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[InstCombine] Expand the simplification of log() 

Expand the simplification of special cases of `log()` to include `log2()`
and `log10()` as well as intrinsics and more types.

Differential revision: https://reviews.llvm.org/D67199

llvm-svn: 373261
This commit is contained in:
Evandro Menezes 2019-09-30 20:52:21 +00:00
parent 496c0564f1
commit 110b1138ba
2 changed files with 180 additions and 68 deletions
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186
llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
View File

@ -35,6 +35,7 @@
#include "llvm/IR/PatternMatch.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/KnownBits.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Transforms/Utils/BuildLibCalls.h"
#include "llvm/Transforms/Utils/SizeOpts.h"
@ -1457,9 +1458,7 @@ Value *LibCallSimplifier::replacePowWithExp(CallInst *Pow, IRBuilder<> &B) {
StringRef ExpName;
Intrinsic::ID ID;
Value *ExpFn;
LibFunc LibFnFloat;
LibFunc LibFnDouble;
LibFunc LibFnLongDouble;
LibFunc LibFnFloat, LibFnDouble, LibFnLongDouble;
switch (LibFn) {
default:
@ -1809,48 +1808,155 @@ Value *LibCallSimplifier::optimizeFMinFMax(CallInst *CI, IRBuilder<> &B) {
return B.CreateCall(F, { CI->getArgOperand(0), CI->getArgOperand(1) });
}
Value *LibCallSimplifier::optimizeLog(CallInst *CI, IRBuilder<> &B) {
Function *Callee = CI->getCalledFunction();
Value *LibCallSimplifier::optimizeLog(CallInst *Log, IRBuilder<> &B) {
Function *LogFn = Log->getCalledFunction();
AttributeList Attrs = LogFn->getAttributes();
StringRef LogNm = LogFn->getName();
Intrinsic::ID LogID = LogFn->getIntrinsicID();
Module *Mod = Log->getModule();
Type *Ty = Log->getType();
Value *Ret = nullptr;
StringRef Name = Callee->getName();
if (UnsafeFPShrink && hasFloatVersion(Name))
Ret = optimizeUnaryDoubleFP(CI, B, true);
if (!CI->isFast())
return Ret;
Value *Op1 = CI->getArgOperand(0);
auto *OpC = dyn_cast<CallInst>(Op1);
if (UnsafeFPShrink && hasFloatVersion(LogNm))
Ret = optimizeUnaryDoubleFP(Log, B, true);
// The earlier call must also be 'fast' in order to do these transforms.
if (!OpC || !OpC->isFast())
CallInst *Arg = dyn_cast<CallInst>(Log->getArgOperand(0));
if (!Log->isFast() || !Arg || !Arg->isFast() || !Arg->hasOneUse())
return Ret;
// log(pow(x,y)) -> y*log(x)
// This is only applicable to log, log2, log10.
if (Name != "log" && Name != "log2" && Name != "log10")
LibFunc LogLb, ExpLb, Exp2Lb, Exp10Lb, PowLb;
// This is only applicable to log(), log2(), log10().
