byteOffsetOf rounds up using bit offset in host integer

src/stage1/ir.cpp

@@ -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;
+    size_t host_int_byte_offset = 0;
-    if (!validate_byte_offset(ira, type_value, field_name_value, &byte_offset))
+    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);
 }
 

test/stage1/behavior/sizeof_and_typeof.zig

@@ -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);