From 0299ff2d551e4b2c7e1703fed017a8de0f427b7f Mon Sep 17 00:00:00 2001 From: Bjorn Steinbrink Date: Thu, 20 Aug 2015 08:58:47 +0000 Subject: [PATCH] Revert "[DSE] Enable removal of lifetime intrinsics in terminating blocks" git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@245543 91177308-0d34-0410-b5e6-96231b3b80d8 --- .../Scalar/DeadStoreElimination.cpp | 33 ++---------- .../DeadStoreElimination/lifetime.ll | 53 +------------------ 2 files changed, 5 insertions(+), 81 deletions(-) diff --git a/lib/Transforms/Scalar/DeadStoreElimination.cpp b/lib/Transforms/Scalar/DeadStoreElimination.cpp index d64c5d24fc8..c8b0ea8c992 100644 --- a/lib/Transforms/Scalar/DeadStoreElimination.cpp +++ b/lib/Transforms/Scalar/DeadStoreElimination.cpp @@ -788,33 +788,15 @@ bool DSE::handleEndBlock(BasicBlock &BB) { const DataLayout &DL = BB.getModule()->getDataLayout(); - // becomes false once lifetime intrinsics are observable or useful for stack - // coloring - bool canRemoveLifetimeIntrinsics = true; - // Scan the basic block backwards for (BasicBlock::iterator BBI = BB.end(); BBI != BB.begin(); ){ --BBI; - Value *V = nullptr; - if (canRemoveLifetimeIntrinsics) - if (IntrinsicInst *II = dyn_cast(BBI)) - switch (II->getIntrinsicID()) { - default: break; - case Intrinsic::lifetime_start: - case Intrinsic::lifetime_end: - V = II->getArgOperand(1); - break; - } - - if (!V && hasMemoryWrite(BBI, *TLI) && isRemovable(BBI)) - V = getStoredPointerOperand(BBI); - - // If we found a store, check to see if it points into a dead stack value. - if (V) { + // If we find a store, check to see if it points into a dead stack value. + if (hasMemoryWrite(BBI, *TLI) && isRemovable(BBI)) { // See through pointer-to-pointer bitcasts SmallVector Pointers; - GetUnderlyingObjects(V, Pointers, DL); + GetUnderlyingObjects(getStoredPointerOperand(BBI), Pointers, DL); // Stores to stack values are valid candidates for removal. bool AllDead = true; @@ -862,15 +844,6 @@ bool DSE::handleEndBlock(BasicBlock &BB) { continue; } - if (IntrinsicInst *II = dyn_cast(BBI)) - if (II->getIntrinsicID() == Intrinsic::lifetime_start) { - // We found a lifetime start for a live object, which we could not - // remove. So we must stop removing lifetime intrinsics from this block - // because they're useful for stack coloring again - canRemoveLifetimeIntrinsics = false; - continue; - } - if (auto CS = CallSite(BBI)) { // Remove allocation function calls from the list of dead stack objects; // there can't be any references before the definition. diff --git a/test/Transforms/DeadStoreElimination/lifetime.ll b/test/Transforms/DeadStoreElimination/lifetime.ll index d68e9c0f51c..305c916dc02 100644 --- a/test/Transforms/DeadStoreElimination/lifetime.ll +++ b/test/Transforms/DeadStoreElimination/lifetime.ll @@ -5,16 +5,14 @@ target datalayout = "E-p:64:64:64-a0:0:8-f32:32:32-f64:64:64-i1:8:8-i8:8:8-i16:1 declare void @llvm.lifetime.start(i64, i8* nocapture) nounwind declare void @llvm.lifetime.end(i64, i8* nocapture) nounwind declare void @llvm.memset.p0i8.i8(i8* nocapture, i8, i8, i32, i1) nounwind -declare void @callee(i8*) define void @test1() { ; CHECK-LABEL: @test1( %A = alloca i8 store i8 0, i8* %A ;; Written to by memset -; CHECK-NOT: store call void @llvm.lifetime.end(i64 1, i8* %A) -; CHECK-NOT: lifetime.end +; CHECK: lifetime.end call void @llvm.memset.p0i8.i8(i8* %A, i8 0, i8 -1, i32 0, i1 false) ; CHECK-NOT: memset @@ -24,7 +22,7 @@ define void @test1() { } define void @test2(i32* %P) { -; CHECK-LABEL: test2 +; CHECK: test2 %Q = getelementptr i32, i32* %P, i32 1 %R = bitcast i32* %Q to i8* call void @llvm.lifetime.start(i64 4, i8* %R) @@ -36,51 +34,4 @@ define void @test2(i32* %P) { ret void } -define void @test3(i8*) { -; CHECK-LABEL: test3 - %a = alloca i8 - call void @llvm.lifetime.start(i64 1, i8* %a) -; CHECK-NOT: lifetime.start - call void @llvm.lifetime.end(i64 1, i8* %a) -; CHECK-NOT: lifetime.end - call void @llvm.lifetime.start(i64 1, i8* undef) -; CHECK-NOT: lifetime.start - call void @llvm.lifetime.end(i64 1, i8* undef) -; CHECK-NOT: lifetime.end - ret void -} - -define void @test4(i8*) { -; CHECK-LABEL: test4 - %a = alloca i8 - call void @llvm.lifetime.start(i64 1, i8* %a) -; CHECK: lifetime.start - call void @llvm.lifetime.end(i64 1, i8* %a) -; CHECK: lifetime.end - call void @llvm.lifetime.start(i64 1, i8* %0) -; CHECK: lifetime.start - call void @llvm.lifetime.end(i64 1, i8* %0) -; CHECK: lifetime.end - call void @llvm.lifetime.start(i64 1, i8* %a) -; CHECK-NOT: lifetime.start - call void @llvm.lifetime.end(i64 1, i8* %a) -; CHECK-NOT: lifetime.end - ret void -} -define void @test5() { -; CHECK-LABEL: test5 - %a = alloca i8 - %b = alloca i8 - call void @llvm.lifetime.start(i64 1, i8* %a) -; CHECK: lifetime.start - call void @llvm.lifetime.end(i64 1, i8* %a) -; CHECK: lifetime.end - call void @llvm.lifetime.start(i64 1, i8* %b) -; CHECK: lifetime.start - call void @callee(i8* %b) -; CHECK: call void @callee - call void @llvm.lifetime.end(i64 1, i8* %b) -; CHECK-NOT: lifetime.end - ret void -} -- 2.34.1