if (TLI->getLibFunc(LogNm, LogLb))
switch (LogLb) {
case LibFunc_logf:
LogID = Intrinsic::log;
ExpLb = LibFunc_expf;
Exp2Lb = LibFunc_exp2f;
Exp10Lb = LibFunc_exp10f;
PowLb = LibFunc_powf;
break;
case LibFunc_log:
LogID = Intrinsic::log;
ExpLb = LibFunc_exp;
Exp2Lb = LibFunc_exp2;
Exp10Lb = LibFunc_exp10;
PowLb = LibFunc_pow;
break;
case LibFunc_logl:
LogID = Intrinsic::log;
ExpLb = LibFunc_expl;
Exp2Lb = LibFunc_exp2l;
Exp10Lb = LibFunc_exp10l;
PowLb = LibFunc_powl;
break;
case LibFunc_log2f:
LogID = Intrinsic::log2;
ExpLb = LibFunc_expf;
Exp2Lb = LibFunc_exp2f;
Exp10Lb = LibFunc_exp10f;
PowLb = LibFunc_powf;
break;
case LibFunc_log2:
LogID = Intrinsic::log2;
ExpLb = LibFunc_exp;
Exp2Lb = LibFunc_exp2;
Exp10Lb = LibFunc_exp10;
PowLb = LibFunc_pow;
break;
case LibFunc_log2l:
LogID = Intrinsic::log2;
ExpLb = LibFunc_expl;
Exp2Lb = LibFunc_exp2l;
Exp10Lb = LibFunc_exp10l;
PowLb = LibFunc_powl;
break;
case LibFunc_log10f:
LogID = Intrinsic::log10;
ExpLb = LibFunc_expf;
Exp2Lb = LibFunc_exp2f;
Exp10Lb = LibFunc_exp10f;
PowLb = LibFunc_powf;
break;
case LibFunc_log10:
LogID = Intrinsic::log10;
ExpLb = LibFunc_exp;
Exp2Lb = LibFunc_exp2;
Exp10Lb = LibFunc_exp10;
PowLb = LibFunc_pow;
break;
case LibFunc_log10l:
LogID = Intrinsic::log10;
ExpLb = LibFunc_expl;
Exp2Lb = LibFunc_exp2l;
Exp10Lb = LibFunc_exp10l;
PowLb = LibFunc_powl;
break;
default:
return Ret;
}
else if (LogID == Intrinsic::log || LogID == Intrinsic::log2 ||
LogID == Intrinsic::log10) {
if (Ty->getScalarType()->isFloatTy()) {
ExpLb = LibFunc_expf;
Exp2Lb = LibFunc_exp2f;
Exp10Lb = LibFunc_exp10f;
PowLb = LibFunc_powf;
} else if (Ty->getScalarType()->isDoubleTy()) {
ExpLb = LibFunc_exp;
Exp2Lb = LibFunc_exp2;
Exp10Lb = LibFunc_exp10;
PowLb = LibFunc_pow;
} else
return Ret;
} else
return Ret;
IRBuilder<>::FastMathFlagGuard Guard(B);
FastMathFlags FMF;
FMF.setFast();
B.setFastMathFlags(FMF);
B.setFastMathFlags(FastMathFlags::getFast());
LibFunc Func;
Function *F = OpC->getCalledFunction();
if (F && ((TLI->getLibFunc(F->getName(), Func) && TLI->has(Func) &&
Func == LibFunc_pow) || F->getIntrinsicID() == Intrinsic::pow))
return B.CreateFMul(OpC->getArgOperand(1),
emitUnaryFloatFnCall(OpC->getOperand(0), Callee->getName(), B,
Callee->getAttributes()), "mul");
Function *ArgFn = Arg->getCalledFunction();
StringRef ArgNm = ArgFn->getName();
Intrinsic::ID ArgID = ArgFn->getIntrinsicID();
LibFunc ArgLb = NotLibFunc;
TLI->getLibFunc(ArgNm, ArgLb);
// log(pow(x,y)) -> y*log(x)
if (ArgLb == PowLb || ArgID == Intrinsic::pow) {
Value *LogX =
Log->doesNotAccessMemory()
? B.CreateCall(Intrinsic::getDeclaration(Mod, LogID, Ty),
Arg->getOperand(0), "log")
: emitUnaryFloatFnCall(Arg->getOperand(0), LogNm, B, Attrs);
Value *MulY = B.CreateFMul(Arg->getArgOperand(1), LogX, "mul");
// Since pow() may have side effects, e.g. errno,
// dead code elimination may not be trusted to remove it.
substituteInParent(Arg, MulY);
return MulY;
}
// log(exp{,2,10}(y)) -> y*log({e,2,10})
// TODO: There is no exp10() intrinsic yet.
else if (ArgLb == ExpLb || ArgLb == Exp2Lb || ArgLb == Exp10Lb ||
ArgID == Intrinsic::exp || ArgID == Intrinsic::exp2) {
Constant *Eul;
if (ArgLb == ExpLb || ArgID == Intrinsic::exp)
Eul = ConstantFP::get(Log->getType(), M_E);
else if (ArgLb == Exp2Lb || ArgID == Intrinsic::exp2)
Eul = ConstantFP::get(Log->getType(), 2.0);
else
Eul = ConstantFP::get(Log->getType(), 10.0);
Value *LogE = Log->doesNotAccessMemory()
? B.CreateCall(Intrinsic::getDeclaration(Mod, LogID, Ty),
Eul, "log")
: emitUnaryFloatFnCall(Eul, LogNm, B, Attrs);
Value *MulY = B.CreateFMul(Arg->getArgOperand(0), LogE, "mul");
// Since exp() may have side effects, e.g. errno,
// dead code elimination may not be trusted to remove it.
