
|
|
|
return ReplaceInstUsesWith(GEP, GEP.getOperand(0));
|
2002-05-02 17:06:02 +00:00
|
|
|
|
2002-08-02 19:29:35 +00:00
|
|
|
// Combine Indices - If the source pointer to this getelementptr instruction
|
|
|
|
// is a getelementptr instruction, combine the indices of the two
|
|
|
|
// getelementptr instructions into a single instruction.
|
|
|
|
//
|
2002-08-17 22:21:59 +00:00
|
|
|
if (GetElementPtrInst *Src = dyn_cast<GetElementPtrInst>(GEP.getOperand(0))) {
|
2002-08-02 19:29:35 +00:00
|
|
|
std::vector<Value *> Indices;
|
2001-12-14 16:52:21 +00:00
|
|
|
|
2002-08-02 19:29:35 +00:00
|
|
|
// Can we combine the two pointer arithmetics offsets?
|
2003-03-05 22:33:14 +00:00
|
|
|
if (Src->getNumOperands() == 2 && isa<Constant>(Src->getOperand(1)) &&
|
|
|
|
isa<Constant>(GEP.getOperand(1))) {
|
|
|
|
// Replace: gep (gep %P, long C1), long C2, ...
|
|
|
|
// With: gep %P, long (C1+C2), ...
|
|
|
|
Value *Sum = *cast<Constant>(Src->getOperand(1)) +
|
2002-08-02 19:29:35 +00:00
|
|
|
*cast<Constant>(GEP.getOperand(1));
|
2003-03-05 22:33:14 +00:00
|
|
|
assert(Sum && "Constant folding of longs failed!?");
|
|
|
|
GEP.setOperand(0, Src->getOperand(0));
|
|
|
|
GEP.setOperand(1, Sum);
|
|
|
|
AddUsesToWorkList(*Src); // Reduce use count of Src
|
|
|
|
return &GEP;
|
|
|
|
} else if (Src->getNumOperands() == 2 && Src->use_size() == 1) {
|
|
|
|
// Replace: gep (gep %P, long B), long A, ...
|
|
|
|
// With: T = long A+B; gep %P, T, ...
|
|
|
|
//
|
|
|
|
Value *Sum = BinaryOperator::create(Instruction::Add, Src->getOperand(1),
|
|
|
|
GEP.getOperand(1),
|
|
|
|
Src->getName()+".sum", &GEP);
|
|
|
|
GEP.setOperand(0, Src->getOperand(0));
|
|
|
|
GEP.setOperand(1, Sum);
|
|
|
|
WorkList.push_back(cast<Instruction>(Sum));
|
|
|
|
return &GEP;
|
2002-11-04 16:43:32 +00:00
|
|
|
} else if (*GEP.idx_begin() == Constant::getNullValue(Type::LongTy) &&
|
2002-09-17 21:05:42 +00:00
|
|
|
Src->getNumOperands() != 1) {
|
2002-08-02 19:29:35 +00:00
|
|
|
// Otherwise we can do the fold if the first index of the GEP is a zero
|
|
|
|
Indices.insert(Indices.end(), Src->idx_begin(), Src->idx_end());
|
|
|
|
Indices.insert(Indices.end(), GEP.idx_begin()+1, GEP.idx_end());
|
2002-11-04 16:43:32 +00:00
|
|
|
} else if (Src->getOperand(Src->getNumOperands()-1) ==
|
|
|
|
Constant::getNullValue(Type::LongTy)) {
|
|
|
|
// If the src gep ends with a constant array index, merge this get into
|
|
|
|
// it, even if we have a non-zero array index.
|
|
|
|
Indices.insert(Indices.end(), Src->idx_begin(), Src->idx_end()-1);
|
|
|
|
Indices.insert(Indices.end(), GEP.idx_begin(), GEP.idx_end());
|
2002-08-02 19:29:35 +00:00
|
|
|
}
|
2001-12-14 16:52:21 +00:00
|
|
|
|
2002-08-02 19:29:35 +00:00
|
|
|
if (!Indices.empty())
|
|
|
|
return new GetElementPtrInst(Src->getOperand(0), Indices, GEP.getName());
|
2002-08-17 22:21:59 +00:00
|
|
|
|
|
|
|
} else if (GlobalValue *GV = dyn_cast<GlobalValue>(GEP.getOperand(0))) {
|
|
|
|
// GEP of global variable. If all of the indices for this GEP are
|
|
|
|
// constants, we can promote this to a constexpr instead of an instruction.
