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align(@alignOf(T)) T does not force resolution of T

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This commit is contained in:
Andrew Kelley 2019-08-30 14:53:44 -04:00
parent 966670645a
commit d9fed5cdfd
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GPG Key ID: 7C5F548F728501A9
4 changed files with 77 additions and 24 deletions
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53
src/ir.cpp
View File

@ -12613,10 +12613,27 @@ static bool ir_resolve_const_align(CodeGen *codegen, IrExecutable *exec, AstNode
return true;
}
static bool ir_resolve_align(IrAnalyze *ira, IrInstruction *value, uint32_t *out) {
static bool ir_resolve_align(IrAnalyze *ira, IrInstruction *value, ZigType *elem_type, uint32_t *out) {
if (type_is_invalid(value->value.type))
return false;
// Look for this pattern: `*align(@alignOf(T)) T`.
// This can be resolved to be `*out = 0` without resolving any alignment.
if (elem_type != nullptr && value->value.special == ConstValSpecialLazy &&
value->value.data.x_lazy->id == LazyValueIdAlignOf)
{
LazyValueAlignOf *lazy_align_of = reinterpret_cast<LazyValueAlignOf *>(value->value.data.x_lazy);
ZigType *lazy_elem_type = ir_resolve_type(lazy_align_of->ira, lazy_align_of->target_type);
if (type_is_invalid(lazy_elem_type))
return false;
if (elem_type == lazy_elem_type) {
*out = 0;
return true;
}
}
IrInstruction *casted_value = ir_implicit_cast(ira, value, get_align_amt_type(ira->codegen));
if (type_is_invalid(casted_value->value.type))
return false;
@ -14424,7 +14441,7 @@ static IrInstruction *ir_analyze_instruction_decl_var(IrAnalyze *ira,
}
var->align_bytes = get_abi_alignment(ira->codegen, result_type);
} else {
if (!ir_resolve_align(ira, decl_var_instruction->align_value->child, &var->align_bytes)) {
if (!ir_resolve_align(ira, decl_var_instruction->align_value->child, nullptr, &var->align_bytes)) {
var->var_type = ira->codegen->builtin_types.entry_invalid;
}
}
@ -14879,7 +14896,7 @@ static IrInstruction *ir_resolve_result_raw(IrAnalyze *ira, IrInstruction *suspe
if (alloca_src->base.child == nullptr || is_comptime) {
uint32_t align = 0;
if (alloca_src->align != nullptr && !ir_resolve_align(ira, alloca_src->align->child, &align)) {
if (alloca_src->align != nullptr && !ir_resolve_align(ira, alloca_src->align->child, nullptr, &align)) {
return ira->codegen->invalid_instruction;
}
IrInstruction *alloca_gen;
@ -15896,7 +15913,7 @@ static IrInstruction *ir_analyze_fn_call(IrAnalyze *ira, IrInstructionCallSrc *c
copy_const_val(&const_instruction->base.value, align_result, true);
uint32_t align_bytes = 0;
ir_resolve_align(ira, &const_instruction->base, &align_bytes);
ir_resolve_align(ira, &const_instruction->base, nullptr, &align_bytes);
impl_fn->align_bytes = align_bytes;
inst_fn_type_id.alignment = align_bytes;
}
@ -23948,7 +23965,7 @@ static IrInstruction *ir_analyze_instruction_ptr_type(IrAnalyze *ira, IrInstruct
static IrInstruction *ir_analyze_instruction_align_cast(IrAnalyze *ira, IrInstructionAlignCast *instruction) {
uint32_t align_bytes;
IrInstruction *align_bytes_inst = instruction->align_bytes->child;
if (!ir_resolve_align(ira, align_bytes_inst, &align_bytes))
if (!ir_resolve_align(ira, align_bytes_inst, nullptr, &align_bytes))
return ira->codegen->invalid_instruction;
IrInstruction *target = instruction->target->child;
@ -23974,7 +23991,7 @@ static IrInstruction *ir_analyze_instruction_opaque_type(IrAnalyze *ira, IrInstr
static IrInstruction *ir_analyze_instruction_set_align_stack(IrAnalyze *ira, IrInstructionSetAlignStack *instruction) {
uint32_t align_bytes;
IrInstruction *align_bytes_inst = instruction->align_bytes->child;
if (!ir_resolve_align(ira, align_bytes_inst, &align_bytes))
if (!ir_resolve_align(ira, align_bytes_inst, nullptr, &align_bytes))
return ira->codegen->invalid_instruction;
if (align_bytes > 256) {
@ -25555,7 +25572,7 @@ static ZigType *ir_resolve_lazy_fn_type(IrAnalyze *ira, AstNode *source_node, La
}
if (lazy_fn_type->align_inst != nullptr) {
if (!ir_resolve_align(ira, lazy_fn_type->align_inst, &fn_type_id.alignment))
if (!ir_resolve_align(ira, lazy_fn_type->align_inst, nullptr, &fn_type_id.alignment))
return nullptr;
}
@ -25690,15 +25707,16 @@ static Error ir_resolve_lazy_raw(AstNode *source_node, ConstExprValue *val) {
LazyValueSliceType *lazy_slice_type = reinterpret_cast<LazyValueSliceType *>(val->data.x_lazy);
IrAnalyze *ira = lazy_slice_type->ira;
uint32_t align_bytes = 0;
if (lazy_slice_type->align_inst != nullptr) {
if (!ir_resolve_align(ira, lazy_slice_type->align_inst, &align_bytes))
return ErrorSemanticAnalyzeFail;
}
ZigType *elem_type = ir_resolve_type(ira, lazy_slice_type->elem_type);
if (type_is_invalid(elem_type))
return ErrorSemanticAnalyzeFail;
uint32_t align_bytes = 0;
if (lazy_slice_type->align_inst != nullptr) {
if (!ir_resolve_align(ira, lazy_slice_type->align_inst, elem_type, &align_bytes))
return ErrorSemanticAnalyzeFail;
}
switch (elem_type->id) {
case ZigTypeIdInvalid: // handled above
zig_unreachable();
@ -25750,15 +25768,16 @@ static Error ir_resolve_lazy_raw(AstNode *source_node, ConstExprValue *val) {
LazyValuePtrType *lazy_ptr_type = reinterpret_cast<LazyValuePtrType *>(val->data.x_lazy);
IrAnalyze *ira = lazy_ptr_type->ira;
uint32_t align_bytes = 0;
if (lazy_ptr_type->align_inst != nullptr) {
if (!ir_resolve_align(ira, lazy_ptr_type->align_inst, &align_bytes))
return ErrorSemanticAnalyzeFail;
}
ZigType *elem_type = ir_resolve_type(ira, lazy_ptr_type->elem_type);
if (type_is_invalid(elem_type))
return ErrorSemanticAnalyzeFail;
uint32_t align_bytes = 0;
if (lazy_ptr_type->align_inst != nullptr) {
if (!ir_resolve_align(ira, lazy_ptr_type->align_inst, elem_type, &align_bytes))
return ErrorSemanticAnalyzeFail;
}
if (elem_type->id == ZigTypeIdUnreachable) {
ir_add_error(ira, lazy_ptr_type->elem_type,
buf_create_from_str("pointer to noreturn not allowed"));

