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goldsteinngoldsteinn
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Revert "Add optimizations for icmp eq/ne (mul(X, Y), 0)"
This reverts commit aa250ce. Caused test failures in Clangd: https://lab.llvm.org/buildbot/#/builders/183/builds/10447 reverting while investigating.
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+21
-52
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3 files changed

+21
-52
lines changed

‎llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp

Lines changed: 0 additions & 42 deletions
Original file line numberDiff line numberDiff line change
@@ -1295,48 +1295,6 @@ Instruction *InstCombinerImpl::foldICmpWithZero(ICmpInst &Cmp) {
12951295
return new ICmpInst(Pred, X, Cmp.getOperand(1));
12961296
}
12971297

1298-
// (icmp eq/ne (mul X Y)) -> (icmp eq/ne X/Y) if we know about whether X/Y are
1299-
// odd/non-zero/there is no overflow.
1300-
if (match(Cmp.getOperand(0), m_Mul(m_Value(X), m_Value(Y))) &&
1301-
ICmpInst::isEquality(Pred)) {
1302-
1303-
KnownBits XKnown = computeKnownBits(X, 0, &Cmp);
1304-
// if X % 2 != 0
1305-
// (icmp eq/ne Y)
1306-
if (XKnown.countMaxTrailingZeros() == 0)
1307-
return new ICmpInst(Pred, Y, Cmp.getOperand(1));
1308-
1309-
KnownBits YKnown = computeKnownBits(Y, 0, &Cmp);
1310-
// if Y % 2 != 0
1311-
// (icmp eq/ne X)
1312-
if (YKnown.countMaxTrailingZeros() == 0)
1313-
return new ICmpInst(Pred, X, Cmp.getOperand(1));
1314-
1315-
auto *BO0 = cast<OverflowingBinaryOperator>(Cmp.getOperand(0));
1316-
if (BO0->hasNoUnsignedWrap() || BO0->hasNoSignedWrap()) {
1317-
const SimplifyQuery Q = SQ.getWithInstruction(&Cmp);
1318-
// `isKnownNonZero` does more analysis than just `!KnownBits.One.isZero()`
1319-
// but to avoid unnecessary work, first just if this is an obvious case.
1320-
1321-
// if X non-zero and NoOverflow(X * Y)
1322-
// (icmp eq/ne Y)
1323-
if (!XKnown.One.isZero() || isKnownNonZero(X, DL, 0, Q.AC, Q.CxtI, Q.DT))
1324-
return new ICmpInst(Pred, Y, Cmp.getOperand(1));
1325-
1326-
// if Y non-zero and NoOverflow(X * Y)
1327-
// (icmp eq/ne X)
1328-
if (!YKnown.One.isZero() || isKnownNonZero(Y, DL, 0, Q.AC, Q.CxtI, Q.DT))
1329-
return new ICmpInst(Pred, X, Cmp.getOperand(1));
1330-
}
1331-
// Note, we are skipping cases:
1332-
// if Y % 2 != 0 AND X % 2 != 0
1333-
// (false/true)
1334-
// if X non-zero and Y non-zero and NoOverflow(X * Y)
1335-
// (false/true)
1336-
// Those can be simplified later as we would have already replaced the (icmp
1337-
// eq/ne (mul X, Y)) with (icmp eq/ne X/Y) and if X/Y is known non-zero that
1338-
// will fold to a constant elsewhere.
1339-
}
13401298
return nullptr;
13411299
}
13421300

‎llvm/test/Transforms/InstCombine/icmp-binop.ll

Lines changed: 18 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,8 @@ declare void @llvm.assume(i1)
66

77
define i1 @mul_unkV_oddC_eq(i32 %v) {
88
; CHECK-LABEL: @mul_unkV_oddC_eq(
9-
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[V:%.*]], 0
9+
; CHECK-NEXT: [[MUL:%.*]] = mul i32 [[V:%.*]], 3
10+
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[MUL]], 0
1011
; CHECK-NEXT: ret i1 [[CMP]]
1112
;
1213
%mul = mul i32 %v, 3
@@ -27,7 +28,8 @@ define i1 @mul_unkV_oddC_eq_nonzero(i32 %v) {
2728

