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Add local constants referenced in a lambda as constant members in the capture impl. #4163

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Add local constants referenced in a lambda as constant members in the capture impl. #4163

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94 changes: 74 additions & 20 deletions xls/dslx/frontend/semantics_analysis.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@
#include <algorithm>
#include <cstddef>
#include <cstdint>
#include <functional>
#include <memory>
#include <optional>
#include <string>
Expand Down Expand Up @@ -267,7 +268,8 @@ class CollectNameRefs : public AstNodeVisitorWithDefault {
}
if (node->GetDefiner() == nullptr ||
(node->GetDefiner()->kind() != AstNodeKind::kFunction &&
node->GetDefiner()->kind() != AstNodeKind::kImport)) {
node->GetDefiner()->kind() != AstNodeKind::kImport &&
node->GetDefiner()->kind() != AstNodeKind::kConstantDef)) {
XLS_RETURN_IF_ERROR(AddNameRef(node));
if (node->GetDefiner() != nullptr && in_type_annotation_) {
XLS_RETURN_IF_ERROR(node->GetDefiner()->Accept(this));
Expand Down Expand Up @@ -299,16 +301,17 @@ class CollectNameRefs : public AstNodeVisitorWithDefault {
return it->second.name_refs;
}

absl::flat_hash_set<const NameDef*> ConstsDefinedPrior(
const Pos start) const {
absl::flat_hash_set<const NameDef*> result;
return NameDefsDefinedPriorInternal(start, is_const);
}

absl::flat_hash_set<const NameDef*> NameDefsDefinedPrior(
const Pos start) const {
absl::flat_hash_set<const NameDef*> result;
for (const auto& [name_def, info] : name_ref_info_) {
if (!info.any_used_in_type_annotation &&
name_def->span().start() < start) {
result.insert(name_def);
}
}
return result;
return NameDefsDefinedPriorInternal(
start, [](const NameDef* name_def) { return !is_const(name_def); });
}

private:
Expand All @@ -333,6 +336,30 @@ class CollectNameRefs : public AstNodeVisitorWithDefault {
return absl::OkStatus();
}

static bool is_const(const NameDef* name_def) {
if (name_def->definer() == nullptr ||
name_def->definer()->kind() != AstNodeKind::kLet) {
return false;
}
auto let = absl::down_cast<Let*>(name_def->definer());
return let->is_const();
}

absl::flat_hash_set<const NameDef*> NameDefsDefinedPriorInternal(
const Pos start,
std::function<bool(const NameDef*)> name_def_filter) const {
absl::flat_hash_set<const NameDef*> result;
for (const auto& [name_def, info] : name_ref_info_) {
if (!info.any_used_in_type_annotation &&
name_def->span().start() < start) {
if (name_def_filter(name_def)) {
result.insert(name_def);
}
}
}
return result;
}

absl::flat_hash_map<const NameDef*, NameRefInfo> name_ref_info_;
bool in_type_annotation_ = false;
};
Expand Down Expand Up @@ -368,7 +395,6 @@ class ReplaceLambdaWithInvocation : public AstNodeVisitorWithDefault {
Span span = node->span();
CollectNameRefs collect_nr;
XLS_RETURN_IF_ERROR(node->body()->Accept(&collect_nr));
absl::flat_hash_set<const NameDef*> seen;

// If there are any parametric bindings in the containing function that are
// referenced in the lambda, they should be added as parametric bindings to
Expand Down Expand Up @@ -410,11 +436,33 @@ class ReplaceLambdaWithInvocation : public AstNodeVisitorWithDefault {
}
}

