llvm/test/CodeGen/ARM/thumb2-it-block.ll
Manman Ren 307473dec0 ARM: optimization for sub+abs.
This patch will optimize abs(x-y)
FROM
sub, movs, rsbmi
TO
subs, rsbmi

For abs, we will use cmp instead of movs. This is necessary because we already
have an existing peephole pass which optimizes away cmp following sub.

rdar: 11633193


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158551 91177308-0d34-0410-b5e6-96231b3b80d8
2012-06-15 21:32:12 +00:00

21 lines
493 B
LLVM

; RUN: llc < %s -march=thumb -mattr=+thumb2 | FileCheck %s
; PR11107
define i32 @test(i32 %a, i32 %b) {
entry:
; CHECK: cmp
; CHECK-NEXT: it mi
; CHECK-NEXT: rsbmi
; CHECK-NEXT: cmp
; CHECK-NEXT: it mi
; CHECK-NEXT: rsbmi
%cmp1 = icmp slt i32 %a, 0
%sub1 = sub nsw i32 0, %a
%abs1 = select i1 %cmp1, i32 %sub1, i32 %a
%cmp2 = icmp slt i32 %b, 0
%sub2 = sub nsw i32 0, %b
%abs2 = select i1 %cmp2, i32 %sub2, i32 %b
%add = add nsw i32 %abs1, %abs2
ret i32 %add
}