|
|
|
|
|
|
|
|
// Scan for nonconstants...
|
|
|
|
std::vector<Constant*> Indices;
|
|
|
|
User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end();
|
|
|
|
for (; I != E && isa<Constant>(*I); ++I)
|
|
|
|
Indices.push_back(cast<Constant>(*I));
|
|
|
|
|
|
|
|
if (I == E) { // If they are all constants...
|
|
|
|
ConstantExpr *CE =
|
|
|
|
ConstantExpr::getGetElementPtr(ConstantPointerRef::get(GV), Indices);
|
|
|
|
|
|
|
|
// Replace all uses of the GEP with the new constexpr...
|
|
|
|
return ReplaceInstUsesWith(GEP, CE);
|
|
|
|
}
|
2001-12-14 16:52:21 +00:00
|
|
|
}
|
2002-08-02 19:29:35 +00:00
|
|
|
|
2001-12-14 16:52:21 +00:00
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
2002-11-04 16:18:53 +00:00
|
|
|
Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) {
|
|
|
|
// Convert: malloc Ty, C - where C is a constant != 1 into: malloc [C x Ty], 1
|
|
|
|
if (AI.isArrayAllocation()) // Check C != 1
|
|
|
|
if (const ConstantUInt *C = dyn_cast<ConstantUInt>(AI.getArraySize())) {
|
|
|
|
const Type *NewTy = ArrayType::get(AI.getAllocatedType(), C->getValue());
|
2002-11-09 00:49:43 +00:00
|
|
|
AllocationInst *New = 0;
|
2002-11-04 16:18:53 +00:00
|
|
|
|
|
|
|
// Create and insert the replacement instruction...
|
|
|
|
if (isa<MallocInst>(AI))
|
|
|
|
New = new MallocInst(NewTy, 0, AI.getName(), &AI);
|
2002-11-09 00:49:43 +00:00
|
|
|
else {
|
|
|
|
assert(isa<AllocaInst>(AI) && "Unknown type of allocation inst!");
|
2002-11-04 16:18:53 +00:00
|
|
|
New = new AllocaInst(NewTy, 0, AI.getName(), &AI);
|
2002-11-09 00:49:43 +00:00
|
|
|
}
|
2002-11-04 16:18:53 +00:00
|
|
|
|
|
|
|
// Scan to the end of the allocation instructions, to skip over a block of
|
|
|
|
// allocas if possible...
|
|
|
|
//
|
|
|
|
BasicBlock::iterator It = New;
|
|
|
|
while (isa<AllocationInst>(*It)) ++It;
|
|
|
|
|
|
|
|
// Now that I is pointing to the first non-allocation-inst in the block,
|
|
|
|
// insert our getelementptr instruction...
|
|
|
|
//
|
|
|
|
std::vector<Value*> Idx(2, Constant::getNullValue(Type::LongTy));
|
|
|
|
Value *V = new GetElementPtrInst(New, Idx, New->getName()+".sub", It);
|
|
|
|
|
|
|
|
// Now make everything use the getelementptr instead of the original
|
|
|
|
// allocation.
|
|
|
|
ReplaceInstUsesWith(AI, V);
|
|
|
|
return &AI;
|
|
|
|
}
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
|
2001-12-14 16:52:21 +00:00
|
|
|
|
2002-09-02 04:59:56 +00:00
|
|
|
void InstCombiner::removeFromWorkList(Instruction *I) {
|
|
|
|
WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), I),
|
|
|
|
WorkList.end());
|
|
|
|
}
|
|
|
|
|
2002-06-25 16:13:24 +00:00
|
|
|
bool InstCombiner::runOnFunction(Function &F) {
|
2002-04-18 17:39:14 +00:00
|
|
|
bool Changed = false;
|
2001-12-14 16:52:21 +00:00
|
|
|
|
2002-04-18 17:39:14 +00:00
|
|
|
WorkList.insert(WorkList.end(), inst_begin(F), inst_end(F));
|
2001-12-14 16:52:21 +00:00
|
|
|
|
|
|
|
while (!WorkList.empty()) {
|
|
|
|
Instruction *I = WorkList.back(); // Get an instruction from the worklist
|
|
|
|
WorkList.pop_back();
|
|
|
|
|
2002-10-29 23:06:16 +00:00
|
|
|
// Check to see if we can DCE or ConstantPropagate the instruction...
