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[InstCombine] Fold fmul X, -0.0 into copysign(0.0, -X) 
1 parent cdb0602 commit 86417bf

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4 files changed

+34
-23
lines changed

4 files changed

+34
-23
lines changed

‎llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp

Lines changed: 13 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -814,8 +814,19 @@ Instruction *InstCombinerImpl::visitFMul(BinaryOperator &I) {
814814
if (match(Op1, m_SpecificFP(-1.0)))
815815
return UnaryOperator::CreateFNegFMF(Op0, &I);
816816

817-
// With no-nans: X * 0.0 --> copysign(0.0, X)
818-
if (I.hasNoNaNs() && match(Op1, m_PosZeroFP())) {
817+
// With no-nans/no-infs:
818+
// X * 0.0 --> copysign(0.0, X)
819+
// X * -0.0 --> copysign(0.0, -X)
820+
const APFloat *FPC;
821+
if (match(Op1, m_APFloatAllowUndef(FPC)) && FPC->isZero() &&
822+
((I.hasNoInfs() &&
823+
isKnownNeverNaN(Op0, /*Depth=*/0, SQ.getWithInstruction(&I))) ||
824+
isKnownNeverNaN(&I, /*Depth=*/0, SQ.getWithInstruction(&I)))) {
825+
if (FPC->isNegative())
826+
Op0 = Builder.CreateFNegFMF(Op0, &I);
827+
Op1 = Constant::replaceUndefsWith(
828+
cast<Constant>(Op1),
829+
ConstantFP::get(Op1->getType()->getScalarType(), *FPC));
819830
CallInst *CopySign = Builder.CreateIntrinsic(Intrinsic::copysign,
820831
{I.getType()}, {Op1, Op0}, &I);
821832
return replaceInstUsesWith(I, CopySign);

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

Lines changed: 7 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -1012,7 +1012,7 @@ define float @missed_nonzero_check_on_constant_for_si_fmul(i1 %c, i1 %.b, ptr %g
10121012
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[C:%.*]], i32 65529, i32 53264
10131013
; CHECK-NEXT: [[CONV_I:%.*]] = trunc i32 [[SEL]] to i16
10141014
; CHECK-NEXT: [[CONV1_I:%.*]] = sitofp i16 [[CONV_I]] to float
1015-
; CHECK-NEXT: [[MUL3_I_I:%.*]] = fmul float [[CONV1_I]], 0.000000e+00
1015+
; CHECK-NEXT: [[MUL3_I_I:%.*]] = call float @llvm.copysign.f32(float 0.000000e+00, float [[CONV1_I]])
10161016
; CHECK-NEXT: store i32 [[SEL]], ptr [[G_2345:%.*]], align 4
10171017
; CHECK-NEXT: ret float [[MUL3_I_I]]
10181018
;
@@ -1031,7 +1031,7 @@ define <2 x float> @missed_nonzero_check_on_constant_for_si_fmul_vec(i1 %c, i1 %
10311031
; CHECK-NEXT: [[CONV_I_V:%.*]] = insertelement <2 x i16> poison, i16 [[CONV_I_S]], i64 0
10321032
; CHECK-NEXT: [[CONV_I:%.*]] = shufflevector <2 x i16> [[CONV_I_V]], <2 x i16> poison, <2 x i32> zeroinitializer
10331033
; CHECK-NEXT: [[CONV1_I:%.*]] = sitofp <2 x i16> [[CONV_I]] to <2 x float>
1034-
