summaryrefslogtreecommitdiffstats
path: root/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'lib/Transforms/InstCombine/InstCombineAndOrXor.cpp')
-rw-r--r--lib/Transforms/InstCombine/InstCombineAndOrXor.cpp184
1 files changed, 160 insertions, 24 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index b474bd8..88bb69b 100644
--- a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -488,6 +488,26 @@ static unsigned getTypeOfMaskedICmp(Value* A, Value* B, Value* C,
return result;
}
+/// Convert an analysis of a masked ICmp into its equivalent if all boolean
+/// operations had the opposite sense. Since each "NotXXX" flag (recording !=)
+/// is adjacent to the corresponding normal flag (recording ==), this just
+/// involves swapping those bits over.
+static unsigned conjugateICmpMask(unsigned Mask) {
+ unsigned NewMask;
+ NewMask = (Mask & (FoldMskICmp_AMask_AllOnes | FoldMskICmp_BMask_AllOnes |
+ FoldMskICmp_Mask_AllZeroes | FoldMskICmp_AMask_Mixed |
+ FoldMskICmp_BMask_Mixed))
+ << 1;
+
+ NewMask |=
+ (Mask & (FoldMskICmp_AMask_NotAllOnes | FoldMskICmp_BMask_NotAllOnes |
+ FoldMskICmp_Mask_NotAllZeroes | FoldMskICmp_AMask_NotMixed |
+ FoldMskICmp_BMask_NotMixed))
+ >> 1;
+
+ return NewMask;
+}
+
/// decomposeBitTestICmp - Decompose an icmp into the form ((X & Y) pred Z)
/// if possible. The returned predicate is either == or !=. Returns false if
/// decomposition fails.
@@ -548,14 +568,22 @@ static unsigned foldLogOpOfMaskedICmpsHelper(Value*& A,
L21 = L22 = L1 = 0;
} else {
// Look for ANDs in the LHS icmp.
- if (match(L1, m_And(m_Value(L11), m_Value(L12)))) {
- if (!match(L2, m_And(m_Value(L21), m_Value(L22))))
- L21 = L22 = 0;
- } else {
- if (!match(L2, m_And(m_Value(L11), m_Value(L12))))
- return 0;
- std::swap(L1, L2);
+ if (!L1->getType()->isIntegerTy()) {
+ // You can icmp pointers, for example. They really aren't masks.
+ L11 = L12 = 0;
+ } else if (!match(L1, m_And(m_Value(L11), m_Value(L12)))) {
+ // Any icmp can be viewed as being trivially masked; if it allows us to
+ // remove one, it's worth it.
+ L11 = L1;
+ L12 = Constant::getAllOnesValue(L1->getType());
+ }
+
+ if (!L2->getType()->isIntegerTy()) {
+ // You can icmp pointers, for example. They really aren't masks.
L21 = L22 = 0;
+ } else if (!match(L2, m_And(m_Value(L21), m_Value(L22)))) {
+ L21 = L2;
+ L22 = Constant::getAllOnesValue(L2->getType());
}
}
@@ -576,7 +604,14 @@ static unsigned foldLogOpOfMaskedICmpsHelper(Value*& A,
return 0;
}
E = R2; R1 = 0; ok = true;
- } else if (match(R1, m_And(m_Value(R11), m_Value(R12)))) {
+ } else if (R1->getType()->isIntegerTy()) {
+ if (!match(R1, m_And(m_Value(R11), m_Value(R12)))) {
+ // As before, model no mask as a trivial mask if it'll let us do an
+ // optimisation.
+ R11 = R1;
+ R12 = Constant::getAllOnesValue(R1->getType());
+ }
+
if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) {
A = R11; D = R12; E = R2; ok = true;
} else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) {
@@ -589,7 +624,12 @@ static unsigned foldLogOpOfMaskedICmpsHelper(Value*& A,
return 0;
// Look for ANDs in on the right side of the RHS icmp.
- if (!ok && match(R2, m_And(m_Value(R11), m_Value(R12)))) {
+ if (!ok && R2->getType()->isIntegerTy()) {
+ if (!match(R2, m_And(m_Value(R11), m_Value(R12)))) {
+ R11 = R2;
+ R12 = Constant::getAllOnesValue(R2->getType());
+ }
+
if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) {
A = R11; D = R12; E = R1; ok = true;
} else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) {
@@ -618,8 +658,7 @@ static unsigned foldLogOpOfMaskedICmpsHelper(Value*& A,
/// foldLogOpOfMaskedICmps:
/// try to fold (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E)
/// into a single (icmp(A & X) ==/!= Y)
-static Value* foldLogOpOfMaskedICmps(ICmpInst *LHS, ICmpInst *RHS,
- ICmpInst::Predicate NEWCC,
+static Value* foldLogOpOfMaskedICmps(ICmpInst *LHS, ICmpInst *RHS, bool IsAnd,
llvm::InstCombiner::BuilderTy* Builder) {
Value *A = 0, *B = 0, *C = 0, *D = 0, *E = 0;
ICmpInst::Predicate LHSCC = LHS->getPredicate(), RHSCC = RHS->getPredicate();
@@ -629,8 +668,24 @@ static Value* foldLogOpOfMaskedICmps(ICmpInst *LHS, ICmpInst *RHS,
assert(ICmpInst::isEquality(LHSCC) && ICmpInst::isEquality(RHSCC) &&
"foldLogOpOfMaskedICmpsHelper must return an equality predicate.");
- if (NEWCC == ICmpInst::ICMP_NE)
- mask >>= 1; // treat "Not"-states as normal states
+ // In full generality:
+ // (icmp (A & B) Op C) | (icmp (A & D) Op E)
+ // == ![ (icmp (A & B) !Op C) & (icmp (A & D) !Op E) ]
+ //
+ // If the latter can be converted into (icmp (A & X) Op Y) then the former is
+ // equivalent to (icmp (A & X) !Op Y).
