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[ConstantFold] Fold ilogb and ilogbf when the input parameter is a constant value. #113014

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Merged
merged 6 commits into from
Oct 20, 2024
Merged

[ConstantFold] Fold ilogb and ilogbf when the input parameter is a constant value. #113014

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constant fold ilogb
c8ef Oct 19, 2024
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Merge branch 'main' into ilogb
c8ef Oct 19, 2024
c2d1a16
address review comments
c8ef Oct 19, 2024
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try deleting check
c8ef Oct 19, 2024
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Revert "try deleting check"
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Merge branch 'main' into ilogb
c8ef Oct 20, 2024
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21 changes: 20 additions & 1 deletion llvm/lib/Analysis/ConstantFolding.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1677,6 +1677,8 @@ bool llvm::canConstantFoldCallTo(const CallBase *Call, const Function *F) {
return Name == "fabs" || Name == "fabsf" ||
Name == "floor" || Name == "floorf" ||
Name == "fmod" || Name == "fmodf";
case 'i':
return Name == "ilogb" || Name == "ilogbf";
case 'l':
return Name == "log" || Name == "logf" || Name == "logl" ||
Name == "log2" || Name == "log2f" || Name == "log10" ||
Expand Down Expand Up @@ -1772,6 +1774,17 @@ inline bool llvm_fenv_testexcept() {
return false;
}

Constant *ConstantFoldInt(int (*NativeFP)(double), const APFloat &V, Type *Ty) {
llvm_fenv_clearexcept();
int Result = NativeFP(V.convertToDouble());
if (llvm_fenv_testexcept()) {
llvm_fenv_clearexcept();
return nullptr;
}

return ConstantInt::get(Ty, Result, true);
}

Constant *ConstantFoldFP(double (*NativeFP)(double), const APFloat &V,
Type *Ty) {
llvm_fenv_clearexcept();
Expand Down Expand Up @@ -2131,7 +2144,8 @@ static Constant *ConstantFoldScalarCall1(StringRef Name,
}
#endif

if (!Ty->isHalfTy() && !Ty->isFloatTy() && !Ty->isDoubleTy())
if (!Ty->isHalfTy() && !Ty->isFloatTy() && !Ty->isDoubleTy() &&
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@arsenm arsenm Oct 19, 2024

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Probably should just handle this case before here, or just delete the whole check.

This function could use some cleanup. Why isn't this using a switch over the intrinsic ID?

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@c8ef c8ef Oct 19, 2024

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Probably should just handle this case before here, or just delete the whole check.

It appears that the check is necessary to guard certain types, such as vector or fp128 types.

!Ty->isIntegerTy())
return nullptr;

// Use internal versions of these intrinsics.
Expand Down Expand Up @@ -2391,6 +2405,11 @@ static Constant *ConstantFoldScalarCall1(StringRef Name,
// TODO: What about hosts that lack a C99 library?
return ConstantFoldFP(log10, APF, Ty);
break;
case LibFunc_ilogb:
case LibFunc_ilogbf:
if (!APF.isZero() && TLI->has(Func))
return ConstantFoldInt(ilogb, APF, Ty);
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@dtcxzyw dtcxzyw Oct 19, 2024

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Use int ilogb(const APFloat &Arg).

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@c8ef c8ef Oct 19, 2024

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Good idea!

break;
case LibFunc_logb:
case LibFunc_logbf:
if (!APF.isZero() && TLI->has(Func))
Expand Down
203 changes: 203 additions & 0 deletions llvm/test/Transforms/InstCombine/ilogb.ll
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@@ -0,0 +1,203 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
; RUN: opt < %s -passes=instcombine -S | FileCheck %s

define i32 @ilogbf_const1() {
; CHECK-LABEL: define i32 @ilogbf_const1() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogbf(float 7.000000e+00)
; CHECK-NEXT: ret i32 2
;
%r = call i32 @ilogbf(float 7.000000e+00)
ret i32 %r
}

define i32 @ilogb_const1() {
; CHECK-LABEL: define i32 @ilogb_const1() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogb(double -7.000000e+00)
; CHECK-NEXT: ret i32 2
;
%r = call i32 @ilogb(double -7.000000e+00)
ret i32 %r
}

define i32 @ilogbf_const2() {
; CHECK-LABEL: define i32 @ilogbf_const2() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogbf(float 5.000000e-01)
; CHECK-NEXT: ret i32 -1
;
%r = call i32 @ilogbf(float 5.000000e-01)
ret i32 %r
}

define i32 @ilogb_const2() {
; CHECK-LABEL: define i32 @ilogb_const2() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogb(double -5.000000e-01)
; CHECK-NEXT: ret i32 -1
;
%r = call i32 @ilogb(double -5.000000e-01)
ret i32 %r
}

define i32 @ilogbf_zero() {
; CHECK-LABEL: define i32 @ilogbf_zero() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogbf(float 0.000000e+00)
; CHECK-NEXT: ret i32 [[R]]
;
%r = call i32 @ilogbf(float 0.000000e+00)
ret i32 %r
}

define i32 @ilogb_zero() {
; CHECK-LABEL: define i32 @ilogb_zero() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogb(double 0.000000e+00)
; CHECK-NEXT: ret i32 [[R]]
;
%r = call i32 @ilogb(double 0.000000e+00)
ret i32 %r
}

