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Nov 20, 2024
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InstCombine: support floating-point equivalences #114975

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2 changes: 1 addition & 1 deletion llvm/lib/Transforms/InstCombine/InstCombineInternal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -750,7 +750,7 @@ class LLVM_LIBRARY_VISIBILITY InstCombinerImpl final
Value *A, Value *B, Instruction &Outer,
SelectPatternFlavor SPF2, Value *C);
Instruction *foldSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI);
Instruction *foldSelectValueEquivalence(SelectInst &SI, ICmpInst &ICI);
Instruction *foldSelectValueEquivalence(SelectInst &SI, CmpInst &CI);
bool replaceInInstruction(Value *V, Value *Old, Value *New,
unsigned Depth = 0);

Expand Down
21 changes: 11 additions & 10 deletions llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
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Expand Up @@ -1327,16 +1327,16 @@ bool InstCombinerImpl::replaceInInstruction(Value *V, Value *Old, Value *New,
/// We can't replace %sel with %add unless we strip away the flags.
/// TODO: Wrapping flags could be preserved in some cases with better analysis.
Instruction *InstCombinerImpl::foldSelectValueEquivalence(SelectInst &Sel,
ICmpInst &Cmp) {
if (!Cmp.isEquality())
return nullptr;

// Canonicalize the pattern to ICMP_EQ by swapping the select operands.
CmpInst &Cmp) {
// Canonicalize the pattern to an equivalence on the predicate by swapping the
// select operands.
Value *TrueVal = Sel.getTrueValue(), *FalseVal = Sel.getFalseValue();
bool Swapped = false;
if (Cmp.getPredicate() == ICmpInst::ICMP_NE) {
if (Cmp.isEquivalence(/*Invert=*/true)) {
std::swap(TrueVal, FalseVal);
Swapped = true;
} else if (!Cmp.isEquivalence()) {
return nullptr;
}

Value *CmpLHS = Cmp.getOperand(0), *CmpRHS = Cmp.getOperand(1);
Expand All @@ -1347,7 +1347,7 @@ Instruction *InstCombinerImpl::foldSelectValueEquivalence(SelectInst &Sel,
// would lead to an infinite replacement cycle.
// If we will be able to evaluate f(Y) to a constant, we can allow undef,
// otherwise Y cannot be undef as we might pick different values for undef
// in the icmp and in f(Y).
// in the cmp and in f(Y).
if (TrueVal == OldOp)
return nullptr;

Expand Down Expand Up @@ -1901,9 +1901,6 @@ static Instruction *foldSelectICmpEq(SelectInst &SI, ICmpInst *ICI,
/// Visit a SelectInst that has an ICmpInst as its first operand.
Instruction *InstCombinerImpl::foldSelectInstWithICmp(SelectInst &SI,
ICmpInst *ICI) {
if (Instruction *NewSel = foldSelectValueEquivalence(SI, *ICI))
return NewSel;

if (Value *V =
canonicalizeSPF(*ICI, SI.getTrueValue(), SI.getFalseValue(), *this))
return replaceInstUsesWith(SI, V);
Expand Down Expand Up @@ -3848,6 +3845,10 @@ Instruction *InstCombinerImpl::visitSelectInst(SelectInst &SI) {
return Fabs;

// See if we are selecting two values based on a comparison of the two values.
if (CmpInst *CI = dyn_cast<CmpInst>(CondVal))
if (Instruction *NewSel = foldSelectValueEquivalence(SI, *CI))
return NewSel;

if (ICmpInst *ICI = dyn_cast<ICmpInst>(CondVal))
if (Instruction *Result = foldSelectInstWithICmp(SI, ICI))
return Result;
Expand Down
65 changes: 31 additions & 34 deletions llvm/test/Transforms/InstCombine/select-binop-cmp.ll
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Expand Up @@ -706,11 +706,10 @@ define i32 @select_lshr_icmp_const_different_values(i32 %x, i32 %y) {
ret i32 %C
}