+ //
+ // Therefore, we can pretend for the rest of this function that we're dealing
+ // with the conjunction, provided we flip the sense of any comparisons (both
+ // input and output).
+
+ // In most cases we're going to produce an EQ for the "&&" case.
+ ICmpInst::Predicate NEWCC = IsAnd ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE;
+ if (!IsAnd) {
+ // Convert the masking analysis into its equivalent with negated
+ // comparisons.
+ mask = conjugateICmpMask(mask);
+ }
if (mask & FoldMskICmp_Mask_AllZeroes) {
// (icmp eq (A & B), 0) & (icmp eq (A & D), 0)
@@ -657,6 +712,40 @@ static Value* foldLogOpOfMaskedICmps(ICmpInst *LHS, ICmpInst *RHS,
Value* newAnd = Builder->CreateAnd(A, newAnd1);
return Builder->CreateICmp(NEWCC, newAnd, A);
}
+
+ // Remaining cases assume at least that B and D are constant, and depend on
+ // their actual values. This isn't strictly, necessary, just a "handle the
+ // easy cases for now" decision.
+ ConstantInt *BCst = dyn_cast<ConstantInt>(B);
+ if (BCst == 0) return 0;
+ ConstantInt *DCst = dyn_cast<ConstantInt>(D);
+ if (DCst == 0) return 0;
+
+ if (mask & (FoldMskICmp_Mask_NotAllZeroes | FoldMskICmp_BMask_NotAllOnes)) {
+ // (icmp ne (A & B), 0) & (icmp ne (A & D), 0) and
+ // (icmp ne (A & B), B) & (icmp ne (A & D), D)
+ // -> (icmp ne (A & B), 0) or (icmp ne (A & D), 0)
+ // Only valid if one of the masks is a superset of the other (check "B&D" is
+ // the same as either B or D).
+ APInt NewMask = BCst->getValue() & DCst->getValue();
+
+ if (NewMask == BCst->getValue())
+ return LHS;
+ else if (NewMask == DCst->getValue())
+ return RHS;
+ }
+ if (mask & FoldMskICmp_AMask_NotAllOnes) {
+ // (icmp ne (A & B), B) & (icmp ne (A & D), D)
+ // -> (icmp ne (A & B), A) or (icmp ne (A & D), A)
+ // Only valid if one of the masks is a superset of the other (check "B|D" is
+ // the same as either B or D).
+ APInt NewMask = BCst->getValue() | DCst->getValue();
+
+ if (NewMask == BCst->getValue())
+ return LHS;
+ else if (NewMask == DCst->getValue())
+ return RHS;
+ }
if (mask & FoldMskICmp_BMask_Mixed) {
// (icmp eq (A & B), C) & (icmp eq (A & D), E)
// We already know that B & C == C && D & E == E.
@@ -665,14 +754,9 @@ static Value* foldLogOpOfMaskedICmps(ICmpInst *LHS, ICmpInst *RHS,
// contradict, then we can transform to
// -> (icmp eq (A & (B|D)), (C|E))
// Currently, we only handle the case of B, C, D, and E being constant.
- ConstantInt *BCst = dyn_cast<ConstantInt>(B);
- if (BCst == 0) return 0;
- ConstantInt *DCst = dyn_cast<ConstantInt>(D);
- if (DCst == 0) return 0;
// we can't simply use C and E, because we might actually handle
// (icmp ne (A & B), B) & (icmp eq (A & D), D)
// with B and D, having a single bit set
-
ConstantInt *CCst = dyn_cast<ConstantInt>(C);
if (CCst == 0) return 0;
if (LHSCC != NEWCC)
@@ -715,7 +799,7 @@ Value *InstCombiner::FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
}
// handle (roughly): (icmp eq (A & B), C) & (icmp eq (A & D), E)
- if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, ICmpInst::ICMP_EQ, Builder))
+ if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, true, Builder))
return V;
// This only handles icmp of constants: (icmp1 A, C1) & (icmp2 B, C2).
@@ -849,10 +933,15 @@ Value *InstCombiner::FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
case ICmpInst::ICMP_SGT: // (X != 13 & X s> 15) -> X s> 15
return RHS;
case ICmpInst::ICMP_NE:
+ // Special case to get the ordering right when the values wrap around
+ // zero.
