Fix a logic bug when copying fast-math flags.
"Setting" does not equal "copying". This bug has sat dormant for 2 reasons:
1. The unit test was not adequate.
2. Every current user of the "copyFastMathFlags" API is operating on a new instruction.
(ie, all existing fast-math flags are off). If you copy flags to an existing
instruction that has some flags on already, you will not necessarily turn them off
as expected.
I uncovered this bug while trying to implement a fix for PR20802.
llvm-svn: 216939
diff --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
index 16993f1..b113d51 100644
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -2043,7 +2043,7 @@
// Copy the fast-math flags.
if (auto *FP = dyn_cast<FPMathOperator>(V))
- setFastMathFlags(FP->getFastMathFlags());
+ copyFastMathFlags(FP->getFastMathFlags());
}
//===----------------------------------------------------------------------===//