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[LegalizeTypes][RISCV] Correctly sign-extend comparison for ATOMIC_CMP_XCHG

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Summary:
Currently, the comparison argument used for ATOMIC_CMP_XCHG is legalised
with GetPromotedInteger, which leaves the upper bits of the value
undefind. Since this is used for comparing in an LR/SC loop with a
full-width comparison, we must sign extend it. We introduce a new
getExtendForAtomicCmpSwapArg to complement getExtendForAtomicOps, since
many targets have compare-and-swap instructions (or pseudos) that
correctly handle an any-extend input, and the existing function
determines the extension of the result, whereas we are concerned with
the input.

This is related to https://reviews.llvm.org/D58829, which solved the
issue for ATOMIC_CMP_SWAP_WITH_SUCCESS, but not the simpler
ATOMIC_CMP_SWAP.

Reviewers: asb, lenary, efriedma

Reviewed By: asb

Subscribers: arichardson, hiraditya, rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, MaskRay, zzheng, edward-jones, rogfer01, MartinMosbeck, brucehoult, the_o, rkruppe, jfb, PkmX, jocewei, psnobl, benna, Jim, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, evandro, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D74453
This commit is contained in:
Jessica Clarke 2020-04-01 15:50:47 +01:00
parent e3033c0ce5
commit 616289ed29
4 changed files with 43 additions and 1 deletions
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12
llvm/include/llvm/CodeGen/TargetLowering.h
View File

@ -1962,6 +1962,18 @@ public:
return ISD::ZERO_EXTEND;
}
/// Returns how the platform's atomic compare and swap expects its comparison
/// value to be extended (ZERO_EXTEND, SIGN_EXTEND, or ANY_EXTEND). This is
/// separate from getExtendForAtomicOps, which is concerned with the
/// sign-extension of the instruction's output, whereas here we are concerned
/// with the sign-extension of the input. For targets with compare-and-swap
/// instructions (or sub-word comparisons in their LL/SC loop expansions),
/// the input can be ANY_EXTEND, but the output will still have a specific
/// extension.
virtual ISD::NodeType getExtendForAtomicCmpSwapArg() const {
return ISD::ANY_EXTEND;
}
/// @}
/// Returns true if we should normalize

18
llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
View File

@ -278,8 +278,24 @@ SDValue DAGTypeLegalizer::PromoteIntRes_AtomicCmpSwap(AtomicSDNode *N,
return Res.getValue(1);
}
SDValue Op2 = GetPromotedInteger(N->getOperand(2));
// Op2 is used for the comparison and thus must be extended according to the
// target's atomic operations. Op3 is merely stored and so can be left alone.
SDValue Op2 = N->getOperand(2);
SDValue Op3 = GetPromotedInteger(N->getOperand(3));
switch (TLI.getExtendForAtomicCmpSwapArg()) {
case ISD::SIGN_EXTEND:
Op2 = SExtPromotedInteger(Op2);
break;
case ISD::ZERO_EXTEND:
Op2 = ZExtPromotedInteger(Op2);
break;
case ISD::ANY_EXTEND:
Op2 = GetPromotedInteger(Op2);
break;
default:
llvm_unreachable("Invalid atomic op extension");
}
SDVTList VTs =
DAG.getVTList(Op2.getValueType(), N->getValueType(1), MVT::Other);
SDValue Res = DAG.getAtomicCmpSwap(

4
llvm/lib/Target/RISCV/RISCVISelLowering.h
View File

@ -129,6 +129,10 @@ public:
return ISD::SIGN_EXTEND;
}
ISD::NodeType getExtendForAtomicCmpSwapArg() const override {
return ISD::SIGN_EXTEND;
}
bool shouldExpandShift(SelectionDAG &DAG, SDNode *N) const override {
if (DAG.getMachineFunction().getFunction().hasMinSize())
return false;

