[NVPTX] Infer __nvvm_reflect as nounwind, readnone

This patch simply mirrors the attributes we give to @llvm.nvvm.reflect
to the __nvvm_reflect libdevice call.  This shaves about 30% of the code
in libdevice away because of CSE opportunities.  It's also helps us
figure out that libdevice implementations of transcendental functions
don't have side-effects.

llvm-svn: 265060

1 files changed, 9 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/IPO/InferFunctionAttrs.cpp b/llvm/lib/Transforms/IPO/InferFunctionAttrs.cpp
index 16922ab9256..030a6464522 100644
--- a/llvm/lib/Transforms/IPO/InferFunctionAttrs.cpp
+++ b/llvm/lib/Transforms/IPO/InferFunctionAttrs.cpp
@@ -924,6 +924,15 @@ static bool inferPrototypeAttributes(Function &F,
     Changed |= setOnlyReadsMemory(F, 2);
     return Changed;
 
+  // int __nvvm_reflect(const char *)
+  case LibFunc::nvvm_reflect:
+    if (FTy->getNumParams() != 1 || !isa<PointerType>(FTy->getParamType(0)))
+      return false;
+
+    Changed |= setDoesNotAccessMemory(F);
+    Changed |= setDoesNotThrow(F);
+    return Changed;
+
   default:
     // FIXME: It'd be really nice to cover all the library functions we're
     // aware of here.