// Any constant that is referenced by the lambda should be added as an impl
// member.
std::vector<ImplMember> impl_members;
absl::flat_hash_set<const NameDef*> impl_constants;
for (const NameDef* constant_nd :
collect_nr.ConstsDefinedPrior(span.start())) {
if (parametric_nds.contains(constant_nd)) {
continue;
}
XLS_RET_CHECK(constant_nd->definer() != nullptr &&
constant_nd->definer()->kind() == AstNodeKind::kLet);
auto let = absl::down_cast<Let*>(constant_nd->definer());
NameDef* new_nd = module->Make<NameDef>(
constant_nd->span(), constant_nd->identifier(), /*definer=*/nullptr);
ConstantDef* constant_def = module->Make<ConstantDef>(
constant_nd->span(), new_nd, let->type_annotation(), let->rhs(),
/*is_public=*/false);
impl_members.push_back(constant_def);
impl_constants.insert(constant_nd);
}

// For any NameDef that is referenced in the lambda, but defined prior to
// the lambda, it must be captured in the struct instance, unless it was
// already added as a parametric binding.
std::vector<StructMemberNode*> struct_members;
std::vector<std::pair<std::string, Expr*>> struct_instance_members;
absl::flat_hash_set<const NameDef*> self_members;
for (const NameDef* original_name_def :
collect_nr.NameDefsDefinedPrior(span.start())) {
if (!parametric_nds.contains(original_name_def)) {
Expand Down Expand Up @@ -450,7 +498,7 @@ class ReplaceLambdaWithInvocation : public AstNodeVisitorWithDefault {
original_name_def);
struct_instance_members.push_back(std::make_pair(
original_name_def->identifier(), struct_instance_nr));
seen.insert(original_name_def);
self_members.insert(original_name_def);
}
}

Expand Down Expand Up @@ -479,7 +527,8 @@ class ReplaceLambdaWithInvocation : public AstNodeVisitorWithDefault {
NameDef* self_nd = module->Make<NameDef>(
span, KeywordToString(Keyword::kSelf), /*definer=*/nullptr);
CloneReplacer insert_self =
[self_nd, seen, name_ref_replacements](
[self_nd, self_members, name_ref_replacements, impl_constants,
struct_type_annotation](
const AstNode* node, const Module* _,
const absl::flat_hash_map<const AstNode*, AstNode*>& replacements)
-> std::optional<AstNode*> {
Expand All @@ -489,37 +538,42 @@ class ReplaceLambdaWithInvocation : public AstNodeVisitorWithDefault {
return std::nullopt;
}
const auto* name_def = std::get<const NameDef*>(name_ref->name_def());
if (name_def != nullptr && seen.contains(name_def)) {
if (name_def != nullptr && self_members.contains(name_def)) {
NameRef* self_nr = node->owner()->Make<NameRef>(
name_ref->span(), self_nd->identifier(), self_nd);
return node->owner()->Make<Attr>(name_def->span(), self_nr,
name_def->identifier(),
/* in_parens= */ false);
} else if (name_def != nullptr && impl_constants.contains(name_def)) {
return node->owner()->Make<ColonRef>(
name_def->span(), struct_type_annotation, name_def->identifier());
} else if (name_ref_replacements.contains(name_ref)) {
return name_ref_replacements.at(name_ref);
}
}
return std::nullopt;
};
XLS_ASSIGN_OR_RETURN(
AstNode * cloned_body,
CloneAst(original_fn->body(),
AstNode * clone,
CloneAst(original_fn,
ChainCloneReplacers(&PreserveTypeDefinitionsReplacer,
std::move(insert_self))));
Function* cloned_function = absl::down_cast<Function*>(clone);
SelfTypeAnnotation* self_type = module->Make<SelfTypeAnnotation>(
span, /*explicit_type=*/false, struct_type_annotation);
std::vector<Param*> params = {module->Make<Param>(self_nd, self_type)};
for (auto* param : original_fn->params()) {
for (auto* param : cloned_function->params()) {
params.push_back(param);
}
Function* impl_fn = module->Make<Function>(
original_fn->span(), original_fn->name_def(),
original_fn->parametric_bindings(), params, original_fn->return_type(),
absl::down_cast<StatementBlock*>(cloned_body),
cloned_function->span(), cloned_function->name_def(),
cloned_function->parametric_bindings(), params,
cloned_function->return_type(),
absl::down_cast<StatementBlock*>(cloned_function->body()),
FunctionTag::kGeneratedFromLambda,
/*is_public=*/false, /*is_stub=*/false);
Impl* impl = module->Make<Impl>(span, struct_type_annotation,
std::vector<ImplMember>{impl_fn},
impl_members.push_back(impl_fn);
Impl* impl = module->Make<Impl>(span, struct_type_annotation, impl_members,
/*is_public=*/false);
impl_fn->set_impl(impl);
full_struct_def->set_impl(impl);
Expand Down
100 changes: 99 additions & 1 deletion xls/dslx/type_system_v2/typecheck_module_v2_lambda_test.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -249,13 +249,111 @@ const_assert!(RES2 == [u32:0, 3, 2]);
HasNodeWithType("RES2", "uN[32][3]"))));
}

