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Merge pull request #7292 from kalsprite/sysv_source_type

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amd64/arm64: classify aggregates from the source type
This commit is contained in:
gingerBill
2026-08-12 19:43:29 +02:00
committed by GitHub
parent 85efa24bdc 2285f4e061
commit fa342bb540
5 changed files with 388 additions and 15 deletions
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311
src/llvm_abi.cpp
View File

@@ -610,11 +610,12 @@ namespace lbAbiAmd64SysV {
};
gb_internal void classify_with(LLVMTypeRef t, Array<RegClass> *cls, i64 ix, i64 off);
gb_internal void unify(Array<RegClass> *cls, i64 i, RegClass const newv);
gb_internal void fixup(LLVMTypeRef t, Array<RegClass> *cls);
gb_internal lbArgType amd64_type(LLVMContextRef c, LLVMTypeRef type, Amd64TypeAttributeKind attribute_kind, ProcCallingConvention calling_convention,
bool is_arg,
i32 *int_regs, i32 *sse_regs);
gb_internal Array<RegClass> classify(LLVMTypeRef t);
i32 *int_regs, i32 *sse_regs, Type *source_type);
gb_internal Array<RegClass> classify(LLVMTypeRef t, Type *source_type);
gb_internal LLVMTypeRef llreg(LLVMContextRef c, Array<RegClass> const &reg_classes, LLVMTypeRef type);
gb_internal LB_ABI_COMPUTE_RETURN_TYPE(compute_return_type) {
@@ -625,11 +626,11 @@ namespace lbAbiAmd64SysV {
return amd64_type(c, return_type, Amd64TypeAttribute_StructRect, ft->calling_convention,
false,
nullptr, nullptr);
nullptr, nullptr, nullptr);
}
gb_internal LB_ABI_INFO(abi_info) {
LLVMContextRef c = m->ctx;
LLVMContextRef c = m->ctx;
lbFunctionType *ft = permanent_alloc_item<lbFunctionType>();
ft->ctx = c;
ft->calling_convention = calling_convention;
@@ -637,14 +638,44 @@ namespace lbAbiAmd64SysV {
i32 int_regs = 6; // rdi, rsi, rdx, rcx, r8, r9
i32 sse_regs = 8; // xmm0-xmm7
ft->args = array_make<lbArgType>(lb_function_type_args_allocator(), arg_count);
for (unsigned i = 0; i < arg_count; i++) {
ft->args[i] = amd64_type(c, arg_types[i], Amd64TypeAttribute_ByVal, calling_convention,
true,
&int_regs, &sse_regs);
// The source type of each parameter, where one exists. `arg_types` can carry entries
// with no counterpart. This walks the tuple the way lbAbiArm64 does and hands back nullptr once it runs out.
Entity **params = nullptr;
isize param_count = 0;
if (original_type != nullptr && original_type->kind == Type_Proc && original_type->Proc.params != nullptr) {
params = original_type->Proc.params->Tuple.variables.data;
param_count = original_type->Proc.params->Tuple.variables.count;
}
ft->ret = compute_return_type(ft, c, return_type, return_is_defined, return_is_tuple);
ft->args = array_make<lbArgType>(lb_function_type_args_allocator(), arg_count);
for (unsigned i = 0, j = 0; i < arg_count; i++, j++) {
while (cast(isize)j < param_count && params[j]->kind != Entity_Variable) {
j++;
}
Type *source_type = cast(isize)j < param_count ? params[j]->type : nullptr;
ft->args[i] = amd64_type(c, arg_types[i], Amd64TypeAttribute_ByVal, calling_convention,
true,
&int_regs, &sse_regs, source_type);
}
// A single result can be classified from its source type too. A tuple keeps the lowered
// path: it is split into out-pointers below, and C has no such return shape anyway.
