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[NFC] Refactor SimplifyCFG to make propagating information easier.

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Reviewers: jdoerfert

Reviewed By: jdoerfert

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77742
This commit is contained in:
Tyker 2020-04-24 21:38:12 +02:00
parent 79feafa514
commit 97ecd91e20
1 changed files with 33 additions and 15 deletions
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48
llvm/lib/Transforms/Utils/SimplifyCFG.cpp
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@ -202,10 +202,23 @@ class SimplifyCFGOpt {
bool simplifyBranch(BranchInst *Branch, IRBuilder<> &Builder);
bool simplifyUncondBranch(BranchInst *BI, IRBuilder<> &Builder);
bool simplifyCondBranch(BranchInst *BI, IRBuilder<> &Builder);
bool SimplifyCondBranchToTwoReturns(BranchInst *BI, IRBuilder<> &Builder);
bool tryToSimplifyUncondBranchWithICmpInIt(ICmpInst *ICI,
IRBuilder<> &Builder);
bool HoistThenElseCodeToIf(BranchInst *BI, const TargetTransformInfo &TTI);
bool SpeculativelyExecuteBB(BranchInst *BI, BasicBlock *ThenBB,
const TargetTransformInfo &TTI);
bool SimplifyTerminatorOnSelect(Instruction *OldTerm, Value *Cond,
BasicBlock *TrueBB, BasicBlock *FalseBB,
uint32_t TrueWeight, uint32_t FalseWeight);
bool SimplifyBranchOnICmpChain(BranchInst *BI, IRBuilder<> &Builder,
const DataLayout &DL);
bool SimplifySwitchOnSelect(SwitchInst *SI, SelectInst *Select);
bool SimplifyIndirectBrOnSelect(IndirectBrInst *IBI, SelectInst *SI);
bool TurnSwitchRangeIntoICmp(SwitchInst *SI, IRBuilder<> &Builder);
public:
SimplifyCFGOpt(const TargetTransformInfo &TTI, const DataLayout &DL,
SmallPtrSetImpl<BasicBlock *> *LoopHeaders,
@ -1235,8 +1248,8 @@ static bool passingValueIsAlwaysUndefined(Value *V, Instruction *I);
/// Given a conditional branch that goes to BB1 and BB2, hoist any common code
/// in the two blocks up into the branch block. The caller of this function
/// guarantees that BI's block dominates BB1 and BB2.
static bool HoistThenElseCodeToIf(BranchInst *BI,
const TargetTransformInfo &TTI) {
bool SimplifyCFGOpt::HoistThenElseCodeToIf(BranchInst *BI,
const TargetTransformInfo &TTI) {
// This does very trivial matching, with limited scanning, to find identical
// instructions in the two blocks. In particular, we don't want to get into
// O(M*N) situations here where M and N are the sizes of BB1 and BB2. As
@ -1969,8 +1982,8 @@ static Value *isSafeToSpeculateStore(Instruction *I, BasicBlock *BrBB,
/// \endcode
///
/// \returns true if the conditional block is removed.
static bool SpeculativelyExecuteBB(BranchInst *BI, BasicBlock *ThenBB,
const TargetTransformInfo &TTI) {
bool SimplifyCFGOpt::SpeculativelyExecuteBB(BranchInst *BI, BasicBlock *ThenBB,
const TargetTransformInfo &TTI) {
// Be conservative for now. FP select instruction can often be expensive.
Value *BrCond = BI->getCondition();
if (isa<FCmpInst>(BrCond))
@ -2462,8 +2475,8 @@ static bool FoldTwoEntryPHINode(PHINode *PN, const TargetTransformInfo &TTI,
/// If we found a conditional branch that goes to two returning blocks,
/// try to merge them together into one return,
/// introducing a select if the return values disagree.
