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[InstCombine] fold cond ? x : -x == 0 into x == 0 (#85673)
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Resolve #85250 
Alive2: https://alive2.llvm.org/ce/z/7DMRCy
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@SahilPatidar
SahilPatidar authored Apr 20, 2024
1 parent 22bf7c5 commit 225ae82
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8 changes: 8 additions & 0 deletions llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -8045,6 +8045,14 @@ Instruction *InstCombinerImpl::visitFCmpInst(FCmpInst &I) {
Constant *RHSC;
if (match(Op0, m_Instruction(LHSI)) && match(Op1, m_Constant(RHSC))) {
switch (LHSI->getOpcode()) {
case Instruction::Select:
// fcmp eq (cond ? x : -x), 0 --> fcmp eq x, 0
if (FCmpInst::isEquality(Pred) && match(RHSC, m_AnyZeroFP()) &&
(match(LHSI,
m_Select(m_Value(), m_Value(X), m_FNeg(m_Deferred(X)))) ||
match(LHSI, m_Select(m_Value(), m_FNeg(m_Value(X)), m_Deferred(X)))))
return replaceOperand(I, 0, X);
break;
case Instruction::PHI:
if (Instruction *NV = foldOpIntoPhi(I, cast<PHINode>(LHSI)))
return NV;
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232 changes: 232 additions & 0 deletions llvm/test/Transforms/InstCombine/fcmp.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -1486,3 +1486,235 @@ define i1 @fcmp_fadd_fast_zero(float %x, float %y) {
%cmp = fcmp ugt float %add, %y
ret i1 %cmp
}

define i1 @fcmp_ueq_sel_x_negx(float %x) {
; CHECK-LABEL: @fcmp_ueq_sel_x_negx(
; CHECK-NEXT: [[RES:%.*]] = fcmp ueq float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: ret i1 [[RES]]
;
%f = fcmp ueq float %x, 0.000000e+00
%neg = fneg float %x
%sel = select i1 %f, float %x, float %neg
%res = fcmp ueq float %sel, 0.000000e+00
ret i1 %res
}

define i1 @fcmp_une_sel_x_negx(float %x) {
; CHECK-LABEL: @fcmp_une_sel_x_negx(
; CHECK-NEXT: [[RES:%.*]] = fcmp une float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: ret i1 [[RES]]
;
%f = fcmp une float %x, 0.000000e+00
%neg = fneg float %x
%sel = select i1 %f, float %x, float %neg
%res = fcmp une float %sel, 0.000000e+00
ret i1 %res
}

define i1 @fcmp_oeq_sel_x_negx(float %x) {
; CHECK-LABEL: @fcmp_oeq_sel_x_negx(
; CHECK-NEXT: [[RES:%.*]] = fcmp oeq float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: ret i1 [[RES]]
;
%f = fcmp oeq float %x, 0.000000e+00
%neg = fneg float %x
%sel = select i1 %f, float %x, float %neg
%res = fcmp oeq float %sel, 0.000000e+00
ret i1 %res
}

define i1 @fcmp_one_sel_x_negx(float %x) {
; CHECK-LABEL: @fcmp_one_sel_x_negx(
; CHECK-NEXT: [[RES:%.*]] = fcmp one float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: ret i1 [[RES]]
;
%f = fcmp one float %x, 0.000000e+00
%neg = fneg float %x
%sel = select i1 %f, float %x, float %neg
%res = fcmp one float %sel, 0.000000e+00
ret i1 %res
}

define i1 @fcmp_ueq_sel_x_negx_nzero(float %x) {
; CHECK-LABEL: @fcmp_ueq_sel_x_negx_nzero(
; CHECK-NEXT: [[RES:%.*]] = fcmp ueq float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: ret i1 [[RES]]
;
%f = fcmp ueq float %x, 0.000000e+00
%neg = fneg float %x
%sel = select i1 %f, float %x, float %neg
%res = fcmp ueq float %sel, -0.000000e+00
ret i1 %res
}

define i1 @fcmp_une_sel_x_negx_nzero(float %x) {
; CHECK-LABEL: @fcmp_une_sel_x_negx_nzero(
; CHECK-NEXT: [[RES:%.*]] = fcmp une float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: ret i1 [[RES]]
;
%f = fcmp une float %x, 0.000000e+00
%neg = fneg float %x
%sel = select i1 %f, float %x, float %neg
%res = fcmp une float %sel, -0.000000e+00
ret i1 %res
}