substituteInParent(Arg, MulY);
return MulY;
}
// log(exp2(y)) -> y*log(2)
if (F && Name == "log" && TLI->getLibFunc(F->getName(), Func) &&
TLI->has(Func) && Func == LibFunc_exp2)
return B.CreateFMul(
OpC->getArgOperand(0),
emitUnaryFloatFnCall(ConstantFP::get(CI->getType(), 2.0),
Callee->getName(), B, Callee->getAttributes()),
"logmul");
return Ret;
}
@ -2801,11 +2907,21 @@ Value *LibCallSimplifier::optimizeFloatingPointLibCall(CallInst *CI,
case LibFunc_sqrt:
case LibFunc_sqrtl:
return optimizeSqrt(CI, Builder);
case LibFunc_logf:
case LibFunc_log:
case LibFunc_logl:
case LibFunc_log10f:
case LibFunc_log10:
case LibFunc_log10l:
case LibFunc_log1pf:
case LibFunc_log1p:
case LibFunc_log1pl:
case LibFunc_log2f:
case LibFunc_log2:
case LibFunc_log2l:
case LibFunc_logbf:
case LibFunc_logb:
case LibFunc_logbl:
return optimizeLog(CI, Builder);
case LibFunc_tan:
case LibFunc_tanf:
@ -2896,6 +3012,8 @@ Value *LibCallSimplifier::optimizeCall(CallInst *CI) {
case Intrinsic::exp2:
return optimizeExp2(CI, Builder);
case Intrinsic::log:
case Intrinsic::log2:
case Intrinsic::log10:
return optimizeLog(CI, Builder);
case Intrinsic::sqrt:
return optimizeSqrt(CI, Builder);

62
llvm/test/Transforms/InstCombine/log-pow.ll
View File

@ -3,7 +3,7 @@
define double @log_pow(double %x, double %y) {
; CHECK-LABEL: @log_pow(
; CHECK-NEXT: [[LOG1:%.*]] = call fast double @log(double [[X:%.*]]) #0
; CHECK-NEXT: [[LOG1:%.*]] = call fast double @llvm.log.f64(double [[X:%.*]])
; CHECK-NEXT: [[MUL:%.*]] = fmul fast double [[LOG1]], [[Y:%.*]]
; CHECK-NEXT: ret double [[MUL]]
;
@ -12,24 +12,22 @@ define double @log_pow(double %x, double %y) {
ret double %log
}
; FIXME: log10f() should also be simplified.
define float @log10f_powf(float %x, float %y) {
; CHECK-LABEL: @log10f_powf(
; CHECK-NEXT: [[POW:%.*]] = call fast float @powf(float [[X:%.*]], float [[Y:%.*]])
; CHECK-NEXT: [[LOG:%.*]] = call fast float @log10f(float [[POW]])
; CHECK-NEXT: ret float [[LOG]]
; CHECK-NEXT: [[LOG1:%.*]] = call fast float @llvm.log10.f32(float [[X:%.*]])
; CHECK-NEXT: [[MUL:%.*]] = fmul fast float [[LOG1]], [[Y:%.*]]
; CHECK-NEXT: ret float [[MUL]]
;
%pow = call fast float @powf(float %x, float %y)
%log = call fast float @log10f(float %pow)
%log = call fast float @llvm.log10.f32(float %pow)
ret float %log
}
; FIXME: Intrinsic log2() should also be simplified.
