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Canonicalize away bit width and embed small integers into IntIds (#4487)
The first change here is to canonicalize away bit width when tracking integers in our shared value store. This lets us have a more definitive model of "what is the mathematical value". It also frees us to use more efficient bit widths when available, such as bits inside the ID itself. For canonicalizing, we try to minimize the width adjustments and maximize the use of the SSO in APInt, and so we never shrink belowe 64-bits and grow in multiples of the word bit width in the implementation. We also canonicalize to the signed 2s compliment representation so we can represent negative numbers in an intuitive way. The canonicalizing requires getting the bit width out of the type and adjusting to it within the toolchain when doing any kind of math, and this PR updates various places to do that, as well as adding some convenience APIs to assist. Then we take advantage of the canonical form and embed small integers into the ID itself rather than allocating storage for them and referencing them with an index. This is especially helpful for the pervasive small integers such as the sizes of types, arrays, etc. Those no longer require indirection at all. Various short-cut APIs to take advantage of this have also been added. This PR improves lexing by about 5% when there are lots of `i32` types. --------- Co-authored-by: Dana Jansens <danakj@orodu.net> Co-authored-by: Carbon Infra Bot <carbon-external-infra@google.com> Co-authored-by: Jon Ross-Perkins <jperkins@google.com>
This commit is contained in:
Chandler Carruth
co-authored by
Dana Jansens
Carbon Infra Bot
Jon Ross-Perkins
Dana Jansens
Carbon Infra Bot
Jon Ross-Perkins
parent
39ed62dad7
commit
3ba4997855
+67
-36
@@ -244,7 +244,7 @@ static auto MakeBoolResult(Context& context, SemIR::TypeId bool_type_id,
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// Converts an APInt value into a ConstantId.
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static auto MakeIntResult(Context& context, SemIR::TypeId type_id,
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llvm::APInt value) -> SemIR::ConstantId {
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auto result = context.ints().Add(std::move(value));
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auto result = context.ints().AddSigned(std::move(value));
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return MakeConstantResult(
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context, SemIR::IntValue{.type_id = type_id, .int_id = result},
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Phase::Template);
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@@ -674,12 +674,14 @@ static auto PerformBuiltinUnaryIntOp(Context& context, SemIRLoc loc,
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SemIR::InstId arg_id)
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-> SemIR::ConstantId {
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auto op = context.insts().GetAs<SemIR::IntValue>(arg_id);
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auto op_val = context.ints().Get(op.int_id);
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auto [is_signed, bit_width_id] = context.sem_ir().GetIntTypeInfo(op.type_id);
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CARBON_CHECK(bit_width_id != IntId::Invalid,
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"Cannot evaluate a generic bit width integer: {0}", op);
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llvm::APInt op_val = context.ints().GetAtWidth(op.int_id, bit_width_id);
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switch (builtin_kind) {
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case SemIR::BuiltinFunctionKind::IntSNegate:
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if (context.types().IsSignedInt(op.type_id) &&
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op_val.isMinSignedValue()) {
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if (is_signed && op_val.isMinSignedValue()) {
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CARBON_DIAGNOSTIC(CompileTimeIntegerNegateOverflow, Error,
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"integer overflow in negation of {0}", TypedInt);
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context.emitter().Emit(loc, CompileTimeIntegerNegateOverflow,
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@@ -708,8 +710,6 @@ static auto PerformBuiltinBinaryIntOp(Context& context, SemIRLoc loc,
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-> SemIR::ConstantId {
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auto lhs = context.insts().GetAs<SemIR::IntValue>(lhs_id);
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auto rhs = context.insts().GetAs<SemIR::IntValue>(rhs_id);
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const auto& lhs_val = context.ints().Get(lhs.int_id);
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const auto& rhs_val = context.ints().Get(rhs.int_id);
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// Check for division by zero.
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switch (builtin_kind) {
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@@ -717,7 +717,7 @@ static auto PerformBuiltinBinaryIntOp(Context& context, SemIRLoc loc,
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case SemIR::BuiltinFunctionKind::IntSMod:
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case SemIR::BuiltinFunctionKind::IntUDiv:
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case SemIR::BuiltinFunctionKind::IntUMod:
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if (rhs_val.isZero()) {
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if (context.ints().Get(rhs.int_id).isZero()) {
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DiagnoseDivisionByZero(context, loc);
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return SemIR::ConstantId::Error;
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}
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@@ -726,9 +726,58 @@ static auto PerformBuiltinBinaryIntOp(Context& context, SemIRLoc loc,
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break;
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}
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bool overflow = false;
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auto [lhs_is_signed, lhs_bit_width_id] =
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context.sem_ir().GetIntTypeInfo(lhs.type_id);
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llvm::APInt lhs_val = context.ints().GetAtWidth(lhs.int_id, lhs_bit_width_id);
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llvm::APInt result_val;
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// First handle shift, which can directly use the canonical RHS and doesn't
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// overflow.
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switch (builtin_kind) {
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// Bit shift.
