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[InstCombine] canonicalize -0.0 to +0.0 in fcmp

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As stated in IEEE-754 and discussed in:
https://bugs.llvm.org/show_bug.cgi?id=38086
...the sign of zero does not affect any FP compare predicate.

Known regressions were fixed with:
rL346097 (D54001)
rL346143

The transform will help reduce pattern-matching complexity to solve:
https://bugs.llvm.org/show_bug.cgi?id=39475
...as well as improve CSE and codegen (a zero constant is almost always
easier to produce than 0x80..00).

llvm-svn: 346147
This commit is contained in:
Sanjay Patel 2018-11-05 17:26:42 +00:00
parent 51ca26e748
commit 2b48e0181b
5 changed files with 32 additions and 25 deletions
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7
lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -5397,6 +5397,13 @@ Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
return nullptr;
}
// The sign of 0.0 is ignored by fcmp, so canonicalize to +0.0:
// fcmp Pred X, -0.0 --> fcmp Pred X, 0.0
if (match(Op1, m_AnyZeroFP()) && !match(Op1, m_PosZeroFP())) {
I.setOperand(1, ConstantFP::getNullValue(Op1->getType()));
return &I;
}
// Handle fcmp with instruction LHS and constant RHS.
Instruction *LHSI;
Constant *RHSC;

12
test/Transforms/InstCombine/fcmp-special.ll
View File

@ -190,7 +190,7 @@ define i1 @nnan_ops_to_fcmp_uno(float %x, float %y) {
define i1 @negative_zero_oeq(float %x) {
; CHECK-LABEL: @negative_zero_oeq(
; CHECK-NEXT: [[R:%.*]] = fcmp oeq float [[X:%.*]], -0.000000e+00
; CHECK-NEXT: [[R:%.*]] = fcmp oeq float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: ret i1 [[R]]
;
%r = fcmp oeq float %x, -0.0
@ -199,7 +199,7 @@ define i1 @negative_zero_oeq(float %x) {
define i1 @negative_zero_oge(double %x) {
; CHECK-LABEL: @negative_zero_oge(
; CHECK-NEXT: [[R:%.*]] = fcmp nnan oge double [[X:%.*]], -0.000000e+00
; CHECK-NEXT: [[R:%.*]] = fcmp nnan oge double [[X:%.*]], 0.000000e+00
; CHECK-NEXT: ret i1 [[R]]
;
%r = fcmp nnan oge double %x, -0.0
@ -208,7 +208,7 @@ define i1 @negative_zero_oge(double %x) {
define i1 @negative_zero_uge(half %x) {
; CHECK-LABEL: @negative_zero_uge(
; CHECK-NEXT: [[R:%.*]] = fcmp fast uge half [[X:%.*]], 0xH8000
; CHECK-NEXT: [[R:%.*]] = fcmp fast uge half [[X:%.*]], 0xH0000
; CHECK-NEXT: ret i1 [[R]]
;
%r = fcmp fast uge half %x, -0.0
@ -217,7 +217,7 @@ define i1 @negative_zero_uge(half %x) {
define <2 x i1> @negative_zero_olt_vec(<2 x float> %x) {
; CHECK-LABEL: @negative_zero_olt_vec(
; CHECK-NEXT: [[R:%.*]] = fcmp reassoc ninf olt <2 x float> [[X:%.*]], <float -0.000000e+00, float -0.000000e+00>
; CHECK-NEXT: [[R:%.*]] = fcmp reassoc ninf olt <2 x float> [[X:%.*]], zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[R]]
;
%r = fcmp reassoc ninf olt <2 x float> %x, <float -0.0, float -0.0>
@ -226,7 +226,7 @@ define <2 x i1> @negative_zero_olt_vec(<2 x float> %x) {
define <2 x i1> @negative_zero_une_vec_undef(<2 x double> %x) {
; CHECK-LABEL: @negative_zero_une_vec_undef(
; CHECK-NEXT: [[R:%.*]] = fcmp nnan une <2 x double> [[X:%.*]], <double -0.000000e+00, double undef>
; CHECK-NEXT: [[R:%.*]] = fcmp nnan une <2 x double> [[X:%.*]], zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[R]]
;
%r = fcmp nnan une <2 x double> %x, <double -0.0, double undef>
@ -235,7 +235,7 @@ define <2 x i1> @negative_zero_une_vec_undef(<2 x double> %x) {
define <2 x i1> @negative_zero_ule_vec_mixed(<2 x float> %x) {
; CHECK-LABEL: @negative_zero_ule_vec_mixed(
; CHECK-NEXT: [[R:%.*]] = fcmp ule <2 x float> [[X:%.*]], <float 0.000000e+00, float -0.000000e+00>
; CHECK-NEXT: [[R:%.*]] = fcmp ule <2 x float> [[X:%.*]], zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[R]]
;
%r = fcmp ule <2 x float> %x, <float 0.0, float -0.0>

