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523f800e90
For functions where esi is used as base pointer, we would previously fall back from lowering memcpy with "rep movs" because that clobbers esi. With this patch, we just store esi in another physical register, and restore it afterwards. This adds a little bit of register preassure, but the more efficient memcpy should be worth it. Differential Revision: http://llvm-reviews.chandlerc.com/D2968 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204174 91177308-0d34-0410-b5e6-96231b3b80d8
49 lines
1.4 KiB
LLVM
49 lines
1.4 KiB
LLVM
; RUN: llc < %s -force-align-stack -mtriple i386-apple-darwin -mcpu=i486 | FileCheck %s
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%struct.foo = type { [88 x i8] }
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declare void @bar(i8* nocapture, %struct.foo* align 4 byval) nounwind
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declare void @baz(i8*) nounwind
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; PR15249
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; We can't use rep;movsl here because it clobbers the base pointer in %esi.
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define void @test1(%struct.foo* nocapture %x, i32 %y) nounwind {
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%dynalloc = alloca i8, i32 %y, align 1
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call void @bar(i8* %dynalloc, %struct.foo* align 4 byval %x)
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ret void
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; CHECK-LABEL: test1:
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; CHECK: andl $-16, %esp
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; CHECK: movl %esp, %esi
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; CHECK: movl %esi, %edx
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; CHECK: rep;movsl
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; CHECK: movl %edx, %esi
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}
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; PR19012
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; Also don't clobber %esi if the dynamic alloca comes after the memcpy.
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define void @test2(%struct.foo* nocapture %x, i32 %y, i8* %z) nounwind {
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call void @bar(i8* %z, %struct.foo* align 4 byval %x)
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%dynalloc = alloca i8, i32 %y, align 1
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call void @baz(i8* %dynalloc)
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ret void
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; CHECK-LABEL: test2:
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; CHECK: movl %esp, %esi
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; CHECK: movl %esi, %edx
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; CHECK: rep;movsl
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; CHECK: movl %edx, %esi
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}
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; Check that we do use rep movs if we make the alloca static.
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define void @test3(%struct.foo* nocapture %x, i32 %y, i8* %z) nounwind {
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call void @bar(i8* %z, %struct.foo* align 4 byval %x)
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%statalloc = alloca i8, i32 8, align 1
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call void @baz(i8* %statalloc)
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ret void
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; CHECK-LABEL: test3:
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; CHECK-NOT: movl %esi, %edx
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; CHECK: rep;movsl
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}
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