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case SemIR::BuiltinFunctionKind::IntLeftShift:
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case SemIR::BuiltinFunctionKind::IntRightShift: {
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const auto& rhs_orig_val = context.ints().Get(rhs.int_id);
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if (rhs_orig_val.uge(lhs_val.getBitWidth()) ||
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(rhs_orig_val.isNegative() && lhs_is_signed)) {
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CARBON_DIAGNOSTIC(
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CompileTimeShiftOutOfRange, Error,
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"shift distance not in range [0, {0}) in {1} {2:<<|>>} {3}",
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unsigned, TypedInt, BoolAsSelect, TypedInt);
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context.emitter().Emit(
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loc, CompileTimeShiftOutOfRange, lhs_val.getBitWidth(),
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{.type = lhs.type_id, .value = lhs_val},
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builtin_kind == SemIR::BuiltinFunctionKind::IntLeftShift,
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{.type = rhs.type_id, .value = rhs_orig_val});
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// TODO: Is it useful to recover by returning 0 or -1?
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return SemIR::ConstantId::Error;
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}
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if (builtin_kind == SemIR::BuiltinFunctionKind::IntLeftShift) {
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result_val = lhs_val.shl(rhs_orig_val);
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} else if (lhs_is_signed) {
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result_val = lhs_val.ashr(rhs_orig_val);
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} else {
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result_val = lhs_val.lshr(rhs_orig_val);
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}
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return MakeIntResult(context, lhs.type_id, std::move(result_val));
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}
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default:
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// Break to do additional setup for other builtin kinds.
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break;
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}
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// Other operations are already checked to be homogeneous, so we can extend
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// the RHS with the LHS bit width.
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CARBON_CHECK(rhs.type_id == lhs.type_id, "Heterogeneous builtin integer op!");
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llvm::APInt rhs_val = context.ints().GetAtWidth(rhs.int_id, lhs_bit_width_id);
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// We may also need to diagnose overflow for these operations.
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bool overflow = false;
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Lex::TokenKind op_token = Lex::TokenKind::Not;
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switch (builtin_kind) {
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// Arithmetic.
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case SemIR::BuiltinFunctionKind::IntSAdd:
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@@ -789,32 +838,9 @@ static auto PerformBuiltinBinaryIntOp(Context& context, SemIRLoc loc,
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op_token = Lex::TokenKind::Caret;
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break;
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// Bit shift.
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case SemIR::BuiltinFunctionKind::IntLeftShift:
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case SemIR::BuiltinFunctionKind::IntRightShift:
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if (rhs_val.uge(lhs_val.getBitWidth()) ||
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(rhs_val.isNegative() && context.types().IsSignedInt(rhs.type_id))) {
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CARBON_DIAGNOSTIC(
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CompileTimeShiftOutOfRange, Error,
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"shift distance not in range [0, {0}) in {1} {2:<<|>>} {3}",
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unsigned, TypedInt, BoolAsSelect, TypedInt);
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context.emitter().Emit(
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loc, CompileTimeShiftOutOfRange, lhs_val.getBitWidth(),
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{.type = lhs.type_id, .value = lhs_val},
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builtin_kind == SemIR::BuiltinFunctionKind::IntLeftShift,
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{.type = rhs.type_id, .value = rhs_val});
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// TODO: Is it useful to recover by returning 0 or -1?
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return SemIR::ConstantId::Error;
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}
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if (builtin_kind == SemIR::BuiltinFunctionKind::IntLeftShift) {
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result_val = lhs_val.shl(rhs_val);
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} else if (context.types().IsSignedInt(lhs.type_id)) {
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result_val = lhs_val.ashr(rhs_val);
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} else {
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result_val = lhs_val.lshr(rhs_val);
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}
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break;
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CARBON_FATAL("Handled specially above.");
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default:
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CARBON_FATAL("Unexpected operation kind.");
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@@ -840,10 +866,15 @@ static auto PerformBuiltinIntComparison(Context& context,
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SemIR::TypeId bool_type_id)
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-> SemIR::ConstantId {
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auto lhs = context.insts().GetAs<SemIR::IntValue>(lhs_id);
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const auto& lhs_val = context.ints().Get(lhs.int_id);
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const auto& rhs_val =
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context.ints().Get(context.insts().GetAs<SemIR::IntValue>(rhs_id).int_id);
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bool is_signed = context.types().IsSignedInt(lhs.type_id);
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auto rhs = context.insts().GetAs<SemIR::IntValue>(rhs_id);
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CARBON_CHECK(lhs.type_id == rhs.type_id,
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"Builtin comparison with mismatched types!");
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auto [is_signed, bit_width_id] = context.sem_ir().GetIntTypeInfo(lhs.type_id);
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CARBON_CHECK(bit_width_id != IntId::Invalid,
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"Cannot evaluate a generic bit width integer: {0}", lhs);
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llvm::APInt lhs_val = context.ints().GetAtWidth(lhs.int_id, bit_width_id);
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llvm::APInt rhs_val = context.ints().GetAtWidth(rhs.int_id, bit_width_id);
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bool result;
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switch (builtin_kind) {
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