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Fix reassociate to postpone certain instruction deletions until

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after it has finished all of its reassociations, because its
habit of unlinking operands and holding them in a datastructure
while working means that it's not easy to determine when an
instruction is really dead until after all its regular work is
done. rdar://9096268.

llvm-svn: 127424
This commit is contained in:
Dan Gohman 2011-03-10 19:51:54 +00:00
parent 5891b1323a
commit bb9c77f5bd
2 changed files with 36 additions and 3 deletions
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14
lib/Transforms/Scalar/Reassociate.cpp
View File

@ -22,6 +22,7 @@
#define DEBUG_TYPE "reassociate"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
@ -74,6 +75,7 @@ namespace {
class Reassociate : public FunctionPass {
DenseMap<BasicBlock*, unsigned> RankMap;
DenseMap<AssertingVH<>, unsigned> ValueRankMap;
SmallVector<WeakVH, 8> DeadInsts;
bool MadeChange;
public:
static char ID; // Pass identification, replacement for typeid
@ -113,13 +115,13 @@ FunctionPass *llvm::createReassociatePass() { return new Reassociate(); }
void Reassociate::RemoveDeadBinaryOp(Value *V) {
Instruction *Op = dyn_cast<Instruction>(V);
if (!Op || !isa<BinaryOperator>(Op) || !Op->use_empty())
if (!Op || !isa<BinaryOperator>(Op))
return;
Value *LHS = Op->getOperand(0), *RHS = Op->getOperand(1);
ValueRankMap.erase(Op);
Op->eraseFromParent();
DeadInsts.push_back(Op);
RemoveDeadBinaryOp(LHS);
RemoveDeadBinaryOp(RHS);
}
@ -603,7 +605,7 @@ Value *Reassociate::RemoveFactorFromExpression(Value *V, Value *Factor) {
// remaining operand.
if (Factors.size() == 1) {
ValueRankMap.erase(BO);
BO->eraseFromParent();
DeadInsts.push_back(BO);
V = Factors[0].Op;
} else {
RewriteExprTree(BO, Factors);
@ -1093,6 +1095,12 @@ bool Reassociate::runOnFunction(Function &F) {
for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
ReassociateBB(FI);
// Now that we're done, delete any instructions which are no longer used.
while (!DeadInsts.empty())
if (Instruction *Inst =
cast_or_null<Instruction>((Value *)DeadInsts.pop_back_val()))
RecursivelyDeleteTriviallyDeadInstructions(Inst);
// We are done with the rank map.
RankMap.clear();
ValueRankMap.clear();

25
test/Transforms/Reassociate/crash.ll
View File

@ -42,3 +42,28 @@ define i32 @test3(i32 %Arg, i32 %x1, i32 %x2, i32 %x3) {
%E = add i32 %D, %C
ret i32 %E
}
; rdar://9096268
define void @x66303361ae3f602889d1b7d0f86e5455(i8* %arg) nounwind {
_:
br label %_33
_33: ; preds = %_33, %_
%tmp348 = load i8* %arg, align 1
%tmp349 = lshr i8 %tmp348, 7
%tmp350 = or i8 %tmp349, 42
%tmp351 = add i8 %tmp350, -42
%tmp352 = zext i8 %tmp351 to i32
%tmp358 = add i32 %tmp352, -501049439
%tmp359 = mul i32 %tmp358, %tmp358
%tmp360 = mul i32 %tmp352, %tmp352
%tmp361 = sub i32 %tmp359, %tmp360
%tmp362 = mul i32 %tmp361, -920056735
%tmp363 = add i32 %tmp362, 501049439
%tmp364 = add i32 %tmp362, -2000262972
%tmp365 = sub i32 %tmp363, %tmp364
%tmp366 = sub i32 -501049439, %tmp362
%tmp367 = add i32 %tmp365, %tmp366
br label %_33
}