2829
define <2 x i1> @mul_unkV_oddC_ne_vec(<2 x i64> %v) {
2930
; CHECK-LABEL: @mul_unkV_oddC_ne_vec(
30-
; CHECK-NEXT: [[CMP:%.*]] = icmp ne <2 x i64> [[V:%.*]], zeroinitializer
31+
; CHECK-NEXT: [[MUL:%.*]] = mul <2 x i64> [[V:%.*]], <i64 3, i64 3>
32+
; CHECK-NEXT: [[CMP:%.*]] = icmp ne <2 x i64> [[MUL]], zeroinitializer
3133
; CHECK-NEXT: ret <2 x i1> [[CMP]]
3234
;
3335
%mul = mul <2 x i64> %v, <i64 3, i64 3>
@@ -70,7 +72,7 @@ define i1 @mul_unkV_oddC_sge(i8 %v) {
7072
define i1 @mul_reused_unkV_oddC_ne(i64 %v) {
7173
; CHECK-LABEL: @mul_reused_unkV_oddC_ne(
7274
; CHECK-NEXT: [[MUL:%.*]] = mul i64 [[V:%.*]], 3
73-
; CHECK-NEXT: [[CMP:%.*]] = icmp ne i64 [[V]], 0
75+
; CHECK-NEXT: [[CMP:%.*]] = icmp ne i64 [[MUL]], 0
7476
; CHECK-NEXT: call void @use64(i64 [[MUL]])
7577
; CHECK-NEXT: ret i1 [[CMP]]
7678
;
@@ -85,7 +87,8 @@ define i1 @mul_assumeoddV_unkV_eq(i16 %v, i16 %v2) {
8587
; CHECK-NEXT: [[LB:%.*]] = and i16 [[V2:%.*]], 1
8688
; CHECK-NEXT: [[ODD:%.*]] = icmp ne i16 [[LB]], 0
8789
; CHECK-NEXT: call void @llvm.assume(i1 [[ODD]])
88-
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i16 [[V:%.*]], 0
90+
; CHECK-NEXT: [[MUL:%.*]] = mul i16 [[V:%.*]], [[V2]]
91+
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i16 [[MUL]], 0
8992
; CHECK-NEXT: ret i1 [[CMP]]
9093
;
9194
%lb = and i16 %v2, 1
@@ -102,7 +105,7 @@ define i1 @mul_reusedassumeoddV_unkV_ne(i64 %v, i64 %v2) {
102105
; CHECK-NEXT: [[ODD:%.*]] = icmp ne i64 [[LB]], 0
103106
; CHECK-NEXT: call void @llvm.assume(i1 [[ODD]])
104107
; CHECK-NEXT: [[MUL:%.*]] = mul i64 [[V]], [[V2:%.*]]
105-
; CHECK-NEXT: [[CMP:%.*]] = icmp ne i64 [[V2]], 0
108+
; CHECK-NEXT: [[CMP:%.*]] = icmp ne i64 [[MUL]], 0
106109
; CHECK-NEXT: call void @use64(i64 [[MUL]])
107110
; CHECK-NEXT: ret i1 [[CMP]]
108111
;
@@ -117,7 +120,9 @@ define i1 @mul_reusedassumeoddV_unkV_ne(i64 %v, i64 %v2) {
117120