define i1 @fcmp_oeq_sel_x_negx_nzero(float %x) {
; CHECK-LABEL: @fcmp_oeq_sel_x_negx_nzero(
; CHECK-NEXT: [[RES:%.*]] = fcmp oeq float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: ret i1 [[RES]]
;
%f = fcmp oeq float %x, 0.000000e+00
%neg = fneg float %x
%sel = select i1 %f, float %x, float %neg
%res = fcmp oeq float %sel, -0.000000e+00
ret i1 %res
}

define i1 @fcmp_one_sel_x_negx_nzero(float %x) {
; CHECK-LABEL: @fcmp_one_sel_x_negx_nzero(
; CHECK-NEXT: [[RES:%.*]] = fcmp one float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: ret i1 [[RES]]
;
%f = fcmp one float %x, 0.000000e+00
%neg = fneg float %x
%sel = select i1 %f, float %x, float %neg
%res = fcmp one float %sel, -0.000000e+00
ret i1 %res
}

define <8 x i1> @fcmp_ueq_sel_x_negx_vec(<8 x float> %x) {
; CHECK-LABEL: @fcmp_ueq_sel_x_negx_vec(
; CHECK-NEXT: [[RES:%.*]] = fcmp ueq <8 x float> [[X:%.*]], zeroinitializer
; CHECK-NEXT: ret <8 x i1> [[RES]]
;
%f = fcmp ueq <8 x float> %x, zeroinitializer
%neg = fneg <8 x float> %x
%sel = select <8 x i1> %f, <8 x float> %x, <8 x float> %neg
%res = fcmp ueq <8 x float> %sel, zeroinitializer
ret <8 x i1> %res
}

define <8 x i1> @fcmp_une_sel_x_negx_vec(<8 x float> %x) {
; CHECK-LABEL: @fcmp_une_sel_x_negx_vec(
; CHECK-NEXT: [[RES:%.*]] = fcmp une <8 x float> [[X:%.*]], zeroinitializer
; CHECK-NEXT: ret <8 x i1> [[RES]]
;
%f = fcmp une <8 x float> %x, zeroinitializer
%neg = fneg <8 x float> %x
%sel = select <8 x i1> %f, <8 x float> %x, <8 x float> %neg
%res = fcmp une <8 x float> %sel, zeroinitializer
ret <8 x i1> %res
}

define <8 x i1> @fcmp_oeq_sel_x_negx_vec(<8 x float> %x) {
; CHECK-LABEL: @fcmp_oeq_sel_x_negx_vec(
; CHECK-NEXT: [[RES:%.*]] = fcmp oeq <8 x float> [[X:%.*]], zeroinitializer
; CHECK-NEXT: ret <8 x i1> [[RES]]
;
%f = fcmp oeq <8 x float> %x, zeroinitializer
%neg = fneg <8 x float> %x
%sel = select <8 x i1> %f, <8 x float> %x, <8 x float> %neg
%res = fcmp oeq <8 x float> %sel, zeroinitializer
ret <8 x i1> %res
}

define <8 x i1> @fcmp_one_sel_x_negx_vec(<8 x float> %x) {
; CHECK-LABEL: @fcmp_one_sel_x_negx_vec(
; CHECK-NEXT: [[RES:%.*]] = fcmp one <8 x float> [[X:%.*]], zeroinitializer
; CHECK-NEXT: ret <8 x i1> [[RES]]
;
%f = fcmp one <8 x float> %x, zeroinitializer
%neg = fneg <8 x float> %x
%sel = select <8 x i1> %f, <8 x float> %x, <8 x float> %neg
%res = fcmp one <8 x float> %sel, zeroinitializer
ret <8 x i1> %res
}

define <2 x i1> @fcmp_oeq_sel_x_negx_with_any_fpzero_ninf_vec(<2 x i1> %cond, <2 x float> %x) {
; CHECK-LABEL: @fcmp_oeq_sel_x_negx_with_any_fpzero_ninf_vec(
; CHECK-NEXT: [[ICMP:%.*]] = fcmp ninf oeq <2 x float> [[X:%.*]], zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[ICMP]]
;
%fneg = fneg <2 x float> %x
%sel = select <2 x i1> %cond, <2 x float> %x, <2 x float> %fneg
%icmp = fcmp ninf oeq <2 x float> %sel, <float 0.0, float -0.0>
ret <2 x i1> %icmp
}