; Invalid identity constant for FP op
define float @select_fadd_fcmp_bad(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fadd_fcmp_bad(
define float @select_fadd_fcmp_equiv(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fadd_fcmp_equiv(
; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], -1.000000e+00
; CHECK-NEXT: [[B:%.*]] = fadd nsz float [[X]], [[Z:%.*]]
; CHECK-NEXT: [[B:%.*]] = fadd nsz float [[Z:%.*]], -1.000000e+00
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
; CHECK-NEXT: ret float [[C]]
;
Expand All @@ -720,6 +719,19 @@ define float @select_fadd_fcmp_bad(float %x, float %y, float %z) {
ret float %C
}

define float @select_fadd_fcmp_equiv2(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fadd_fcmp_equiv2(
; CHECK-NEXT: [[A:%.*]] = fcmp une float [[X:%.*]], -1.000000e+00
; CHECK-NEXT: [[B:%.*]] = fadd nsz float [[Z:%.*]], -1.000000e+00
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[B]]
; CHECK-NEXT: ret float [[C]]
;
%A = fcmp une float %x, -1.0
%B = fadd nsz float %x, %z
%C = select i1 %A, float %y, float %B
ret float %C
}

; Invalid comparison type
define float @select_fadd_fcmp_bad_2(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fadd_fcmp_bad_2(
Expand Down Expand Up @@ -893,24 +905,10 @@ define float @select_fadd_fcmp_bad_13(float %x, float %y, float %z) {
ret float %C
}

; Invalid identity constant for FP op
define float @select_fadd_fcmp_bad_14(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fadd_fcmp_bad_14(
; CHECK-NEXT: [[A:%.*]] = fcmp une float [[X:%.*]], -1.000000e+00
; CHECK-NEXT: [[B:%.*]] = fadd nsz float [[X]], [[Z:%.*]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[Y:%.*]], float [[B]]
; CHECK-NEXT: ret float [[C]]
;
%A = fcmp une float %x, -1.0
%B = fadd nsz float %x, %z
%C = select i1 %A, float %y, float %B
ret float %C
}

define float @select_fmul_fcmp_bad(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fmul_fcmp_bad(
define float @select_fmul_fcmp_equiv(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fmul_fcmp_equiv(
; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], 3.000000e+00
; CHECK-NEXT: [[B:%.*]] = fmul nsz float [[X]], [[Z:%.*]]
; CHECK-NEXT: [[B:%.*]] = fmul nsz float [[Z:%.*]], 3.000000e+00
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
; CHECK-NEXT: ret float [[C]]
;
Expand All @@ -920,11 +918,10 @@ define float @select_fmul_fcmp_bad(float %x, float %y, float %z) {
ret float %C
}

define float @select_fmul_fcmp_bad_2(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fmul_fcmp_bad_2(
define float @select_fmul_fcmp_equiv2(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fmul_fcmp_equiv2(
; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], 1.000000e+00
; CHECK-NEXT: [[B:%.*]] = fmul float [[X]], [[Z:%.*]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[B:%.*]], float [[Y:%.*]]
; CHECK-NEXT: ret float [[C]]
;
%A = fcmp oeq float %x, 1.0
Expand Down Expand Up @@ -959,10 +956,10 @@ define float @select_fmul_icmp_bad_2(float %x, float %y, float %z, i32 %k) {
ret float %C
}

define float @select_fdiv_fcmp_bad(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fdiv_fcmp_bad(
define float @select_fdiv_fcmp_equiv(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fdiv_fcmp_equiv(
; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], 1.000000e+00
; CHECK-NEXT: [[B:%.*]] = fdiv float [[X]], [[Z:%.*]]
; CHECK-NEXT: [[B:%.*]] = fdiv float 1.000000e+00, [[Z:%.*]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
; CHECK-NEXT: ret float [[C]]
;
Expand All @@ -972,10 +969,10 @@ define float @select_fdiv_fcmp_bad(float %x, float %y, float %z) {
ret float %C
}

define float @select_fdiv_fcmp_bad_2(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fdiv_fcmp_bad_2(
define float @select_fdiv_fcmp_equiv2(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fdiv_fcmp_equiv2(
; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], 3.000000e+00
; CHECK-NEXT: [[B:%.*]] = fdiv nsz float [[X]], [[Z:%.*]]
; CHECK-NEXT: [[B:%.*]] = fdiv nsz float 3.000000e+00, [[Z:%.*]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
; CHECK-NEXT: ret float [[C]]
;
Expand All @@ -1001,10 +998,10 @@ define float @select_fsub_fcmp_bad(float %x, float %y, float %z) {
ret float %C
}

