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byteOffsetOf rounds up using bit offset in host integer

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This commit is contained in:
vegecode 2020-07-04 10:04:15 -05:00 committed by Andrew Kelley
parent 79ef96b6a4
commit 0456b2145d
2 changed files with 56 additions and 7 deletions
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15
src/stage1/ir.cpp
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@ -24646,7 +24646,7 @@ static IrInstGen *ir_analyze_instruction_field_parent_ptr(IrAnalyze *ira,
return ir_build_field_parent_ptr_gen(ira, &instruction->base.base, casted_field_ptr, field, result_type);
}
static TypeStructField *validate_byte_offset(IrAnalyze *ira,
static TypeStructField *validate_host_int_byte_offset(IrAnalyze *ira,
IrInstGen *type_value,
IrInstGen *field_name_value,
size_t *byte_offset)
@ -24694,11 +24694,12 @@ static IrInstGen *ir_analyze_instruction_byte_offset_of(IrAnalyze *ira, IrInstSr
return ira->codegen->invalid_inst_gen;
IrInstGen *field_name_value = instruction->field_name->child;
size_t byte_offset = 0;
if (!validate_byte_offset(ira, type_value, field_name_value, &byte_offset))
size_t host_int_byte_offset = 0;
TypeStructField *field = nullptr;
if (!(field = validate_host_int_byte_offset(ira, type_value, field_name_value, &host_int_byte_offset)))
return ira->codegen->invalid_inst_gen;
size_t byte_offset = host_int_byte_offset + (field->bit_offset_in_host / 8);
return ir_const_unsigned(ira, &instruction->base.base, byte_offset);
}
@ -24707,12 +24708,12 @@ static IrInstGen *ir_analyze_instruction_bit_offset_of(IrAnalyze *ira, IrInstSrc
if (type_is_invalid(type_value->value->type))
return ira->codegen->invalid_inst_gen;
IrInstGen *field_name_value = instruction->field_name->child;
size_t byte_offset = 0;
size_t host_int_byte_offset = 0;
TypeStructField *field = nullptr;
if (!(field = validate_byte_offset(ira, type_value, field_name_value, &byte_offset)))
if (!(field = validate_host_int_byte_offset(ira, type_value, field_name_value, &host_int_byte_offset)))
return ira->codegen->invalid_inst_gen;
size_t bit_offset = byte_offset * 8 + field->bit_offset_in_host;
size_t bit_offset = host_int_byte_offset * 8 + field->bit_offset_in_host;
return ir_const_unsigned(ira, &instruction->base.base, bit_offset);
}

48
test/stage1/behavior/sizeof_and_typeof.zig
View File

@ -28,6 +28,8 @@ const P = packed struct {
e: u5,
f: u16,
g: u16,
h: u9,
i: u7,
};
test "@byteOffsetOf" {
@ -39,6 +41,8 @@ test "@byteOffsetOf" {
expect(@byteOffsetOf(P, "e") == 6);
expect(@byteOffsetOf(P, "f") == 7);
expect(@byteOffsetOf(P, "g") == 9);
expect(@byteOffsetOf(P, "h") == 11);
expect(@byteOffsetOf(P, "i") == 12);
// Normal struct fields can be moved/padded
var a: A = undefined;
@ -51,6 +55,50 @@ test "@byteOffsetOf" {
expect(@ptrToInt(&a.g) - @ptrToInt(&a) == @byteOffsetOf(A, "g"));
}
test "@byteOffsetOf packed struct, array length not power of 2 or multiple of native pointer width in bytes" {
const p3a_len = 3;
const P3 = packed struct {
a: [p3a_len]u8,
b: usize,
};
std.testing.expectEqual(0, @byteOffsetOf(P3, "a"));
std.testing.expectEqual(p3a_len, @byteOffsetOf(P3, "b"));
const p5a_len = 5;
const P5 = packed struct {
a: [p5a_len]u8,
b: usize,
};
std.testing.expectEqual(0, @byteOffsetOf(P5, "a"));
std.testing.expectEqual(p5a_len, @byteOffsetOf(P5, "b"));
const p6a_len = 6;
const P6 = packed struct {
a: [p6a_len]u8,
b: usize,
};
std.testing.expectEqual(0, @byteOffsetOf(P6, "a"));
std.testing.expectEqual(p6a_len, @byteOffsetOf(P6, "b"));
const p7a_len = 7;
const P7 = packed struct {
a: [p7a_len]u8,
b: usize,
};
std.testing.expectEqual(0, @byteOffsetOf(P7, "a"));
std.testing.expectEqual(p7a_len, @byteOffsetOf(P7, "b"));
const p9a_len = 9;
const P9 = packed struct {
a: [p9a_len]u8,
b: usize,
};
std.testing.expectEqual(0, @byteOffsetOf(P9, "a"));
std.testing.expectEqual(p9a_len, @byteOffsetOf(P9, "b"));
// 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 25 etc. are further cases
}
test "@bitOffsetOf" {
// Packed structs have fixed memory layout
expect(@bitOffsetOf(P, "a") == 0);