llvm-6502/test/CodeGen/X86/stack-align-memcpy.ll
Hans Wennborg 2f471c83a0 Check for dynamic allocas and inline asm that clobbers sp before building
selection dag (PR19012)

In X86SelectionDagInfo::EmitTargetCodeForMemcpy we check with MachineFrameInfo
to make sure that ESI isn't used as a base pointer register before we choose to
emit rep movs (which clobbers esi).

The problem is that MachineFrameInfo wouldn't know about dynamic allocas or
inline asm that clobbers the stack pointer until SelectionDAGBuilder has
encountered them.

This patch fixes the problem by checking for such things when building the
FunctionLoweringInfo.

Differential Revision: http://llvm-reviews.chandlerc.com/D2954

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202930 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-05 02:43:26 +00:00

44 lines
1.3 KiB
LLVM

; RUN: llc < %s -force-align-stack -mtriple i386-apple-darwin -mcpu=i486 | FileCheck %s
%struct.foo = type { [88 x i8] }
declare void @bar(i8* nocapture, %struct.foo* align 4 byval) nounwind
declare void @baz(i8*) nounwind
; PR15249
; We can't use rep;movsl here because it clobbers the base pointer in %esi.
define void @test1(%struct.foo* nocapture %x, i32 %y) nounwind {
%dynalloc = alloca i8, i32 %y, align 1
call void @bar(i8* %dynalloc, %struct.foo* align 4 byval %x)
ret void
; CHECK-LABEL: test1:
; CHECK: andl $-16, %esp
; CHECK: movl %esp, %esi
; CHECK-NOT: rep;movsl
}
; PR19012
; Also don't clobber %esi if the dynamic alloca comes after the memcpy.
define void @test2(%struct.foo* nocapture %x, i32 %y, i8* %z) nounwind {
call void @bar(i8* %z, %struct.foo* align 4 byval %x)
%dynalloc = alloca i8, i32 %y, align 1
call void @baz(i8* %dynalloc)
ret void
; CHECK-LABEL: test2:
; CHECK: movl %esp, %esi
; CHECK-NOT: rep;movsl
}
; Check that we do use rep movs if we make the alloca static.
define void @test3(%struct.foo* nocapture %x, i32 %y, i8* %z) nounwind {
call void @bar(i8* %z, %struct.foo* align 4 byval %x)
%statalloc = alloca i8, i32 8, align 1
call void @baz(i8* %statalloc)
ret void
; CHECK-LABEL: test3:
; CHECK: rep;movsl
}