Type *return_source = nullptr;
if (return_is_defined && !return_is_tuple &&
original_type != nullptr && original_type->kind == Type_Proc &&
original_type->Proc.results != nullptr &&
original_type->Proc.results->Tuple.variables.count == 1) {
return_source = original_type->Proc.results->Tuple.variables[0]->type;
}
if (return_source != nullptr) {
ft->ret = amd64_type(c, return_type, Amd64TypeAttribute_StructRect, calling_convention,
false,
nullptr, nullptr, return_source);
} else {
ft->ret = compute_return_type(ft, c, return_type, return_is_defined, return_is_tuple);
}
return ft;
}
@@ -705,8 +736,8 @@ namespace lbAbiAmd64SysV {
gb_internal lbArgType amd64_type(LLVMContextRef c, LLVMTypeRef type, Amd64TypeAttributeKind attribute_kind, ProcCallingConvention calling_convention,
bool is_arg,
i32 *int_regs, i32 *sse_regs) {
auto cls = classify(type);
i32 *int_regs, i32 *sse_regs, Type *source_type) {
auto cls = classify(type, source_type);
i32 needed_int = 0;
i32 needed_sse = 0;
for (auto c : cls) {
@@ -793,15 +824,158 @@ namespace lbAbiAmd64SysV {
return lb_arg_type_direct(type, nullptr, nullptr, attr);
}
gb_internal Array<RegClass> classify(LLVMTypeRef t) {
// `classify_with` walks the LOWERED type, and lowering has already destroyed two
// distinctions the ABI rules need: Odin materializes padding as an explicit `[N x i8]`
// member, which is indistinguishable from a real `[N]u8` field, and a `#raw_union` becomes
// an opaque integer, which is indistinguishable from a real integer. §3.2.3 says padding
// contributes no class, and that a union merges the classes of all of its members.
//
// The source type still has both, so classify that instead where it is available. Only the
// kinds handled below are eligible; anything else falls back to the lowered walk, so an
// unrecognised type behaves exactly as it did before.
gb_internal bool source_is_classifiable(Type *t) {
Type *bt = base_type(t);
if (bt == nullptr) {
return false;
}
switch (bt->kind) {
case Type_Basic:
switch (bt->Basic.kind) {
case Basic_bool: case Basic_b8: case Basic_b16: case Basic_b32: case Basic_b64:
case Basic_i8: case Basic_u8: case Basic_i16: case Basic_u16:
case Basic_i32: case Basic_u32: case Basic_i64: case Basic_u64:
case Basic_i128: case Basic_u128: case Basic_int: case Basic_uint:
case Basic_uintptr: case Basic_rawptr: case Basic_rune:
case Basic_f16: case Basic_f32: case Basic_f64:
return true;
// Multi-word, but every word of them is a pointer or an integer, so the leaf rule
// below classifies them correctly without knowing their shape.
case Basic_string: case Basic_cstring: case Basic_any: case Basic_typeid:
return true;
}
return false;
case Type_Pointer:
case Type_MultiPointer:
case Type_Proc:
// Integer-backed, or aggregates of pointers and integers. None of them can contain a
// floating-point member, which is the only thing the leaf rule needs to tell apart.
case Type_Enum:
case Type_BitSet:
case Type_Slice:
case Type_DynamicArray:
return true;
case Type_Array:
return source_is_classifiable(bt->Array.elem);
// Odin matrices are laid out with no padding at all; see the note on
// matrix_type_stride_in_bytes
case Type_Matrix:
return source_is_classifiable(bt->Matrix.elem);
case Type_Struct:
if (bt->Struct.is_packed || bt->Struct.soa_kind != StructSoa_None) {
return false;
}
for (Entity *f : bt->Struct.fields) {
if (!source_is_classifiable(f->type)) {
return false;
}
}
return true;
}
return false;
}
gb_internal void classify_source(Type *t, Array<RegClass> *cls, i64 ix, i64 off) {
Type *bt = base_type(t);
i64 t_size = type_size_of(bt);
i64 t_align = type_align_of(bt);
if (t_align != 0 && (off % t_align) != 0) {
i64 e = (off + t_size + 7) / 8;
for (i64 i = off / 8; i < e; i++) {
unify(cls, ix+i, RegClass_Memory);
}
return;
}
switch (bt->kind) {
case Type_Struct:
// A `#raw_union` has every member at offset zero, and §3.2.3 merges them all --
// which is what makes `union{f32, u32}` INTEGER while `union{f32, f32}` is SSE.
