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Factor check for the assume intrinsic out of checks in computeKnownBi…
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…tsFromAssume

We were matching against the assume intrinsic in every check.  Since we know that it must be an assume, this is just wasted work.  Somewhat surprisingly, matching an intrinsic id is actually relatively expensive.  It devolves to a string construction and comparison in Function::isIntrinsic.

I originally spotted this because it showed up in a performance profile of my compiler.  I've since discovered a separate issue which seems to be the actual root cause, but this is minor perf goodness regardless.  

I'm likely to follow up with another change to factor out the comparison matching.  There's no need to match the compare instruction in every single one of the tests.

Differential Revision: http://reviews.llvm.org/D6312

llvm-svn: 222709
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@preames
preames committed Nov 24, 2014
1 parent 4e21001 commit 00d3b27
Showing 1 changed file with 39 additions and 42 deletions.
81 changes: 39 additions & 42 deletions llvm/lib/Analysis/ValueTracking.cpp
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Expand Up @@ -491,7 +491,17 @@ static void computeKnownBitsFromAssume(Value *V, APInt &KnownZero,
if (Q.ExclInvs.count(I))
continue;

if (match(I, m_Intrinsic<Intrinsic::assume>(m_Specific(V))) &&
// Warning: This loop can end up being somewhat performance sensetive.
// We're running this loop for once for each value queried resulting in a
// runtime of ~O(#assumes * #values).

assert(isa<IntrinsicInst>(I) &&
dyn_cast<IntrinsicInst>(I)->getIntrinsicID() == Intrinsic::assume &&
"must be an assume intrinsic");

Value *Arg = I->getArgOperand(0);