2
test/Transforms/InstCombine/fcmp.ll
View File

@ -360,7 +360,7 @@ define i1 @test26_recipX_unorderd(float %X) {
; Fold <-1.0, -1.0> / X > <-0.0, -0.0>
define <2 x i1> @test27_recipX_gt_vecsplat(<2 x float> %X) {
; CHECK-LABEL: @test27_recipX_gt_vecsplat(
; CHECK-NEXT: [[CMP:%.*]] = fcmp ninf olt <2 x float> [[X:%.*]], <float -0.000000e+00, float -0.000000e+00>
; CHECK-NEXT: [[CMP:%.*]] = fcmp ninf olt <2 x float> [[X:%.*]], zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[CMP]]
;
%div = fdiv ninf <2 x float> <float -1.0, float -1.0>, %X

2
test/Transforms/InstCombine/minmax-fp.ll
View File

@ -78,7 +78,7 @@ define double @t6(float %a) {
define double @t7(float %a) {
; CHECK-LABEL: @t7(
; CHECK-NEXT: [[DOTINV:%.*]] = fcmp oge float [[A:%.*]], -0.000000e+00
; CHECK-NEXT: [[DOTINV:%.*]] = fcmp oge float [[A:%.*]], 0.000000e+00
; CHECK-NEXT: [[TMP1:%.*]] = select i1 [[DOTINV]], float -0.000000e+00, float [[A]]
; CHECK-NEXT: [[TMP2:%.*]] = fpext float [[TMP1]] to double
; CHECK-NEXT: ret double [[TMP2]]

