From 604ae0b712af9143d2211c42c2584b529791cdfd Mon Sep 17 00:00:00 2001
From: Pete Cooper <peter_cooper@apple.com>
Date: Fri, 27 May 2016 02:13:53 +0000
Subject: [PATCH] Form objc_storeStrong in the presence of bitcasts.

objc_storeStrong can be formed from a sequence such as

  %0 = tail call i8* @objc_retain(i8* %p) nounwind
  %tmp = load i8*, i8** @x, align 8
  store i8* %0, i8** @x, align 8
  tail call void @objc_release(i8* %tmp) nounwind

The code was already looking through bitcasts for most of the values
involved, but had missed one case where the pointer operand for the
store was a bitcast.  Ultimately the pointer for the load and store
have to be the same value, after stripping casts.

llvm-svn: 270955
---
 lib/Transforms/ObjCARC/ObjCARCContract.cpp    |  3 ++-
 .../ObjCARC/contract-storestrong.ll           | 26 +++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/lib/Transforms/ObjCARC/ObjCARCContract.cpp b/lib/Transforms/ObjCARC/ObjCARCContract.cpp
index ef70d4c4392..11e2d03e17d 100644
--- a/lib/Transforms/ObjCARC/ObjCARCContract.cpp
+++ b/lib/Transforms/ObjCARC/ObjCARCContract.cpp
@@ -201,6 +201,7 @@ static StoreInst *findSafeStoreForStoreStrongContraction(LoadInst *Load,
 
   // Get the location associated with Load.
   MemoryLocation Loc = MemoryLocation::get(Load);
+  auto *LocPtr = Loc.Ptr->stripPointerCasts();
 
   // Walk down to find the store and the release, which may be in either order.
   for (auto I = std::next(BasicBlock::iterator(Load)),
@@ -261,7 +262,7 @@ static StoreInst *findSafeStoreForStoreStrongContraction(LoadInst *Load,
 
     // Then make sure that the pointer we are storing to is Ptr. If so, we
     // found our Store!
-    if (Store->getPointerOperand() == Loc.Ptr)
+    if (Store->getPointerOperand()->stripPointerCasts() == LocPtr)
       continue;
 
     // Otherwise, we have an unknown store to some other ptr that clobbers
diff --git a/test/Transforms/ObjCARC/contract-storestrong.ll b/test/Transforms/ObjCARC/contract-storestrong.ll
index aadc3a26539..2b83bdb9bfb 100644
--- a/test/Transforms/ObjCARC/contract-storestrong.ll
+++ b/test/Transforms/ObjCARC/contract-storestrong.ll
@@ -217,6 +217,32 @@ entry:
   ret i1 %t
 }
 
+; Make sure that we form the store strong even if there are bitcasts on
+; the pointers.
+; CHECK-LABEL: define void @test12(
+; CHECK: entry:
+; CHECK-NEXT: %p16 = bitcast i8** @x to i16**
+; CHECK-NEXT: %tmp16 = load i16*, i16** %p16, align 8
+; CHECK-NEXT: %tmp8 = bitcast i16* %tmp16 to i8*
+; CHECK-NEXT: %p32 = bitcast i8** @x to i32**
+; CHECK-NEXT: %v32 = bitcast i8* %p to i32*
+; CHECK-NEXT: %0 = bitcast i16** %p16 to i8**
+; CHECK-NEXT: tail call void @objc_storeStrong(i8** %0, i8* %p)
+; CHECK-NEXT: ret void
+; CHECK-NEXT: }
+define void @test12(i8* %p) {
+entry:
+  %retain = tail call i8* @objc_retain(i8* %p) nounwind
+  %p16 = bitcast i8** @x to i16**
+  %tmp16 = load i16*, i16** %p16, align 8
+  %tmp8 = bitcast i16* %tmp16 to i8*
+  %p32 = bitcast i8** @x to i32**
+  %v32 = bitcast i8* %retain to i32*
+  store i32* %v32, i32** %p32, align 8
+  tail call void @objc_release(i8* %tmp8) nounwind
+  ret void
+}
+
 !0 = !{}
 
 ; CHECK: attributes [[NUW]] = { nounwind }