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spirv: optional constants

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Implements lowering optional constants in the SPIR-V backend.
This commit is contained in:
Robin Voetter
2022-12-11 14:40:18 +01:00
parent 0c53fea42c
commit 75abe3b43b
1 changed files with 60 additions and 19 deletions
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79
src/codegen/spirv.zig
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@@ -238,7 +238,7 @@ pub const DeclGen = struct {
return try self.resolveDecl(fn_decl_index);
}
return try self.genConstant(ty, val, .direct);
return try self.constant(ty, val, .direct);
}
const index = Air.refToIndex(inst).?;
return self.inst_results.get(index).?; // Assertion means instruction does not dominate usage.
@@ -394,15 +394,15 @@ pub const DeclGen = struct {
return result_id;
}
fn genConstant(self: *DeclGen, ty: Type, val: Value, repr: Repr) Error!IdRef {
fn constant(self: *DeclGen, ty: Type, val: Value, repr: Repr) Error!IdRef {
const result_id = self.spv.allocId();
try self.genConstantForId(result_id, ty, val, repr);
try self.genConstant(result_id, ty, val, repr);
return result_id;
}
/// Generate a constant representing `val`.
/// TODO: Deduplication?
fn genConstantForId(self: *DeclGen, result_id: IdRef, ty: Type, val: Value, repr: Repr) Error!void {
fn genConstant(self: *DeclGen, result_id: IdRef, ty: Type, val: Value, repr: Repr) Error!void {
const target = self.getTarget();
const section = &self.spv.sections.types_globals_constants;
const result_ty_ref = try self.resolveType(ty, repr);
@@ -453,7 +453,7 @@ pub const DeclGen = struct {
const constituents = try self.spv.gpa.alloc(IdRef, len);
defer self.spv.gpa.free(constituents);
for (elem_vals[0..len], 0..) |elem_val, i| {
constituents[i] = try self.genConstant(elem_ty, elem_val, repr);
constituents[i] = try self.constant(elem_ty, elem_val, repr);
}
try section.emit(self.spv.gpa, .OpSpecConstantComposite, .{
.id_result_type = result_ty_id,
@@ -469,12 +469,12 @@ pub const DeclGen = struct {
const constituents = try self.spv.gpa.alloc(IdRef, total_len);
defer self.spv.gpa.free(constituents);
const elem_val_id = try self.genConstant(elem_ty, elem_val, repr);
const elem_val_id = try self.constant(elem_ty, elem_val, repr);
for (constituents[0..len]) |*elem| {
elem.* = elem_val_id;
}
if (ty.sentinel()) |sentinel| {
constituents[len] = try self.genConstant(elem_ty, sentinel, repr);
constituents[len] = try self.constant(elem_ty, sentinel, repr);
}
try section.emit(self.spv.gpa, .OpSpecConstantComposite, .{
.id_result_type = result_ty_id,
@@ -492,7 +492,7 @@ pub const DeclGen = struct {
const total_len = @intCast(u32, ty.arrayLenIncludingSentinel());
const constituents = try self.spv.gpa.alloc(IdRef, total_len);
defer self.spv.gpa.free(constituents);
for (bytes) |byte, i| {
for (bytes, 0..) |byte, i| {
constituents[i] = self.spv.allocId();
try self.spv.emitConstant(elem_ty_id, constituents[i], .{ .uint32 = byte });
}
@@ -518,7 +518,7 @@ pub const DeclGen = struct {
const elem_refs = try self.gpa.alloc(IdRef, vector_len);
defer self.gpa.free(elem_refs);
for (elem_refs, 0..) |*elem, i| {
elem.* = try self.genConstant(elem_ty, elem_vals[i], repr);
elem.* = try self.constant(elem_ty, elem_vals[i], repr);
}
try section.emit(self.spv.gpa, .OpSpecConstantComposite, .{
.id_result_type = result_ty_id,
@@ -543,7 +543,7 @@ pub const DeclGen = struct {
for (tuple.types, 0..) |field_ty, i| {
const field_val = tuple.values[i];
if (field_val.tag() != .unreachable_value or !field_ty.hasRuntimeBits()) continue;
constituents[member_i] = try self.genConstant(field_ty, field_val, repr);
constituents[member_i] = try self.constant(field_ty, field_val, repr);
member_i += 1;
}
@@ -561,7 +561,7 @@ pub const DeclGen = struct {
var member_i: usize = 0;
for (struct_ty.fields.values(), 0..) |field, i| {
if (field.is_comptime or !field.ty.hasRuntimeBits()) continue;
constituents[member_i] = try self.genConstant(field.ty, field_vals[i], repr);
constituents[member_i] = try self.constant(field.ty, field_vals[i], repr);
member_i += 1;
}
@@ -582,8 +582,8 @@ pub const DeclGen = struct {
const slice = val.castTag(.slice).?.data;
var buf: Type.SlicePtrFieldTypeBuffer = undefined;
const ptr_id = try self.genConstant(ty.slicePtrFieldType(&buf), slice.ptr, .indirect);
const len_id = try self.genConstant(Type.usize, slice.len, .indirect);
const ptr_id = try self.constant(ty.slicePtrFieldType(&buf), slice.ptr, .indirect);
const len_id = try self.constant(Type.usize, slice.len, .indirect);
const constituents = [_]IdRef{ ptr_id, len_id };
try section.emit(self.spv.gpa, .OpSpecConstantComposite, .{
@@ -594,6 +594,45 @@ pub const DeclGen = struct {
},
else => return self.todo("pointer of value type {s}", .{@tagName(val.tag())}),
},
.Optional => {
var buf: Type.Payload.ElemType = undefined;
const payload_ty = ty.optionalChild(&buf);
const has_payload = !val.isNull();
// Note: keep in sync with the resolveType implementation for optionals.
