Add support for objc_unsafeClaimAutoreleasedReturnValue to the

ObjC ARC Optimizer.

The main implication of this is:

1. Ensuring that we treat it conservatively in terms of optimization.
2. We put the ASM marker on it so that the runtime can recognize
objc_unsafeClaimAutoreleasedReturnValue from releaseRV.

<rdar://problem/21567064>

Patch by Michael Gottesman!

llvm-svn: 258970

7 files changed, 90 insertions, 19 deletions

diff --git a/llvm/include/llvm/Analysis/ObjCARCAnalysisUtils.h b/llvm/include/llvm/Analysis/ObjCARCAnalysisUtils.h
index 29d99c9d316..5f4d8ecbbfb 100644
--- a/llvm/include/llvm/Analysis/ObjCARCAnalysisUtils.h
+++ b/llvm/include/llvm/Analysis/ObjCARCAnalysisUtils.h
@@ -54,6 +54,7 @@ inline bool ModuleHasARC(const Module &M) {
     M.getNamedValue("objc_release") ||
     M.getNamedValue("objc_autorelease") ||
     M.getNamedValue("objc_retainAutoreleasedReturnValue") ||
+    M.getNamedValue("objc_unsafeClaimAutoreleasedReturnValue") ||
     M.getNamedValue("objc_retainBlock") ||
     M.getNamedValue("objc_autoreleaseReturnValue") ||
     M.getNamedValue("objc_autoreleasePoolPush") ||
diff --git a/llvm/include/llvm/Analysis/ObjCARCInstKind.h b/llvm/include/llvm/Analysis/ObjCARCInstKind.h
index 13efb4b160b..3b37ddf78f5 100644
--- a/llvm/include/llvm/Analysis/ObjCARCInstKind.h
+++ b/llvm/include/llvm/Analysis/ObjCARCInstKind.h
@@ -30,6 +30,7 @@ namespace objcarc {
 enum class ARCInstKind {
   Retain,                   ///< objc_retain
   RetainRV,                 ///< objc_retainAutoreleasedReturnValue
+  ClaimRV,                  ///< objc_unsafeClaimAutoreleasedReturnValue
   RetainBlock,              ///< objc_retainBlock
   Release,                  ///< objc_release
   Autorelease,              ///< objc_autorelease
diff --git a/llvm/lib/Analysis/ObjCARCInstKind.cpp b/llvm/lib/Analysis/ObjCARCInstKind.cpp
index 133b63513c8..3dc1463b8d8 100644
--- a/llvm/lib/Analysis/ObjCARCInstKind.cpp
+++ b/llvm/lib/Analysis/ObjCARCInstKind.cpp
@@ -34,6 +34,8 @@ raw_ostream &llvm::objcarc::operator<<(raw_ostream &OS,
     return OS << "ARCInstKind::Retain";
   case ARCInstKind::RetainRV:
     return OS << "ARCInstKind::RetainRV";
+  case ARCInstKind::ClaimRV:
+    return OS << "ARCInstKind::ClaimRV";
   case ARCInstKind::RetainBlock:
     return OS << "ARCInstKind::RetainBlock";
   case ARCInstKind::Release:
@@ -103,6 +105,8 @@ ARCInstKind llvm::objcarc::GetFunctionClass(const Function *F) {
         return StringSwitch<ARCInstKind>(F->getName())
             .Case("objc_retain", ARCInstKind::Retain)
             .Case("objc_retainAutoreleasedReturnValue", ARCInstKind::RetainRV)
+            .Case("objc_unsafeClaimAutoreleasedReturnValue",
+                  ARCInstKind::ClaimRV)
             .Case("objc_retainBlock", ARCInstKind::RetainBlock)
             .Case("objc_release", ARCInstKind::Release)
             .Case("objc_autorelease", ARCInstKind::Autorelease)
@@ -350,6 +354,7 @@ bool llvm::objcarc::IsUser(ARCInstKind Class) {
   case ARCInstKind::StoreStrong:
   case ARCInstKind::Call:
   case ARCInstKind::None:
+  case ARCInstKind::ClaimRV:
     return false;
   }
   llvm_unreachable("covered switch isn't covered?");
@@ -385,6 +390,7 @@ bool llvm::objcarc::IsRetain(ARCInstKind Class) {
   case ARCInstKind::Call:
   case ARCInstKind::User:
   case ARCInstKind::None:
+  case ARCInstKind::ClaimRV:
     return false;
   }
   llvm_unreachable("covered switch isn't covered?");
@@ -398,6 +404,7 @@ bool llvm::objcarc::IsAutorelease(ARCInstKind Class) {
     return true;
   case ARCInstKind::Retain:
   case ARCInstKind::RetainRV:
+  case ARCInstKind::ClaimRV:
   case ARCInstKind::RetainBlock:
   case ARCInstKind::Release:
   case ARCInstKind::AutoreleasepoolPush:
@@ -429,6 +436,7 @@ bool llvm::objcarc::IsForwarding(ARCInstKind Class) {
   switch (Class) {
   case ARCInstKind::Retain:
   case ARCInstKind::RetainRV:
+  case ARCInstKind::ClaimRV:
   case ARCInstKind::Autorelease:
   case ARCInstKind::AutoreleaseRV:
   case ARCInstKind::NoopCast:
@@ -463,6 +471,7 @@ bool llvm::objcarc::IsNoopOnNull(ARCInstKind Class) {
   switch (Class) {
   case ARCInstKind::Retain:
   case ARCInstKind::RetainRV:
+  case ARCInstKind::ClaimRV:
   case ARCInstKind::Release:
   case ARCInstKind::Autorelease:
   case ARCInstKind::AutoreleaseRV:
@@ -498,6 +507,7 @@ bool llvm::objcarc::IsAlwaysTail(ARCInstKind Class) {
   switch (Class) {
   case ARCInstKind::Retain:
   case ARCInstKind::RetainRV:
+  case ARCInstKind::ClaimRV:
   case ARCInstKind::AutoreleaseRV:
     return true;
   case ARCInstKind::Release:
@@ -538,6 +548,7 @@ bool llvm::objcarc::IsNeverTail(ARCInstKind Class) {
     return true;
   case ARCInstKind::Retain:
   case ARCInstKind::RetainRV:
+  case ARCInstKind::ClaimRV:
   case ARCInstKind::AutoreleaseRV:
   case ARCInstKind::Release:
   case ARCInstKind::RetainBlock:
@@ -572,6 +583,7 @@ bool llvm::objcarc::IsNoThrow(ARCInstKind Class) {
   switch (Class) {
   case ARCInstKind::Retain:
   case ARCInstKind::RetainRV:
+  case ARCInstKind::ClaimRV:
   case ARCInstKind::Release:
   case ARCInstKind::Autorelease:
   case ARCInstKind::AutoreleaseRV:
@@ -616,6 +628,7 @@ bool llvm::objcarc::CanInterruptRV(ARCInstKind Class) {
     return true;
   case ARCInstKind::Retain:
   case ARCInstKind::RetainRV:
+  case ARCInstKind::ClaimRV:
   case ARCInstKind::Release:
   case ARCInstKind::AutoreleasepoolPush:
   case ARCInstKind::RetainBlock:
@@ -668,6 +681,7 @@ bool llvm::objcarc::CanDecrementRefCount(ARCInstKind Kind) {
   case ARCInstKind::StoreStrong:
   case ARCInstKind::CallOrUser:
   case ARCInstKind::Call:
+  case ARCInstKind::ClaimRV:
     return true;
   }
 
