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Rename Instruction::isIdenticalTo to Instruction::isIdenticalToWhenDefined,

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and introduce a new Instruction::isIdenticalTo which tests for full
identity, including the SubclassOptionalData flags. Also, fix the
Instruction::clone implementations to preserve the SubclassOptionalData
flags. Finally, teach several optimizations how to handle
SubclassOptionalData correctly, given these changes.

This fixes the counterintuitive behavior of isIdenticalTo not comparing
the full value, and clone not returning an identical clone, as well as
some subtle bugs that could be caused by these.

Thanks to Nick Lewycky for reporting this, and for an initial patch!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80038 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman
2009-08-25 22:11:20 +00:00
parent 415c8cf837
commit 58cfa3b137
10 changed files with 176 additions and 157 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
lib/Transforms/IPO/MergeFunctions.cpp
View File

@@ -188,7 +188,8 @@ static bool
isEquivalentOperation(const Instruction *I1, const Instruction *I2) {
if (I1->getOpcode() != I2->getOpcode() ||
I1->getNumOperands() != I2->getNumOperands() ||
!isEquivalentType(I1->getType(), I2->getType()))
!isEquivalentType(I1->getType(), I2->getType()) ||
!I1->hasSameSubclassOptionalData(I2))
return false;
// We have two instructions of identical opcode and #operands. Check to see

6
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@@ -11815,12 +11815,16 @@ static bool equivalentAddressValues(Value *A, Value *B) {
if (A == B) return true;
// Test if the values come form identical arithmetic instructions.
// This uses isIdenticalToWhenDefined instead of isIdenticalTo because
// its only used to compare two uses within the same basic block, which
// means that they'll always either have the same value or one of them
// will have an undefined value.
if (isa<BinaryOperator>(A) ||
isa<CastInst>(A) ||
isa<PHINode>(A) ||
isa<GetElementPtrInst>(A))
if (Instruction *BI = dyn_cast<Instruction>(B))
if (cast<Instruction>(A)->isIdenticalTo(BI))
if (cast<Instruction>(A)->isIdenticalToWhenDefined(BI))
return true;
// Otherwise they may not be equivalent.

8
lib/Transforms/Utils/BasicBlockUtils.cpp
View File

@@ -504,11 +504,15 @@ static bool AreEquivalentAddressValues(const Value *A, const Value *B) {
// Test if the values are trivially equivalent.
if (A == B) return true;
// Test if the values come form identical arithmetic instructions.
// Test if the values come from identical arithmetic instructions.
// Use isIdenticalToWhenDefined instead of isIdenticalTo because
// this function is only used when one address use dominates the
// other, which means that they'll always either have the same
// value or one of them will have an undefined value.
if (isa<BinaryOperator>(A) || isa<CastInst>(A) ||
isa<PHINode>(A) || isa<GetElementPtrInst>(A))
if (const Instruction *BI = dyn_cast<Instruction>(B))
if (cast<Instruction>(A)->isIdenticalTo(BI))
if (cast<Instruction>(A)->isIdenticalToWhenDefined(BI))
return true;
// Otherwise they may not be equivalent.

6
lib/Transforms/Utils/SimplifyCFG.cpp
View File

@@ -872,7 +872,7 @@ static bool HoistThenElseCodeToIf(BranchInst *BI) {
while (isa<DbgInfoIntrinsic>(I2))
I2 = BB2_Itr++;
if (I1->getOpcode() != I2->getOpcode() || isa<PHINode>(I1) ||
!I1->isIdenticalTo(I2) ||
!I1->isIdenticalToWhenDefined(I2) ||
(isa<InvokeInst>(I1) && !isSafeToHoistInvoke(BB1, BB2, I1, I2)))
return false;
@@ -891,6 +891,7 @@ static bool HoistThenElseCodeToIf(BranchInst *BI) {
BIParent->getInstList().splice(BI, BB1->getInstList(), I1);
if (!I2->use_empty())
I2->replaceAllUsesWith(I1);
I1->intersectOptionalDataWith(I2);
BB2->getInstList().erase(I2);
I1 = BB1_Itr++;
@@ -899,7 +900,8 @@ static bool HoistThenElseCodeToIf(BranchInst *BI) {
I2 = BB2_Itr++;
while (isa<DbgInfoIntrinsic>(I2))
I2 = BB2_Itr++;
} while (I1->getOpcode() == I2->getOpcode() && I1->isIdenticalTo(I2));
} while (I1->getOpcode() == I2->getOpcode() &&
I1->isIdenticalToWhenDefined(I2));
return true;