define <2 x i1> @fcmp_one_sel_x_negx_with_any_fpzero_ninf_vec(<2 x i1> %cond, <2 x float> %x) {
; CHECK-LABEL: @fcmp_one_sel_x_negx_with_any_fpzero_ninf_vec(
; CHECK-NEXT: [[ICMP:%.*]] = fcmp ninf one <2 x float> [[X:%.*]], zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[ICMP]]
;
%fneg = fneg <2 x float> %x
%sel = select <2 x i1> %cond, <2 x float> %x, <2 x float> %fneg
%icmp = fcmp ninf one <2 x float> %sel, <float 0.0, float -0.0>
ret <2 x i1> %icmp
}

define <2 x i1> @fcmp_ueq_sel_x_negx_with_any_fpzero_ninf_vec(<2 x i1> %cond, <2 x float> %x) {
; CHECK-LABEL: @fcmp_ueq_sel_x_negx_with_any_fpzero_ninf_vec(
; CHECK-NEXT: [[ICMP:%.*]] = fcmp ninf ueq <2 x float> [[X:%.*]], zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[ICMP]]
;
%fneg = fneg <2 x float> %x
%sel = select <2 x i1> %cond, <2 x float> %x, <2 x float> %fneg
%icmp = fcmp ninf ueq <2 x float> %sel, <float 0.0, float -0.0>
ret <2 x i1> %icmp
}

define <2 x i1> @fcmp_une_sel_x_negx_with_any_fpzero_ninf_vec(<2 x i1> %cond, <2 x float> %x) {
; CHECK-LABEL: @fcmp_une_sel_x_negx_with_any_fpzero_ninf_vec(
; CHECK-NEXT: [[ICMP:%.*]] = fcmp ninf une <2 x float> [[X:%.*]], zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[ICMP]]
;
%fneg = fneg <2 x float> %x
%sel = select <2 x i1> %cond, <2 x float> %x, <2 x float> %fneg
%icmp = fcmp ninf une <2 x float> %sel, <float 0.0, float -0.0>
ret <2 x i1> %icmp
}

define <2 x i1> @fcmp_oeq_sel_x_negx_with_any_fpzero_nnan_vec(<2 x i1> %cond, <2 x float> %x) {
; CHECK-LABEL: @fcmp_oeq_sel_x_negx_with_any_fpzero_nnan_vec(
; CHECK-NEXT: [[ICMP:%.*]] = fcmp nnan oeq <2 x float> [[X:%.*]], zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[ICMP]]
;
%fneg = fneg <2 x float> %x
%sel = select <2 x i1> %cond, <2 x float> %x, <2 x float> %fneg
%icmp = fcmp nnan oeq <2 x float> %sel, <float 0.0, float -0.0>
ret <2 x i1> %icmp
}

define <2 x i1> @fcmp_one_sel_x_negx_with_any_fpzero_nnan_vec(<2 x i1> %cond, <2 x float> %x) {
; CHECK-LABEL: @fcmp_one_sel_x_negx_with_any_fpzero_nnan_vec(
; CHECK-NEXT: [[ICMP:%.*]] = fcmp nnan one <2 x float> [[X:%.*]], zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[ICMP]]
;
%fneg = fneg <2 x float> %x
%sel = select <2 x i1> %cond, <2 x float> %x, <2 x float> %fneg
%icmp = fcmp nnan one <2 x float> %sel, <float 0.0, float -0.0>
ret <2 x i1> %icmp
}

define <2 x i1> @fcmp_ueq_sel_x_negx_with_any_fpzero_nnan_vec(<2 x i1> %cond, <2 x float> %x) {
; CHECK-LABEL: @fcmp_ueq_sel_x_negx_with_any_fpzero_nnan_vec(
; CHECK-NEXT: [[ICMP:%.*]] = fcmp nnan ueq <2 x float> [[X:%.*]], zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[ICMP]]
;
%fneg = fneg <2 x float> %x
%sel = select <2 x i1> %cond, <2 x float> %x, <2 x float> %fneg
%icmp = fcmp nnan ueq <2 x float> %sel, <float 0.0, float -0.0>
ret <2 x i1> %icmp
}

define <2 x i1> @fcmp_une_sel_x_negx_with_any_fpzero_nnan_vec(<2 x i1> %cond, <2 x float> %x) {
; CHECK-LABEL: @fcmp_une_sel_x_negx_with_any_fpzero_nnan_vec(
; CHECK-NEXT: [[ICMP:%.*]] = fcmp nnan une <2 x float> [[X:%.*]], zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[ICMP]]
;
%fneg = fneg <2 x float> %x
%sel = select <2 x i1> %cond, <2 x float> %x, <2 x float> %fneg
%icmp = fcmp nnan une <2 x float> %sel, <float 0.0, float -0.0>
ret <2 x i1> %icmp
}

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