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Revert r114097, adding back in the assertion against replacing an Instruction by itself. Now that CorrelatedValuePropagation is

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more careful not to call SimplifyInstructionsInBlock() on an unreachable block, the issue has been fixed at a higher level.  Add
a big warning to SimplifyInstructionsInBlock() to hopefully prevent this in the future.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114117 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson 2010-09-16 20:51:41 +00:00
parent 35aa94b229
commit 4e282decf3
3 changed files with 17 additions and 24 deletions
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2
include/llvm/Analysis/InstructionSimplify.h
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@ -71,6 +71,8 @@ namespace llvm {
/// SimplifyInstruction - See if we can compute a simplified version of this
/// instruction. If not, this returns null.
/// WARNING: If called on unreachable code, an instruction may be reported
/// to simplify to itself.
Value *SimplifyInstruction(Instruction *I, const TargetData *TD = 0);

4
include/llvm/Transforms/Utils/Local.h
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@ -69,6 +69,10 @@ bool RecursivelyDeleteDeadPHINode(PHINode *PN);
///
/// This returns true if it changed the code, note that it can delete
/// instructions in other blocks as well in this block.
///
/// WARNING: Do not use this function on unreachable blocks, as recursive
/// simplification is not able to handle corner-case scenarios that can
/// arise in them.
bool SimplifyInstructionsInBlock(BasicBlock *BB, const TargetData *TD = 0);
//===----------------------------------------------------------------------===//

35
lib/Analysis/InstructionSimplify.cpp
View File

@ -423,44 +423,31 @@ Value *llvm::SimplifyCmpInst(unsigned Predicate, Value *LHS, Value *RHS,
/// SimplifyInstruction - See if we can compute a simplified version of this
/// instruction. If not, this returns null.
Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD) {
Value *Ret = 0;
switch (I->getOpcode()) {
default:
return ConstantFoldInstruction(I, TD);
case Instruction::Add:
Ret = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
cast<BinaryOperator>(I)->hasNoSignedWrap(),
cast<BinaryOperator>(I)->hasNoUnsignedWrap(), TD);
break;
return SimplifyAddInst(I->getOperand(0), I->getOperand(1),
cast<BinaryOperator>(I)->hasNoSignedWrap(),
cast<BinaryOperator>(I)->hasNoUnsignedWrap(), TD);
case Instruction::And:
Ret = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD);
break;
return SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD);
case Instruction::Or:
Ret = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD);
break;
return SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD);
case Instruction::ICmp:
Ret = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
I->getOperand(0), I->getOperand(1), TD);
break;
return SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
I->getOperand(0), I->getOperand(1), TD);
case Instruction::FCmp:
Ret = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
I->getOperand(0), I->getOperand(1), TD);
break;
return SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
I->getOperand(0), I->getOperand(1), TD);
case Instruction::Select:
Ret = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
return SimplifySelectInst(I->getOperand(0), I->getOperand(1),
I->getOperand(2), TD);
break;
case Instruction::GetElementPtr: {
SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
Ret = SimplifyGEPInst(&Ops[0], Ops.size(), TD);
break;
return SimplifyGEPInst(&Ops[0], Ops.size(), TD);
}
}
// It is possible, in situations involving unreachable loops, to
// have a replacement that, through recursive simplification, ends up
// simplifying to itself.
return Ret != I ? Ret : 0;
}
/// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then