34
test/Transforms/InstCombine/select-binop-cmp.ll
View File

@ -142,7 +142,7 @@ define i32 @select_xor_inv_icmp2(i32 %x, i32 %y, i32 %z) {
define float @select_fadd_fcmp(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fadd_fcmp(
; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], -0.000000e+00
; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[Z:%.*]], float [[Y:%.*]]
; CHECK-NEXT: ret float [[C]]
;
@ -168,7 +168,7 @@ define float @select_fadd_fcmp_poszero(float %x, float %y, float %z) {
define float @select_fadd_fcmp_2(float %x, float %y, float %v) {
; CHECK-LABEL: @select_fadd_fcmp_2(
; CHECK-NEXT: [[A:%.*]] = fcmp une float [[X:%.*]], -0.000000e+00
; CHECK-NEXT: [[A:%.*]] = fcmp une float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[Z:%.*]] = fadd float [[V:%.*]], 0.000000e+00
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[Z]]
; CHECK-NEXT: ret float [[C]]
@ -198,7 +198,7 @@ define float @select_fadd_fcmp_2_poszero(float %x, float %y, float %v) {
define float @select_fadd_fcmp_3(float %x, float %y) {
; CHECK-LABEL: @select_fadd_fcmp_3(
; CHECK-NEXT: [[A:%.*]] = fcmp une float [[X:%.*]], -0.000000e+00
; CHECK-NEXT: [[A:%.*]] = fcmp une float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float 6.000000e+00
; CHECK-NEXT: ret float [[C]]
;
@ -224,7 +224,7 @@ define float @select_fadd_fcmp_3_poszero(float %x, float %y) {
define float @select_fadd_fcmp_4(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fadd_fcmp_4(
; CHECK-NEXT: [[A:%.*]] = fcmp une float [[X:%.*]], -0.000000e+00
; CHECK-NEXT: [[A:%.*]] = fcmp une float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[Z:%.*]]
; CHECK-NEXT: ret float [[C]]
;
@ -250,7 +250,7 @@ define float @select_fadd_fcmp_4_poszero(float %x, float %y, float %z) {
define float @select_fadd_fcmp_5(float %x, float %y, float %v) {
; CHECK-LABEL: @select_fadd_fcmp_5(
; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], -0.000000e+00
; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[Z:%.*]] = fadd float [[V:%.*]], 0.000000e+00
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[Z]], float [[Y:%.*]]
; CHECK-NEXT: ret float [[C]]
@ -280,7 +280,7 @@ define float @select_fadd_fcmp_5_poszero(float %x, float %y, float %v) {
define float @select_fadd_fcmp_6(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fadd_fcmp_6(
; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], -0.000000e+00
; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float 6.000000e+00, float [[Y:%.*]]
; CHECK-NEXT: ret float [[C]]
;
@ -332,7 +332,7 @@ define float @select_fsub_fcmp(float %x, float %y, float %z) {
define float @select_fsub_fcmp_negzero(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fsub_fcmp_negzero(
; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], -0.000000e+00
; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[Z:%.*]], float [[Y:%.*]]
; CHECK-NEXT: ret float [[C]]
;
@ -675,7 +675,7 @@ define float @select_fadd_fcmp_bad_3(float %x, float %y, float %z, float %k) {
; Invalid order of operands of select
define float @select_fadd_fcmp_bad_4(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fadd_fcmp_bad_4(
; CHECK-NEXT: [[A:%.*]] = fcmp une float [[X:%.*]], -0.000000e+00
; CHECK-NEXT: [[A:%.*]] = fcmp une float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[B:%.*]] = fadd float [[X]], [[Z:%.*]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
; CHECK-NEXT: ret float [[C]]
@ -689,7 +689,7 @@ define float @select_fadd_fcmp_bad_4(float %x, float %y, float %z) {
; Invalid comparison type
define float @select_fadd_fcmp_bad_5(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fadd_fcmp_bad_5(
; CHECK-NEXT: [[A:%.*]] = fcmp one float [[X:%.*]], -0.000000e+00
; CHECK-NEXT: [[A:%.*]] = fcmp one float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[B:%.*]] = fadd nsz float [[Z:%.*]], [[X]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[B]]
; CHECK-NEXT: ret float [[C]]
@ -703,7 +703,7 @@ define float @select_fadd_fcmp_bad_5(float %x, float %y, float %z) {
; Invalid order of operands of select
define float @select_fadd_fcmp_bad_6(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fadd_fcmp_bad_6(
; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], -0.000000e+00
; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[B:%.*]] = fadd nsz float [[Z:%.*]], [[X]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[B]]
; CHECK-NEXT: ret float [[C]]
@ -717,7 +717,7 @@ define float @select_fadd_fcmp_bad_6(float %x, float %y, float %z) {
; Do not transform if we have signed zeros and if Z is possibly negative zero
define float @select_fadd_fcmp_bad_7(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fadd_fcmp_bad_7(
; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], -0.000000e+00
; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[B:%.*]] = fadd float [[X]], [[Z:%.*]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
; CHECK-NEXT: ret float [[C]]
@ -731,7 +731,7 @@ define float @select_fadd_fcmp_bad_7(float %x, float %y, float %z) {
; Invalid comparison type
define float @select_fadd_fcmp_bad_8(float %x, float %y, float %v) {
; CHECK-LABEL: @select_fadd_fcmp_bad_8(
; CHECK-NEXT: [[A:%.*]] = fcmp one float [[X:%.*]], -0.000000e+00
; CHECK-NEXT: [[A:%.*]] = fcmp one float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[Z:%.*]] = fadd float [[V:%.*]], -1.000000e+00
; CHECK-NEXT: [[B:%.*]] = fadd float [[Z]], [[X]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[B]]
@ -747,7 +747,7 @@ define float @select_fadd_fcmp_bad_8(float %x, float %y, float %v) {
; Invalid comparison type
define float @select_fadd_fcmp_bad_9(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fadd_fcmp_bad_9(
; CHECK-NEXT: [[A:%.*]] = fcmp one float [[X:%.*]], -0.000000e+00
; CHECK-NEXT: [[A:%.*]] = fcmp one float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[B:%.*]] = fadd nsz float [[Z:%.*]], [[X]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[B]]
; CHECK-NEXT: ret float [[C]]
@ -761,7 +761,7 @@ define float @select_fadd_fcmp_bad_9(float %x, float %y, float %z) {
; Invalid comparison type
define float @select_fadd_fcmp_bad_10(float %x, float %y, float %v) {
; CHECK-LABEL: @select_fadd_fcmp_bad_10(
; CHECK-NEXT: [[A:%.*]] = fcmp one float [[X:%.*]], -0.000000e+00
; CHECK-NEXT: [[A:%.*]] = fcmp one float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[Z:%.*]] = fadd float [[V:%.*]], 0.000000e+00
; CHECK-NEXT: [[B:%.*]] = fadd float [[Z]], [[X]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[B]]
@ -777,7 +777,7 @@ define float @select_fadd_fcmp_bad_10(float %x, float %y, float %v) {
; Do not transform if Z is possibly negative zero
define float @select_fadd_fcmp_bad_11(float %x, float %y, float %v) {
; CHECK-LABEL: @select_fadd_fcmp_bad_11(
; CHECK-NEXT: [[A:%.*]] = fcmp une float [[X:%.*]], -0.000000e+00
; CHECK-NEXT: [[A:%.*]] = fcmp une float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[Z:%.*]] = fadd float [[V:%.*]], -1.000000e+00
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[Z]]
; CHECK-NEXT: ret float [[C]]
@ -792,7 +792,7 @@ define float @select_fadd_fcmp_bad_11(float %x, float %y, float %v) {
; Do not transform if we have signed zeros and if Z is possibly negative zero
define float @select_fadd_fcmp_bad_12(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fadd_fcmp_bad_12(
; CHECK-NEXT: [[A:%.*]] = fcmp une float [[X:%.*]], -0.000000e+00
; CHECK-NEXT: [[A:%.*]] = fcmp une float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[B:%.*]] = fadd float [[Z:%.*]], [[X]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[B]]
; CHECK-NEXT: ret float [[C]]
@ -806,7 +806,7 @@ define float @select_fadd_fcmp_bad_12(float %x, float %y, float %z) {
; Invalid order of operands of select
define float @select_fadd_fcmp_bad_13(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fadd_fcmp_bad_13(
; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], -0.000000e+00
; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[B:%.*]] = fadd nsz float [[X]], [[Z:%.*]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[B]]
; CHECK-NEXT: ret float [[C]]