118121
define <2 x i1> @mul_setoddV_unkV_ne(<2 x i32> %v1, <2 x i32> %v2) {
119122
; CHECK-LABEL: @mul_setoddV_unkV_ne(
120-
; CHECK-NEXT: [[CMP:%.*]] = icmp ne <2 x i32> [[V2:%.*]], zeroinitializer
123+
; CHECK-NEXT: [[V:%.*]] = or <2 x i32> [[V1:%.*]], <i32 1, i32 1>
124+
; CHECK-NEXT: [[MUL:%.*]] = mul <2 x i32> [[V]], [[V2:%.*]]
125+
; CHECK-NEXT: [[CMP:%.*]] = icmp ne <2 x i32> [[MUL]], zeroinitializer
121126
; CHECK-NEXT: ret <2 x i1> [[CMP]]
122127
;
123128
%v = or <2 x i32> %v1, <i32 1, i32 1>
@@ -185,7 +190,8 @@ define i1 @mul_assumenzV_unkV_nsw_ne(i32 %v, i32 %v2) {
185190
; CHECK-LABEL: @mul_assumenzV_unkV_nsw_ne(
186191
; CHECK-NEXT: [[NZ:%.*]] = icmp ne i32 [[V:%.*]], 0
187192
; CHECK-NEXT: call void @llvm.assume(i1 [[NZ]])
188-
; CHECK-NEXT: [[CMP:%.*]] = icmp ne i32 [[V2:%.*]], 0
193+
; CHECK-NEXT: [[MUL:%.*]] = mul nsw i32 [[V]], [[V2:%.*]]
194+
; CHECK-NEXT: [[CMP:%.*]] = icmp ne i32 [[MUL]], 0
189195
; CHECK-NEXT: ret i1 [[CMP]]
190196
;
191197
%nz = icmp ne i32 %v, 0
@@ -223,7 +229,9 @@ define <2 x i1> @mul_unkV_unkV_nsw_nuw_ne(<2 x i16> %v, <2 x i16> %v2) {
223229

224230
define i1 @mul_setnzV_unkV_nuw_eq(i8 %v1, i8 %v2) {
225231
; CHECK-LABEL: @mul_setnzV_unkV_nuw_eq(
226-
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[V2:%.*]], 0
232+
; CHECK-NEXT: [[V:%.*]] = or i8 [[V1:%.*]], 2
233+
; CHECK-NEXT: [[MUL:%.*]] = mul nuw i8 [[V]], [[V2:%.*]]
234+
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[MUL]], 0
227235
; CHECK-NEXT: ret i1 [[CMP]]
228236
;
229237
%v = or i8 %v1, 2
@@ -237,7 +245,8 @@ define i1 @mul_brnzV_unkV_nuw_eq(i64 %v, i64 %v2) {
237245
; CHECK-NEXT: [[NZ_NOT:%.*]] = icmp eq i64 [[V2:%.*]], 0
238246
; CHECK-NEXT: br i1 [[NZ_NOT]], label [[FALSE:%.*]], label [[TRUE:%.*]]
239247
; CHECK: true:
240-
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i64 [[V:%.*]], 0
248+
; CHECK-NEXT: [[MUL:%.*]] = mul nuw i64 [[V:%.*]], [[V2]]
249+
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i64 [[MUL]], 0
241250
; CHECK-NEXT: ret i1 [[CMP]]
242251
; CHECK: false:
243252
; CHECK-NEXT: call void @use64(i64 [[V]])

‎llvm/test/Transforms/InstCombine/pr38677.ll

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -12,7 +12,9 @@ define i32 @foo(i1 %which, ptr %dst) {
1212
; CHECK-NEXT: br label [[FINAL]]
1313
; CHECK: final:
1414
; CHECK-NEXT: [[USE2:%.*]] = phi i32 [ 1, [[ENTRY:%.*]] ], [ select (i1 icmp eq (ptr @A, ptr @B), i32 2, i32 1), [[DELAY]] ]
15-
; CHECK-NEXT: store i1 false, ptr [[DST:%.*]], align 1
15+
; CHECK-NEXT: [[B7:%.*]] = mul i32 [[USE2]], 2147483647
16+
; CHECK-NEXT: [[C3:%.*]] = icmp eq i32 [[B7]], 0
17+
; CHECK-NEXT: store i1 [[C3]], ptr [[DST:%.*]], align 1
1618
; CHECK-NEXT: ret i32 [[USE2]]
1719
;
1820
entry:

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