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48e4d991e8
The arm condition codes for GE is N==V (and for LT is N!=V). If the source of flags cannot set V (overflow), such as a cmp against #0, then we can use the simpler PL and MI conditions that only check N. As these PL/MI conditions are simpler than GE/LT, other passes like the peephole optimiser can have a better time optimising away the redundant CMPs. The exception is the VSEL instruction, which cannot take the PL code, so there the transform favours GE. Differential Revision: https://reviews.llvm.org/D64160 llvm-svn: 365117
74 lines
2.1 KiB
LLVM
74 lines
2.1 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
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; RUN: llc -mtriple=arm-eabi %s -o - | FileCheck %s
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; RUN: llc -mtriple=armv6m-eabi %s -o - | FileCheck %s --check-prefix=EXPAND
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define i64 @test_shl(i64 %val, i64 %amt) {
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; CHECK-LABEL: test_shl:
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; CHECK: @ %bb.0:
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; CHECK-NEXT: rsb r3, r2, #32
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; CHECK-NEXT: lsr r3, r0, r3
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; CHECK-NEXT: orr r1, r3, r1, lsl r2
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; CHECK-NEXT: subs r3, r2, #32
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; CHECK-NEXT: lslpl r1, r0, r3
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; CHECK-NEXT: lsl r0, r0, r2
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; CHECK-NEXT: movpl r0, #0
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; CHECK-NEXT: mov pc, lr
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;
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; EXPAND-LABEL: test_shl:
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; EXPAND: @ %bb.0:
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; EXPAND-NEXT: .save {r7, lr}
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; EXPAND-NEXT: push {r7, lr}
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; EXPAND-NEXT: bl __aeabi_llsl
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; EXPAND-NEXT: pop {r7, pc}
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%res = shl i64 %val, %amt
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ret i64 %res
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}
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; Explanation for lshr is pretty much the reverse of shl.
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define i64 @test_lshr(i64 %val, i64 %amt) {
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; CHECK-LABEL: test_lshr:
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; CHECK: @ %bb.0:
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; CHECK-NEXT: rsb r3, r2, #32
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; CHECK-NEXT: lsr r0, r0, r2
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; CHECK-NEXT: orr r0, r0, r1, lsl r3
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; CHECK-NEXT: subs r3, r2, #32
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; CHECK-NEXT: lsrpl r0, r1, r3
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; CHECK-NEXT: lsr r1, r1, r2
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; CHECK-NEXT: movpl r1, #0
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; CHECK-NEXT: mov pc, lr
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;
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; EXPAND-LABEL: test_lshr:
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; EXPAND: @ %bb.0:
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; EXPAND-NEXT: .save {r7, lr}
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; EXPAND-NEXT: push {r7, lr}
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; EXPAND-NEXT: bl __aeabi_llsr
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; EXPAND-NEXT: pop {r7, pc}
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%res = lshr i64 %val, %amt
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ret i64 %res
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}
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; One minor difference for ashr: the high bits must be "hi >> 31" if the shift
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; amount is large to get the right sign bit.
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define i64 @test_ashr(i64 %val, i64 %amt) {
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; CHECK-LABEL: test_ashr:
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; CHECK: @ %bb.0:
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; CHECK-NEXT: asr r3, r1, r2
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; CHECK-NEXT: subs r12, r2, #32
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; CHECK-NEXT: lsr r0, r0, r2
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; CHECK-NEXT: rsb r2, r2, #32
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; CHECK-NEXT: asrpl r3, r1, #31
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; CHECK-NEXT: orr r0, r0, r1, lsl r2
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; CHECK-NEXT: asrpl r0, r1, r12
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; CHECK-NEXT: mov r1, r3
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; CHECK-NEXT: mov pc, lr
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;
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; EXPAND-LABEL: test_ashr:
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; EXPAND: @ %bb.0:
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; EXPAND-NEXT: .save {r7, lr}
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; EXPAND-NEXT: push {r7, lr}
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; EXPAND-NEXT: bl __aeabi_lasr
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; EXPAND-NEXT: pop {r7, pc}
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%res = ashr i64 %val, %amt
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ret i64 %res
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}
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