Skip to content

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

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Apr 2, 2019
Merged

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

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
64 changes: 32 additions & 32 deletions lib/SILOptimizer/Utils/ConstantFolding.cpp
View file
Open in desktop
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