fix a really nasty basicaa mod/ref calculation bug that was causing miscompilation of

UnitTests/ObjC/messages-2.m with the recent optimizer improvements.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131897 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp
index f1bb8a38f090b59a67727b963ef819018eba61eb..989d8e0e82de01cfc9189a921aeb7f6cdc72f334 100644 (file)
--- a/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/lib/Analysis/BasicAliasAnalysis.cpp
@@ -680,9 +680,12 @@ BasicAliasAnalysis::getModRefInfo(ImmutableCallSite CS,
     unsigned ArgNo = 0;
     for (ImmutableCallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end();
          CI != CE; ++CI, ++ArgNo) {
-      // Only look at the no-capture pointer arguments.
+      // Only look at the no-capture or byval pointer arguments.  If this
+      // pointer were passed to arguments that were neither of these, then it
+      // couldn't be no-capture.
       if (!(*CI)->getType()->isPointerTy() ||
-          !CS.paramHasAttr(ArgNo+1, Attribute::NoCapture))
+          (!CS.paramHasAttr(ArgNo+1, Attribute::NoCapture) &&
+           !CS.paramHasAttr(ArgNo+1, Attribute::ByVal)))
         continue;
       
       // If this is a no-capture pointer argument, see if we can tell that it

diff --git a/test/Transforms/DeadStoreElimination/simple.ll b/test/Transforms/DeadStoreElimination/simple.ll
index a61eac9729e8db072fdf817a50792061a76078b3..23576dadcf34371afcc59a279ead88717a3519f6 100644 (file)
--- a/test/Transforms/DeadStoreElimination/simple.ll
+++ b/test/Transforms/DeadStoreElimination/simple.ll
@@ -236,3 +236,20 @@ define void @test18(i8* %P, i8* %Q, i8* %R) nounwind ssp {
 ; CHECK-NEXT: call void @llvm.memcpy
 ; CHECK-NEXT: ret
 }
+
+
+; The store here is not dead because the byval call reads it.
+declare void @test19f({i32}* byval align 4 %P)
+
+define void @test19({i32} * nocapture byval align 4 %arg5) nounwind ssp {
+bb:
+  %tmp7 = getelementptr inbounds {i32}* %arg5, i32 0, i32 0
+  store i32 912, i32* %tmp7
+  call void @test19f({i32}* byval align 4 %arg5)
+  ret void
+
+; CHECK: @test19(
+; CHECK: store i32 912
+; CHECK: call void @test19f
+}
+