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AArch64: enforce even/odd register pairs for CASP instructions.

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ARMv8.1a CASP instructions need the first of the pair to be an even register
(otherwise the encoding is unallocated). We enforced this during assembly, but
not CodeGen before.

llvm-svn: 353308
This commit is contained in:
Tim Northover 2019-02-06 15:26:35 +00:00
parent 5df33b90f1
commit 009fdea45c
3 changed files with 25 additions and 6 deletions
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10
lib/Target/AArch64/AArch64RegisterInfo.td
View File

@ -653,10 +653,12 @@ def FPR128Op : RegisterOperand<FPR128, "printOperand"> {
// ARMv8.1a atomic CASP register operands
def WSeqPairs : RegisterTuples<[sube32, subo32],
[(rotl GPR32, 0), (rotl GPR32, 1)]>;
def XSeqPairs : RegisterTuples<[sube64, subo64],
[(rotl GPR64, 0), (rotl GPR64, 1)]>;
def WSeqPairs : RegisterTuples<[sube32, subo32],
[(decimate (rotl GPR32, 0), 2),
(decimate (rotl GPR32, 1), 2)]>;
def XSeqPairs : RegisterTuples<[sube64, subo64],
[(decimate (rotl GPR64, 0), 2),
(decimate (rotl GPR64, 1), 2)]>;
def WSeqPairsClass : RegisterClass<"AArch64", [untyped], 32,
(add WSeqPairs)>{

4
lib/Target/AArch64/Disassembler/AArch64Disassembler.cpp
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@ -1778,8 +1778,8 @@ static DecodeStatus DecodeGPRSeqPairsClassRegisterClass(MCInst &Inst,
if (RegNo & 0x1)
return Fail;
unsigned Register = AArch64MCRegisterClasses[RegClassID].getRegister(RegNo);
Inst.addOperand(MCOperand::createReg(Register));
unsigned Reg = AArch64MCRegisterClasses[RegClassID].getRegister(RegNo / 2);
Inst.addOperand(MCOperand::createReg(Reg));
return Success;
}

17
test/CodeGen/AArch64/cmpxchg-lse-even-regs.ll Normal file
View File

@ -0,0 +1,17 @@
; RUN: llc -mtriple arm64-apple-ios -mattr=+lse %s -o - | FileCheck %s
; Only "even,even+1" pairs are valid for CASP instructions. Make sure LLVM
; doesn't allocate odd ones and that it can copy them around properly. N.b. we
; don't actually check that they're sequential because FileCheck can't; odd/even
; will have to be good enough.
define void @test_atomic_cmpxchg_i128_register_shuffling(i128* %addr, i128 %desired, i128 %new) nounwind {
; CHECK-LABEL: test_atomic_cmpxchg_i128_register_shuffling:
; CHECK-DAG: mov [[DESIRED_LO:x[0-9]*[02468]]], x1
; CHECK-DAG: mov [[DESIRED_HI:x[0-9]*[13579]]], x2
; CHECK-DAG: mov [[NEW_LO:x[0-9]*[02468]]], x3
; CHECK-DAG: mov [[NEW_HI:x[0-9]*[13579]]], x4
; CHECK: caspal [[DESIRED_LO]], [[DESIRED_HI]], [[NEW_LO]], [[NEW_HI]], [x0]
%res = cmpxchg i128* %addr, i128 %desired, i128 %new seq_cst seq_cst
ret void
}