From 0a80c1240284c764c0f9cd043a2a18ff4152a203 Mon Sep 17 00:00:00 2001
From: Michael Gottesman <mgottesman@apple.com>
Date: Sun, 7 Jul 2013 01:52:55 +0000
Subject: [PATCH] [objc-arc] Teach the ARC optimizer that
objc_sync_enter/objc_sync_exit do not modify the ref count of an objc object
and additionally are inert for modref purposes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185769 91177308-0d34-0410-b5e6-96231b3b80d8
---
.../ObjCARC/ObjCARCAliasAnalysis.cpp | 8 +++++++
lib/Transforms/ObjCARC/ObjCARCUtil.cpp | 2 ++
test/Transforms/ObjCARC/basic.ll | 23 ++++++++++++++++--
test/Transforms/ObjCARC/gvn.ll | 24 ++++++++++++++++---
4 files changed, 52 insertions(+), 5 deletions(-)
diff --git a/lib/Transforms/ObjCARC/ObjCARCAliasAnalysis.cpp b/lib/Transforms/ObjCARC/ObjCARCAliasAnalysis.cpp
index 46b2de71374..1a3f383d4c0 100644
--- a/lib/Transforms/ObjCARC/ObjCARCAliasAnalysis.cpp
+++ b/lib/Transforms/ObjCARC/ObjCARCAliasAnalysis.cpp
@@ -150,6 +150,14 @@ ObjCARCAliasAnalysis::getModRefInfo(ImmutableCallSite CS, const Location &Loc) {
break;
}
+ // Handle special objective c calls defaulting to chaining.
+ const Function *F = CS.getCalledFunction();
+ if (F)
+ return StringSwitch<AliasAnalysis::ModRefResult>(F->getName())
+ .Case("objc_sync_start", NoModRef)
+ .Case("objc_sync_stop", NoModRef)
+ .Default(AliasAnalysis::getModRefInfo(CS, Loc));
+
return AliasAnalysis::getModRefInfo(CS, Loc);
}
diff --git a/lib/Transforms/ObjCARC/ObjCARCUtil.cpp b/lib/Transforms/ObjCARC/ObjCARCUtil.cpp
index 03e12d4fd76..415e76355db 100644
--- a/lib/Transforms/ObjCARC/ObjCARCUtil.cpp
+++ b/lib/Transforms/ObjCARC/ObjCARCUtil.cpp
@@ -112,6 +112,8 @@ InstructionClass llvm::objcarc::GetFunctionClass(const Function *F) {
.Case("objc_retain_autorelease", IC_FusedRetainAutorelease)
.Case("objc_retainAutorelease", IC_FusedRetainAutorelease)
.Case("objc_retainAutoreleaseReturnValue",IC_FusedRetainAutoreleaseRV)
+ .Case("objc_sync_enter", IC_User)
+ .Case("objc_sync_exit", IC_User)
.Default(IC_CallOrUser);
// Argument is i8**
diff --git a/test/Transforms/ObjCARC/basic.ll b/test/Transforms/ObjCARC/basic.ll
index ca127920659..2bb312bf260 100644
--- a/test/Transforms/ObjCARC/basic.ll
+++ b/test/Transforms/ObjCARC/basic.ll
@@ -3037,9 +3037,28 @@ end: ; preds = %if.end125, %if.end1
ret void
}
-!0 = metadata !{}
-
declare i32 @__gxx_personality_v0(...)
+declare i32 @objc_sync_enter(i8*)
+declare i32 @objc_sync_exit(i8*)
+
+; Make sure that we understand that objc_sync_{enter,exit} are IC_User not
+; IC_Call/IC_CallOrUser.
+
+; CHECK: define void @test67
+; CHECK-NEXT: call i32 @objc_sync_enter(i8* %x)
+; CHECK-NEXT: call i32 @objc_sync_exit(i8* %x)
+; CHECK-NEXT: ret void
+; CHECK-NEXT: }
+define void @test67(i8* %x) {
+ call i8* @objc_retain(i8* %x)
+ call i32 @objc_sync_enter(i8* %x)
+ call i32 @objc_sync_exit(i8* %x)
+ call void @objc_release(i8* %x), !clang.imprecise_release !0
+ ret void
+}
+
+!0 = metadata !{}
+
; CHECK: attributes #0 = { nounwind readnone }
; CHECK: attributes [[NUW]] = { nounwind }
diff --git a/test/Transforms/ObjCARC/gvn.ll b/test/Transforms/ObjCARC/gvn.ll
index a828b5485f4..0773b69ee1e 100644
--- a/test/Transforms/ObjCARC/gvn.ll
+++ b/test/Transforms/ObjCARC/gvn.ll
@@ -3,20 +3,38 @@
@x = common global i8* null, align 8
declare i8* @objc_retain(i8*)
+declare i32 @objc_sync_start(i8*)
+declare i32 @objc_sync_stop(i8*)
; GVN should be able to eliminate this redundant load, with ARC-specific
; alias analysis.
-; CHECK: define i8* @foo(i32 %n)
+; CHECK: define i8* @test0(i32 %n)
; CHECK-NEXT: entry:
; CHECK-NEXT: %s = load i8** @x
; CHECK-NOT: load
; CHECK: ret i8* %s
; CHECK-NEXT: }
-define i8* @foo(i32 %n) nounwind {
+define i8* @test0(i32 %n) nounwind {
entry:
%s = load i8** @x
%0 = tail call i8* @objc_retain(i8* %s) nounwind
%t = load i8** @x
- ret i8* %s
+ ret i8* %t
+}
+
+; CHECK: define i8* @test1(i32 %n)
+; CHECK-NEXT: entry:
+; CHECK-NEXT: %s = load i8** @x
+; CHECK-NEXT: call i32 @objc_sync_start
+; CHECK-NEXT: call i32 @objc_sync_stop
+; CHECK-NEXT: ret i8* %s
+; CHECK-NEXT: }
+define i8* @test1(i32 %n) nounwind {
+entry:
+ %s = load i8** @x
+ %0 = call i32 @objc_sync_start(i8* %s)
+ %t = load i8** @x
+ %1 = call i32 @objc_sync_stop(i8* %s)
+ ret i8* %t
}