; CHECK-NEXT: [[MUL3_I_I:%.*]] = fmul <2 x float> [[CONV1_I]], zeroinitializer
1034+
; CHECK-NEXT: [[MUL3_I_I:%.*]] = call <2 x float> @llvm.copysign.v2f32(<2 x float> zeroinitializer, <2 x float> [[CONV1_I]])
10351035
; CHECK-NEXT: store i32 [[SEL]], ptr [[G_2345:%.*]], align 4
10361036
; CHECK-NEXT: ret <2 x float> [[MUL3_I_I]]
10371037
;
@@ -1050,7 +1050,8 @@ define float @negzero_check_on_constant_for_si_fmul(i1 %c, i1 %.b, ptr %g_2345)
10501050
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[C:%.*]], i32 65529, i32 53264
10511051
; CHECK-NEXT: [[CONV_I:%.*]] = trunc i32 [[SEL]] to i16
10521052
; CHECK-NEXT: [[CONV1_I:%.*]] = sitofp i16 [[CONV_I]] to float
1053-
; CHECK-NEXT: [[MUL3_I_I:%.*]] = fmul float [[CONV1_I]], -0.000000e+00
1053+
; CHECK-NEXT: [[TMP1:%.*]] = fneg float [[CONV1_I]]
1054+
; CHECK-NEXT: [[MUL3_I_I:%.*]] = call float @llvm.copysign.f32(float 0.000000e+00, float [[TMP1]])
10541055
; CHECK-NEXT: store i32 [[SEL]], ptr [[G_2345:%.*]], align 4
10551056
; CHECK-NEXT: ret float [[MUL3_I_I]]
10561057
;
@@ -1069,7 +1070,7 @@ define <2 x float> @nonzero_check_on_constant_for_si_fmul_vec_w_undef(i1 %c, i1
10691070
; CHECK-NEXT: [[CONV_I_V:%.*]] = insertelement <2 x i16> poison, i16 [[CONV_I_S]], i64 0
10701071
; CHECK-NEXT: [[CONV_I:%.*]] = shufflevector <2 x i16> [[CONV_I_V]], <2 x i16> poison, <2 x i32> zeroinitializer
10711072
; CHECK-NEXT: [[CONV1_I:%.*]] = sitofp <2 x i16> [[CONV_I]] to <2 x float>
1072-
; CHECK-NEXT: [[MUL3_I_I:%.*]] = fmul <2 x float> [[CONV1_I]], <float undef, float 0.000000e+00>
1073+
; CHECK-NEXT: [[MUL3_I_I:%.*]] = call <2 x float> @llvm.copysign.v2f32(<2 x float> zeroinitializer, <2 x float> [[CONV1_I]])
10731074
; CHECK-NEXT: store i32 [[SEL]], ptr [[G_2345:%.*]], align 4
10741075
; CHECK-NEXT: ret <2 x float> [[MUL3_I_I]]
10751076
;
@@ -1111,7 +1112,8 @@ define <2 x float> @nonzero_check_on_constant_for_si_fmul_negz_vec_w_undef(i1 %c
11111112
; CHECK-NEXT: [[CONV_I_V:%.*]] = insertelement <2 x i16> poison, i16 [[CONV_I_S]], i64 0
11121113
; CHECK-NEXT: [[CONV_I:%.*]] = shufflevector <2 x i16> [[CONV_I_V]], <2 x i16> poison, <2 x i32> zeroinitializer
11131114
; CHECK-NEXT: [[CONV1_I:%.*]] = sitofp <2 x i16> [[CONV_I]] to <2 x float>
1114-
; CHECK-NEXT: [[MUL3_I_I:%.*]] = fmul <2 x float> [[CONV1_I]], <float undef, float -0.000000e+00>
1115+
; CHECK-NEXT: [[TMP1:%.*]] = fneg <2 x float> [[CONV1_I]]
1116+
; CHECK-NEXT: [[MUL3_I_I:%.*]] = call <2 x float> @llvm.copysign.v2f32(<2 x float> zeroinitializer, <2 x float> [[TMP1]])
11151117
; CHECK-NEXT: store i32 [[SEL]], ptr [[G_2345:%.*]], align 4
11161118
; CHECK-NEXT: ret <2 x float> [[MUL3_I_I]]
11171119
;

