commit b6befc3bc4d7b7677e71be471d3a6ed1c2ac4199
author Eli Friedman <efriedma@codeaurora.org> Wed Nov 02 20:48:11 2016 +0000
committer Eli Friedman <efriedma@codeaurora.org> Wed Nov 02 20:48:11 2016 +0000
tree d235e6032ca8b43546739d2ff5d66a78dd17c5b5
parent ce65364afc657318d937ace660afff305817935d

DCE math library calls with a constant operand.

On platforms which use -fmath-errno, math libcalls without any uses
require some extra checks to figure out if they are actually dead.

Fixes https://llvm.org/bugs/show_bug.cgi?id=30464 .

Differential Revision: https://reviews.llvm.org/D25970

llvm-svn: 285857

llvm/lib/Transforms/Utils/Local.cpp

diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 5c46111..e52d87a 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -340,6 +340,10 @@
     if (Constant *C = dyn_cast<Constant>(CI->getArgOperand(0)))
       return C->isNullValue() || isa<UndefValue>(C);
 
+  if (CallSite CS = CallSite(I))
+    if (isMathLibCallNoop(CS, TLI))
+      return true;
+
   return false;
 }