5
std/array_list.zig
View File

@ -10,6 +10,11 @@ pub fn ArrayList(comptime T: type) type {
}
pub fn AlignedArrayList(comptime T: type, comptime alignment: ?u29) type {
if (alignment) |a| {
if (a == @alignOf(T)) {
return AlignedArrayList(T, null);
}
}
return struct {
const Self = @This();

18
std/mem.zig
View File

@ -94,24 +94,30 @@ pub const Allocator = struct {
}
pub fn alloc(self: *Allocator, comptime T: type, n: usize) Error![]T {
return self.alignedAlloc(T, @alignOf(T), n);
return self.alignedAlloc(T, null, n);
}
pub fn alignedAlloc(
self: *Allocator,
comptime T: type,
comptime alignment: u29,
/// null means naturally aligned
comptime alignment: ?u29,
n: usize,
) Error![]align(alignment) T {
) Error![]align(alignment orelse @alignOf(T)) T {
const a = if (alignment) |a| blk: {
if (a == @alignOf(T)) return alignedAlloc(self, T, null, n);
break :blk a;
} else @alignOf(T);
if (n == 0) {
return ([*]align(alignment) T)(undefined)[0..0];
return ([*]align(a) T)(undefined)[0..0];
}
const byte_count = math.mul(usize, @sizeOf(T), n) catch return Error.OutOfMemory;
const byte_slice = try self.reallocFn(self, ([*]u8)(undefined)[0..0], undefined, byte_count, alignment);
const byte_slice = try self.reallocFn(self, ([*]u8)(undefined)[0..0], undefined, byte_count, a);
assert(byte_slice.len == byte_count);
@memset(byte_slice.ptr, undefined, byte_slice.len);
return @bytesToSlice(T, @alignCast(alignment, byte_slice));
return @bytesToSlice(T, @alignCast(a, byte_slice));
}
/// This function requests a new byte size for an existing allocation,

25
test/stage1/behavior/align.zig
View File

@ -1,4 +1,5 @@
const expect = @import("std").testing.expect;
const std = @import("std");
const expect = std.testing.expect;
const builtin = @import("builtin");
var foo: u8 align(4) = 100;
@ -305,3 +306,25 @@ test "struct field explicit alignment" {
comptime expect(@typeOf(&node.massive_byte) == *align(64) u8);
expect(@ptrToInt(&node.massive_byte) % 64 == 0);
}
test "align(@alignOf(T)) T does not force resolution of T" {
const S = struct {
const A = struct {
a: *align(@alignOf(A)) A,
};
fn doTheTest() void {
suspend {
resume @frame();
}
_ = bar(@Frame(doTheTest));
}
fn bar(comptime T: type) *align(@alignOf(T)) T {
ok = true;
return undefined;
}
var ok = false;
};
_ = async S.doTheTest();
expect(S.ok);
}