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fix PR4815: some cases where DeleteDeadInstruction can delete

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the instruction BBI points to.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80768 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2009-09-02 06:31:02 +00:00
parent 20a2faa980
commit 40ef630a46
2 changed files with 39 additions and 3 deletions
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14
lib/Transforms/Scalar/DeadStoreElimination.cpp
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@ -83,7 +83,7 @@ bool DSE::runOnBasicBlock(BasicBlock &BB) {
bool MadeChange = false; bool MadeChange = false;
// Do a top-down walk on the BB // Do a top-down walk on the BB.
for (BasicBlock::iterator BBI = BB.begin(), BBE = BB.end(); BBI != BBE; ) { for (BasicBlock::iterator BBI = BB.begin(), BBE = BB.end(); BBI != BBE; ) {
Instruction *Inst = BBI++; Instruction *Inst = BBI++;
@ -125,6 +125,9 @@ bool DSE::runOnBasicBlock(BasicBlock &BB) {
NumFastStores++; NumFastStores++;
MadeChange = true; MadeChange = true;
// DeleteDeadInstruction can delete the current instruction in loop
// cases, reset BBI.
BBI = Inst;
if (BBI != BB.begin()) if (BBI != BB.begin())
--BBI; --BBI;
continue; continue;
@ -135,8 +138,15 @@ bool DSE::runOnBasicBlock(BasicBlock &BB) {
if (LoadInst *DepLoad = dyn_cast<LoadInst>(InstDep.getInst())) { if (LoadInst *DepLoad = dyn_cast<LoadInst>(InstDep.getInst())) {
if (SI->getPointerOperand() == DepLoad->getPointerOperand() && if (SI->getPointerOperand() == DepLoad->getPointerOperand() &&
SI->getOperand(0) == DepLoad) { SI->getOperand(0) == DepLoad) {
// DeleteDeadInstruction can delete the current instruction. Save BBI
// in case we need it.
WeakVH NextInst(BBI);
DeleteDeadInstruction(SI); DeleteDeadInstruction(SI);
if (BBI != BB.begin())
if (NextInst == 0) // Next instruction deleted.
BBI = BB.begin();
else if (BBI != BB.begin()) // Revisit this instruction if possible.
--BBI; --BBI;
NumFastStores++; NumFastStores++;
MadeChange = true; MadeChange = true;

26
test/Transforms/DeadStoreElimination/crash.ll Normal file
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@ -0,0 +1,26 @@
; RUN: llvm-as < %s | opt -dse | llvm-dis
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
target triple = "i386-apple-darwin10.0"
@g80 = external global i8 ; <i8*> [#uses=3]
declare signext i8 @foo(i8 signext, i8 signext) nounwind readnone ssp
declare i32 @func68(i32) nounwind readonly ssp
; PR4815
define void @test1(i32 %int32p54) noreturn nounwind ssp {
entry:
br label %bb
bb: ; preds = %bb, %entry
%storemerge = phi i8 [ %2, %bb ], [ 1, %entry ] ; <i8> [#uses=1]
store i8 %storemerge, i8* @g80
%0 = tail call i32 @func68(i32 1) nounwind ssp ; <i32> [#uses=1]
%1 = trunc i32 %0 to i8 ; <i8> [#uses=1]
store i8 %1, i8* @g80, align 1
store i8 undef, i8* @g80, align 1
%2 = tail call signext i8 @foo(i8 signext undef, i8 signext 1) nounwind ; <i8> [#uses=1]
br label %bb
}