diff --git a/llvm/lib/Transforms/ObjCARC/ObjCARCContract.cpp b/llvm/lib/Transforms/ObjCARC/ObjCARCContract.cpp
index 1cdf5689f42..edef360be61 100644
--- a/llvm/lib/Transforms/ObjCARC/ObjCARCContract.cpp
+++ b/llvm/lib/Transforms/ObjCARC/ObjCARCContract.cpp
@@ -66,7 +66,7 @@ namespace {
 
     /// The inline asm string to insert between calls and RetainRV calls to make
     /// the optimization work on targets which need it.
-    const MDString *RetainRVMarker;
+    const MDString *RVInstMarker;
 
     /// The set of inserted objc_storeStrong calls. If at the end of walking the
     /// function we have found no alloca instructions, these calls can be marked
@@ -423,16 +423,16 @@ bool ObjCARCContract::tryToPeepholeInstruction(
         return false;
       // If we succeed in our optimization, fall through.
       // FALLTHROUGH
-    case ARCInstKind::RetainRV: {
+    case ARCInstKind::RetainRV:
+    case ARCInstKind::ClaimRV: {
       // If we're compiling for a target which needs a special inline-asm
-      // marker to do the retainAutoreleasedReturnValue optimization,
-      // insert it now.
-      if (!RetainRVMarker)
+      // marker to do the return value optimization, insert it now.
+      if (!RVInstMarker)
         return false;
       BasicBlock::iterator BBI = Inst->getIterator();
       BasicBlock *InstParent = Inst->getParent();
 
