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[SDAG] avoid udiv/urem transform for vector/scalar type mismatches
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This solves the crashing from issue #58994.
I don't know anything about VE, so I don't know if the output
is as expected or even correct.
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rotateright committed Nov 15, 2022
1 parent e487356 commit fe05a0a
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Showing 2 changed files with 49 additions and 2 deletions.
6 changes: 4 additions & 2 deletions llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -4477,10 +4477,11 @@ SDValue DAGCombiner::visitUDIV(SDNode *N) {

// fold (udiv X, -1) -> select(X == -1, 1, 0)
ConstantSDNode *N1C = isConstOrConstSplat(N1);
if (N1C && N1C->isAllOnes())
if (N1C && N1C->isAllOnes() && CCVT.isVector() == VT.isVector()) {
return DAG.getSelect(DL, VT, DAG.getSetCC(DL, CCVT, N0, N1, ISD::SETEQ),
DAG.getConstant(1, DL, VT),
DAG.getConstant(0, DL, VT));
}

if (SDValue V = simplifyDivRem(N, DAG))
return V;
Expand Down Expand Up @@ -4583,7 +4584,8 @@ SDValue DAGCombiner::visitREM(SDNode *N) {

// fold (urem X, -1) -> select(FX == -1, 0, FX)
// Freeze the numerator to avoid a miscompile with an undefined value.
if (!isSigned && llvm::isAllOnesOrAllOnesSplat(N1, /*AllowUndefs*/ false)) {
if (!isSigned && llvm::isAllOnesOrAllOnesSplat(N1, /*AllowUndefs*/ false) &&
CCVT.isVector() == VT.isVector()) {
SDValue F0 = DAG.getFreeze(N0);
SDValue EqualsNeg1 = DAG.getSetCC(DL, CCVT, F0, N1, ISD::SETEQ);
return DAG.getSelect(DL, VT, EqualsNeg1, DAG.getConstant(0, DL, VT), F0);
Expand Down
45 changes: 45 additions & 0 deletions llvm/test/CodeGen/VE/Vector/vec_divrem.ll
Original file line number Diff line number Diff line change
@@ -0,0 +1,45 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc < %s -mtriple=ve -mattr=+vpu | FileCheck %s

; This would assert because VE specified that all setcc
; nodes (even with vector operands) return a scalar value.

define <4 x i8> @udiv_by_minus_one(<4 x i8> %x) {
; CHECK-LABEL: udiv_by_minus_one:
; CHECK: # %bb.0:
; CHECK-NEXT: and %s0, %s0, (56)0
; CHECK-NEXT: and %s1, %s1, (56)0
; CHECK-NEXT: and %s2, %s2, (56)0
; CHECK-NEXT: and %s3, %s3, (56)0
; CHECK-NEXT: divu.w %s3, %s3, (56)0
; CHECK-NEXT: divu.w %s2, %s2, (56)0
; CHECK-NEXT: divu.w %s1, %s1, (56)0
; CHECK-NEXT: divu.w %s0, %s0, (56)0
; CHECK-NEXT: b.l.t (, %s10)
%r = udiv <4 x i8> %x, <i8 255, i8 255, i8 255, i8 255>
ret <4 x i8> %r
}

define <4 x i8> @urem_by_minus_one(<4 x i8> %x) {
; CHECK-LABEL: urem_by_minus_one:
; CHECK: # %bb.0:
; CHECK-NEXT: and %s0, %s0, (56)0
; CHECK-NEXT: and %s1, %s1, (56)0
; CHECK-NEXT: and %s2, %s2, (56)0
; CHECK-NEXT: and %s3, %s3, (56)0
; CHECK-NEXT: divu.w %s4, %s3, (56)0
; CHECK-NEXT: muls.w.sx %s4, %s4, (56)0
; CHECK-NEXT: subs.w.sx %s3, %s3, %s4
; CHECK-NEXT: divu.w %s4, %s2, (56)0
; CHECK-NEXT: muls.w.sx %s4, %s4, (56)0
; CHECK-NEXT: subs.w.sx %s2, %s2, %s4
; CHECK-NEXT: divu.w %s4, %s1, (56)0
; CHECK-NEXT: muls.w.sx %s4, %s4, (56)0
; CHECK-NEXT: subs.w.sx %s1, %s1, %s4
; CHECK-NEXT: divu.w %s4, %s0, (56)0
; CHECK-NEXT: muls.w.sx %s4, %s4, (56)0
; CHECK-NEXT: subs.w.sx %s0, %s0, %s4
; CHECK-NEXT: b.l.t (, %s10)
%r = urem <4 x i8> %x, <i8 255, i8 255, i8 255, i8 255>
ret <4 x i8> %r
}

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