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dcf4c81cd2
This introduces a custom lowering for ISD::SETCCE (introduced in r253572)
that allows us to emit a short code sequence for 64-bit compares.
Before:
push {r7, lr}
cmp r0, r2
mov.w r0, #0
mov.w r12, #0
it hs
movhs r0, #1
cmp r1, r3
it ge
movge.w r12, #1
it eq
moveq r12, r0
cmp.w r12, #0
bne .LBB1_2
@ BB#1: @ %bb1
bl f
pop {r7, pc}
.LBB1_2: @ %bb2
bl g
pop {r7, pc}
After:
push {r7, lr}
subs r0, r0, r2
sbcs.w r0, r1, r3
bge .LBB1_2
@ BB#1: @ %bb1
bl f
pop {r7, pc}
.LBB1_2: @ %bb2
bl g
pop {r7, pc}
Saves around 80KB in Chromium's libchrome.so.
Some notes on this patch:
- I don't much like the ARMISD::BRCOND and ARMISD::CMOV combines I
introduced (nothing else needs them). However, they are necessary in
order to avoid poor codegen, and they seem similar to existing combines
in other backends (e.g. X86 combines (brcond (cmp (setcc Compare))) to
(brcond Compare)).
- No support for Thumb-1. This is in principle possible, but we'd need
to implement ARMISD::SUBE for Thumb-1.
Differential Revision: http://reviews.llvm.org/D15256
llvm-svn: 263962
53 lines
1.4 KiB
LLVM
53 lines
1.4 KiB
LLVM
; RUN: llc -mtriple=armv7-unknown-linux < %s | FileCheck --check-prefix=CHECK --check-prefix=CHECK-ARM %s
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; RUN: llc -mtriple=thumbv6-unknown-linux < %s | FileCheck --check-prefix=CHECK-THUMB1 %s
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; RUN: llc -mtriple=thumbv7-unknown-linux < %s | FileCheck --check-prefix=CHECK --check-prefix=CHECK-THUMB2 %s
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; CHECK-THUMB1-NOT: sbc
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; CHECK-LABEL: test_slt1:
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define i32 @test_slt1(i64 %a, i64 %b) {
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entry:
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; CHECK-ARM: subs {{[^,]+}}, r0, r2
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; CHECK-ARM: mov [[TMP:[0-9a-z]+]], #2
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; CHECK-ARM: sbcs {{[^,]+}}, r1, r3
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; CHECK-ARM: movwlt [[TMP]], #1
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; CHECK-ARM: mov r0, [[TMP]]
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; CHECK-ARM: bx lr
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; CHECK-THUMB2: subs {{[^,]+}}, r0, r2
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; CHECK-THUMB2: mov.w [[TMP:[0-9a-z]+]], #2
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; CHECK-THUMB2: sbcs.w {{[^,]+}}, r1, r3
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; CHECK-THUMB2: it lt
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; CHECK-THUMB2: movlt.w [[TMP]], #1
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; CHECK-THUMB2: mov r0, [[TMP]]
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; CHECK-THUMB2: bx lr
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%cmp = icmp slt i64 %a, %b
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br i1 %cmp, label %bb1, label %bb2
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bb1:
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ret i32 1
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bb2:
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ret i32 2
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}
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; CHECK-LABEL: test_slt2:
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define void @test_slt2(i64 %a, i64 %b) {
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entry:
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%cmp = icmp slt i64 %a, %b
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; CHECK-ARM: subs {{[^,]+}}, r0, r2
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; CHECK-ARM: sbcs {{[^,]+}}, r1, r3
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; CHECK-THUMB2: subs {{[^,]+}}, r0, r2
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; CHECK-THUMB2: sbcs.w {{[^,]+}}, r1, r3
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; CHECK: bge [[BB2:\.[0-9A-Za-z_]+]]
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br i1 %cmp, label %bb1, label %bb2
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bb1:
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call void @f()
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ret void
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bb2:
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; CHECK: [[BB2]]:
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; CHECK-NEXT: bl g
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call void @g()
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ret void
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}
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declare void @f()
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declare void @g()
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