commit 85893f48a6994d71414773175440c421e5341810
author Michael Ilseman <milseman@apple.com> Thu Dec 06 00:07:09 2012 +0000
committer Michael Ilseman <milseman@apple.com> Thu Dec 06 00:07:09 2012 +0000
tree c405de6a94e7ea8e90aedc76cd888fec6488fefa
parent 6e3411375e3ec2c99eebcda30f99a29504566566

Have CannotBeNegativeZero() be aware of the nsz fast-math flag

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169452 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Analysis/ValueTracking.cpp

diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index 47b1db6..eee231d 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -1312,7 +1312,12 @@
 
   const Operator *I = dyn_cast<Operator>(V);
   if (I == 0) return false;
-  
+
+  // Check if the nsz fast-math flag is set
+  if (const FPMathOperator *FPO = dyn_cast<FPMathOperator>(I))
+    if (FPO->hasNoSignedZeros())
+      return true;
+
   // (add x, 0.0) is guaranteed to return +0.0, not -0.0.
   if (I->getOpcode() == Instruction::FAdd &&
       isa<ConstantFP>(I->getOperand(1)) &&