if (bt->Struct.is_raw_union) {
for (Entity *f : bt->Struct.fields) {
classify_source(f->type, cls, ix, off);
}
} else {
for_array(i, bt->Struct.fields) {
Type *ft = nullptr;
i64 foff = type_offset_of(bt, i, &ft);
classify_source(ft, cls, ix, off + foff);
}
}
break;
case Type_Array: {
Type *elem = bt->Array.elem;
i64 stride = type_size_of(elem);
for (i64 i = 0; i < bt->Array.count; i++) {
classify_source(elem, cls, ix, off + i*stride);
}
break;
}
case Type_Matrix: {
Type *elem = bt->Matrix.elem;
i64 stride = type_size_of(elem);
i64 count = matrix_type_total_internal_elems(bt);
for (i64 i = 0; i < count; i++) {
classify_source(elem, cls, ix, off + i*stride);
}
break;
}
default:
if (is_type_float(bt)) {
switch (t_size) {
case 2: unify(cls, ix + off/8, (off%8 != 0) ? RegClass_SSEHv : RegClass_SSEHs); break;
case 4: unify(cls, ix + off/8, (off%8 == 4) ? RegClass_SSEFv : RegClass_SSEFs); break;
default: unify(cls, ix + off/8, RegClass_SSEDs); break;
}
} else {
i64 s = t_size;
while (s > 0) {
unify(cls, ix + off/8, RegClass_Int);
off += 8;
s -= 8;
}
}
break;
}
}
gb_internal Array<RegClass> classify(LLVMTypeRef t, Type *source_type) {
i64 sz = lb_sizeof(t);
i64 words = (sz + 7)/8;
auto reg_classes = array_make<RegClass>(heap_allocator(), cast(isize)words);
if (words > 4) {
all_mem(&reg_classes);
} else {
classify_with(t, &reg_classes, 0, 0);
bool from_source = source_type != nullptr && source_is_classifiable(source_type) &&
type_size_of(base_type(source_type)) == sz;
if (from_source) {
classify_source(source_type, &reg_classes, 0, 0);
} else {
classify_with(t, &reg_classes, 0, 0);
}
fixup(t, &reg_classes);
if (from_source) {
// An eightbyte that ends up NO_CLASS is not passed at all. Only the source walk
// can produce one, the lowered walk classifies padding as INTEGER, and
// nothing downstream has a case for it.
//
// This has to come AFTER `fixup`, which counts eightbytes to apply "larger than
// two eightbytes is MEMORY". Dropping them first makes `#align(32){f32}` look
// like a single SSE eightbyte instead of the memory argument it is.
while (reg_classes.count > 0 && reg_classes[reg_classes.count-1] == RegClass_NoClass) {
array_pop(&reg_classes);
}
}
}
return reg_classes;
}
@@ -1136,6 +1310,10 @@ namespace lbAbiAmd64SysV {
namespace lbAbiArm64 {
gb_internal Array<lbArgType> compute_arg_types(LLVMContextRef c, LLVMTypeRef *arg_types, unsigned arg_count, Type* original_type);
gb_internal bool is_register(LLVMTypeRef type);
gb_internal bool is_homogenous_aggregate(LLVMContextRef c, LLVMTypeRef type, LLVMTypeRef *base_type_, unsigned *member_count_);
gb_internal bool is_homogenous_aggregate_source(LLVMContextRef c, Type *t, LLVMTypeRef *base_type_, unsigned *member_count_);
gb_internal unsigned is_homogenous_aggregate_small_enough(LLVMTypeRef base_type, unsigned member_count);
gb_internal LB_ABI_COMPUTE_RETURN_TYPE(compute_return_type);
gb_internal bool is_homogenous_aggregate(LLVMContextRef c, LLVMTypeRef type, LLVMTypeRef *base_type_, unsigned *member_count_);
@@ -1144,7 +1322,30 @@ namespace lbAbiArm64 {
lbFunctionType *ft = permanent_alloc_item<lbFunctionType>();
ft->ctx = c;
ft->args = compute_arg_types(c, arg_types, arg_count, original_type);
ft->ret = compute_return_type(ft, c, return_type, return_is_defined, return_is_tuple);
// The same union case as in compute_arg_types, in return position. A tuple keeps the
// lowered path; C has no such return shape, and the split into out-pointers below is
// driven by the lowered type.
