diff options
| -rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 28 | ||||
| -rw-r--r-- | test/Transforms/InstCombine/stacksaverestore.ll | 43 |
2 files changed, 58 insertions, 13 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 1ecefeb..9d0990f 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -8199,22 +8199,30 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) { } } - // If the stack restore is in a return/unwind block and if there are no - // allocas or calls between the restore and the return, nuke the restore. + // Scan down this block to see if there is another stack restore in the + // same block without an intervening call/alloca. + BasicBlock::iterator BI = II; TerminatorInst *TI = II->getParent()->getTerminator(); - if (isa<ReturnInst>(TI) || isa<UnwindInst>(TI)) { - BasicBlock::iterator BI = II; - bool CannotRemove = false; - for (++BI; &*BI != TI; ++BI) { - if (isa<AllocaInst>(BI) || - (isa<CallInst>(BI) && !isa<IntrinsicInst>(BI))) { + bool CannotRemove = false; + for (++BI; &*BI != TI; ++BI) { + if (isa<AllocaInst>(BI)) { + CannotRemove = true; + break; + } + if (isa<CallInst>(BI)) { + if (!isa<IntrinsicInst>(BI)) { CannotRemove = true; break; } - } - if (!CannotRemove) + // If there is a stackrestore below this one, remove this one. return EraseInstFromFunction(CI); + } } + + // If the stack restore is in a return/unwind block and if there are no + // allocas or calls between the restore and the return, nuke the restore. + if (!CannotRemove && (isa<ReturnInst>(TI) || isa<UnwindInst>(TI))) + return EraseInstFromFunction(CI); break; } } diff --git a/test/Transforms/InstCombine/stacksaverestore.ll b/test/Transforms/InstCombine/stacksaverestore.ll index 29001a0..c82a425 100644 --- a/test/Transforms/InstCombine/stacksaverestore.ll +++ b/test/Transforms/InstCombine/stacksaverestore.ll @@ -1,4 +1,7 @@ -; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep {call.*stackrestore} +; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {call.*stackrestore} | count 1 + +declare i8* @llvm.stacksave() +declare void @llvm.stackrestore(i8*) ;; Test that llvm.stackrestore is removed when possible. define i32* @test1(i32 %P) { @@ -13,7 +16,41 @@ define void @test2(i8* %X) { ret void } -declare i8* @llvm.stacksave() +define void @foo(i32 %size) nounwind { +entry: + %tmp118124 = icmp sgt i32 %size, 0 ; <i1> [#uses=1] + br i1 %tmp118124, label %bb.preheader, label %return -declare void @llvm.stackrestore(i8*) +bb.preheader: ; preds = %entry + %tmp25 = add i32 %size, -1 ; <i32> [#uses=1] + %tmp125 = icmp slt i32 %size, 1 ; <i1> [#uses=1] + %smax = select i1 %tmp125, i32 1, i32 %size ; <i32> [#uses=1] + br label %bb + +bb: ; preds = %bb, %bb.preheader + %i.0.reg2mem.0 = phi i32 [ 0, %bb.preheader ], [ %indvar.next, %bb ] ; <i32> [#uses=2] + %tmp = call i8* @llvm.stacksave( ) ; <i8*> [#uses=1] + %tmp23 = alloca i8, i32 %size ; <i8*> [#uses=2] + %tmp27 = getelementptr i8* %tmp23, i32 %tmp25 ; <i8*> [#uses=1] + store i8 0, i8* %tmp27, align 1 + %tmp28 = call i8* @llvm.stacksave( ) ; <i8*> [#uses=1] + %tmp52 = alloca i8, i32 %size ; <i8*> [#uses=1] + %tmp53 = call i8* @llvm.stacksave( ) ; <i8*> [#uses=1] + %tmp77 = alloca i8, i32 %size ; <i8*> [#uses=1] + %tmp78 = call i8* @llvm.stacksave( ) ; <i8*> [#uses=1] + %tmp102 = alloca i8, i32 %size ; <i8*> [#uses=1] + call void @bar( i32 %i.0.reg2mem.0, i8* %tmp23, i8* %tmp52, i8* %tmp77, i8* %tmp102, i32 %size ) nounwind + call void @llvm.stackrestore( i8* %tmp78 ) + call void @llvm.stackrestore( i8* %tmp53 ) + call void @llvm.stackrestore( i8* %tmp28 ) + call void @llvm.stackrestore( i8* %tmp ) + %indvar.next = add i32 %i.0.reg2mem.0, 1 ; <i32> [#uses=2] + %exitcond = icmp eq i32 %indvar.next, %smax ; <i1> [#uses=1] + br i1 %exitcond, label %return, label %bb + +return: ; preds = %bb, %entry + ret void +} + +declare void @bar(i32, i8*, i8*, i8*, i8*, i32) |