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Update InstCombine worklist after instruction transform is complete.

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When updating the worklist for InstCombine, the Add/AddUsersToWorklist
functions may access the instruction(s) being added, for debug output for
example. If the instructions aren't yet added to the basic block, this
can result in a crash. Finish the instruction transformation before
adjusting the worklist instead.

rdar://10238555

llvm-svn: 141203
This commit is contained in:
Jim Grosbach 2011-10-05 20:05:00 +00:00
parent 195e8b81e8
commit a03dd9189f
2 changed files with 11 additions and 10 deletions
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17
lib/Transforms/InstCombine/InstructionCombining.cpp
View File

@ -2009,21 +2009,18 @@ bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
++NumCombined;
// Should we replace the old instruction with a new one?
if (Result != I) {
DEBUG(errs() << "IC: Old = " << *I << '\n'
<< " New = " << *Result << '\n');
if (!I->getDebugLoc().isUnknown())
Result->setDebugLoc(I->getDebugLoc());
// Everything uses the new instruction now.
I->replaceAllUsesWith(Result);
// Push the new instruction and any users onto the worklist.
Worklist.Add(Result);
Worklist.AddUsersToWorkList(*Result);
// Move the name to the new instruction first.
// Move the name to the new instruction.
Result->takeName(I);
DEBUG(errs() << "IC: Old = " << *I << '\n'
<< " New = " << *Result << '\n');
// Insert the new instruction into the basic block...
BasicBlock *InstParent = I->getParent();
BasicBlock::iterator InsertPos = I;
@ -2035,6 +2032,10 @@ bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
InstParent->getInstList().insert(InsertPos, Result);
EraseInstFromFunction(*I);
// Push the new instruction and any users onto the worklist.
Worklist.Add(Result);
Worklist.AddUsersToWorkList(*Result);
} else {
#ifndef NDEBUG
DEBUG(errs() << "IC: Mod = " << OrigI << '\n'

4
test/Transforms/InstCombine/2010-11-01-lshr-mask.ll
View File

@ -5,8 +5,8 @@
define i32 @main(i32 %argc) nounwind ssp {
entry:
%tmp3151 = trunc i32 %argc to i8
; CHECK: %tmp3162 = shl i8 %tmp3151, 5
; CHECK: and i8 %tmp3162, 64
; CHECK: %0 = shl i8 %tmp3151, 5
; CHECK: and i8 %0, 64
; CHECK-NOT: shl
; CHECK-NOT: shr
%tmp3161 = or i8 %tmp3151, -17