Allow speculating llvm.sqrt, fma and fmuladd

This doesn't set errno, so this should be OK.
Also update the documentation to explicitly state
that errno are not set.

llvm-svn: 200501

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 1e423c45126..5ebb6130fbb 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -2036,6 +2036,12 @@ bool llvm::isSafeToSpeculativelyExecute(const Value *V,
        case Intrinsic::umul_with_overflow:
        case Intrinsic::usub_with_overflow:
          return true;
+       // Sqrt should be OK, since the llvm sqrt intrinsic isn't defined to set
+       // errno like libm sqrt would.
+       case Intrinsic::sqrt:
+       case Intrinsic::fma:
+       case Intrinsic::fmuladd:
+         return true;
        // TODO: some fp intrinsics are marked as having the same error handling
        // as libm. They're safe to speculate when they won't error.
        // TODO: are convert_{from,to}_fp16 safe?