if (Arg == V &&
isValidAssumeForContext(I, Q, DL)) {
assert(BitWidth == 1 && "assume operand is not i1?");
KnownZero.clearAllBits();
Expand All @@ -507,16 +517,15 @@ static void computeKnownBitsFromAssume(Value *V, APInt &KnownZero,
CmpInst::Predicate Pred;
ConstantInt *C;
// assume(v = a)
if (match(I, m_Intrinsic<Intrinsic::assume>(
m_c_ICmp(Pred, m_V, m_Value(A)))) &&
if (match(Arg, m_c_ICmp(Pred, m_V, m_Value(A))) &&
Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) {
APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0);
computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I));
KnownZero |= RHSKnownZero;
KnownOne |= RHSKnownOne;
// assume(v & b = a)
} else if (match(I, m_Intrinsic<Intrinsic::assume>(
m_c_ICmp(Pred, m_c_And(m_V, m_Value(B)), m_Value(A)))) &&
} else if (match(Arg, m_c_ICmp(Pred, m_c_And(m_V, m_Value(B)),
m_Value(A))) &&
Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) {
APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0);
computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I));
Expand All @@ -528,9 +537,8 @@ static void computeKnownBitsFromAssume(Value *V, APInt &KnownZero,
KnownZero |= RHSKnownZero & MaskKnownOne;
KnownOne |= RHSKnownOne & MaskKnownOne;
// assume(~(v & b) = a)
} else if (match(I, m_Intrinsic<Intrinsic::assume>(
m_c_ICmp(Pred, m_Not(m_c_And(m_V, m_Value(B))),
m_Value(A)))) &&
} else if (match(Arg, m_c_ICmp(Pred, m_Not(m_c_And(m_V, m_Value(B))),
m_Value(A))) &&
Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) {
APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0);
computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I));
Expand All @@ -542,8 +550,8 @@ static void computeKnownBitsFromAssume(Value *V, APInt &KnownZero,
KnownZero |= RHSKnownOne & MaskKnownOne;
KnownOne |= RHSKnownZero & MaskKnownOne;
// assume(v | b = a)
} else if (match(I, m_Intrinsic<Intrinsic::assume>(
m_c_ICmp(Pred, m_c_Or(m_V, m_Value(B)), m_Value(A)))) &&
} else if (match(Arg, m_c_ICmp(Pred, m_c_Or(m_V, m_Value(B)),
m_Value(A))) &&
Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) {
APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0);
computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I));
Expand All @@ -555,9 +563,8 @@ static void computeKnownBitsFromAssume(Value *V, APInt &KnownZero,
KnownZero |= RHSKnownZero & BKnownZero;
KnownOne |= RHSKnownOne & BKnownZero;
// assume(~(v | b) = a)
} else if (match(I, m_Intrinsic<Intrinsic::assume>(
m_c_ICmp(Pred, m_Not(m_c_Or(m_V, m_Value(B))),
m_Value(A)))) &&
} else if (match(Arg, m_c_ICmp(Pred, m_Not(m_c_Or(m_V, m_Value(B))),
m_Value(A))) &&
Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) {
APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0);
computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I));
Expand All @@ -569,8 +576,8 @@ static void computeKnownBitsFromAssume(Value *V, APInt &KnownZero,
KnownZero |= RHSKnownOne & BKnownZero;
KnownOne |= RHSKnownZero & BKnownZero;
// assume(v ^ b = a)
} else if (match(I, m_Intrinsic<Intrinsic::assume>(
m_c_ICmp(Pred, m_c_Xor(m_V, m_Value(B)), m_Value(A)))) &&
} else if (match(Arg, m_c_ICmp(Pred, m_c_Xor(m_V, m_Value(B)),
m_Value(A))) &&
Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) {
APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0);
computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I));
Expand All @@ -585,9 +592,8 @@ static void computeKnownBitsFromAssume(Value *V, APInt &KnownZero,
KnownZero |= RHSKnownOne & BKnownOne;
KnownOne |= RHSKnownZero & BKnownOne;
// assume(~(v ^ b) = a)
} else if (match(I, m_Intrinsic<Intrinsic::assume>(
m_c_ICmp(Pred, m_Not(m_c_Xor(m_V, m_Value(B))),
m_Value(A)))) &&
} else if (match(Arg, m_c_ICmp(Pred, m_Not(m_c_Xor(m_V, m_Value(B))),
m_Value(A))) &&
Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) {
APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0);
computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I));
Expand All @@ -602,9 +608,8 @@ static void computeKnownBitsFromAssume(Value *V, APInt &KnownZero,
KnownZero |= RHSKnownZero & BKnownOne;
KnownOne |= RHSKnownOne & BKnownOne;
// assume(v << c = a)
} else if (match(I, m_Intrinsic<Intrinsic::assume>(
m_c_ICmp(Pred, m_Shl(m_V, m_ConstantInt(C)),
m_Value(A)))) &&
} else if (match(Arg, m_c_ICmp(Pred, m_Shl(m_V, m_ConstantInt(C)),
m_Value(A))) &&
Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) {
APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0);
computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I));
Expand All @@ -613,9 +618,8 @@ static void computeKnownBitsFromAssume(Value *V, APInt &KnownZero,