Type *return_source = nullptr;
if (return_is_defined && !return_is_tuple &&
original_type != nullptr && original_type->kind == Type_Proc &&
original_type->Proc.results != nullptr &&
original_type->Proc.results->Tuple.variables.count == 1) {
return_source = original_type->Proc.results->Tuple.variables[0]->type;
}
LLVMTypeRef ret_base_type = nullptr;
unsigned ret_member_count = 0;
if (return_source != nullptr &&
!is_register(return_type) &&
!is_homogenous_aggregate(c, return_type, nullptr, nullptr) &&
is_homogenous_aggregate_source(c, return_source, &ret_base_type, &ret_member_count) &&
is_homogenous_aggregate_small_enough(ret_base_type, ret_member_count)) {
ft->ret = lb_arg_type_direct(return_type, llvm_array_type(ret_base_type, ret_member_count), nullptr, nullptr);
} else {
ft->ret = compute_return_type(ft, c, return_type, return_is_defined, return_is_tuple);
}
ft->calling_convention = calling_convention;
return ft;
}
@@ -1272,6 +1473,77 @@ namespace lbAbiArm64 {
return false;
}
// §5.9.5 defines a Homogeneous Floating-point Aggregate over Composite Types
// Odin lowers `#raw_union` to an opaque integer, so by the time the lowered type is
// inspected the members are gone and `union{f32, f32}` is indistinguishable from an `i32`.
// The source type still has them.
gb_internal bool is_homogenous_aggregate_source(LLVMContextRef c, Type *t, LLVMTypeRef *base_type_, unsigned *member_count_) {
if (t == nullptr) {
return false;
}
Type *bt = base_type(t);
if (bt == nullptr) {
return false;
}
switch (bt->kind) {
case Type_Basic:
switch (bt->Basic.kind) {
case Basic_f32:
if (base_type_) *base_type_ = LLVMFloatTypeInContext(c);
if (member_count_) *member_count_ = 1;
return true;
case Basic_f64:
if (base_type_) *base_type_ = LLVMDoubleTypeInContext(c);
if (member_count_) *member_count_ = 1;
return true;
}
return false;
case Type_Array: {
LLVMTypeRef elem_base = nullptr;
unsigned elem_count = 0;
if (!is_homogenous_aggregate_source(c, bt->Array.elem, &elem_base, &elem_count)) {
return false;
}
if (base_type_) *base_type_ = elem_base;
if (member_count_) *member_count_ = cast(unsigned)(elem_count * bt->Array.count);
return true;
}
case Type_Struct: {
if (bt->Struct.is_packed || bt->Struct.soa_kind != StructSoa_None) {
return false;
}
LLVMTypeRef found_base = nullptr;
unsigned total = 0;
for (Entity *f : bt->Struct.fields) {
LLVMTypeRef field_base = nullptr;
unsigned field_count = 0;
if (!is_homogenous_aggregate_source(c, f->type, &field_base, &field_count)) {
return false;
}
if (found_base == nullptr) {
found_base = field_base;
total = field_count;
} else if (found_base != field_base) {
return false;
} else {
total = bt->Struct.is_raw_union ? gb_max(total, field_count) : total + field_count;
}
}
if (found_base == nullptr) {
return false;
}
// Rejects anything with padding, matching is_homogenous_struct.
