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4a7aefefaa07bf5fe40f7ceb2990f792ea1e6f91
carbon-lang/toolchain/lower/handle_call.cpp
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Richard Smith 4a7aefefaa Add support for operators on Core.IntLiteral. (#4716) 
Fixes integer builtins to produce the correct values (and not
CHECK-fail) when used on integer literals. Also adds impls to the
prelude to use the new builtins to perform operations on integer
literals.

Perhaps most importantly, this allows directly initializing `i32` values
with negative numbers, as the negation operation on integer literals now
works.

For testing I've added tests for use of literals with one operator in
each class (addition, multiplication, ordering, bitwise, etc) for which
there are distinct rules or overflow behavior, rather than exhaustively
testing all the combinations. This is aimed at finding a good tradeoff
between maintainability of the tests and thorough test coverage.

Also fixes lowering of heterogeneous shifts and comparisons. These are
currently disabled when one of the operands is an integer literal, but
we may want to allow that when the integer literal operand has a known
constant value.
2024-12-31 06:36:43 +00:00

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// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
#include "llvm/IR/Type.h"
#include "llvm/IR/Value.h"
#include "toolchain/lower/function_context.h"
#include "toolchain/sem_ir/builtin_function_kind.h"
#include "toolchain/sem_ir/ids.h"
#include "toolchain/sem_ir/typed_insts.h"
namespace Carbon::Lower {
// Get the predicate to use for an `icmp` instruction generated for the
// specified builtin.
static auto GetBuiltinICmpPredicate(SemIR::BuiltinFunctionKind builtin_kind,
bool is_signed)
-> llvm::CmpInst::Predicate {
switch (builtin_kind) {
case SemIR::BuiltinFunctionKind::IntEq:
case SemIR::BuiltinFunctionKind::BoolEq:
return llvm::CmpInst::ICMP_EQ;
case SemIR::BuiltinFunctionKind::IntNeq:
case SemIR::BuiltinFunctionKind::BoolNeq:
return llvm::CmpInst::ICMP_NE;
case SemIR::BuiltinFunctionKind::IntLess:
return is_signed ? llvm::CmpInst::ICMP_SLT : llvm::CmpInst::ICMP_ULT;
case SemIR::BuiltinFunctionKind::IntLessEq:
return is_signed ? llvm::CmpInst::ICMP_SLE : llvm::CmpInst::ICMP_ULE;
case SemIR::BuiltinFunctionKind::IntGreater:
return is_signed ? llvm::CmpInst::ICMP_SGT : llvm::CmpInst::ICMP_UGT;
case SemIR::BuiltinFunctionKind::IntGreaterEq:
return is_signed ? llvm::CmpInst::ICMP_SGE : llvm::CmpInst::ICMP_UGE;
default:
CARBON_FATAL("Unexpected builtin kind {0}", builtin_kind);
}
}
// Get the predicate to use for an `fcmp` instruction generated for the
// specified builtin.
static auto GetBuiltinFCmpPredicate(SemIR::BuiltinFunctionKind builtin_kind)
-> llvm::CmpInst::Predicate {
switch (builtin_kind) {
case SemIR::BuiltinFunctionKind::FloatEq:
return llvm::CmpInst::FCMP_OEQ;
case SemIR::BuiltinFunctionKind::FloatNeq:
return llvm::CmpInst::FCMP_ONE;
case SemIR::BuiltinFunctionKind::FloatLess:
return llvm::CmpInst::FCMP_OLT;
case SemIR::BuiltinFunctionKind::FloatLessEq:
return llvm::CmpInst::FCMP_OLE;
case SemIR::BuiltinFunctionKind::FloatGreater:
return llvm::CmpInst::FCMP_OGT;
case SemIR::BuiltinFunctionKind::FloatGreaterEq:
return llvm::CmpInst::FCMP_OGE;
default:
CARBON_FATAL("Unexpected builtin kind {0}", builtin_kind);
}
}
// Returns whether the specified instruction has a signed integer type.