static bool SimplifyCondBranchToTwoReturns(BranchInst *BI,
IRBuilder<> &Builder) {
bool SimplifyCFGOpt::SimplifyCondBranchToTwoReturns(BranchInst *BI,
IRBuilder<> &Builder) {
assert(BI->isConditional() && "Must be a conditional branch");
BasicBlock *TrueSucc = BI->getSuccessor(0);
BasicBlock *FalseSucc = BI->getSuccessor(1);
@ -3522,10 +3535,11 @@ static bool SimplifyCondBranchToCondBranch(BranchInst *PBI, BranchInst *BI,
// Takes care of updating the successors and removing the old terminator.
// Also makes sure not to introduce new successors by assuming that edges to
// non-successor TrueBBs and FalseBBs aren't reachable.
static bool SimplifyTerminatorOnSelect(Instruction *OldTerm, Value *Cond,
BasicBlock *TrueBB, BasicBlock *FalseBB,
uint32_t TrueWeight,
uint32_t FalseWeight) {
bool SimplifyCFGOpt::SimplifyTerminatorOnSelect(Instruction *OldTerm,
Value *Cond, BasicBlock *TrueBB,
BasicBlock *FalseBB,
uint32_t TrueWeight,
uint32_t FalseWeight) {
// Remove any superfluous successor edges from the CFG.
// First, figure out which successors to preserve.
// If TrueBB and FalseBB are equal, only try to preserve one copy of that
@ -3585,7 +3599,8 @@ static bool SimplifyTerminatorOnSelect(Instruction *OldTerm, Value *Cond,
// (switch (select cond, X, Y)) on constant X, Y
// with a branch - conditional if X and Y lead to distinct BBs,
// unconditional otherwise.
static bool SimplifySwitchOnSelect(SwitchInst *SI, SelectInst *Select) {
bool SimplifyCFGOpt::SimplifySwitchOnSelect(SwitchInst *SI,
SelectInst *Select) {
// Check for constant integer values in the select.
ConstantInt *TrueVal = dyn_cast<ConstantInt>(Select->getTrueValue());
ConstantInt *FalseVal = dyn_cast<ConstantInt>(Select->getFalseValue());
@ -3621,7 +3636,8 @@ static bool SimplifySwitchOnSelect(SwitchInst *SI, SelectInst *Select) {
// blockaddress(@fn, BlockB)))
// with
// (br cond, BlockA, BlockB).
static bool SimplifyIndirectBrOnSelect(IndirectBrInst *IBI, SelectInst *SI) {
bool SimplifyCFGOpt::SimplifyIndirectBrOnSelect(IndirectBrInst *IBI,
SelectInst *SI) {
// Check that both operands of the select are block addresses.
BlockAddress *TBA = dyn_cast<BlockAddress>(SI->getTrueValue());
BlockAddress *FBA = dyn_cast<BlockAddress>(SI->getFalseValue());
@ -3756,8 +3772,9 @@ bool SimplifyCFGOpt::tryToSimplifyUncondBranchWithICmpInIt(
/// The specified branch is a conditional branch.
/// Check to see if it is branching on an or/and chain of icmp instructions, and
/// fold it into a switch instruction if so.
static bool SimplifyBranchOnICmpChain(BranchInst *BI, IRBuilder<> &Builder,
const DataLayout &DL) {
bool SimplifyCFGOpt::SimplifyBranchOnICmpChain(BranchInst *BI,
IRBuilder<> &Builder,
const DataLayout &DL) {
Instruction *Cond = dyn_cast<Instruction>(BI->getCondition());
if (!Cond)
return false;
@ -4407,7 +4424,8 @@ static void createUnreachableSwitchDefault(SwitchInst *Switch) {
/// Turn a switch with two reachable destinations into an integer range
/// comparison and branch.
static bool TurnSwitchRangeIntoICmp(SwitchInst *SI, IRBuilder<> &Builder) {
bool SimplifyCFGOpt::TurnSwitchRangeIntoICmp(SwitchInst *SI,
IRBuilder<> &Builder) {
assert(SI->getNumCases() > 1 && "Degenerate switch?");
bool HasDefault =