diff options
| author | Andrew Trick <atrick@apple.com> | 2011-11-17 23:36:35 +0000 |
|---|---|---|
| committer | Andrew Trick <atrick@apple.com> | 2011-11-17 23:36:35 +0000 |
| commit | 4f3052403ca5ea9542a118c2e54ff9c82038f41c (patch) | |
| tree | 1dd30660130db7eec9772488e057b352767226cb | |
| parent | 7cf2a04361e8613264498e50babe52d65c070473 (diff) | |
Fix an overly general check in SimplifyIndvar to handle useless phi cycles.
The right way to check for a binary operation is
cast<BinaryOperator>. The original check: cast<Instruction> &&
numOperands() == 2 would match phi "instructions", leading to an
infinite loop in extreme corner case: a useless phi with operands
[self, constant] that prior optimization passes failed to remove,
being used in the loop by another useless phi, in turn being used by an
lshr or udiv.
Fixes PR11350: runaway iteration assertion.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@144935 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Transforms/Utils/SimplifyIndVar.cpp | 4 | ||||
| -rw-r--r-- | test/Transforms/IndVarSimplify/2011-11-17-selfphi.ll | 29 |
2 files changed, 31 insertions, 2 deletions
diff --git a/lib/Transforms/Utils/SimplifyIndVar.cpp b/lib/Transforms/Utils/SimplifyIndVar.cpp index 76289c055b..6732a789d5 100644 --- a/lib/Transforms/Utils/SimplifyIndVar.cpp +++ b/lib/Transforms/Utils/SimplifyIndVar.cpp @@ -107,8 +107,8 @@ Value *SimplifyIndvar::foldIVUser(Instruction *UseInst, Instruction *IVOperand) // Attempt to fold a binary operator with constant operand. // e.g. ((I + 1) >> 2) => I >> 2 - if (IVOperand->getNumOperands() != 2 || - !isa<ConstantInt>(IVOperand->getOperand(1))) + if (!isa<BinaryOperator>(IVOperand) + || !isa<ConstantInt>(IVOperand->getOperand(1))) return 0; IVSrc = IVOperand->getOperand(0); diff --git a/test/Transforms/IndVarSimplify/2011-11-17-selfphi.ll b/test/Transforms/IndVarSimplify/2011-11-17-selfphi.ll new file mode 100644 index 0000000000..ccf259597e --- /dev/null +++ b/test/Transforms/IndVarSimplify/2011-11-17-selfphi.ll @@ -0,0 +1,29 @@ +; RUN: opt < %s -indvars -S | FileCheck %s +; PR11350: Check that SimplifyIndvar handles a cycle of useless self-phis. + +; CHECK: @test +; CHECK-NOT: lcssa = phi +define void @test() nounwind { +entry: + br label %for.cond.preheader + +for.cond.preheader: ; preds = %entry + br label %for.cond.outer + +for.cond.outer: ; preds = %for.cond.preheader, %for.end + %p_41.addr.0.ph = phi i32 [ %p_41.addr.1.lcssa, %for.end ], [ 1, %for.cond.preheader ] + br label %for.cond + +for.cond: + br i1 true, label %for.end, label %for.ph + +for.ph: ; preds = %for.cond4.preheader + br label %for.end + +for.end: + %p_41.addr.1.lcssa = phi i32 [ undef, %for.ph ], [ %p_41.addr.0.ph, %for.cond ] + %p_68.lobit.i = lshr i32 %p_41.addr.1.lcssa, 31 + %cmp7 = icmp eq i32 %p_41.addr.1.lcssa, 0 + %conv8 = zext i1 %cmp7 to i32 + br label %for.cond.outer +} |