if (type_size_of(bt) != lb_sizeof(found_base) * cast(i64)total) {
return false;
}
if (base_type_) *base_type_ = found_base;
if (member_count_) *member_count_ = total;
return true;
}
}
return false;
}
gb_internal unsigned is_homogenous_aggregate_small_enough(LLVMTypeRef base_type, unsigned member_count) {
return (member_count <= 4);
}
@@ -1336,6 +1608,12 @@ namespace lbAbiArm64 {
LLVMTypeRef homo_base_type = {};
unsigned homo_member_count = 0;
// A `#raw_union` lowers to a struct wrapping an opaque integer, so it is not a
// homogeneous aggregate by the lowered type and falls through to the generic size
// path below. §5.9.5 counts a union as a Composite Type, so ask the source type.
LLVMTypeRef src_base_type = nullptr;
unsigned src_member_count = 0;
if (is_register(type)) {
args[i] = non_struct(c, type, ptype);
} else if (is_homogenous_aggregate(c, type, &homo_base_type, &homo_member_count)) {
@@ -1344,6 +1622,9 @@ namespace lbAbiArm64 {
} else {
args[i] = lb_arg_type_indirect(type, nullptr);;
}
} else if (is_homogenous_aggregate_source(c, ptype, &src_base_type, &src_member_count) &&
is_homogenous_aggregate_small_enough(src_base_type, src_member_count)) {
args[i] = lb_arg_type_direct(type, llvm_array_type(src_base_type, src_member_count), nullptr, nullptr);
} else {
i64 size = lb_sizeof(type);
if (size <= 16) {

2
tests/issues/run.bat
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@@ -43,6 +43,8 @@ set COMMON=-define:ODIN_TEST_FANCY=false -file -vet -strict-style -ignore-unused
..\..\..\odin check ..\test_issue_7012.odin -no-entry-point %COMMON% || exit /b
..\..\..\odin build ..\test_issue_7037.odin %COMMON% -o:none || exit /b
..\..\..\odin build ..\test_issue_7188.odin %COMMON% || exit /b
clang -c ..\test_issue_sysv_abi.c -o test_issue_sysv_abi_c.o || exit /b
..\..\..\odin test ..\test_issue_sysv_abi.odin %COMMON% || exit /b
..\..\..\odin build ..\test_issue_7073-1.odin %COMMON% 2>&1 | find /c "Error:" | findstr /x "2" || exit /b
@echo off

3
tests/issues/run.sh
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@@ -110,6 +110,9 @@ fi
clang -c ../test_issue_7010.c -o test_issue_7010_c.o
$ODIN test ../test_issue_7010.odin $COMMON
clang -c ../test_issue_sysv_abi.c -o test_issue_sysv_abi_c.o
$ODIN test ../test_issue_sysv_abi.odin $COMMON
clang -c ../test_issue_6809_6816.c -o test_issue_6809_6816_c.o -O3
$ODIN test ../test_issue_6809_6816.odin -o:speed $COMMON

23
tests/issues/test_issue_sysv_abi.c Normal file
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@@ -0,0 +1,23 @@
// Support file for test_issue_sysv_abi.odin
//
// Each callee returns its second argument, so the value that comes back says
// where the struct before it went. If the aggregate consumes the wrong number or
// the wrong file of registers, the following argument is read from the wrong
// place deterministically rather than by scratch-register coincidence.