+ if (LHSCst->getValue() == 0 && RHSCst->getValue().isAllOnesValue())
+ std::swap(LHSCst, RHSCst);
if (LHSCst == SubOne(RHSCst)){// (X != 13 & X != 14) -> X-13 >u 1
Constant *AddCST = ConstantExpr::getNeg(LHSCst);
Value *Add = Builder->CreateAdd(Val, AddCST, Val->getName()+".off");
- return Builder->CreateICmpUGT(Add, ConstantInt::get(Add->getType(), 1));
+ return Builder->CreateICmpUGT(Add, ConstantInt::get(Add->getType(), 1),
+ Val->getName()+".cmp");
}
break; // (X != 13 & X != 15) -> no change
}
@@ -1454,10 +1543,60 @@ static Instruction *MatchSelectFromAndOr(Value *A, Value *B,
return 0;
}
+/// IsOneHotValue - Returns true for "one-hot" values (values where at most
+/// one bit can be set).
+static bool IsOneHotValue(Value *V) {
+ // Match 1<<K.
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(V))
+ if (BO->getOpcode() == Instruction::Shl) {
+ ConstantInt *One = dyn_cast<ConstantInt>(BO->getOperand(0));
+ return One && One->isOne();
+ }
+
+ // Check for power of two integer constants.
+ if (ConstantInt *K = dyn_cast<ConstantInt>(V))
+ return K->getValue().isPowerOf2();
+
+ return false;
+}
+
/// FoldOrOfICmps - Fold (icmp)|(icmp) if possible.
Value *InstCombiner::FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
ICmpInst::Predicate LHSCC = LHS->getPredicate(), RHSCC = RHS->getPredicate();
+ // Fold (iszero(A & K1) | iszero(A & K2)) -> (A & (K1 | K2)) != (K1 | K2)
+ // if K1 and K2 are a one-bit mask.
+ ConstantInt *LHSCst = dyn_cast<ConstantInt>(LHS->getOperand(1));
+ ConstantInt *RHSCst = dyn_cast<ConstantInt>(RHS->getOperand(1));
+
+ if (LHS->getPredicate() == ICmpInst::ICMP_EQ && LHSCst && LHSCst->isZero() &&
+ RHS->getPredicate() == ICmpInst::ICMP_EQ && RHSCst && RHSCst->isZero()) {
+
+ BinaryOperator *LAnd = dyn_cast<BinaryOperator>(LHS->getOperand(0));
+ BinaryOperator *RAnd = dyn_cast<BinaryOperator>(RHS->getOperand(0));
+ if (LAnd && RAnd && LAnd->hasOneUse() && RHS->hasOneUse() &&
+ LAnd->getOpcode() == Instruction::And &&
+ RAnd->getOpcode() == Instruction::And) {
+
+ Value *Mask = 0;
+ Value *Masked = 0;
+ if (LAnd->getOperand(0) == RAnd->getOperand(0) &&
+ IsOneHotValue(LAnd->getOperand(1)) &&
+ IsOneHotValue(RAnd->getOperand(1))) {
+ Mask = Builder->CreateOr(LAnd->getOperand(1), RAnd->getOperand(1));
+ Masked = Builder->CreateAnd(LAnd->getOperand(0), Mask);
+ } else if (LAnd->getOperand(1) == RAnd->getOperand(1) &&
+ IsOneHotValue(LAnd->getOperand(0)) &&
+ IsOneHotValue(RAnd->getOperand(0))) {
+ Mask = Builder->CreateOr(LAnd->getOperand(0), RAnd->getOperand(0));
+ Masked = Builder->CreateAnd(LAnd->getOperand(1), Mask);
+ }
+
+ if (Masked)
+ return Builder->CreateICmp(ICmpInst::ICMP_NE, Masked, Mask);
+ }
+ }
+
// (icmp1 A, B) | (icmp2 A, B) --> (icmp3 A, B)
if (PredicatesFoldable(LHSCC, RHSCC)) {
if (LHS->getOperand(0) == RHS->getOperand(1) &&
@@ -1474,13 +1613,10 @@ Value *InstCombiner::FoldOrOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
// handle (roughly):
// (icmp ne (A & B), C) | (icmp ne (A & D), E)
- if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, ICmpInst::ICMP_NE, Builder))
+ if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, false, Builder))
return V;
Value *Val = LHS->getOperand(0), *Val2 = RHS->getOperand(0);
- ConstantInt *LHSCst = dyn_cast<ConstantInt>(LHS->getOperand(1));
- ConstantInt *RHSCst = dyn_cast<ConstantInt>(RHS->getOperand(1));
-
if (LHS->hasOneUse() || RHS->hasOneUse()) {
// (icmp eq B, 0) | (icmp ult A, B) -> (icmp ule A, B-1)
// (icmp eq B, 0) | (icmp ugt B, A) -> (icmp ule A, B-1)
generated by cgit v1.1 at 2024-12-22 15:43:35 +0000