define float @select_fsub_fcmp_bad_2(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fsub_fcmp_bad_2(
define float @select_fsub_fcmp_equiv(float %x, float %y, float %z) {
; CHECK-LABEL: @select_fsub_fcmp_equiv(
; CHECK-NEXT: [[A:%.*]] = fcmp oeq float [[X:%.*]], 1.000000e+00
; CHECK-NEXT: [[B:%.*]] = fsub nsz float [[Z:%.*]], [[X]]
; CHECK-NEXT: [[B:%.*]] = fadd nsz float [[Z:%.*]], -1.000000e+00
; CHECK-NEXT: [[C:%.*]] = select i1 [[A]], float [[B]], float [[Y:%.*]]
; CHECK-NEXT: ret float [[C]]
;
Expand Down
16 changes: 8 additions & 8 deletions llvm/test/Transforms/InstCombine/select-value-equivalence.ll
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Expand Up @@ -90,7 +90,7 @@ define float @select_fcmp_fadd_oeq_not_zero(float %x, float %y) {
; CHECK-LABEL: define float @select_fcmp_fadd_oeq_not_zero(
; CHECK-SAME: float [[X:%.*]], float [[Y:%.*]]) {
; CHECK-NEXT: [[FCMP:%.*]] = fcmp oeq float [[Y]], 2.000000e+00
; CHECK-NEXT: [[FADD:%.*]] = fadd float [[X]], [[Y]]
; CHECK-NEXT: [[FADD:%.*]] = fadd float [[X]], 2.000000e+00
; CHECK-NEXT: [[RETVAL:%.*]] = select i1 [[FCMP]], float [[FADD]], float [[X]]
; CHECK-NEXT: ret float [[RETVAL]]
;
Expand All @@ -104,7 +104,7 @@ define float @select_fcmp_fadd_une_not_zero(float %x, float %y) {
; CHECK-LABEL: define float @select_fcmp_fadd_une_not_zero(
; CHECK-SAME: float [[X:%.*]], float [[Y:%.*]]) {
; CHECK-NEXT: [[FCMP:%.*]] = fcmp une float [[Y]], 2.000000e+00
; CHECK-NEXT: [[FADD:%.*]] = fadd float [[X]], [[Y]]
; CHECK-NEXT: [[FADD:%.*]] = fadd float [[X]], 2.000000e+00
; CHECK-NEXT: [[RETVAL:%.*]] = select i1 [[FCMP]], float [[X]], float [[FADD]]
; CHECK-NEXT: ret float [[RETVAL]]
;
Expand All @@ -118,7 +118,7 @@ define float @select_fcmp_fadd_ueq_nnan_not_zero(float %x, float %y) {
; CHECK-LABEL: define float @select_fcmp_fadd_ueq_nnan_not_zero(
; CHECK-SAME: float [[X:%.*]], float [[Y:%.*]]) {
; CHECK-NEXT: [[FCMP:%.*]] = fcmp nnan ueq float [[Y]], 2.000000e+00
; CHECK-NEXT: [[FADD:%.*]] = fadd float [[X]], [[Y]]
; CHECK-NEXT: [[FADD:%.*]] = fadd float [[X]], 2.000000e+00
; CHECK-NEXT: [[RETVAL:%.*]] = select i1 [[FCMP]], float [[FADD]], float [[X]]
; CHECK-NEXT: ret float [[RETVAL]]
;
Expand All @@ -132,7 +132,7 @@ define float @select_fcmp_fadd_one_nnan_not_zero(float %x, float %y) {
; CHECK-LABEL: define float @select_fcmp_fadd_one_nnan_not_zero(
; CHECK-SAME: float [[X:%.*]], float [[Y:%.*]]) {
; CHECK-NEXT: [[FCMP:%.*]] = fcmp nnan one float [[Y]], 2.000000e+00
; CHECK-NEXT: [[FADD:%.*]] = fadd float [[X]], [[Y]]
; CHECK-NEXT: [[FADD:%.*]] = fadd float [[X]], 2.000000e+00
