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[SILOptimizer] Constant Folding - Style modifications based on review #23739

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Apr 2, 2019
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[SILOptimizer] Constant Folding - Style modifications based on review #23739

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64 changes: 32 additions & 32 deletions lib/SILOptimizer/Utils/ConstantFolding.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -278,42 +278,38 @@ constantFoldBinaryWithOverflow(BuiltinInst *BI, BuiltinValueKind ID,
ResultsInError);
}

static SILValue countZeros(BuiltinInst *BI, llvm::Intrinsic::ID ID) {
assert(BI->getArguments().size() == 2 && "Ctlz should have 2 args.");
OperandValueArrayRef Args = BI->getArguments();
/// Constant fold a cttz or ctlz builtin inst of an integer literal.
/// If \p countLeadingZeros is set to true, then we assume \p bi must be ctlz.
/// If false, \p bi must be cttz.
///
/// NOTE: We assert that \p bi is either cttz or ctlz.
static SILValue
constantFoldCountLeadingOrTrialingZeroIntrinsic(BuiltinInst *bi,
bool countLeadingZeros) {
assert(bi->getIntrinsicID() == llvm::Intrinsic::ctlz ||
bi->getIntrinsicID() == llvm::Intrinsic::cttz &&
"Invalid Intrinsic - expected Ctlz/Cllz");
OperandValueArrayRef args = bi->getArguments();

// Fold for integer constant arguments.
auto *LHS = dyn_cast<IntegerLiteralInst>(Args[0]);
if (!LHS) {
auto *lhs = dyn_cast<IntegerLiteralInst>(args[0]);
if (!lhs) {
return nullptr;
}
APInt LHSI = LHS->getValue();
unsigned LZ = 0;
// Check corner-case of source == zero
if (LHSI == 0) {
auto *RHS = dyn_cast<IntegerLiteralInst>(Args[1]);
if (!RHS || RHS->getValue() != 0) {
// Undefined
return nullptr;
APInt lhsi = lhs->getValue();
unsigned lz = [&] {
if (lhsi == 0) {
// Check corner-case of source == zero
return lhsi.getBitWidth();
}
LZ = LHSI.getBitWidth();
} else {
switch (ID) {
default:
return nullptr;
case llvm::Intrinsic::ctlz: {
LZ = LHSI.countLeadingZeros();
break;
}
case llvm::Intrinsic::cttz: {
LZ = LHSI.countTrailingZeros();
break;
if (countLeadingZeros) {
return lhsi.countLeadingZeros();
}
}
}
APInt LZAsAPInt = APInt(LHSI.getBitWidth(), LZ);
SILBuilderWithScope B(BI);
return B.createIntegerLiteral(BI->getLoc(), LHS->getType(), LZAsAPInt);
return lhsi.countTrailingZeros();
}();
APInt lzAsAPInt = APInt(lhsi.getBitWidth(), lz);
SILBuilderWithScope builder(bi);
return builder.createIntegerLiteral(bi->getLoc(), lhs->getType(), lzAsAPInt);
}

static SILValue constantFoldIntrinsic(BuiltinInst *BI, llvm::Intrinsic::ID ID,
Expand All @@ -329,9 +325,13 @@ static SILValue constantFoldIntrinsic(BuiltinInst *BI, llvm::Intrinsic::ID ID,
return Op1;
}

case llvm::Intrinsic::ctlz:
case llvm::Intrinsic::ctlz: {
return constantFoldCountLeadingOrTrialingZeroIntrinsic(
BI, true /*countLeadingZeros*/);
}
case llvm::Intrinsic::cttz: {
return countZeros(BI, ID);
return constantFoldCountLeadingOrTrialingZeroIntrinsic(
BI, false /*countLeadingZeros*/);
}

case llvm::Intrinsic::sadd_with_overflow:
Expand Down