10
llvm/test/CodeGen/RISCV/atomic-cmpxchg.ll
View File

@ -1628,6 +1628,7 @@ define void @cmpxchg_i32_monotonic_monotonic(i32* %ptr, i32 %cmp, i32 %val) noun
;
; RV64IA-LABEL: cmpxchg_i32_monotonic_monotonic:
; RV64IA: # %bb.0:
; RV64IA-NEXT: sext.w a1, a1
; RV64IA-NEXT: .LBB20_1: # =>This Inner Loop Header: Depth=1
; RV64IA-NEXT: lr.w a3, (a0)
; RV64IA-NEXT: bne a3, a1, .LBB20_3
@ -1680,6 +1681,7 @@ define void @cmpxchg_i32_acquire_monotonic(i32* %ptr, i32 %cmp, i32 %val) nounwi
;
; RV64IA-LABEL: cmpxchg_i32_acquire_monotonic:
; RV64IA: # %bb.0:
; RV64IA-NEXT: sext.w a1, a1
; RV64IA-NEXT: .LBB21_1: # =>This Inner Loop Header: Depth=1
; RV64IA-NEXT: lr.w.aq a3, (a0)
; RV64IA-NEXT: bne a3, a1, .LBB21_3
@ -1732,6 +1734,7 @@ define void @cmpxchg_i32_acquire_acquire(i32* %ptr, i32 %cmp, i32 %val) nounwind
;
; RV64IA-LABEL: cmpxchg_i32_acquire_acquire:
; RV64IA: # %bb.0:
; RV64IA-NEXT: sext.w a1, a1
; RV64IA-NEXT: .LBB22_1: # =>This Inner Loop Header: Depth=1
; RV64IA-NEXT: lr.w.aq a3, (a0)
; RV64IA-NEXT: bne a3, a1, .LBB22_3
@ -1784,6 +1787,7 @@ define void @cmpxchg_i32_release_monotonic(i32* %ptr, i32 %cmp, i32 %val) nounwi
;
; RV64IA-LABEL: cmpxchg_i32_release_monotonic:
; RV64IA: # %bb.0:
; RV64IA-NEXT: sext.w a1, a1
; RV64IA-NEXT: .LBB23_1: # =>This Inner Loop Header: Depth=1
; RV64IA-NEXT: lr.w a3, (a0)
; RV64IA-NEXT: bne a3, a1, .LBB23_3
@ -1836,6 +1840,7 @@ define void @cmpxchg_i32_release_acquire(i32* %ptr, i32 %cmp, i32 %val) nounwind
;
; RV64IA-LABEL: cmpxchg_i32_release_acquire:
; RV64IA: # %bb.0:
; RV64IA-NEXT: sext.w a1, a1
; RV64IA-NEXT: .LBB24_1: # =>This Inner Loop Header: Depth=1
; RV64IA-NEXT: lr.w a3, (a0)
; RV64IA-NEXT: bne a3, a1, .LBB24_3
@ -1888,6 +1893,7 @@ define void @cmpxchg_i32_acq_rel_monotonic(i32* %ptr, i32 %cmp, i32 %val) nounwi
;
; RV64IA-LABEL: cmpxchg_i32_acq_rel_monotonic:
; RV64IA: # %bb.0:
; RV64IA-NEXT: sext.w a1, a1
; RV64IA-NEXT: .LBB25_1: # =>This Inner Loop Header: Depth=1
; RV64IA-NEXT: lr.w.aq a3, (a0)
; RV64IA-NEXT: bne a3, a1, .LBB25_3
@ -1940,6 +1946,7 @@ define void @cmpxchg_i32_acq_rel_acquire(i32* %ptr, i32 %cmp, i32 %val) nounwind
;
; RV64IA-LABEL: cmpxchg_i32_acq_rel_acquire:
; RV64IA: # %bb.0:
; RV64IA-NEXT: sext.w a1, a1
; RV64IA-NEXT: .LBB26_1: # =>This Inner Loop Header: Depth=1
; RV64IA-NEXT: lr.w.aq a3, (a0)
; RV64IA-NEXT: bne a3, a1, .LBB26_3
@ -1992,6 +1999,7 @@ define void @cmpxchg_i32_seq_cst_monotonic(i32* %ptr, i32 %cmp, i32 %val) nounwi
;
; RV64IA-LABEL: cmpxchg_i32_seq_cst_monotonic:
; RV64IA: # %bb.0:
; RV64IA-NEXT: sext.w a1, a1
; RV64IA-NEXT: .LBB27_1: # =>This Inner Loop Header: Depth=1
; RV64IA-NEXT: lr.w.aqrl a3, (a0)
; RV64IA-NEXT: bne a3, a1, .LBB27_3
@ -2044,6 +2052,7 @@ define void @cmpxchg_i32_seq_cst_acquire(i32* %ptr, i32 %cmp, i32 %val) nounwind
;
; RV64IA-LABEL: cmpxchg_i32_seq_cst_acquire:
; RV64IA: # %bb.0:
; RV64IA-NEXT: sext.w a1, a1
; RV64IA-NEXT: .LBB28_1: # =>This Inner Loop Header: Depth=1
; RV64IA-NEXT: lr.w.aqrl a3, (a0)
; RV64IA-NEXT: bne a3, a1, .LBB28_3
@ -2096,6 +2105,7 @@ define void @cmpxchg_i32_seq_cst_seq_cst(i32* %ptr, i32 %cmp, i32 %val) nounwind
;
; RV64IA-LABEL: cmpxchg_i32_seq_cst_seq_cst:
; RV64IA: # %bb.0:
; RV64IA-NEXT: sext.w a1, a1
; RV64IA-NEXT: .LBB29_1: # =>This Inner Loop Header: Depth=1
; RV64IA-NEXT: lr.w.aqrl a3, (a0)
; RV64IA-NEXT: bne a3, a1, .LBB29_3