[llvm] r180698 - [objc-arc] Apply the RV optimization to retains next to calls in ObjCARCContract instead of ObjCARCOpts.

Michael Gottesman mgottesman at apple.com
Sun Apr 28 23:53:53 PDT 2013


Author: mgottesman
Date: Mon Apr 29 01:53:53 2013
New Revision: 180698

URL: http://llvm.org/viewvc/llvm-project?rev=180698&view=rev
Log:
[objc-arc] Apply the RV optimization to retains next to calls in ObjCARCContract instead of ObjCARCOpts.

Turning retains into retainRV calls disrupts the data flow analysis in
ObjCARCOpts. Thus we move it as late as we can by moving it into
ObjCARCContract.

We leave in the conversion from retainRV -> retain in ObjCARCOpt since
it enables the dataflow analysis.

rdar://10813093

Modified:
    llvm/trunk/lib/Transforms/ObjCARC/ObjCARCContract.cpp
    llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
    llvm/trunk/test/Transforms/ObjCARC/contract.ll
    llvm/trunk/test/Transforms/ObjCARC/move-and-merge-autorelease.ll
    llvm/trunk/test/Transforms/ObjCARC/rv.ll

Modified: llvm/trunk/lib/Transforms/ObjCARC/ObjCARCContract.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/ObjCARC/ObjCARCContract.cpp?rev=180698&r1=180697&r2=180698&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/ObjCARC/ObjCARCContract.cpp (original)
+++ llvm/trunk/lib/Transforms/ObjCARC/ObjCARCContract.cpp Mon Apr 29 01:53:53 2013
@@ -66,6 +66,8 @@ namespace {
     Constant *RetainAutoreleaseCallee;
     /// Declaration for objc_retainAutoreleaseReturnValue().
     Constant *RetainAutoreleaseRVCallee;
+    /// Declaration for objc_retainAutoreleasedReturnValue().
+    Constant *RetainRVCallee;
 
     /// The inline asm string to insert between calls and RetainRV calls to make
     /// the optimization work on targets which need it.
@@ -77,9 +79,12 @@ namespace {
     SmallPtrSet<CallInst *, 8> StoreStrongCalls;
 
     Constant *getStoreStrongCallee(Module *M);
+    Constant *getRetainRVCallee(Module *M);
     Constant *getRetainAutoreleaseCallee(Module *M);
     Constant *getRetainAutoreleaseRVCallee(Module *M);
 
+    bool OptimizeRetainCall(Function &F, Instruction *Retain);
+
     bool ContractAutorelease(Function &F, Instruction *Autorelease,
                              InstructionClass Class,
                              SmallPtrSet<Instruction *, 4>
@@ -172,6 +177,57 @@ Constant *ObjCARCContract::getRetainAuto
   return RetainAutoreleaseRVCallee;
 }
 
+Constant *ObjCARCContract::getRetainRVCallee(Module *M) {
+  if (!RetainRVCallee) {
+    LLVMContext &C = M->getContext();
+    Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
+    Type *Params[] = { I8X };
+    FunctionType *FTy = FunctionType::get(I8X, Params, /*isVarArg=*/false);
+    AttributeSet Attribute =
+      AttributeSet().addAttribute(M->getContext(), AttributeSet::FunctionIndex,
+                                  Attribute::NoUnwind);
+    RetainRVCallee =
+      M->getOrInsertFunction("objc_retainAutoreleasedReturnValue", FTy,
+                             Attribute);
+  }
+  return RetainRVCallee;
+}
+
+/// Turn objc_retain into objc_retainAutoreleasedReturnValue if the operand is a
+/// return value. We do this late so we do not disrupt the dataflow analysis in
+/// ObjCARCOpt.
+bool
+ObjCARCContract::OptimizeRetainCall(Function &F, Instruction *Retain) {
+  ImmutableCallSite CS(GetObjCArg(Retain));
+  const Instruction *Call = CS.getInstruction();
+  if (!Call)
+    return false;
+  if (Call->getParent() != Retain->getParent())
+    return false;
+
+  // Check that the call is next to the retain.
+  BasicBlock::const_iterator I = Call;
+  ++I;
+  while (IsNoopInstruction(I)) ++I;
+  if (&*I != Retain)
+    return false;
+
+  // Turn it to an objc_retainAutoreleasedReturnValue.
+  Changed = true;
+  ++NumPeeps;
+
+  DEBUG(dbgs() << "Transforming objc_retain => "
+                  "objc_retainAutoreleasedReturnValue since the operand is a "
+                  "return value.\nOld: "<< *Retain << "\n");
+
+  // We do not have to worry about tail calls/does not throw since
+  // retain/retainRV have the same properties.
+  cast<CallInst>(Retain)->setCalledFunction(getRetainRVCallee(F.getParent()));
+
+  DEBUG(dbgs() << "New: " << *Retain << "\n");
+  return true;
+}
+
 /// Merge an autorelease with a retain into a fused call.
 bool
 ObjCARCContract::ContractAutorelease(Function &F, Instruction *Autorelease,
@@ -329,6 +385,7 @@ bool ObjCARCContract::doInitialization(M
   StoreStrongCallee = 0;
   RetainAutoreleaseCallee = 0;
   RetainAutoreleaseRVCallee = 0;
+  RetainRVCallee = 0;
 