TEST(TypecheckV2Test, NestedLambdaIteratesOverLocalConst) {
EXPECT_THAT(
R"(
fn nested() -> u1[2][3] {
const X = u32:2;
const Y = u32:3;
map(0..Y, | y_idx: u32 | {
map(0..X, | x_idx: u32 | {
if (x_idx + y_idx) % 2 == 0 {
u1:1
} else {
u1:0
}
})
})
}

const RES = nested();
const EX = [
[u1:1, u1:0],
[u1:0, u1:1],
[u1:1, u1:0],
];
const_assert!(RES == EX);

)",
TypecheckSucceeds(AllOf(
HasNodeWithType("RES", "uN[1][2][3]"),
HasNodeWithType("lambda_capture_struct_at_fake.x:7:14-15:5::X",
"uN[32]"),
HasNodeWithType("lambda_capture_struct_at_fake.x:8:18-14:9<u32>",
"typeof(lambda_capture_struct_at_fake.x:8:18-14:9 { "
"y_idx: uN[32] }"))));
}

TEST(TypecheckV2Test, NestedLambdaIteratesOverLocalConstWithExplicitReturn) {
EXPECT_THAT(
R"(
fn nested() -> u1[2][3] {
const X = u32:2;
const Y = u32:3;
map(0..Y, | y_idx: u32 | -> u1[X] {
map(0..X, | x_idx: u32 | {
if (x_idx + y_idx) % 2 == 0 {
u1:1
} else {
u1:0
}
})
})
}

const RES = nested();
const EX = [
[u1:1, u1:0],
[u1:0, u1:1],
[u1:1, u1:0],
];
const_assert!(RES == EX);

)",
TypecheckSucceeds(
AllOf(HasNodeWithType("RES", "uN[1][2][3]"),
HasNodeWithType("lambda_capture_struct_at_fake.x:7:14-15:5::X",
"uN[32]"))));
}

TEST(TypecheckV2Test, NestedLambdaIteratesOverGlobalConst) {
EXPECT_THAT(
R"(
const X = u32:2;
const Y = u32:3;
type Results = u1[X][Y];

fn nested() -> Results {
map(0..Y, | y_idx | {
map(0..X, | x_idx | {
if (x_idx + y_idx) % 2 == 0 {
1
} else {
0
}
})
})
}

const RES = nested();
const EX = [
[u1:1, u1:0],
[u1:0, u1:1],
[u1:1, u1:0],
];
const_assert!(RES == EX);

)",
TypecheckSucceeds(HasNodeWithType("RES", "uN[1][2][3]")));
}

TEST(TypecheckV2Test, LambdaUsesUnrollForOutput) {
EXPECT_THAT(
R"(
const A = u32:1;
fn foo() -> u32[5] {
let B = u32:2;
const X = unroll_for! (i, a) in u32:0..5 {
let X = unroll_for! (i, a) in u32:0..5 {
let C = B + i;
let D = A * a;
C + D
Expand Down
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