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llvm-mirror/test/CodeGen/X86/i686-win-shrink-wrapping.ll
Quentin Colombet c01de3fc6a [X86] Make sure it is safe to clobber EFLAGS, if need be, when choosing
the prologue.

Do not use basic blocks that have EFLAGS live-in as prologue if we need
to realign the stack. Realigning the stack uses AND instruction and this
clobbers EFLAGS.

An other alternative would have been to save and restore EFLAGS around
the stack realignment code, but this is likely inefficient.

Fixes PR27531.

llvm-svn: 267634
2016-04-26 23:44:14 +00:00

45 lines
1.7 KiB
LLVM

; RUN: llc %s -o - -enable-shrink-wrap=true | FileCheck %s --check-prefix=CHECK --check-prefix=ENABLE
; RUN: llc %s -o - -enable-shrink-wrap=false | FileCheck %s --check-prefix=CHECK --check-prefix=DISABLE
target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
target triple = "i686-pc-windows-msvc18.0.0"
%struct.S = type { i32 }
; Check that we do not use a basic block that has EFLAGS as live-in
; if we need to realign the stack.
; PR27531.
; CHECK-LABEL: stackRealignment:
; Prologue code.
; CHECK: pushl
; Make sure we actually perform some stack realignment.
; CHECK: andl ${{[-0-9]+}}, %esp
; This is the end of the entry block.
; The prologue should have happened before that point because past
; this point, EFLAGS is live.
; CHECK: jg
define x86_thiscallcc void @stackRealignment(%struct.S* %this) {
entry:
%data = alloca [1 x i32], align 4
%d = alloca double, align 8
%tmp = bitcast [1 x i32]* %data to i8*
%arrayinit.begin = getelementptr inbounds [1 x i32], [1 x i32]* %data, i32 0, i32 0
%x_ = getelementptr inbounds %struct.S, %struct.S* %this, i32 0, i32 0
%tmp1 = load i32, i32* %x_, align 4
%cmp = icmp sgt i32 %tmp1, 32
%cond = select i1 %cmp, i32 42, i32 128
store i32 %cond, i32* %arrayinit.begin, align 4
%cmp3 = icmp slt i32 %tmp1, 32
br i1 %cmp3, label %cleanup, label %if.end
if.end: ; preds = %entry
%tmp2 = bitcast double* %d to i8*
call x86_thiscallcc void @bar(%struct.S* nonnull %this, i32* %arrayinit.begin, double* nonnull %d)
br label %cleanup
cleanup: ; preds = %if.end, %entry
ret void
}
; Function Attrs: optsize
declare x86_thiscallcc void @bar(%struct.S*, i32*, double*)