static auto IsSignedInt(FunctionContext& context, SemIR::InstId int_id)
-> bool {
return context.sem_ir().types().IsSignedInt(
context.sem_ir().insts().Get(int_id).type_id());
}
// Creates a zext or sext instruction depending on the signedness of the
// operand.
static auto CreateZExtOrSExt(FunctionContext& context, llvm::Value* value,
llvm::Type* type, bool is_signed,
const llvm::Twine& name = "") -> llvm::Value* {
return is_signed ? context.builder().CreateSExt(value, type, name)
: context.builder().CreateZExt(value, type, name);
}
// Handles a call to a builtin integer bit shift operator.
static auto HandleIntShift(FunctionContext& context, SemIR::InstId inst_id,
llvm::Instruction::BinaryOps bin_op,
SemIR::InstId lhs_id, SemIR::InstId rhs_id) -> void {
llvm::Value* lhs = context.GetValue(lhs_id);
llvm::Value* rhs = context.GetValue(rhs_id);
// Weirdly, LLVM requires the operands of bit shift operators to be of the
// same type. We can always use the width of the LHS, because if the RHS
// doesn't fit in that then the cast is out of range anyway. Zero-extending is
// always fine because it's an error for the RHS to be negative.
//
// TODO: In a development build we should trap if the RHS is signed and
// negative or greater than or equal to the number of bits in the left-hand
// type.
rhs = context.builder().CreateZExtOrTrunc(rhs, lhs->getType(), "rhs");
context.SetLocal(inst_id, context.builder().CreateBinOp(bin_op, lhs, rhs));
}
// Handles a call to a builtin integer comparison operator.
static auto HandleIntComparison(FunctionContext& context, SemIR::InstId inst_id,
SemIR::BuiltinFunctionKind builtin_kind,
SemIR::InstId lhs_id, SemIR::InstId rhs_id)
-> void {
llvm::Value* lhs = context.GetValue(lhs_id);
llvm::Value* rhs = context.GetValue(rhs_id);
const auto* lhs_type = cast<llvm::IntegerType>(lhs->getType());
const auto* rhs_type = cast<llvm::IntegerType>(rhs->getType());
// We perform a signed comparison if either operand is signed.
bool lhs_signed = IsSignedInt(context, lhs_id);
bool rhs_signed = IsSignedInt(context, rhs_id);
bool cmp_signed = lhs_signed || rhs_signed;
// Compute the width for the comparison. This is the smallest width that
// fits both types, after widening them to include a sign bit if
// necessary.
auto width_for_cmp = [&](const llvm::IntegerType* type, bool is_signed) {
unsigned width = type->getBitWidth();
if (!is_signed && cmp_signed) {
// We're performing a signed comparison but this input is unsigned.
// Widen it by at least one bit to provide a sign bit.
++width;
}
return width;
};
// TODO: This might be an awkward size, such as 33 or 65 bits, for a
// signed/unsigned comparison. Would it be better to round this up to a
// "nicer" bit width?
unsigned cmp_width = std::max(width_for_cmp(lhs_type, lhs_signed),
width_for_cmp(rhs_type, rhs_signed));
auto* cmp_type = llvm::IntegerType::get(context.llvm_context(), cmp_width);
// Widen the operands as needed.
lhs = CreateZExtOrSExt(context, lhs, cmp_type, lhs_signed, "lhs");
rhs = CreateZExtOrSExt(context, rhs, cmp_type, rhs_signed, "rhs");
context.SetLocal(
inst_id,
context.builder().CreateICmp(
GetBuiltinICmpPredicate(builtin_kind, cmp_signed), lhs, rhs));
}
// Handles a call to a builtin function.
static auto HandleBuiltinCall(FunctionContext& context, SemIR::InstId inst_id,
SemIR::BuiltinFunctionKind builtin_kind,
llvm::ArrayRef<SemIR::InstId> arg_ids) -> void {
// TODO: Consider setting this to true in the performance build mode if the
// result type is a signed integer type.