KnownZero |= RHSKnownZero.lshr(C->getZExtValue());
KnownOne |= RHSKnownOne.lshr(C->getZExtValue());
// assume(~(v << c) = a)
} else if (match(I, m_Intrinsic<Intrinsic::assume>(
m_c_ICmp(Pred, m_Not(m_Shl(m_V, m_ConstantInt(C))),
m_Value(A)))) &&
} else if (match(Arg, m_c_ICmp(Pred, m_Not(m_Shl(m_V, m_ConstantInt(C))),
m_Value(A))) &&
Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) {
APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0);
computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I));
Expand All @@ -624,11 +628,11 @@ static void computeKnownBitsFromAssume(Value *V, APInt &KnownZero,
KnownZero |= RHSKnownOne.lshr(C->getZExtValue());
KnownOne |= RHSKnownZero.lshr(C->getZExtValue());
// assume(v >> c = a)
} else if (match(I, m_Intrinsic<Intrinsic::assume>(
m_c_ICmp(Pred, m_CombineOr(m_LShr(m_V, m_ConstantInt(C)),
} else if (match(Arg,
m_c_ICmp(Pred, m_CombineOr(m_LShr(m_V, m_ConstantInt(C)),
m_AShr(m_V,
m_ConstantInt(C))),
m_Value(A)))) &&
m_Value(A))) &&
Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) {
APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0);
computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I));
Expand All @@ -637,11 +641,10 @@ static void computeKnownBitsFromAssume(Value *V, APInt &KnownZero,
KnownZero |= RHSKnownZero << C->getZExtValue();
KnownOne |= RHSKnownOne << C->getZExtValue();
// assume(~(v >> c) = a)
} else if (match(I, m_Intrinsic<Intrinsic::assume>(
m_c_ICmp(Pred, m_Not(m_CombineOr(
} else if (match(Arg, m_c_ICmp(Pred, m_Not(m_CombineOr(
m_LShr(m_V, m_ConstantInt(C)),
m_AShr(m_V, m_ConstantInt(C)))),
m_Value(A)))) &&
m_Value(A))) &&
Pred == ICmpInst::ICMP_EQ && isValidAssumeForContext(I, Q, DL)) {
APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0);
computeKnownBits(A, RHSKnownZero, RHSKnownOne, DL, Depth+1, Query(Q, I));
Expand All @@ -650,8 +653,7 @@ static void computeKnownBitsFromAssume(Value *V, APInt &KnownZero,
KnownZero |= RHSKnownOne << C->getZExtValue();
KnownOne |= RHSKnownZero << C->getZExtValue();
// assume(v >=_s c) where c is non-negative
} else if (match(I, m_Intrinsic<Intrinsic::assume>(
m_ICmp(Pred, m_V, m_Value(A)))) &&
} else if (match(Arg, m_ICmp(Pred, m_V, m_Value(A))) &&
Pred == ICmpInst::ICMP_SGE &&
isValidAssumeForContext(I, Q, DL)) {
APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0);
Expand All @@ -662,8 +664,7 @@ static void computeKnownBitsFromAssume(Value *V, APInt &KnownZero,
KnownZero |= APInt::getSignBit(BitWidth);
}
// assume(v >_s c) where c is at least -1.
} else if (match(I, m_Intrinsic<Intrinsic::assume>(
m_ICmp(Pred, m_V, m_Value(A)))) &&
} else if (match(Arg, m_ICmp(Pred, m_V, m_Value(A))) &&
Pred == ICmpInst::ICMP_SGT &&
isValidAssumeForContext(I, Q, DL)) {
APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0);
Expand All @@ -674,8 +675,7 @@ static void computeKnownBitsFromAssume(Value *V, APInt &KnownZero,
KnownZero |= APInt::getSignBit(BitWidth);
}
// assume(v <=_s c) where c is negative
} else if (match(I, m_Intrinsic<Intrinsic::assume>(
m_ICmp(Pred, m_V, m_Value(A)))) &&
} else if (match(Arg, m_ICmp(Pred, m_V, m_Value(A))) &&
Pred == ICmpInst::ICMP_SLE &&
isValidAssumeForContext(I, Q, DL)) {
APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0);
Expand All @@ -686,8 +686,7 @@ static void computeKnownBitsFromAssume(Value *V, APInt &KnownZero,
KnownOne |= APInt::getSignBit(BitWidth);
}
// assume(v <_s c) where c is non-positive
} else if (match(I, m_Intrinsic<Intrinsic::assume>(
m_ICmp(Pred, m_V, m_Value(A)))) &&
} else if (match(Arg, m_ICmp(Pred, m_V, m_Value(A))) &&
Pred == ICmpInst::ICMP_SLT &&
isValidAssumeForContext(I, Q, DL)) {
APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0);
Expand All @@ -698,8 +697,7 @@ static void computeKnownBitsFromAssume(Value *V, APInt &KnownZero,
KnownOne |= APInt::getSignBit(BitWidth);
}
// assume(v <=_u c)
} else if (match(I, m_Intrinsic<Intrinsic::assume>(
m_ICmp(Pred, m_V, m_Value(A)))) &&
} else if (match(Arg, m_ICmp(Pred, m_V, m_Value(A))) &&
Pred == ICmpInst::ICMP_ULE &&
isValidAssumeForContext(I, Q, DL)) {
APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0);
Expand All @@ -709,8 +707,7 @@ static void computeKnownBitsFromAssume(Value *V, APInt &KnownZero,
KnownZero |=
APInt::getHighBitsSet(BitWidth, RHSKnownZero.countLeadingOnes());
// assume(v <_u c)
} else if (match(I, m_Intrinsic<Intrinsic::assume>(
m_ICmp(Pred, m_V, m_Value(A)))) &&
} else if (match(Arg, m_ICmp(Pred, m_V, m_Value(A))) &&
Pred == ICmpInst::ICMP_ULT &&
isValidAssumeForContext(I, Q, DL)) {
APInt RHSKnownZero(BitWidth, 0), RHSKnownOne(BitWidth, 0);
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