Teach FunctionAttrs about the VAArg instruction.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118627 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/IPO/FunctionAttrs.cpp b/lib/Transforms/IPO/FunctionAttrs.cpp
index fcdc5f18f16c1fef5ad685bb340712eef4fe4e19..8bdf5d75dadf2b07de0f8bfb66dac949bf130908 100644 (file)
--- a/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -195,6 +195,13 @@ bool FunctionAttrs::AddReadAttrs(const CallGraphSCC &SCC) {
           if (AA->pointsToConstantMemory(Loc, /*OrLocal=*/true))
             continue;
         }
+      } else if (VAArgInst *VI = dyn_cast<VAArgInst>(I)) {
+        // Ignore vaargs on local memory.
+        AliasAnalysis::Location Loc(VI->getPointerOperand(),
+                                    AliasAnalysis::UnknownSize,
+                                    VI->getMetadata(LLVMContext::MD_tbaa));
+        if (AA->pointsToConstantMemory(Loc, /*OrLocal=*/true))
+          continue;
       }
 
       // Any remaining instructions need to be taken seriously!  Check if they

diff --git a/test/Analysis/TypeBasedAliasAnalysis/functionattrs.ll b/test/Analysis/TypeBasedAliasAnalysis/functionattrs.ll
index 5ef355fd93bb3be83811c28ccdb8f0523dddf4b7..53cce0c94f76a8aece030392be261194c0c22423 100644 (file)
--- a/test/Analysis/TypeBasedAliasAnalysis/functionattrs.ll
+++ b/test/Analysis/TypeBasedAliasAnalysis/functionattrs.ll
@@ -55,6 +55,20 @@ define void @test2_no(i8* %p, i8* %q, i64 %n) nounwind {
   ret void
 }
 
+; Similar to the others, va_arg only accesses memory through its operand.
+
+; CHECK: define i32 @test3_yes(i8* nocapture %p) nounwind readnone {
+define i32 @test3_yes(i8* %p) nounwind {
+  %t = va_arg i8* %p, i32, !tbaa !1
+  ret i32 %t
+}
+
+; CHECK: define i32 @test3_no(i8* nocapture %p) nounwind {
+define i32 @test3_no(i8* %p) nounwind {
+  %t = va_arg i8* %p, i32, !tbaa !2
+  ret i32 %t
+}
+
 declare void @callee(i32* %p) nounwind
 declare void @llvm.memcpy.p0i8.p0i8.i64(i8*, i8*, i64, i32, i1) nounwind