‎llvm/test/Transforms/InstCombine/fmul.ll

Lines changed: 13 additions & 12 deletions
Original file line numberDiff line numberDiff line change
@@ -1250,7 +1250,7 @@ define half @mul_zero_nnan(half %x) {
12501250

12511251
define <2 x float> @mul_zero_nnan_vec_poison(<2 x float> %x) {
12521252
; CHECK-LABEL: @mul_zero_nnan_vec_poison(
1253-
; CHECK-NEXT: [[R:%.*]] = call nnan <2 x float> @llvm.copysign.v2f32(<2 x float> <float 0.000000e+00, float poison>, <2 x float> [[X:%.*]])
1253+
; CHECK-NEXT: [[R:%.*]] = call nnan <2 x float> @llvm.copysign.v2f32(<2 x float> zeroinitializer, <2 x float> [[X:%.*]])
12541254
; CHECK-NEXT: ret <2 x float> [[R]]
12551255
;
12561256
%r = fmul nnan <2 x float> %x, <float 0.0, float poison>
@@ -1268,11 +1268,10 @@ define half @mul_zero(half %x) {
12681268
ret half %r
12691269
}
12701270

1271-
; TODO: This could be fneg+copysign.
1272-
12731271
define half @mul_negzero_nnan(half %x) {
12741272
; CHECK-LABEL: @mul_negzero_nnan(
1275-
; CHECK-NEXT: [[R:%.*]] = fmul nnan half [[X:%.*]], 0xH8000
1273+
; CHECK-NEXT: [[TMP1:%.*]] = fneg nnan half [[X:%.*]]
1274+
; CHECK-NEXT: [[R:%.*]] = call nnan half @llvm.copysign.f16(half 0xH0000, half [[TMP1]])
12761275
; CHECK-NEXT: ret half [[R]]
12771276
;
12781277
%r = fmul nnan half %x, -0.0
@@ -1282,7 +1281,7 @@ define half @mul_negzero_nnan(half %x) {
12821281
define float @mul_pos_zero_nnan_ninf(float nofpclass(inf nan) %a) {
12831282
; CHECK-LABEL: @mul_pos_zero_nnan_ninf(
12841283
; CHECK-NEXT: entry:
1285-
; CHECK-NEXT: [[RET:%.*]] = fmul float [[A:%.*]], 0.000000e+00
1284+
; CHECK-NEXT: [[RET:%.*]] = call float @llvm.copysign.f32(float 0.000000e+00, float [[A:%.*]])
12861285
; CHECK-NEXT: ret float [[RET]]
12871286
;
12881287
entry:
@@ -1304,7 +1303,7 @@ entry:
13041303
define float @mul_pos_zero_nnan_ninf_fmf(float nofpclass(nan) %a) {
13051304
; CHECK-LABEL: @mul_pos_zero_nnan_ninf_fmf(
13061305
; CHECK-NEXT: entry:
1307-
; CHECK-NEXT: [[RET:%.*]] = fmul ninf float [[A:%.*]], 0.000000e+00
1306+
; CHECK-NEXT: [[RET:%.*]] = call ninf float @llvm.copysign.f32(float 0.000000e+00, float [[A:%.*]])
13081307
; CHECK-NEXT: ret float [[RET]]
13091308
;
13101309
entry:
@@ -1315,7 +1314,8 @@ entry:
13151314
define float @mul_neg_zero_nnan_ninf(float nofpclass(inf nan) %a) {
13161315
; CHECK-LABEL: @mul_neg_zero_nnan_ninf(
13171316
; CHECK-NEXT: entry:
1318-
; CHECK-NEXT: [[RET:%.*]] = fmul float [[A:%.*]], -0.000000e+00
1317+
; CHECK-NEXT: [[TMP0:%.*]] = fneg float [[A:%.*]]
1318+
; CHECK-NEXT: [[RET:%.*]] = call float @llvm.copysign.f32(float 0.000000e+00, float [[TMP0]])
13191319
; CHECK-NEXT: ret float [[RET]]
13201320
;
13211321
entry:
@@ -1326,7 +1326,8 @@ entry:
13261326
define float @mul_neg_zero_nnan_fmf(float %a) {
13271327
; CHECK-LABEL: @mul_neg_zero_nnan_fmf(
13281328
; CHECK-NEXT: entry:
1329-
; CHECK-NEXT: [[RET:%.*]] = fmul nnan float [[A:%.*]], -0.000000e+00
1329+
; CHECK-NEXT: [[TMP0:%.*]] = fneg nnan float [[A:%.*]]
1330+
; CHECK-NEXT: [[RET:%.*]] = call nnan float @llvm.copysign.f32(float 0.000000e+00, float [[TMP0]])
13301331
; CHECK-NEXT: ret float [[RET]]
13311332
;
13321333
entry:
@@ -1337,20 +1338,20 @@ entry:
13371338
define float @mul_neg_zero_nnan_ninf_fmf(float nofpclass(inf nan) %a) {
13381339
; CHECK-LABEL: @mul_neg_zero_nnan_ninf_fmf(
13391340
; CHECK-NEXT: entry:
1340-
; CHECK-NEXT: [[RET:%.*]] = fmul nnan ninf float [[A:%.*]], -0.000000e+00
1341+
; CHECK-NEXT: [[TMP0:%.*]] = fneg nnan ninf float [[A:%.*]]
1342+
; CHECK-NEXT: [[RET:%.*]] = call nnan ninf float @llvm.copysign.f32(float 0.000000e+00, float [[TMP0]])
13411343
; CHECK-NEXT: ret float [[RET]]
13421344
;
13431345
entry:
13441346
%ret = fmul nnan ninf float %a, -0.000000e+00
13451347
ret float %ret
13461348
}
13471349

1348-
; poison propagates through vector elements
1349-
13501350
define <3 x float> @mul_neg_zero_nnan_ninf_vec(<3 x float> nofpclass(inf nan) %a) {
13511351
; CHECK-LABEL: @mul_neg_zero_nnan_ninf_vec(
13521352
; CHECK-NEXT: entry:
1353-
; CHECK-NEXT: [[RET:%.*]] = fmul <3 x float> [[A:%.*]], <float -0.000000e+00, float undef, float poison>
1353+
; CHECK-NEXT: [[TMP0:%.*]] = fneg <3 x float> [[A:%.*]]
1354+
; CHECK-NEXT: [[RET:%.*]] = call <3 x float> @llvm.copysign.v3f32(<3 x float> zeroinitializer, <3 x float> [[TMP0]])
13541355
; CHECK-NEXT: ret <3 x float> [[RET]]
13551356
;
13561357
entry:

‎llvm/test/Transforms/InstCombine/fpcast.ll

Lines changed: 1 addition & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -424,10 +424,7 @@ define i32 @fptosi_select(i1 %cond) {
424424
define i32 @mul_pos_zero_convert(i32 %a) {
425425
; CHECK-LABEL: @mul_pos_zero_convert(
426426
; CHECK-NEXT: entry:
427-
; CHECK-NEXT: [[FP:%.*]] = sitofp i32 [[A:%.*]] to float
428-
; CHECK-NEXT: [[RET:%.*]] = fmul float [[FP]], 0.000000e+00
429-
; CHECK-NEXT: [[CONV:%.*]] = fptosi float [[RET]] to i32
430-
; CHECK-NEXT: ret i32 [[CONV]]
427+
; CHECK-NEXT: ret i32 0
431428
;
432429
entry:
433430
%fp = sitofp i32 %a to float

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