From 9236362a64ce1609222512fe3f17eeb886a3ddea Mon Sep 17 00:00:00 2001
From: Manman Ren <mren@apple.com>
Date: Thu, 7 Jun 2012 22:39:10 +0000
Subject: X86: optimize generated code for integer ABS

This patch will generate the following for integer ABS:
      movl    %edi, %eax
      negl    %eax
      cmovll  %edi, %eax
INSTEAD OF
      movl    %edi, %ecx
      sarl    $31, %ecx
      leal    (%rdi,%rcx), %eax
      xorl    %ecx, %eax

There exists a target-independent DAG combine for integer ABS, which converts
integer ABS to sar+add+xor. For X86, we match this pattern back to neg+cmov.
This is implemented in PerformXorCombine.

rdar://10695237


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158175 91177308-0d34-0410-b5e6-96231b3b80d8
---
 test/CodeGen/X86/iabs.ll | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

(limited to 'test/CodeGen/X86/iabs.ll')

diff --git a/test/CodeGen/X86/iabs.ll b/test/CodeGen/X86/iabs.ll
index a8ba015..9196cce 100644
--- a/test/CodeGen/X86/iabs.ll
+++ b/test/CodeGen/X86/iabs.ll
@@ -1,13 +1,17 @@
-; RUN: llc < %s -march=x86-64 -stats  |& \
-; RUN:   grep {5 .*Number of machine instrs printed}
+; RUN: llc < %s -march=x86-64 | FileCheck %s
 
 ;; Integer absolute value, should produce something at least as good as:
-;;       movl %edi, %ecx
-;;       sarl $31, %ecx
-;;       leal (%rdi,%rcx), %eax
-;;       xorl %ecx, %eax
+;;       movl   %edi, %eax
+;;       negl   %eax
+;;       cmovll %edi, %eax
 ;;       ret
+; rdar://10695237
 define i32 @test(i32 %a) nounwind {
+; CHECK: test:
+; CHECK: mov
+; CHECK-NEXT: neg
+; CHECK-NEXT: cmov
+; CHECK-NEXT: ret
         %tmp1neg = sub i32 0, %a
         %b = icmp sgt i32 %a, -1
         %abs = select i1 %b, i32 %a, i32 %tmp1neg
-- 
cgit v1.1