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stage2: Fix codegen for unions and error unions

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When an union had a zero-sized payload type, we would lower the tag twice. This is fixed
by exiting early when `payload_size` is 0.

With regards to error unions, we were only accounting for padding for the payload field.
However, the errorset value can have a smaller alignment than the payload as well, i.e. error!usize.
We fix this by also accounting for padding/alignment of the error set tag of an error union.
This commit is contained in:
Luuk de Gram
2022-03-06 15:57:28 +01:00
parent bf972e44d5
commit 23e2368ac3
1 changed files with 29 additions and 26 deletions
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55
src/codegen.zig
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@@ -573,16 +573,10 @@ pub fn generateSymbol(
const layout = typed_value.ty.unionGetLayout(target);
if (layout.payload_size == 0) {
switch (try generateSymbol(bin_file, src_loc, .{
return generateSymbol(bin_file, src_loc, .{
.ty = typed_value.ty.unionTagType().?,
.val = union_obj.tag,
}, code, debug_output, reloc_info)) {
.appended => {},
.externally_managed => |external_slice| {
code.appendSliceAssumeCapacity(external_slice);
},
.fail => |em| return Result{ .fail = em },
}
}, code, debug_output, reloc_info);
}
// Check if we should store the tag first.
@@ -703,20 +697,30 @@ pub fn generateSymbol(
const abi_align = typed_value.ty.abiAlignment(target);
const error_val = if (!is_payload) typed_value.val else Value.initTag(.zero);
const begin = code.items.len;
switch (try generateSymbol(bin_file, src_loc, .{
.ty = error_ty,
.val = error_val,
}, code, debug_output, reloc_info)) {
.appended => {},
.externally_managed => |external_slice| {
code.appendSliceAssumeCapacity(external_slice);
},
.fail => |em| return Result{ .fail = em },
{
const error_val = if (!is_payload) typed_value.val else Value.initTag(.zero);
const begin = code.items.len;
switch (try generateSymbol(bin_file, src_loc, .{
.ty = error_ty,
.val = error_val,
}, code, debug_output, reloc_info)) {
.appended => {},
.externally_managed => |external_slice| {
code.appendSliceAssumeCapacity(external_slice);
},
.fail => |em| return Result{ .fail = em },
}
const unpadded_end = code.items.len - begin;
const padded_end = mem.alignForwardGeneric(u64, unpadded_end, abi_align);
const padding = try math.cast(usize, padded_end - unpadded_end);
if (padding > 0) {
try code.writer().writeByteNTimes(0, padding);
}
}
if (payload_ty.hasRuntimeBits()) {
const begin = code.items.len;
const payload_val = if (typed_value.val.castTag(.eu_payload)) |val| val.data else Value.initTag(.undef);
switch (try generateSymbol(bin_file, src_loc, .{
.ty = payload_ty,
@@ -728,14 +732,13 @@ pub fn generateSymbol(
},
.fail => |em| return Result{ .fail = em },
}
}
const unpadded_end = code.items.len - begin;
const padded_end = mem.alignForwardGeneric(u64, unpadded_end, abi_align);
const padding = try math.cast(usize, padded_end - unpadded_end);
const unpadded_end = code.items.len - begin;
const padded_end = mem.alignForwardGeneric(u64, unpadded_end, abi_align);
const padding = try math.cast(usize, padded_end - unpadded_end);
if (padding > 0) {
try code.writer().writeByteNTimes(0, padding);
if (padding > 0) {
try code.writer().writeByteNTimes(0, padding);
}
}
return Result{ .appended = {} };