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| author | Sanjay Patel <spatel@rotateright.com> | 2017-05-15 19:16:49 +0000 |
|---|---|---|
| committer | Sanjay Patel <spatel@rotateright.com> | 2017-05-15 19:16:49 +0000 |
| commit | a23b141cd2120232ef0a7088fa9bc480773dcfe1 (patch) | |
| tree | 99a2de6eb5158674db6f8b04d7d2f9709c0c0cf2 | |
| parent | 12588d76db3fb291405b42ba49568b76c6602ba0 (diff) | |
| download | bcm5719-llvm-a23b141cd2120232ef0a7088fa9bc480773dcfe1.tar.gz bcm5719-llvm-a23b141cd2120232ef0a7088fa9bc480773dcfe1.zip | |
[InstSimplify] restrict icmp fold with 2 sdiv exact operands (PR32949)
These folds were introduced with https://reviews.llvm.org/rL127064 as part of solving:
https://bugs.llvm.org/show_bug.cgi?id=9343
As shown here:
http://rise4fun.com/Alive/C8
...however, the sdiv exact case needs a stronger predicate.
I opted for duplicated code instead of adding another fallthrough because I think that's
easier to read (and edit in case we need/want to restrict/loosen the predicates any more).
This should fix:
https://bugs.llvm.org/show_bug.cgi?id=32949
https://bugs.llvm.org/show_bug.cgi?id=32948
Differential Revision: https://reviews.llvm.org/D32954
llvm-svn: 303104
| -rw-r--r-- | llvm/lib/Analysis/InstructionSimplify.cpp | 13 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstSimplify/compare.ll | 7 |
2 files changed, 16 insertions, 4 deletions
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp index 6293c2a08a1..5728887cc1e 100644 --- a/llvm/lib/Analysis/InstructionSimplify.cpp +++ b/llvm/lib/Analysis/InstructionSimplify.cpp @@ -2827,10 +2827,19 @@ static Value *simplifyICmpWithBinOp(CmpInst::Predicate Pred, Value *LHS, break; case Instruction::UDiv: case Instruction::LShr: - if (ICmpInst::isSigned(Pred)) + if (ICmpInst::isSigned(Pred) || !LBO->isExact() || !RBO->isExact()) break; - LLVM_FALLTHROUGH; + if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0), + RBO->getOperand(0), Q, MaxRecurse - 1)) + return V; + break; case Instruction::SDiv: + if (!ICmpInst::isEquality(Pred) || !LBO->isExact() || !RBO->isExact()) + break; + if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0), + RBO->getOperand(0), Q, MaxRecurse - 1)) + return V; + break; case Instruction::AShr: if (!LBO->isExact() || !RBO->isExact()) break; diff --git a/llvm/test/Transforms/InstSimplify/compare.ll b/llvm/test/Transforms/InstSimplify/compare.ll index 883bf31ff77..d6f1b634102 100644 --- a/llvm/test/Transforms/InstSimplify/compare.ll +++ b/llvm/test/Transforms/InstSimplify/compare.ll @@ -598,11 +598,14 @@ define i1 @sdiv_exact_equality(i32 %Z) { ret i1 %C } -; FIXME: But not other preds: PR32949 - https://bugs.llvm.org/show_bug.cgi?id=32949 +; But not other preds: PR32949 - https://bugs.llvm.org/show_bug.cgi?id=32949 define i1 @sdiv_exact_not_equality(i32 %Z) { ; CHECK-LABEL: @sdiv_exact_not_equality( -; CHECK-NEXT: ret i1 true +; CHECK-NEXT: [[A:%.*]] = sdiv exact i32 10, %Z +; CHECK-NEXT: [[B:%.*]] = sdiv exact i32 20, %Z +; CHECK-NEXT: [[C:%.*]] = icmp ult i32 [[A]], [[B]] +; CHECK-NEXT: ret i1 [[C]] ; %A = sdiv exact i32 10, %Z %B = sdiv exact i32 20, %Z |