   // Initialize RetainRVMarker.
   RetainRVMarker = 0;
@@ -380,7 +437,6 @@ bool ObjCARCContract::runOnFunction(Func
     // objc_retainBlock does not necessarily return its argument.
     InstructionClass Class = GetBasicInstructionClass(Inst);
     switch (Class) {
-    case IC_Retain:
     case IC_FusedRetainAutorelease:
     case IC_FusedRetainAutoreleaseRV:
       break;
@@ -389,6 +445,13 @@ bool ObjCARCContract::runOnFunction(Func
       if (ContractAutorelease(F, Inst, Class, DependingInstructions, Visited))
         continue;
       break;
+    case IC_Retain:
+      // Attempt to convert retains to retainrvs if they are next to function
+      // calls.
+      if (!OptimizeRetainCall(F, Inst))
+        break;
+      // If we succeed in our optimization, fall through.
+      // FALLTHROUGH
     case IC_RetainRV: {
       // If we're compiling for a target which needs a special inline-asm
       // marker to do the retainAutoreleasedReturnValue optimization,

Modified: llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp?rev=180698&r1=180697&r2=180698&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp (original)
+++ llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp Mon Apr 29 01:53:53 2013
@@ -997,9 +997,6 @@ namespace {
     /// them. These are initialized lazily to avoid cluttering up the Module
     /// with unused declarations.
 
-    /// Declaration for ObjC runtime function
-    /// objc_retainAutoreleasedReturnValue.
-    Constant *RetainRVCallee;
     /// Declaration for ObjC runtime function objc_autoreleaseReturnValue.
     Constant *AutoreleaseRVCallee;
     /// Declaration for ObjC runtime function objc_release.
@@ -1033,7 +1030,6 @@ namespace {
     unsigned ARCAnnotationProvenanceSourceMDKind;
 #endif // ARC_ANNOATIONS
 
-    Constant *getRetainRVCallee(Module *M);
     Constant *getAutoreleaseRVCallee(Module *M);
     Constant *getReleaseCallee(Module *M);
     Constant *getRetainCallee(Module *M);
@@ -1042,7 +1038,6 @@ namespace {
 
     bool IsRetainBlockOptimizable(const Instruction *Inst);
 
-    void OptimizeRetainCall(Function &F, Instruction *Retain);
     bool OptimizeRetainRVCall(Function &F, Instruction *RetainRV);
     void OptimizeAutoreleaseRVCall(Function &F, Instruction *AutoreleaseRV,
                                    InstructionClass &Class);
@@ -1152,22 +1147,6 @@ bool ObjCARCOpt::IsRetainBlockOptimizabl
   return true;
 }
 
-Constant *ObjCARCOpt::getRetainRVCallee(Module *M) {
-  if (!RetainRVCallee) {
-    LLVMContext &C = M->getContext();
-    Type *I8X = PointerType::getUnqual(Type::getInt8Ty(C));
-    Type *Params[] = { I8X };
-    FunctionType *FTy = FunctionType::get(I8X, Params, /*isVarArg=*/false);
-    AttributeSet Attribute =
-      AttributeSet().addAttribute(M->getContext(), AttributeSet::FunctionIndex,
-                                  Attribute::NoUnwind);
-    RetainRVCallee =
-      M->getOrInsertFunction("objc_retainAutoreleasedReturnValue", FTy,
-                             Attribute);
-  }
-  return RetainRVCallee;
-}
-
 Constant *ObjCARCOpt::getAutoreleaseRVCallee(Module *M) {
   if (!AutoreleaseRVCallee) {
     LLVMContext &C = M->getContext();
@@ -1247,35 +1226,6 @@ Constant *ObjCARCOpt::getAutoreleaseCall
   return AutoreleaseCallee;
 }
 
