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rdar://12753946

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Implement rule : "x * (select cond 1.0, 0.0) -> select cond x, 0.0"


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170226 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Shuxin Yang 2012-12-14 18:46:06 +00:00
parent 63cab6c9d2
commit a5ed031fbc
2 changed files with 66 additions and 6 deletions
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32
lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
View File

@ -341,6 +341,38 @@ Instruction *InstCombiner::visitFMul(BinaryOperator &I) {
}
}
// X * cond ? 1.0 : 0.0 => cond ? X : 0.0
if (I.hasNoNaNs() && I.hasNoSignedZeros()) {
Value *V0 = I.getOperand(0);
Value *V1 = I.getOperand(1);
Value *Cond, *SLHS, *SRHS;
bool Match = false;
if (match(V0, m_Select(m_Value(Cond), m_Value(SLHS), m_Value(SRHS)))) {
Match = true;
} else if (match(V1, m_Select(m_Value(Cond), m_Value(SLHS),
m_Value(SRHS)))) {
Match = true;
std::swap(V0, V1);
}
if (Match) {
ConstantFP *C0 = dyn_cast<ConstantFP>(SLHS);
ConstantFP *C1 = dyn_cast<ConstantFP>(SRHS);
if (C0 && C1 &&
((C0->isZero() && C1->isExactlyValue(1.0)) ||
(C1->isZero() && C0->isExactlyValue(1.0)))) {
Value *T;
if (C0->isZero())
T = Builder->CreateSelect(Cond, SLHS, V1);
else
T = Builder->CreateSelect(Cond, V1, SRHS);
return ReplaceInstUsesWith(I, T);
}
}
}
return Changed ? &I : 0;
}

40
test/Transforms/InstCombine/fast-math.ll
View File

@ -3,19 +3,17 @@
; testing-case "float fold(float a) { return 1.2f * a * 2.3f; }"
; 1.2f and 2.3f is supposed to be fold.
define float @fold(float %a) {
fold:
%mul = fmul fast float %a, 0x3FF3333340000000
%mul1 = fmul fast float %mul, 0x4002666660000000
ret float %mul1
; CHECK: fold
; CHECK: @fold
; CHECK: fmul float %a, 0x4006147AE0000000
}
; Same testing-case as the one used in fold() except that the operators have
; fixed FP mode.
define float @notfold(float %a) {
notfold:
; CHECK: notfold
; CHECK: @notfold
; CHECK: %mul = fmul fast float %a, 0x3FF3333340000000
%mul = fmul fast float %a, 0x3FF3333340000000
%mul1 = fmul float %mul, 0x4002666660000000
@ -23,10 +21,40 @@ notfold:
}
define float @fold2(float %a) {
fold2:
; CHECK: fold2
; CHECK: @fold2
; CHECK: fmul float %a, 0x4006147AE0000000
%mul = fmul float %a, 0x3FF3333340000000
%mul1 = fmul fast float %mul, 0x4002666660000000
ret float %mul1
}
; rdar://12753946: x * cond ? 1.0 : 0.0 => cond ? x : 0.0
define double @select1(i32 %cond, double %x, double %y) {
%tobool = icmp ne i32 %cond, 0
%cond1 = select i1 %tobool, double 1.000000e+00, double 0.000000e+00
%mul = fmul nnan nsz double %cond1, %x
%add = fadd double %mul, %y
ret double %add
; CHECK: @select1
; CHECK: select i1 %tobool, double %x, double 0.000000e+00
}
define double @select2(i32 %cond, double %x, double %y) {
%tobool = icmp ne i32 %cond, 0
%cond1 = select i1 %tobool, double 0.000000e+00, double 1.000000e+00
%mul = fmul nnan nsz double %cond1, %x
%add = fadd double %mul, %y
ret double %add
; CHECK: @select2
; CHECK: select i1 %tobool, double 0.000000e+00, double %x
}
define double @select3(i32 %cond, double %x, double %y) {
%tobool = icmp ne i32 %cond, 0
%cond1 = select i1 %tobool, double 0.000000e+00, double 2.000000e+00
%mul = fmul nnan nsz double %cond1, %x
%add = fadd double %mul, %y
ret double %add
; CHECK: @select3
; CHECK: fmul nnan nsz double %cond1, %x
}