constexpr bool SignedOverflowIsUB = false;
// TODO: Move the instruction names here into InstNamer.
switch (builtin_kind) {
case SemIR::BuiltinFunctionKind::None:
CARBON_FATAL("No callee in function call.");
case SemIR::BuiltinFunctionKind::PrintChar: {
auto* i32_type = llvm::IntegerType::getInt32Ty(context.llvm_context());
llvm::Value* arg_value = context.builder().CreateSExtOrTrunc(
context.GetValue(arg_ids[0]), i32_type);
auto putchar = context.llvm_module().getOrInsertFunction(
"putchar", i32_type, i32_type);
auto* result = context.builder().CreateCall(putchar, {arg_value});
context.SetLocal(
inst_id,
context.builder().CreateSExtOrTrunc(
result, context.GetType(
context.sem_ir().insts().Get(inst_id).type_id())));
return;
}
case SemIR::BuiltinFunctionKind::PrintInt: {
auto* i32_type = llvm::IntegerType::getInt32Ty(context.llvm_context());
auto* ptr_type = llvm::PointerType::get(context.llvm_context(), 0);
auto* printf_type = llvm::FunctionType::get(i32_type, {ptr_type},
/*isVarArg=*/true);
llvm::FunctionCallee printf =
context.llvm_module().getOrInsertFunction("printf", printf_type);
llvm::Value* format_string =
context.builder().CreateGlobalString("%d\n", "printf.int.format");
llvm::Value* arg_value = context.builder().CreateSExtOrTrunc(
context.GetValue(arg_ids[0]), i32_type);
context.SetLocal(inst_id, context.builder().CreateCall(
printf, {format_string, arg_value}));
return;
}
case SemIR::BuiltinFunctionKind::ReadChar: {
auto* i32_type = llvm::IntegerType::getInt32Ty(context.llvm_context());
auto getchar =
context.llvm_module().getOrInsertFunction("getchar", i32_type);
auto* result = context.builder().CreateCall(getchar, {});
context.SetLocal(
inst_id,
context.builder().CreateSExtOrTrunc(
result, context.GetType(
context.sem_ir().insts().Get(inst_id).type_id())));
return;
}
case SemIR::BuiltinFunctionKind::BoolMakeType:
case SemIR::BuiltinFunctionKind::FloatMakeType:
case SemIR::BuiltinFunctionKind::IntLiteralMakeType:
case SemIR::BuiltinFunctionKind::IntMakeTypeSigned:
case SemIR::BuiltinFunctionKind::IntMakeTypeUnsigned:
context.SetLocal(inst_id, context.GetTypeAsValue());
return;
case SemIR::BuiltinFunctionKind::IntSNegate: {
// Lower `-x` as `0 - x`.
auto* operand = context.GetValue(arg_ids[0]);
context.SetLocal(
inst_id,
context.builder().CreateSub(
llvm::ConstantInt::getNullValue(operand->getType()), operand, "",
/*HasNUW=*/false,
/*HasNSW=*/SignedOverflowIsUB));
return;
}
case SemIR::BuiltinFunctionKind::IntUNegate: {
// Lower `-x` as `0 - x`.
auto* operand = context.GetValue(arg_ids[0]);
context.SetLocal(
inst_id,
context.builder().CreateSub(
llvm::ConstantInt::getNullValue(operand->getType()), operand));
return;
}
case SemIR::BuiltinFunctionKind::IntComplement: {
// Lower `^x` as `-1 ^ x`.