-/// Turn objc_retain into objc_retainAutoreleasedReturnValue if the operand is a
-/// return value.
-void
-ObjCARCOpt::OptimizeRetainCall(Function &F, Instruction *Retain) {
-  ImmutableCallSite CS(GetObjCArg(Retain));
-  const Instruction *Call = CS.getInstruction();
-  if (!Call) return;
-  if (Call->getParent() != Retain->getParent()) return;
-
-  // Check that the call is next to the retain.
-  BasicBlock::const_iterator I = Call;
-  ++I;
-  while (IsNoopInstruction(I)) ++I;
-  if (&*I != Retain)
-    return;
-
-  // Turn it to an objc_retainAutoreleasedReturnValue..
-  Changed = true;
-  ++NumPeeps;
-
-  DEBUG(dbgs() << "Transforming objc_retain => "
-                  "objc_retainAutoreleasedReturnValue since the operand is a "
-                  "return value.\nOld: "<< *Retain << "\n");
-
-  cast<CallInst>(Retain)->setCalledFunction(getRetainRVCallee(F.getParent()));
-
-  DEBUG(dbgs() << "New: " << *Retain << "\n");
-}
-
 /// Turn objc_retainAutoreleasedReturnValue into objc_retain if the operand is
 /// not a return value.  Or, if it can be paired with an
 /// objc_autoreleaseReturnValue, delete the pair and return true.
@@ -1493,7 +1443,6 @@ void ObjCARCOpt::OptimizeIndividualCalls
       // FALLTHROUGH
     case IC_Retain:
       ++NumRetainsBeforeOpt;
-      OptimizeRetainCall(F, Inst);
       break;
     case IC_RetainRV:
       if (OptimizeRetainRVCall(F, Inst))
@@ -3076,7 +3025,6 @@ bool ObjCARCOpt::doInitialization(Module
   // calls finalizers which can have arbitrary side effects.
 
   // These are initialized lazily.
-  RetainRVCallee = 0;
   AutoreleaseRVCallee = 0;
   ReleaseCallee = 0;
   RetainCallee = 0;

Modified: llvm/trunk/test/Transforms/ObjCARC/contract.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ObjCARC/contract.ll?rev=180698&r1=180697&r2=180698&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ObjCARC/contract.ll (original)
+++ llvm/trunk/test/Transforms/ObjCARC/contract.ll Mon Apr 29 01:53:53 2013
@@ -10,6 +10,7 @@ declare i8* @objc_retainAutoreleasedRetu
 
 declare void @use_pointer(i8*)
 declare i8* @returner()
+declare void @callee()
 
 ; CHECK: define void @test0
 ; CHECK: call void @use_pointer(i8* %0)
@@ -172,6 +173,60 @@ define void @test9(i8* %a, i8* %b) {
   ret void
 }
 
+
+; Turn objc_retain into objc_retainAutoreleasedReturnValue if its operand
+; is a return value.
+
+; CHECK: define void @test10()
+; CHECK: tail call i8* @objc_retainAutoreleasedReturnValue(i8* %p)
+define void @test10() {
+  %p = call i8* @returner()
+  tail call i8* @objc_retain(i8* %p) nounwind
+  ret void
+}
+
+; Convert objc_retain to objc_retainAutoreleasedReturnValue if its
+; argument is a return value.
+
+; CHECK: define void @test11(
+; CHECK-NEXT: %y = call i8* @returner()
+; CHECK-NEXT: tail call i8* @objc_retainAutoreleasedReturnValue(i8* %y) [[NUW]]
+; CHECK-NEXT: ret void
+define void @test11() {
+  %y = call i8* @returner()
+  tail call i8* @objc_retain(i8* %y) nounwind
+  ret void
+}
+
+; Don't convert objc_retain to objc_retainAutoreleasedReturnValue if its
+; argument is not a return value.
+
+; CHECK: define void @test12(
+; CHECK-NEXT: tail call i8* @objc_retain(i8* %y) [[NUW]]
+; CHECK-NEXT: ret void
+; CHECK-NEXT: }
+define void @test12(i8* %y) {
+  tail call i8* @objc_retain(i8* %y) nounwind
+  ret void
+}
+
+; Don't Convert objc_retain to objc_retainAutoreleasedReturnValue if it
+; isn't next to the call providing its return value.
+
+; CHECK: define void @test13(
+; CHECK-NEXT: %y = call i8* @returner()
+; CHECK-NEXT: call void @callee()
+; CHECK-NEXT: tail call i8* @objc_retain(i8* %y) [[NUW]]
+; CHECK-NEXT: ret void
+; CHECK-NEXT: }
+define void @test13() {
+  %y = call i8* @returner()
+  call void @callee()
+  tail call i8* @objc_retain(i8* %y) nounwind
+  ret void
+}
+
+
 declare void @clang.arc.use(...) nounwind
 