-      // Step up to see if the call immediately precedes the RetainRV call.
+      // Step up to see if the call immediately precedes the RV call.
       // If it's an invoke, we have to cross a block boundary. And we have
       // to carefully dodge no-op instructions.
       do {
@@ -447,14 +447,14 @@ bool ObjCARCContract::tryToPeepholeInstruction(
       } while (IsNoopInstruction(&*BBI));
 
       if (&*BBI == GetArgRCIdentityRoot(Inst)) {
-        DEBUG(dbgs() << "Adding inline asm marker for "
-                        "retainAutoreleasedReturnValue optimization.\n");
+        DEBUG(dbgs() << "Adding inline asm marker for the return value "
+                        "optimization.\n");
         Changed = true;
-        InlineAsm *IA =
-          InlineAsm::get(FunctionType::get(Type::getVoidTy(Inst->getContext()),
-                                           /*isVarArg=*/false),
-                         RetainRVMarker->getString(),
-                         /*Constraints=*/"", /*hasSideEffects=*/true);
+        InlineAsm *IA = InlineAsm::get(
+            FunctionType::get(Type::getVoidTy(Inst->getContext()),
+                              /*isVarArg=*/false),
+            RVInstMarker->getString(),
+            /*Constraints=*/"", /*hasSideEffects=*/true);
         CallInst::Create(IA, "", Inst);
       }
     decline_rv_optimization:
@@ -650,15 +650,15 @@ bool ObjCARCContract::doInitialization(Module &M) {
 
   EP.init(&M);
 
-  // Initialize RetainRVMarker.
-  RetainRVMarker = nullptr;
+  // Initialize RVInstMarker.
+  RVInstMarker = nullptr;
   if (NamedMDNode *NMD =
           M.getNamedMetadata("clang.arc.retainAutoreleasedReturnValueMarker"))
     if (NMD->getNumOperands() == 1) {
       const MDNode *N = NMD->getOperand(0);
       if (N->getNumOperands() == 1)
         if (const MDString *S = dyn_cast<MDString>(N->getOperand(0)))
-          RetainRVMarker = S;
+          RVInstMarker = S;
     }
 
   return false;
diff --git a/llvm/test/Transforms/ObjCARC/basic.ll b/llvm/test/Transforms/ObjCARC/basic.ll
index fc1d087794d..a6fdf5efa1a 100644
--- a/llvm/test/Transforms/ObjCARC/basic.ll
+++ b/llvm/test/Transforms/ObjCARC/basic.ll
@@ -4,6 +4,7 @@ target datalayout = "e-p:64:64:64"
 
 declare i8* @objc_retain(i8*)
 declare i8* @objc_retainAutoreleasedReturnValue(i8*)
+declare i8* @objc_unsafeClaimAutoreleasedReturnValue(i8*)
 declare void @objc_release(i8*)
 declare i8* @objc_autorelease(i8*)
 declare i8* @objc_autoreleaseReturnValue(i8*)
@@ -2573,6 +2574,27 @@ return:                                           ; preds = %if.then, %entry
   ret i8* %retval
 }
 
+; CHECK-LABEL: define i8* @test65d(
+; CHECK: if.then:
+; CHECK-NOT: @objc_autorelease
+; CHECK: return:
+; CHECK:   call i8* @objc_autoreleaseReturnValue(
+; CHECK: }
+define i8* @test65d(i1 %x) {
+entry:
+  br i1 %x, label %return, label %if.then
+
+if.then:                                          ; preds = %entry
+  %c = call i8* @returner()
+  %s = call i8* @objc_unsafeClaimAutoreleasedReturnValue(i8* %c) nounwind
+  br label %return
+
+return:                                           ; preds = %if.then, %entry
+  %retval = phi i8* [ %s, %if.then ], [ null, %entry ]
+  %q = call i8* @objc_autoreleaseReturnValue(i8* %retval) nounwind
+  ret i8* %retval
+}
+
 ; An objc_retain can serve as a may-use for a different pointer.
 ; rdar://11931823
 
diff --git a/llvm/test/Transforms/ObjCARC/contract-marker.ll b/llvm/test/Transforms/ObjCARC/contract-marker.ll
index a8282607cb3..bf70d4e9d04 100644
--- a/llvm/test/Transforms/ObjCARC/contract-marker.ll
+++ b/llvm/test/Transforms/ObjCARC/contract-marker.ll
@@ -1,9 +1,9 @@
 ; RUN: opt -S -objc-arc-contract < %s | FileCheck %s
 