; CHECK-NEXT: [[RETVAL:%.*]] = select i1 [[FCMP]], float [[X]], float [[FADD]]
; CHECK-NEXT: ret float [[RETVAL]]
;
Expand Down Expand Up @@ -202,7 +202,7 @@ define <2 x float> @select_fcmp_fadd_oeq_not_zero_vec(<2 x float> %x, <2 x float
; CHECK-LABEL: define <2 x float> @select_fcmp_fadd_oeq_not_zero_vec(
; CHECK-SAME: <2 x float> [[X:%.*]], <2 x float> [[Y:%.*]]) {
; CHECK-NEXT: [[FCMP:%.*]] = fcmp oeq <2 x float> [[Y]], splat (float 2.000000e+00)
; CHECK-NEXT: [[FADD:%.*]] = fadd <2 x float> [[X]], [[Y]]
; CHECK-NEXT: [[FADD:%.*]] = fadd <2 x float> [[X]], splat (float 2.000000e+00)
; CHECK-NEXT: [[RETVAL:%.*]] = select <2 x i1> [[FCMP]], <2 x float> [[FADD]], <2 x float> [[X]]
; CHECK-NEXT: ret <2 x float> [[RETVAL]]
;
Expand All @@ -216,7 +216,7 @@ define <2 x float> @select_fcmp_fadd_une_not_zero_vec(<2 x float> %x, <2 x float
; CHECK-LABEL: define <2 x float> @select_fcmp_fadd_une_not_zero_vec(
; CHECK-SAME: <2 x float> [[X:%.*]], <2 x float> [[Y:%.*]]) {
; CHECK-NEXT: [[FCMP:%.*]] = fcmp une <2 x float> [[Y]], splat (float 2.000000e+00)
; CHECK-NEXT: [[FADD:%.*]] = fadd <2 x float> [[X]], [[Y]]
; CHECK-NEXT: [[FADD:%.*]] = fadd <2 x float> [[X]], splat (float 2.000000e+00)
; CHECK-NEXT: [[RETVAL:%.*]] = select <2 x i1> [[FCMP]], <2 x float> [[X]], <2 x float> [[FADD]]
; CHECK-NEXT: ret <2 x float> [[RETVAL]]
;
Expand All @@ -230,7 +230,7 @@ define <2 x float> @select_fcmp_fadd_ueq_nnan_not_zero_vec(<2 x float> %x, <2 x
; CHECK-LABEL: define <2 x float> @select_fcmp_fadd_ueq_nnan_not_zero_vec(
; CHECK-SAME: <2 x float> [[X:%.*]], <2 x float> [[Y:%.*]]) {
; CHECK-NEXT: [[FCMP:%.*]] = fcmp nnan ueq <2 x float> [[Y]], splat (float 2.000000e+00)
; CHECK-NEXT: [[FADD:%.*]] = fadd <2 x float> [[X]], [[Y]]
; CHECK-NEXT: [[FADD:%.*]] = fadd <2 x float> [[X]], splat (float 2.000000e+00)
; CHECK-NEXT: [[RETVAL:%.*]] = select <2 x i1> [[FCMP]], <2 x float> [[FADD]], <2 x float> [[X]]
; CHECK-NEXT: ret <2 x float> [[RETVAL]]
;
Expand All @@ -244,7 +244,7 @@ define <2 x float> @select_fcmp_fadd_one_nnan_not_zero_vec(<2 x float> %x, <2 x
; CHECK-LABEL: define <2 x float> @select_fcmp_fadd_one_nnan_not_zero_vec(
; CHECK-SAME: <2 x float> [[X:%.*]], <2 x float> [[Y:%.*]]) {
; CHECK-NEXT: [[FCMP:%.*]] = fcmp nnan one <2 x float> [[Y]], splat (float 2.000000e+00)
; CHECK-NEXT: [[FADD:%.*]] = fadd <2 x float> [[X]], [[Y]]
; CHECK-NEXT: [[FADD:%.*]] = fadd <2 x float> [[X]], splat (float 2.000000e+00)
; CHECK-NEXT: [[RETVAL:%.*]] = select <2 x i1> [[FCMP]], <2 x float> [[X]], <2 x float> [[FADD]]
; CHECK-NEXT: ret <2 x float> [[RETVAL]]
;
Expand Down
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