llvm/test/CodeGen/X86/clobber-fi0.ll
Nadav Rotem d0696ef8c3 In some cases, due to scheduling constraints we copy the EFLAGS.
The only way to read the eflags is using push and pop. If we don't
adjust the stack then we run over the first frame index. This is
not something that we want to do, so we have to make sure that
our machine function does not copy the flags. If it does then
we have to emit the prolog that adjusts the stack.

rdar://12896831



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170961 91177308-0d34-0410-b5e6-96231b3b80d8
2012-12-21 23:48:49 +00:00

38 lines
1.5 KiB
LLVM

; RUN: llc < %s -mcpu=generic -mtriple=x86_64-linux | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.7.0"
; In the code below we need to copy the EFLAGS because of scheduling constraints.
; When copying the EFLAGS we need to write to the stack with push/pop. This forces
; us to emit the prolog.
; CHECK: main
; CHECK: subq{{.*}}rsp
; CHECK: ret
define i32 @main(i32 %arg, i8** %arg1) nounwind {
bb:
%tmp = alloca i32, align 4 ; [#uses=3 type=i32*]
%tmp2 = alloca i32, align 4 ; [#uses=3 type=i32*]
%tmp3 = alloca i32 ; [#uses=1 type=i32*]
store i32 1, i32* %tmp, align 4
store i32 1, i32* %tmp2, align 4
br label %bb4
bb4: ; preds = %bb4, %bb
%tmp6 = load i32* %tmp2, align 4 ; [#uses=1 type=i32]
%tmp7 = add i32 %tmp6, -1 ; [#uses=2 type=i32]
store i32 %tmp7, i32* %tmp2, align 4
%tmp8 = icmp eq i32 %tmp7, 0 ; [#uses=1 type=i1]
%tmp9 = load i32* %tmp ; [#uses=1 type=i32]
%tmp10 = add i32 %tmp9, -1 ; [#uses=1 type=i32]
store i32 %tmp10, i32* %tmp3
br i1 %tmp8, label %bb11, label %bb4
bb11: ; preds = %bb4
%tmp12 = load i32* %tmp, align 4 ; [#uses=1 type=i32]
ret i32 %tmp12
}