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[GlobalISel] Add lowering support for G_ABS and use for AArch64. 

Differential Revision: https://reviews.llvm.org/D87952
This commit is contained in:
Amara Emerson 2020-09-18 15:13:12 -07:00
parent 37e7673c21
commit 5d34d7f1a0
4 changed files with 55 additions and 2 deletions
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16
llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
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@ -3090,6 +3090,22 @@ LegalizerHelper::lower(MachineInstr &MI, unsigned TypeIdx, LLT LowerHintTy) {
case G_SSHLSAT:
case G_USHLSAT:
return lowerShlSat(MI);
case G_ABS: {
// Expand %res = G_ABS %a into:
// %v1 = G_ASHR %a, scalar_size-1
// %v2 = G_ADD %a, %v1
// %res = G_XOR %v2, %v1
LLT DstTy = MRI.getType(MI.getOperand(0).getReg());
Register OpReg = MI.getOperand(1).getReg();
auto ShiftAmt =
MIRBuilder.buildConstant(DstTy, DstTy.getScalarSizeInBits() - 1);
auto Shift =
MIRBuilder.buildAShr(DstTy, OpReg, ShiftAmt);
auto Add = MIRBuilder.buildAdd(DstTy, OpReg, Shift);
MIRBuilder.buildXor(MI.getOperand(0).getReg(), Add, Shift);
MI.eraseFromParent();
return Legalized;
}
}
}

3
llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
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@ -657,6 +657,9 @@ AArch64LegalizerInfo::AArch64LegalizerInfo(const AArch64Subtarget &ST)
getActionDefinitionsBuilder({G_MEMCPY, G_MEMMOVE, G_MEMSET}).libcall();
getActionDefinitionsBuilder(G_ABS).lowerIf(
[=](const LegalityQuery &Query) { return Query.Types[0].isScalar(); });
computeTables();
verify(*ST.getInstrInfo());
}

34
llvm/test/CodeGen/AArch64/GlobalISel/legalize-abs.mir Normal file
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@ -0,0 +1,34 @@
# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
# RUN: llc -march=aarch64 -run-pass=legalizer -global-isel-abort=1 %s -o - | FileCheck %s
---
name: abs_s32
liveins:
body: |
bb.0:
; CHECK-LABEL: name: abs_s32
; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $w0
; CHECK: [[C:%[0-9]+]]:_(s64) = G_CONSTANT i64 31
; CHECK: [[ASHR:%[0-9]+]]:_(s32) = G_ASHR [[COPY]], [[C]](s64)
; CHECK: [[ADD:%[0-9]+]]:_(s32) = G_ADD [[COPY]], [[ASHR]]
; CHECK: [[XOR:%[0-9]+]]:_(s32) = G_XOR [[ADD]], [[ASHR]]
; CHECK: $w0 = COPY [[XOR]](s32)
%0:_(s32) = COPY $w0
%1:_(s32) = G_ABS %0(s32)
$w0 = COPY %1(s32)
...
---
name: abs_s64
liveins:
body: |
bb.0:
; CHECK-LABEL: name: abs_s64
; CHECK: [[COPY:%[0-9]+]]:_(s64) = COPY $x0
; CHECK: [[C:%[0-9]+]]:_(s64) = G_CONSTANT i64 63
; CHECK: [[ASHR:%[0-9]+]]:_(s64) = G_ASHR [[COPY]], [[C]](s64)
; CHECK: [[ADD:%[0-9]+]]:_(s64) = G_ADD [[COPY]], [[ASHR]]
; CHECK: [[XOR:%[0-9]+]]:_(s64) = G_XOR [[ADD]], [[ASHR]]
; CHECK: $x0 = COPY [[XOR]](s64)
%0:_(s64) = COPY $x0
%1:_(s64) = G_ABS %0(s64)
$x0 = COPY %1(s64)
...

4
llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir
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@ -497,8 +497,8 @@
# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
# DEBUG-NEXT: G_ABS (opcode {{[0-9]+}}): 1 type index, 0 imm indices
# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
# DEBUG-NEXT: .. type index coverage check SKIPPED: user-defined predicate detected
# DEBUG-NEXT: .. imm index coverage check SKIPPED: user-defined predicate detected
# DEBUG-NEXT: G_BR (opcode {{[0-9]+}}): 0 type indices, 0 imm indices
# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined
# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined