diff options
| -rw-r--r-- | lib/Transforms/ObjCARC/ObjCARCOpts.cpp | 55 | ||||
| -rw-r--r-- | test/Transforms/ObjCARC/basic.ll | 4 | ||||
| -rw-r--r-- | test/Transforms/ObjCARC/no-objc-arc-exceptions.ll | 7 |
3 files changed, 51 insertions, 15 deletions
diff --git a/lib/Transforms/ObjCARC/ObjCARCOpts.cpp b/lib/Transforms/ObjCARC/ObjCARCOpts.cpp index a21d92e..8e076e0 100644 --- a/lib/Transforms/ObjCARC/ObjCARCOpts.cpp +++ b/lib/Transforms/ObjCARC/ObjCARCOpts.cpp @@ -986,6 +986,8 @@ namespace { bool OptimizeRetainRVCall(Function &F, Instruction *RetainRV); void OptimizeAutoreleaseRVCall(Function &F, Instruction *AutoreleaseRV, InstructionClass &Class); + bool OptimizeRetainBlockCall(Function &F, Instruction *RetainBlock, + InstructionClass &Class); void OptimizeIndividualCalls(Function &F); void CheckForCFGHazards(const BasicBlock *BB, @@ -1319,6 +1321,35 @@ ObjCARCOpt::OptimizeAutoreleaseRVCall(Function &F, Instruction *AutoreleaseRV, } +// \brief Attempt to strength reduce objc_retainBlock calls to objc_retain +// calls. +// +// Specifically: If an objc_retainBlock call has the copy_on_escape metadata and +// does not escape (following the rules of block escaping), strength reduce the +// objc_retainBlock to an objc_retain. +// +// TODO: If an objc_retainBlock call is dominated period by a previous +// objc_retainBlock call, strength reduce the objc_retainBlock to an +// objc_retain. +bool +ObjCARCOpt::OptimizeRetainBlockCall(Function &F, Instruction *Inst, + InstructionClass &Class) { + assert(GetBasicInstructionClass(Inst) == Class); + assert(IC_RetainBlock == Class); + + // If we can not optimize Inst, return false. + if (!IsRetainBlockOptimizable(Inst)) + return false; + + CallInst *RetainBlock = cast<CallInst>(Inst); + RetainBlock->setCalledFunction(getRetainCallee(F.getParent())); + // Remove copy_on_escape metadata. + RetainBlock->setMetadata(CopyOnEscapeMDKind, 0); + Class = IC_Retain; + + return true; +} + /// Visit each call, one at a time, and make simplifications without doing any /// additional analysis. void ObjCARCOpt::OptimizeIndividualCalls(Function &F) { @@ -1402,6 +1433,12 @@ void ObjCARCOpt::OptimizeIndividualCalls(Function &F) { } break; } + case IC_RetainBlock: + // If we strength reduce an objc_retainBlock to amn objc_retain, continue + // onto the objc_retain peephole optimizations. Otherwise break. + if (!OptimizeRetainBlockCall(F, Inst, Class)) + break; + // FALLTHROUGH case IC_Retain: OptimizeRetainCall(F, Inst); break; @@ -1748,11 +1785,10 @@ ObjCARCOpt::VisitInstructionBottomUp(Instruction *Inst, break; } case IC_RetainBlock: - // An objc_retainBlock call with just a use may need to be kept, - // because it may be copying a block from the stack to the heap. - if (!IsRetainBlockOptimizable(Inst)) - break; - // FALLTHROUGH + // In OptimizeIndividualCalls, we have strength reduced all optimizable + // objc_retainBlocks to objc_retains. Thus at this point any + // objc_retainBlocks that we see are not optimizable. + break; case IC_Retain: case IC_RetainRV: { Arg = GetObjCArg(Inst); @@ -1961,11 +1997,10 @@ ObjCARCOpt::VisitInstructionTopDown(Instruction *Inst, switch (Class) { case IC_RetainBlock: - // An objc_retainBlock call with just a use may need to be kept, - // because it may be copying a block from the stack to the heap. - if (!IsRetainBlockOptimizable(Inst)) - break; - // FALLTHROUGH + // In OptimizeIndividualCalls, we have strength reduced all optimizable + // objc_retainBlocks to objc_retains. Thus at this point any + // objc_retainBlocks that we see are not optimizable. + break; case IC_Retain: case IC_RetainRV: { Arg = GetObjCArg(Inst); diff --git a/test/Transforms/ObjCARC/basic.ll b/test/Transforms/ObjCARC/basic.ll index 4c24ebf..bf6ccc8 100644 --- a/test/Transforms/ObjCARC/basic.ll +++ b/test/Transforms/ObjCARC/basic.ll @@ -795,10 +795,10 @@ entry: ret void } -; Don't optimize objc_retainBlock. +; Don't optimize objc_retainBlock, but do strength reduce it. ; CHECK: define void @test23b -; CHECK: @objc_retainBlock +; CHECK: @objc_retain ; CHECK: @objc_release ; CHECK: } define void @test23b(i8* %p) { diff --git a/test/Transforms/ObjCARC/no-objc-arc-exceptions.ll b/test/Transforms/ObjCARC/no-objc-arc-exceptions.ll index 9728f6e..58b5bbe 100644 --- a/test/Transforms/ObjCARC/no-objc-arc-exceptions.ll +++ b/test/Transforms/ObjCARC/no-objc-arc-exceptions.ll @@ -59,11 +59,12 @@ lpad: ; preds = %entry resume { i8*, i32 } %t8 } -; There is no !clang.arc.no_objc_arc_exceptions -; metadata here, so the optimizer shouldn't eliminate anything. +; There is no !clang.arc.no_objc_arc_exceptions metadata here, so the optimizer +; shouldn't eliminate anything, but *CAN* strength reduce the objc_retainBlock +; to an objc_retain. ; CHECK: define void @test0_no_metadata( -; CHECK: call i8* @objc_retainBlock( +; CHECK: call i8* @objc_retain( ; CHECK: invoke ; CHECK: call void @objc_release( ; CHECK: } |