define <2 x double> @log2v_powv(<2 x double> %x, <2 x double> %y) {
; CHECK-LABEL: @log2v_powv(
; CHECK-NEXT: [[POW:%.*]] = call fast <2 x double> @llvm.pow.v2f64(<2 x double> [[X:%.*]], <2 x double> [[Y:%.*]])
; CHECK-NEXT: [[LOG:%.*]] = call fast <2 x double> @llvm.log2.v2f64(<2 x double> [[POW]])
; CHECK-NEXT: ret <2 x double> [[LOG]]
; CHECK-NEXT: [[LOG1:%.*]] = call fast <2 x double> @llvm.log2.v2f64(<2 x double> [[X:%.*]])
; CHECK-NEXT: [[MUL:%.*]] = fmul fast <2 x double> [[LOG1]], [[Y:%.*]]
; CHECK-NEXT: ret <2 x double> [[MUL]]
;
%pow = call fast <2 x double> @llvm.pow.v2f64(<2 x double> %x, <2 x double> %y)
%log = call fast <2 x double> @llvm.log2.v2f64(<2 x double> %pow)
@ -58,39 +56,33 @@ define float @function_pointer(float ()* %fptr, float %p1) {
ret float %log
}
; FIXME: The call to exp2() should be removed.
define double @log_exp2(double %x) {
; CHECK-LABEL: @log_exp2(
; CHECK-NEXT: [[EXP:%.*]] = call fast double @exp2(double [[X:%.*]])
; CHECK-NEXT: [[LOGMUL:%.*]] = fmul fast double [[X]], 0x3FE62E42FEFA39EF
; CHECK-NEXT: ret double [[LOGMUL]]
define double @log10_exp(double %x) {
; CHECK-LABEL: @log10_exp(
; CHECK-NEXT: [[MUL:%.*]] = fmul fast double [[X:%.*]], 0x3FDBCB7B1526E50E
; CHECK-NEXT: ret double [[MUL]]
;
%exp = call fast double @exp2(double %x)
%log = call fast double @log(double %exp)
%exp = call fast double @exp(double %x)
%log = call fast double @log10(double %exp)
ret double %log
}
; FIXME: Intrinsic logf() should also be simplified.
define <2 x float> @logv_exp2v(<2 x float> %x) {
; CHECK-LABEL: @logv_exp2v(
; CHECK-NEXT: [[EXP:%.*]] = call fast <2 x float> @llvm.exp2.v2f32(<2 x float> [[X:%.*]])
; CHECK-NEXT: [[LOG:%.*]] = call fast <2 x float> @llvm.log.v2f32(<2 x float> [[EXP]])
; CHECK-NEXT: ret <2 x float> [[LOG]]
; CHECK-NEXT: [[MUL:%.*]] = fmul fast <2 x float> [[X:%.*]], <float 0x3FE62E4300000000, float 0x3FE62E4300000000>
; CHECK-NEXT: ret <2 x float> [[MUL]]
;
%exp = call fast <2 x float> @llvm.exp2.v2f32(<2 x float> %x)
%log = call fast <2 x float> @llvm.log.v2f32(<2 x float> %exp)
ret <2 x float> %log
}
; FIXME: log10f() should also be simplified.
define float @log10f_exp2f(float %x) {
; CHECK-LABEL: @log10f_exp2f(
; CHECK-NEXT: [[EXP:%.*]] = call fast float @exp2f(float [[X:%.*]])
; CHECK-NEXT: [[LOG:%.*]] = call fast float @log10f(float [[EXP]])
; CHECK-NEXT: ret float [[LOG]]
define float @log2f_exp10f(float %x) {
; CHECK-LABEL: @log2f_exp10f(
; CHECK-NEXT: [[MUL:%.*]] = fmul fast float [[X:%.*]], 0x400A934F00000000
; CHECK-NEXT: ret float [[MUL]]
;
%exp = call fast float @exp2f(float %x)
%log = call fast float @log10f(float %exp)
%exp = call fast float @exp10f(float %x)
%log = call fast float @log2f(float %exp)
ret float %log
}
@ -108,11 +100,13 @@ define double @log_exp2_not_fast(double %x) {
declare double @log(double) #0
declare float @logf(float) #0
declare <2 x float> @llvm.log.v2f32(<2 x float>)
declare double @log2(double) #0
declare float @log2f(float) #0
declare <2 x double> @llvm.log2.v2f64(<2 x double>)
declare float @log10f(float) #0
declare double @exp2(double)
declare float @exp2f(float)
declare double @log10(double) #0
declare float @llvm.log10.f32(float)
declare double @exp(double %x) #0
declare double @exp2(double) #0
declare float @exp10f(float) #0
declare <2 x float> @llvm.exp2.v2f32(<2 x float>)
declare double @pow(double, double) #0
declare float @powf(float, float) #0