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Implement asm view-of parameters pred: i64, predb: u8 = pred

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gingerBill
2026-08-12 10:33:53 +01:00
parent db41921a16
commit bef386b1fb
3 changed files with 100 additions and 14 deletions
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67
src/check_asm.cpp
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@@ -469,16 +469,65 @@ gb_internal void check_asm_specs(CheckerContext *ctx, Scope *scope, Slice<Ast *>
ed.pin = pin;
if (other_scratch != nullptr) {
// TODO(bill): subsetting parameters
// p0: u64 = %rax,
// p0b: u8 = p0,
//
// or
//
// p0: u64, // implied = %any
// p0b: u8 = p0, // the 8-bit subsection of the same register, if possible
// Width-view of another operand: `p0b: u8 = p0`.
// p0b shares p0's register, viewed at p0b's declared width.
GB_ASSERT(spec->value != nullptr);
error(spec->value, "Another parameter must be assigned/paired with a scratch parameter declaration");
i32 src_index = -1;
auto src_group = check_asm_find_group(other_scratch, *asm_template_entity_decls, &src_index);
// 1. The source must already exist and be a register-class operand
// (you cannot take a width-view of an immediate or memory operand).
if (src_index < 0) {
error(spec->value, "'%.*s' must refer to a previously declared parameter", LIT(other_scratch->token.string));
} else {
auto &src = (*asm_template_entity_decls)[src_index];
bool src_is_reg = src_group == AsmTemplateEntityDeclParamGroup_Input ||
src_group == AsmTemplateEntityDeclParamGroup_Output ||
src_group == AsmTemplateEntityDeclParamGroup_Scratch;
if (src.kind == AsmTemplateEntityDecl_Immediate || src.kind == AsmTemplateEntityDecl_Memory) {
src_is_reg = false;
}
if (!src_is_reg) {
error(spec->value, "A width-view can only be taken of a register operand, not '%.*s'", LIT(other_scratch->token.string));
}
// 2. The view width must be a legal sub-register width and no wider
// than the source (only narrowing views exist).
i32 view_w = check_asm_operand_bit_width(type); // this decl's type (u8 -> 8)
i32 src_w = check_asm_operand_bit_width(src.entity->type);
AsmRegClass view_class = check_asm_reg_class_from_type(type);
AsmRegClass src_class = check_asm_reg_class_from_type(src.entity->type);
if (view_class != AsmRegClass_Integer || src_class != AsmRegClass_Integer) {
error(spec->type, "Width-views are only supported for integer registers");
} else {
switch (view_w) {
case 8: case 16: case 32: case 64:
if (view_w > src_w) {
error(spec->type, "A width-view (%d-bit) cannot be wider than its source '%.*s' (%d-bit)",
cast(int)view_w, LIT(other_scratch->token.string), cast(int)src_w);
}
break;
default:
error(spec->type, "A width-view must be an 8, 16, 32, or 64-bit integer type, got a %d-bit type", cast(int)view_w);
break;
}
}
// 3. A view does not carry its own pin; it inherits the source's register.
if (pin.len != 0) {
error(spec->value, "A width-view cannot also be pinned to a register; it inherits the source operand's register");
}
ed.kind = AsmTemplateEntityDecl_Register;
ed.view_of = src_index;
ed.view_bits = view_w;
// A view is not itself an input/output/scratch slot for allocation:
// mark it so the lowering passes skip it. Reuse the Scratch group but
// with view_of >= 0 as the discriminator (see lowering note).
}
}
array_add(asm_template_entity_decls, ed);