 ; CHECK: attributes [[NUW]] = { nounwind }

Modified: llvm/trunk/test/Transforms/ObjCARC/move-and-merge-autorelease.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ObjCARC/move-and-merge-autorelease.ll?rev=180698&r1=180697&r2=180698&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ObjCARC/move-and-merge-autorelease.ll (original)
+++ llvm/trunk/test/Transforms/ObjCARC/move-and-merge-autorelease.ll Mon Apr 29 01:53:53 2013
@@ -1,4 +1,4 @@
-; RUN: opt -S -objc-arc < %s | FileCheck %s
+; RUN: opt -S -objc-arc -objc-arc-contract < %s | FileCheck %s
 
 ; The optimizer should be able to move the autorelease past two phi nodes
 ; and fold it with the release in bb65.

Modified: llvm/trunk/test/Transforms/ObjCARC/rv.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ObjCARC/rv.ll?rev=180698&r1=180697&r2=180698&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ObjCARC/rv.ll (original)
+++ llvm/trunk/test/Transforms/ObjCARC/rv.ll Mon Apr 29 01:53:53 2013
@@ -136,17 +136,6 @@ define i8* @test7b() {
   ret i8* %p
 }
 
-; Turn objc_retain into objc_retainAutoreleasedReturnValue if its operand
-; is a return value.
-
-; CHECK: define void @test8()
-; CHECK: tail call i8* @objc_retainAutoreleasedReturnValue(i8* %p)
-define void @test8() {
-  %p = call i8* @returner()
-  call i8* @objc_retain(i8* %p)
-  ret void
-}
-
 ; Don't apply the RV optimization to autorelease if there's no retain.
 
 ; CHECK: define i8* @test9(i8* %p)
@@ -235,45 +224,6 @@ define void @test15() {
   ret void
 }
 
-; Convert objc_retain to objc_retainAutoreleasedReturnValue if its
-; argument is a return value.
-
-; CHECK: define void @test16(
-; CHECK-NEXT: %y = call i8* @returner()
-; CHECK-NEXT: tail call i8* @objc_retainAutoreleasedReturnValue(i8* %y) [[NUW]]
-; CHECK-NEXT: ret void
-define void @test16() {
-  %y = call i8* @returner()
-  call i8* @objc_retain(i8* %y)
-  ret void
-}
-
-; Don't convert objc_retain to objc_retainAutoreleasedReturnValue if its
-; argument is not a return value.
-
-; CHECK: define void @test17(
-; CHECK-NEXT: tail call i8* @objc_retain(i8* %y) [[NUW]]
-; CHECK-NEXT: ret void
-define void @test17(i8* %y) {
-  call i8* @objc_retain(i8* %y)
-  ret void
-}
-
-; Don't Convert objc_retain to objc_retainAutoreleasedReturnValue if it
-; isn't next to the call providing its return value.
-
-; CHECK: define void @test18(
-; CHECK-NEXT: %y = call i8* @returner()
-; CHECK-NEXT: call void @callee()
-; CHECK-NEXT: tail call i8* @objc_retain(i8* %y) [[NUW]]
-; CHECK-NEXT: ret void
-define void @test18() {
-  %y = call i8* @returner()
-  call void @callee()
-  call i8* @objc_retain(i8* %y)
-  ret void
-}
-
 ; Delete autoreleaseRV+retainRV pairs.
 
 ; CHECK: define i8* @test19(i8* %p) {





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