[PATCH] Ignore lifetime intrinsics in use list for MemCpyOptimizer.

[Luqman Aden]

Ping


On Thu, Aug 21, 2014 at 9:28 PM, Luqman Aden <me+llvm at luqman.ca> wrote:

> Lifetime intrinsics were preventing various optimizations like turning
> memset+memcpy to just memset.
>
> http://reviews.llvm.org/D5020
>
> Files:
>   lib/Transforms/Scalar/MemCpyOptimizer.cpp
>   test/Transforms/MemCpyOpt/memcpy-to-memset-with-lifetimes.ll
>
> Index: lib/Transforms/Scalar/MemCpyOptimizer.cpp
> ===================================================================
> --- lib/Transforms/Scalar/MemCpyOptimizer.cpp
> +++ lib/Transforms/Scalar/MemCpyOptimizer.cpp
> @@ -679,6 +679,10 @@
>            srcUseList.push_back(UU);
>        else
>          return false;
> +    } else if (const IntrinsicInst *IT = dyn_cast<IntrinsicInst>(U)) {
> +      if (IT->getIntrinsicID() != Intrinsic::lifetime_start &&
> +          IT->getIntrinsicID() != Intrinsic::lifetime_end)
> +        continue;
>      } else if (U != C && U != cpy) {
>        return false;
>      }
> Index: test/Transforms/MemCpyOpt/memcpy-to-memset-with-lifetimes.ll
> ===================================================================
> --- test/Transforms/MemCpyOpt/memcpy-to-memset-with-lifetimes.ll
> +++ test/Transforms/MemCpyOpt/memcpy-to-memset-with-lifetimes.ll
> @@ -0,0 +1,28 @@
> +; RUN: opt -basicaa -memcpyopt -instcombine -S < %s | FileCheck %s
> +
> +target datalayout = "e-i64:64-f80:128-n8:16:32:64-S128"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> +define void @foo([8 x i64]* noalias nocapture sret dereferenceable(64)) {
> +entry-block:
> +  %a = alloca [8 x i64], align 8
> +  %1 = bitcast [8 x i64]* %a to i8*
> +  call void @llvm.lifetime.start(i64 64, i8* %1)
> +  call void @llvm.memset.p0i8.i64(i8* %1, i8 0, i64 64, i32 8, i1 false)
> +  %2 = bitcast [8 x i64]* %0 to i8*
> +  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %2, i8* %1, i64 64, i32 8, i1
> false)
> +  call void @llvm.lifetime.end(i64 64, i8* %1)
> +  ret void
> +
> +; CHECK-LABEL: @foo(
> +; CHECK: %1 = bitcast
> +; CHECK: call void @llvm.memset
> +; CHECK-NOT: call void @llvm.memcpy
> +; CHECK: ret void
> +}
> +
> +declare void @llvm.lifetime.start(i64, i8* nocapture) nounwind
> +declare void @llvm.lifetime.end(i64, i8* nocapture) nounwind
> +
> +declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture
> readonly, i64, i32, i1) nounwind
> +declare void @llvm.memset.p0i8.i64(i8* nocapture, i8, i64, i32, i1)
> nounwind
>
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