auto* operand = context.GetValue(arg_ids[0]);
context.SetLocal(
inst_id,
context.builder().CreateXor(
llvm::ConstantInt::getSigned(operand->getType(), -1), operand));
return;
}
case SemIR::BuiltinFunctionKind::IntSAdd: {
context.SetLocal(
inst_id, context.builder().CreateAdd(context.GetValue(arg_ids[0]),
context.GetValue(arg_ids[1]), "",
/*HasNUW=*/false,
/*HasNSW=*/SignedOverflowIsUB));
return;
}
case SemIR::BuiltinFunctionKind::IntSSub: {
context.SetLocal(
inst_id, context.builder().CreateSub(context.GetValue(arg_ids[0]),
context.GetValue(arg_ids[1]), "",
/*HasNUW=*/false,
/*HasNSW=*/SignedOverflowIsUB));
return;
}
case SemIR::BuiltinFunctionKind::IntSMul: {
context.SetLocal(
inst_id, context.builder().CreateMul(context.GetValue(arg_ids[0]),
context.GetValue(arg_ids[1]), "",
/*HasNUW=*/false,
/*HasNSW=*/SignedOverflowIsUB));
return;
}
case SemIR::BuiltinFunctionKind::IntSDiv: {
context.SetLocal(
inst_id, context.builder().CreateSDiv(context.GetValue(arg_ids[0]),
context.GetValue(arg_ids[1])));
return;
}
case SemIR::BuiltinFunctionKind::IntSMod: {
context.SetLocal(
inst_id, context.builder().CreateSRem(context.GetValue(arg_ids[0]),
context.GetValue(arg_ids[1])));
return;
}
case SemIR::BuiltinFunctionKind::IntUAdd: {
context.SetLocal(
inst_id, context.builder().CreateAdd(context.GetValue(arg_ids[0]),
context.GetValue(arg_ids[1])));
return;
}
case SemIR::BuiltinFunctionKind::IntUSub: {
context.SetLocal(
inst_id, context.builder().CreateSub(context.GetValue(arg_ids[0]),
context.GetValue(arg_ids[1])));
return;
}
case SemIR::BuiltinFunctionKind::IntUMul: {
context.SetLocal(
inst_id, context.builder().CreateMul(context.GetValue(arg_ids[0]),
context.GetValue(arg_ids[1])));
return;
}
case SemIR::BuiltinFunctionKind::IntUDiv: {
context.SetLocal(
inst_id, context.builder().CreateUDiv(context.GetValue(arg_ids[0]),
context.GetValue(arg_ids[1])));
return;
}
case SemIR::BuiltinFunctionKind::IntUMod: {
context.SetLocal(
inst_id, context.builder().CreateURem(context.GetValue(arg_ids[0]),
context.GetValue(arg_ids[1])));
return;
}
case SemIR::BuiltinFunctionKind::IntAnd: {
context.SetLocal(
inst_id, context.builder().CreateAnd(context.GetValue(arg_ids[0]),
context.GetValue(arg_ids[1])));
return;
}
case SemIR::BuiltinFunctionKind::IntOr: {
context.SetLocal(
inst_id, context.builder().CreateOr(context.GetValue(arg_ids[0]),
context.GetValue(arg_ids[1])));
return;
}
case SemIR::BuiltinFunctionKind::IntXor: {
context.SetLocal(
inst_id, context.builder().CreateXor(context.GetValue(arg_ids[0]),
context.GetValue(arg_ids[1])));
return;
}
case SemIR::BuiltinFunctionKind::IntLeftShift: {
HandleIntShift(context, inst_id, llvm::Instruction::Shl, arg_ids[0],
arg_ids[1]);
return;
}
case SemIR::BuiltinFunctionKind::IntRightShift: {
HandleIntShift(context, inst_id,
IsSignedInt(context, inst_id) ? llvm::Instruction::AShr
: llvm::Instruction::LShr,
arg_ids[0], arg_ids[1]);
return;
}
case SemIR::BuiltinFunctionKind::IntEq:
case SemIR::BuiltinFunctionKind::IntNeq:
case SemIR::BuiltinFunctionKind::IntLess:
case SemIR::BuiltinFunctionKind::IntLessEq:
case SemIR::BuiltinFunctionKind::IntGreater:
case SemIR::BuiltinFunctionKind::IntGreaterEq:
case SemIR::BuiltinFunctionKind::BoolEq:
case SemIR::BuiltinFunctionKind::BoolNeq: {
HandleIntComparison(context, inst_id, builtin_kind, arg_ids[0],
arg_ids[1]);
return;
}
case SemIR::BuiltinFunctionKind::FloatNegate: {
context.SetLocal(
inst_id, context.builder().CreateFNeg(context.GetValue(arg_ids[0])));
return;
}
case SemIR::BuiltinFunctionKind::FloatAdd: {
context.SetLocal(
inst_id, context.builder().CreateFAdd(context.GetValue(arg_ids[0]),
context.GetValue(arg_ids[1])));
return;
}
case SemIR::BuiltinFunctionKind::FloatSub: {
context.SetLocal(
inst_id, context.builder().CreateFSub(context.GetValue(arg_ids[0]),
context.GetValue(arg_ids[1])));
return;
}
case SemIR::BuiltinFunctionKind::FloatMul: {
context.SetLocal(
inst_id, context.builder().CreateFMul(context.GetValue(arg_ids[0]),
context.GetValue(arg_ids[1])));
return;
}
case SemIR::BuiltinFunctionKind::FloatDiv: {
context.SetLocal(
inst_id, context.builder().CreateFDiv(context.GetValue(arg_ids[0]),
context.GetValue(arg_ids[1])));
return;
}
case SemIR::BuiltinFunctionKind::FloatEq:
case SemIR::BuiltinFunctionKind::FloatNeq:
case SemIR::BuiltinFunctionKind::FloatLess:
case SemIR::BuiltinFunctionKind::FloatLessEq:
case SemIR::BuiltinFunctionKind::FloatGreater:
case SemIR::BuiltinFunctionKind::FloatGreaterEq: {
context.SetLocal(inst_id, context.builder().CreateFCmp(
GetBuiltinFCmpPredicate(builtin_kind),
context.GetValue(arg_ids[0]),
context.GetValue(arg_ids[1])));
return;
}
case SemIR::BuiltinFunctionKind::IntConvertChecked: {
// TODO: Check this statically.
CARBON_CHECK(builtin_kind.IsCompTimeOnly(
context.sem_ir(), arg_ids,
context.sem_ir().insts().Get(inst_id).type_id()));
CARBON_FATAL("Missing constant value for call to comptime-only function");
}
}
CARBON_FATAL("Unsupported builtin call.");
}
auto HandleInst(FunctionContext& context, SemIR::InstId inst_id,
SemIR::Call inst) -> void {
llvm::ArrayRef<SemIR::InstId> arg_ids =
context.sem_ir().inst_blocks().Get(inst.args_id);
auto callee_function =
SemIR::GetCalleeFunction(context.sem_ir(), inst.callee_id);
CARBON_CHECK(callee_function.function_id.is_valid());
if (auto builtin_kind = context.sem_ir()
.functions()
.Get(callee_function.function_id)
.builtin_function_kind;
builtin_kind != SemIR::BuiltinFunctionKind::None) {
HandleBuiltinCall(context, inst_id, builtin_kind, arg_ids);
return;
}
auto* callee = context.GetOrCreateFunction(
callee_function.function_id, callee_function.resolved_specific_id);
std::vector<llvm::Value*> args;
if (SemIR::ReturnTypeInfo::ForType(context.sem_ir(), inst.type_id)
.has_return_slot()) {
args.push_back(context.GetValue(arg_ids.back()));
arg_ids = arg_ids.drop_back();
}
for (auto arg_id : arg_ids) {
auto arg_type_id = context.sem_ir().insts().Get(arg_id).type_id();
if (SemIR::ValueRepr::ForType(context.sem_ir(), arg_type_id).kind !=
SemIR::ValueRepr::None) {
args.push_back(context.GetValue(arg_id));
}
}
context.SetLocal(inst_id, context.builder().CreateCall(callee, args));
}
} // namespace Carbon::Lower
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