From 7ee3ca10f53aacce1f3aa052f81f9598ac09db33 Mon Sep 17 00:00:00 2001 From: Jakob Stoklund Olesen Date: Fri, 22 Jun 2012 16:36:43 +0000 Subject: [PATCH] Revert remaining part of r93200: "Disable folding sext(trunc(x)) -> x" This fixes PR5997. These transforms were disabled because codegen couldn't deal with other uses of trunc(x). This is now handled by the peephole pass. This causes no regressions on x86-64. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159003 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/InstCombine/InstCombineCasts.cpp | 13 ++++--------- test/Transforms/InstCombine/trunc.ll | 13 +++++++------ 2 files changed, 11 insertions(+), 15 deletions(-) diff --git a/lib/Transforms/InstCombine/InstCombineCasts.cpp b/lib/Transforms/InstCombine/InstCombineCasts.cpp index fa24800717e..555b4428d2e 100644 --- a/lib/Transforms/InstCombine/InstCombineCasts.cpp +++ b/lib/Transforms/InstCombine/InstCombineCasts.cpp @@ -648,10 +648,8 @@ static bool CanEvaluateZExtd(Value *V, Type *Ty, unsigned &BitsToClear) { if (!I) return false; // If the input is a truncate from the destination type, we can trivially - // eliminate it, even if it has multiple uses. - // FIXME: This is currently disabled until codegen can handle this without - // pessimizing code, PR5997. - if (0 && isa(I) && I->getOperand(0)->getType() == Ty) + // eliminate it. + if (isa(I) && I->getOperand(0)->getType() == Ty) return true; // We can't extend or shrink something that has multiple uses: doing so would @@ -992,11 +990,8 @@ static bool CanEvaluateSExtd(Value *V, Type *Ty) { Instruction *I = dyn_cast(V); if (!I) return false; - // If this is a truncate from the dest type, we can trivially eliminate it, - // even if it has multiple uses. - // FIXME: This is currently disabled until codegen can handle this without - // pessimizing code, PR5997. - if (0 && isa(I) && I->getOperand(0)->getType() == Ty) + // If this is a truncate from the dest type, we can trivially eliminate it. + if (isa(I) && I->getOperand(0)->getType() == Ty) return true; // We can't extend or shrink something that has multiple uses: doing so would diff --git a/test/Transforms/InstCombine/trunc.ll b/test/Transforms/InstCombine/trunc.ll index 6ec342a4f5c..cbbad7f7977 100644 --- a/test/Transforms/InstCombine/trunc.ll +++ b/test/Transforms/InstCombine/trunc.ll @@ -12,8 +12,8 @@ define i64 @test1(i64 %a) { call void @use(i32 %b) ret i64 %d ; CHECK: @test1 -; CHECK: %d = and i64 %a, 15 -; CHECK: ret i64 %d +; CHECK-NOT: ext +; CHECK: ret } define i64 @test2(i64 %a) { %b = trunc i64 %a to i32 @@ -34,8 +34,8 @@ define i64 @test3(i64 %a) { call void @use(i32 %b) ret i64 %d ; CHECK: @test3 -; CHECK: %d = and i64 %a, 8 -; CHECK: ret i64 %d +; CHECK-NOT: ext +; CHECK: ret } define i64 @test4(i64 %a) { %b = trunc i64 %a to i32 @@ -46,8 +46,9 @@ define i64 @test4(i64 %a) { ret i64 %d ; CHECK: @test4 ; CHECK: = and i64 %a, 8 -; CHECK: %d = xor i64 {{.*}}, 8 -; CHECK: ret i64 %d +; CHECK: = xor i64 {{.*}}, 8 +; CHECK-NOT: ext +; CHECK: ret } define i32 @test5(i32 %A) { -- 2.34.1