stage2 llvm: Use unpacked struct for unions and arrays
Our lowerings for various LLVM types assume that we can anticipate the alignment/layout that LLVM will generate. Among other things, this requires that we keep the alignment of our lowered LLVM types synchronized with their expected alignment in Zig. - Arrays were using packed struct types, which is seems to be incorrect since array elements are supposed to be self-aligned. - Unions were using packed struct types for their payload, which causes layout divergence between what stage2 expects and what LLVM generates Consider this lowered union type: ```llvm %Value = type { <{ i64, [8 x i8] }>, i1, [7 x i8] } ; 24 bytes, align(1) %ErrorUnion = type { %Value, i16 } ; 26 bytes, align(2) ``` Zig expects Value to be align(8) and, by extension, for ErrorUnion to be size 32.
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@ -2689,7 +2689,7 @@ pub const DeclGen = struct {
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llvm_aligned_field_ty,
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dg.context.intType(8).arrayType(padding_len),
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};
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break :t dg.context.structType(&fields, fields.len, .True);
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break :t dg.context.structType(&fields, fields.len, .False);
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};
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if (layout.tag_size == 0) {
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@ -3002,7 +3002,7 @@ pub const DeclGen = struct {
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return dg.context.constStruct(
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llvm_elems.ptr,
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@intCast(c_uint, llvm_elems.len),
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.True,
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.False,
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);
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} else {
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const llvm_elem_ty = try dg.lowerType(elem_ty);
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@ -3039,7 +3039,7 @@ pub const DeclGen = struct {
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return dg.context.constStruct(
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llvm_elems.ptr,
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@intCast(c_uint, llvm_elems.len),
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.True,
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.False,
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);
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} else {
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const llvm_elem_ty = try dg.lowerType(elem_ty);
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@ -3056,7 +3056,7 @@ pub const DeclGen = struct {
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const llvm_elems: [1]*const llvm.Value = .{sentinel};
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const need_unnamed = dg.isUnnamedType(elem_ty, llvm_elems[0]);
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if (need_unnamed) {
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return dg.context.constStruct(&llvm_elems, llvm_elems.len, .True);
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return dg.context.constStruct(&llvm_elems, llvm_elems.len, .False);
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} else {
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const llvm_elem_ty = try dg.lowerType(elem_ty);
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return llvm_elem_ty.constArray(&llvm_elems, llvm_elems.len);
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@ -3343,7 +3343,7 @@ pub const DeclGen = struct {
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const fields: [2]*const llvm.Value = .{
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field, dg.context.intType(8).arrayType(padding_len).getUndef(),
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};
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break :p dg.context.constStruct(&fields, fields.len, .True);
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break :p dg.context.constStruct(&fields, fields.len, .False);
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};
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if (layout.tag_size == 0) {
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