define i32 @ilogbf_neg_zero() {
; CHECK-LABEL: define i32 @ilogbf_neg_zero() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogbf(float -0.000000e+00)
; CHECK-NEXT: ret i32 [[R]]
;
%r = call i32 @ilogbf(float -0.000000e+00)
ret i32 %r
}

define i32 @ilogb_neg_zero() {
; CHECK-LABEL: define i32 @ilogb_neg_zero() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogb(double -0.000000e+00)
; CHECK-NEXT: ret i32 [[R]]
;
%r = call i32 @ilogb(double -0.000000e+00)
ret i32 %r
}

define i32 @ilogbf_inf() {
; CHECK-LABEL: define i32 @ilogbf_inf() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogbf(float 0x7FF0000000000000)
; CHECK-NEXT: ret i32 [[R]]
;
%r = call i32 @ilogbf(float 0x7FF0000000000000)
ret i32 %r
}

define i32 @ilogb_inf() {
; CHECK-LABEL: define i32 @ilogb_inf() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogb(double 0x7FF0000000000000)
; CHECK-NEXT: ret i32 [[R]]
;
%r = call i32 @ilogb(double 0x7FF0000000000000)
ret i32 %r
}

define i32 @ilogbf_nan() {
; CHECK-LABEL: define i32 @ilogbf_nan() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogbf(float 0x7FF8000000000000)
; CHECK-NEXT: ret i32 [[R]]
;
%r = call i32 @ilogbf(float 0x7FF8000000000000)
ret i32 %r
}

define i32 @ilogb_nan() {
; CHECK-LABEL: define i32 @ilogb_nan() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogb(double 0x7FF8000000000000)
; CHECK-NEXT: ret i32 [[R]]
;
%r = call i32 @ilogb(double 0x7FF8000000000000)
ret i32 %r
}

define i32 @ilogbf_zero_readnone() {
; CHECK-LABEL: define i32 @ilogbf_zero_readnone() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogbf(float 0.000000e+00) #[[ATTR0:[0-9]+]]
; CHECK-NEXT: ret i32 [[R]]
;
%r = call i32 @ilogbf(float 0.000000e+00) readnone
ret i32 %r
}

define i32 @ilogb_zero_readnone() {
; CHECK-LABEL: define i32 @ilogb_zero_readnone() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogb(double 0.000000e+00) #[[ATTR0]]
; CHECK-NEXT: ret i32 [[R]]
;
%r = call i32 @ilogb(double 0.000000e+00) readnone
ret i32 %r
}

define i32 @ilogbf_neg_zero_readnone() {
; CHECK-LABEL: define i32 @ilogbf_neg_zero_readnone() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogbf(float -0.000000e+00) #[[ATTR0]]
; CHECK-NEXT: ret i32 [[R]]
;
%r = call i32 @ilogbf(float -0.000000e+00) readnone
ret i32 %r
}

define i32 @ilogb_neg_zero_readnone() {
; CHECK-LABEL: define i32 @ilogb_neg_zero_readnone() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogb(double -0.000000e+00) #[[ATTR0]]
; CHECK-NEXT: ret i32 [[R]]
;
%r = call i32 @ilogb(double -0.000000e+00) readnone
ret i32 %r
}

define i32 @ilogbf_inf_readnone() {
; CHECK-LABEL: define i32 @ilogbf_inf_readnone() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogbf(float 0x7FF0000000000000) #[[ATTR0]]
; CHECK-NEXT: ret i32 [[R]]
;
%r = call i32 @ilogbf(float 0x7FF0000000000000) readnone
ret i32 %r
}

define i32 @ilogb_inf_readnone() {
; CHECK-LABEL: define i32 @ilogb_inf_readnone() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogb(double 0x7FF0000000000000) #[[ATTR0]]
; CHECK-NEXT: ret i32 [[R]]
;
%r = call i32 @ilogb(double 0x7FF0000000000000) readnone
ret i32 %r
}

define i32 @ilogbf_nan_readnone() {
; CHECK-LABEL: define i32 @ilogbf_nan_readnone() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogbf(float 0x7FF8000000000000) #[[ATTR0]]
; CHECK-NEXT: ret i32 [[R]]
;
%r = call i32 @ilogbf(float 0x7FF8000000000000) readnone
ret i32 %r
}

define i32 @ilogb_nan_readnone() {
; CHECK-LABEL: define i32 @ilogb_nan_readnone() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogb(double 0x7FF8000000000000) #[[ATTR0]]
; CHECK-NEXT: ret i32 [[R]]
;
%r = call i32 @ilogb(double 0x7FF8000000000000) readnone
ret i32 %r
}

define i32 @ilogbf_poison() {
; CHECK-LABEL: define i32 @ilogbf_poison() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogbf(float poison)
; CHECK-NEXT: ret i32 [[R]]
;
%r = call i32 @ilogbf(float poison)
ret i32 %r
}

define i32 @ilogb_poison() {
; CHECK-LABEL: define i32 @ilogb_poison() {
; CHECK-NEXT: [[R:%.*]] = call i32 @ilogb(double poison)
; CHECK-NEXT: ret i32 [[R]]
;
%r = call i32 @ilogb(double poison)
ret i32 %r
}

declare i32 @ilogbf(float)
declare i32 @ilogb(double)
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