-; CHECK: define void @foo() {
+; CHECK-LABEL: define void @foo() {
 ; CHECK:      %call = tail call i32* @qux()
 ; CHECK-NEXT: %tcall = bitcast i32* %call to i8*
-; CHECK-NEXT: call void asm sideeffect "mov\09r7, r7\09\09@ marker for objc_retainAutoreleaseReturnValue", ""()
+; CHECK-NEXT: call void asm sideeffect "mov\09r7, r7\09\09@ marker for return value optimization", ""()
 ; CHECK-NEXT: %0 = tail call i8* @objc_retainAutoreleasedReturnValue(i8* %tcall) [[NUW:#[0-9]+]]
 ; CHECK: }
 
@@ -16,12 +16,30 @@ entry:
   ret void
 }
 
+; CHECK-LABEL: define void @foo2() {
+; CHECK:      %call = tail call i32* @qux()
+; CHECK-NEXT: %tcall = bitcast i32* %call to i8*
+; CHECK-NEXT: call void asm sideeffect "mov\09r7, r7\09\09@ marker for return value optimization", ""()
+; CHECK-NEXT: %0 = tail call i8* @objc_unsafeClaimAutoreleasedReturnValue(i8* %tcall) [[NUW:#[0-9]+]]
+; CHECK: }
+
+define void @foo2() {
+entry:
+  %call = tail call i32* @qux()
+  %tcall = bitcast i32* %call to i8*
+  %0 = tail call i8* @objc_unsafeClaimAutoreleasedReturnValue(i8* %tcall) nounwind
+  tail call void @bar(i8* %0)
+  ret void
+}
+
+
 declare i32* @qux()
 declare i8* @objc_retainAutoreleasedReturnValue(i8*)
+declare i8* @objc_unsafeClaimAutoreleasedReturnValue(i8*)
 declare void @bar(i8*)
 
 !clang.arc.retainAutoreleasedReturnValueMarker = !{!0}
 
-!0 = !{!"mov\09r7, r7\09\09@ marker for objc_retainAutoreleaseReturnValue"}
+!0 = !{!"mov\09r7, r7\09\09@ marker for return value optimization"}
 
 ; CHECK: attributes [[NUW]] = { nounwind }
diff --git a/llvm/test/Transforms/ObjCARC/tail-call-invariant-enforcement.ll b/llvm/test/Transforms/ObjCARC/tail-call-invariant-enforcement.ll
index 1ec61c84810..3073abf7bf5 100644
--- a/llvm/test/Transforms/ObjCARC/tail-call-invariant-enforcement.ll
+++ b/llvm/test/Transforms/ObjCARC/tail-call-invariant-enforcement.ll
@@ -5,6 +5,7 @@ declare i8* @objc_retain(i8* %x)
 declare i8* @objc_autorelease(i8* %x)
 declare i8* @objc_autoreleaseReturnValue(i8* %x)
 declare i8* @objc_retainAutoreleasedReturnValue(i8* %x)
+declare i8* @objc_unsafeClaimAutoreleasedReturnValue(i8* %x)
 declare i8* @tmp(i8*)
 
 ; Never tail call objc_autorelease.
@@ -85,5 +86,19 @@ entry:
   ret i8* %tmp0
 }
 
+; Always tail call objc_unsafeClaimAutoreleasedReturnValue.
+; CHECK: define i8* @test6(i8* %x) [[NUW]] {
+; CHECK: %tmp0 = tail call i8* @objc_unsafeClaimAutoreleasedReturnValue(i8* %y) [[NUW]]
+; CHECK: %tmp1 = tail call i8* @objc_unsafeClaimAutoreleasedReturnValue(i8* %z) [[NUW]]
+; CHECK: }
+define i8* @test6(i8* %x) nounwind {
+entry:
+  %y = call i8* @tmp(i8* %x)
+  %tmp0 = call i8* @objc_unsafeClaimAutoreleasedReturnValue(i8* %y)
+  %z = call i8* @tmp(i8* %x)
+  %tmp1 = tail call i8* @objc_unsafeClaimAutoreleasedReturnValue(i8* %z)
+  ret i8* %x
+}
+
 ; CHECK: attributes [[NUW]] = { nounwind }