[IPCP] Don't propagate return value for naked functions.

This is pretty much the same change made in SCCP.

llvm-svn: 294098

llvm/lib/Transforms/IPO/IPConstantPropagation.cpp

@@ -136,7 +136,13 @@ static bool PropagateConstantReturn(Function &F) {
   // For more details, see GlobalValue::mayBeDerefined.
   if (!F.isDefinitionExact())
     return false;
-    
+
+  // Don't touch naked functions. The may contain asm returning
+  // value we don't see, so we may end up interprocedurally propagating
+  // the return value incorrectly.
+  if (F.hasFnAttribute(Attribute::Naked))
+    return false;
+
   // Check to see if this function returns a constant.
   SmallVector<Value *,4> RetVals;
   StructType *STy = dyn_cast<StructType>(F.getReturnType());

llvm/test/Transforms/IPConstantProp/naked-return.ll

@@ -1,4 +1,5 @@
 ; RUN: opt -ipsccp -S %s | FileCheck %s
+; RUN: opt -ipconstprop -S %s | FileCheck %s
 
 target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
 target triple = "i686-pc-windows-msvc19.0.24215"