typedef struct { long a; float b; } Pad_Int_Float;
typedef struct { float a; double b; } Pad_Float_Double;
typedef struct { float a, b; } No_Pad;
typedef struct { struct { float x; } a; double b; } Nested;
typedef union { float x; float y; } Union_Float;
typedef struct { union { float x; float y; } u; double b; } Union_In_Struct;
double c_pad_int_float (Pad_Int_Float s, double next) { (void)s; return next; }
double c_pad_float_double(Pad_Float_Double s, double next) { (void)s; return next; }
double c_no_pad (No_Pad s, double next) { (void)s; return next; }
double c_nested (Nested s, double next) { (void)s; return next; }
double c_union_float (Union_Float s, double next) { (void)s; return next; }
double c_union_in_struct (Union_In_Struct s, double next) { (void)s; return next; }
Pad_Int_Float c_make_pad_int_float(void) { Pad_Int_Float s = {11, 2.5f}; return s; }
Union_Float c_make_union_float(void) { Union_Float s; s.x = 2.5f; return s; }

64
tests/issues/test_issue_sysv_abi.odin Normal file
View File

@@ -0,0 +1,64 @@
// The ABI classifiers ran over the lowered type, where Odin has already turned
// padding into an explicit `[N x i8]` member and a `#raw_union` into an opaque
// integer. SysV contributes no class for padding and merges a union's members,
// and AAPCS64 counts a union as a Composite Type. So a struct with an `f32`
// alone in an eightbyte went to an integer register where C uses SSE, and a
// union of floats never reached a floating-point register at all.
//
// Being an ABI guarantee, must be cross-checked against a c compiler
package test_issues
import "core:testing"
Pad_Int_Float :: struct { a: i64, b: f32 } // f32 alone in eightbyte 1
Pad_Float_Double :: struct { a: f32, b: f64 } // f32 alone in eightbyte 0
No_Pad :: struct { a: f32, b: f32 } // fills its eightbyte exactly
Nested :: struct { a: struct{ x: f32 }, b: f64 }
Union_Float :: struct #raw_union { x: f32, y: f32 }
Union_In_Struct :: struct { u: Union_Float, b: f64 }
foreign import lib "build/test_issue_sysv_abi_c.o"
@(default_calling_convention="c")
foreign lib {
c_pad_int_float :: proc(s: Pad_Int_Float, next: f64) -> f64 ---
c_pad_float_double :: proc(s: Pad_Float_Double, next: f64) -> f64 ---
c_no_pad :: proc(s: No_Pad, next: f64) -> f64 ---
c_nested :: proc(s: Nested, next: f64) -> f64 ---
c_union_float :: proc(s: Union_Float, next: f64) -> f64 ---
c_union_in_struct :: proc(s: Union_In_Struct, next: f64) -> f64 ---
c_make_pad_int_float :: proc() -> Pad_Int_Float ---
c_make_union_float :: proc() -> Union_Float ---
}
// The control. It has no padding and no union, so it was correct before the fix
// and must stay correct. Without it, "padding is misclassified" and "f32 pairs
// are broken" would look the same.
@(test)
test_no_padding_control :: proc(t: ^testing.T) {
testing.expect_value(t, c_no_pad(No_Pad{1, 3.5}, 7), f64(7))
}
@(test)
test_padded_struct_arguments :: proc(t: ^testing.T) {
testing.expect_value(t, c_pad_int_float(Pad_Int_Float{1, 3.5}, 7), f64(7))
testing.expect_value(t, c_pad_float_double(Pad_Float_Double{3.5, 2}, 7), f64(7))
testing.expect_value(t, c_nested(Nested{{3.5}, 2}, 7), f64(7))
}
@(test)
test_raw_union_arguments :: proc(t: ^testing.T) {
testing.expect_value(t, c_union_float(Union_Float{x = 3.5}, 7), f64(7))
testing.expect_value(t, c_union_in_struct(Union_In_Struct{Union_Float{x = 3.5}, 2}, 7), f64(7))
}
@(test)
test_returns :: proc(t: ^testing.T) {
s := c_make_pad_int_float()
testing.expect_value(t, s.a, i64(11))
testing.expect_value(t, s.b, f32(2.5))
u := c_make_union_float()
testing.expect_value(t, u.x, f32(2.5))
}