|
2002-09-02 04:59:56 +00:00
|
|
|
// Check to see if we can DIE the instruction...
|
|
|
|
if (isInstructionTriviallyDead(I)) {
|
|
|
|
// Add operands to the worklist...
|
|
|
|
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
|
|
|
|
if (Instruction *Op = dyn_cast<Instruction>(I->getOperand(i)))
|
|
|
|
WorkList.push_back(Op);
|
|
|
|
|
|
|
|
++NumDeadInst;
|
|
|
|
BasicBlock::iterator BBI = I;
|
|
|
|
if (dceInstruction(BBI)) {
|
|
|
|
removeFromWorkList(I);
|
|
|
|
continue;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2002-10-29 23:06:16 +00:00
|
|
|
// Instruction isn't dead, see if we can constant propagate it...
|
2002-09-02 04:59:56 +00:00
|
|
|
if (Constant *C = ConstantFoldInstruction(I)) {
|
|
|
|
// Add operands to the worklist...
|
|
|
|
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
|
|
|
|
if (Instruction *Op = dyn_cast<Instruction>(I->getOperand(i)))
|
|
|
|
WorkList.push_back(Op);
|
2002-12-05 22:41:53 +00:00
|
|
|
ReplaceInstUsesWith(*I, C);
|
|
|
|
|
2002-09-02 04:59:56 +00:00
|
|
|
++NumConstProp;
|
|
|
|
BasicBlock::iterator BBI = I;
|
|
|
|
if (dceInstruction(BBI)) {
|
|
|
|
removeFromWorkList(I);
|
|
|
|
continue;
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2001-12-14 16:52:21 +00:00
|
|
|
// Now that we have an instruction, try combining it to simplify it...
|
2002-08-02 19:29:35 +00:00
|
|
|
if (Instruction *Result = visit(*I)) {
|
2002-05-10 15:38:35 +00:00
|
|
|
++NumCombined;
|
2002-04-18 17:39:14 +00:00
|
|
|
// Should we replace the old instruction with a new one?
|
2002-05-14 15:24:07 +00:00
|
|
|
if (Result != I) {
|
|
|
|
// Instructions can end up on the worklist more than once. Make sure
|
|
|
|
// we do not process an instruction that has been deleted.
|
2002-09-02 04:59:56 +00:00
|
|
|
removeFromWorkList(I);
|
2002-04-18 17:39:14 +00:00
|
|
|
ReplaceInstWithInst(I, Result);
|
2002-06-25 16:13:24 +00:00
|
|
|
} else {
|
2002-08-02 19:29:35 +00:00
|
|
|
BasicBlock::iterator II = I;
|
|
|
|
|
|
|
|
// If the instruction was modified, it's possible that it is now dead.
|
|
|
|
// if so, remove it.
|
|
|
|
if (dceInstruction(II)) {
|
|
|
|
// Instructions may end up in the worklist more than once. Erase them
|
|
|
|
// all.
|
2002-09-02 04:59:56 +00:00
|
|
|
removeFromWorkList(I);
|
2002-08-02 19:29:35 +00:00
|
|
|
Result = 0;
|
|
|
|
}
|
2002-05-14 15:24:07 +00:00
|
|
|
}
|
2002-04-18 17:39:14 +00:00
|
|
|
|
2002-08-02 19:29:35 +00:00
|
|
|
if (Result) {
|
|
|
|
WorkList.push_back(Result);
|
|
|
|
AddUsesToWorkList(*Result);
|
|
|
|
}
|
2002-04-18 17:39:14 +00:00
|
|
|
Changed = true;
|
2001-12-14 16:52:21 +00:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2002-04-18 17:39:14 +00:00
|
|
|
return Changed;
|
2002-02-26 21:46:54 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
Pass *createInstructionCombiningPass() {
|
2002-04-18 17:39:14 +00:00
|
|
|
return new InstCombiner();
|
2002-02-26 21:46:54 +00:00
|
|
|
}
|