if (!payload_ty.hasRuntimeBitsIgnoreComptime()) {
// Just a bool. Note: always in indirect representation.
try self.genConstInt(result_ty_ref, result_id, @boolToInt(has_payload));
} else if (ty.optionalReprIsPayload()) {
// A nullable pointer.
if (val.castTag(.opt_payload)) |payload| {
try self.genConstant(result_id, payload_ty, payload.data, repr);
} else if (has_payload) {
try self.genConstant(result_id, payload_ty, val, repr);
} else {
try section.emit(self.spv.gpa, .OpConstantNull, .{
.id_result_type = result_ty_id,
.id_result = result_id,
});
}
return;
}
// Struct-and-field pair.
// Note: If this optional has no payload, we initialize the the data member with OpUndef.
const bool_ty_ref = try self.resolveType(Type.bool, .indirect);
const valid_id = try self.constInt(bool_ty_ref, @boolToInt(has_payload));
const payload_val = if (val.castTag(.opt_payload)) |pl| pl.data else Value.undef;
const payload_id = try self.constant(payload_ty, payload_val, .indirect);
const constituents = [_]IdRef{ payload_id, valid_id };
try section.emit(self.spv.gpa, .OpSpecConstantComposite, .{
.id_result_type = result_ty_id,
.id_result = result_id,
.constituents = &constituents,
});
},
.Fn => switch (repr) {
.direct => unreachable,
.indirect => return self.todo("function pointers", .{}),
@@ -606,7 +645,7 @@ pub const DeclGen = struct {
fn genDeclRef(self: *DeclGen, result_ty_ref: SpvType.Ref, result_id: IdRef, decl_index: Decl.Index) Error!void {
const decl = self.module.declPtr(decl_index);
self.module.markDeclAlive(decl);
const decl_id = try self.genConstant(decl.ty, decl.val, .indirect);
const decl_id = try self.constant(decl.ty, decl.val, .indirect);
try self.variable(.global, result_id, result_ty_ref, decl_id);
}
@@ -814,7 +853,9 @@ pub const DeclGen = struct {
const payload_ty = ty.optionalChild(&buf);
if (!payload_ty.hasRuntimeBitsIgnoreComptime()) {
// Just use a bool.
return try self.resolveType(Type.initTag(.bool), repr);
// Note: Always generate the bool with indirect format, to save on some sanity
// Perform the converison to a direct bool when the field is extracted.
return try self.resolveType(Type.bool, .indirect);
}
const payload_ty_ref = try self.resolveType(payload_ty, .indirect);
@@ -823,7 +864,7 @@ pub const DeclGen = struct {
return payload_ty_ref;
}
const bool_ty_ref = try self.resolveType(Type.initTag(.bool), .indirect);
const bool_ty_ref = try self.resolveType(Type.bool, .indirect);
// its an actual optional
return try self.simpleStructType(&.{
@@ -906,7 +947,7 @@ pub const DeclGen = struct {
.name = fqn,
});
} else {
try self.genConstantForId(result_id, decl.ty, decl.val, .direct);
try self.genConstant(result_id, decl.ty, decl.val, .direct);
}
}
@@ -1256,7 +1297,7 @@ pub const DeclGen = struct {
var lhs_id = try self.resolve(bin_op.lhs);
var rhs_id = try self.resolve(bin_op.rhs);
const result_id = self.spv.allocId();
const result_type_id = try self.resolveTypeId(Type.initTag(.bool));
const result_type_id = try self.resolveTypeId(Type.bool);
const op_ty = self.air.typeOf(bin_op.lhs);
assert(op_ty.eql(self.air.typeOf(bin_op.rhs), self.module));
@@ -1350,7 +1391,7 @@ pub const DeclGen = struct {
const ty_op = self.air.instructions.items(.data)[inst].ty_op;
const operand_id = try self.resolve(ty_op.operand);
const result_id = self.spv.allocId();
const result_type_id = try self.resolveTypeId(Type.initTag(.bool));
const result_type_id = try self.resolveTypeId(Type.bool);
try self.func.body.emit(self.spv.gpa, .OpLogicalNot, .{
.id_result_type = result_type_id,
.id_result = result_id,