| author |  Matthew Knight <mattnite@proton.me> 2026-07-22 20:23:36+02:00 |
| committer |  Matthew Lugg <mlugg@mlugg.co.uk> 2026-07-22 20:23:36+02:00 |
| log | cad234174ae7ae990ebc526b6fcd92d18516e3c1 |
| tree | 5d9d734257766db53e38094feff90c50e9f28898 |
| parent | aad9870a284410b9b7fa4d5c5d84f4a4d697c71b |
llvm: fix address space of global aliases
#32108 contains my process for root causing this issue. In short, while the LLVM language does not associate aliases with address spaces, the address space does get serialized alongside the alias, and that value was hardcoded to `.default`, and the error observed was from a failed sanity check. I added an assertion on the serialization side and observed it get hit, showing the difference in address space. I followed that up with a patch to grab the address space from the aliasee instead of hardcoding it.
The AVR repro now compiles:
```zig
export fn anything() void {}
```
Fixes: https://codeberg.org/ziglang/zig/issues/32108
Reviewed-on: https://codeberg.org/ziglang/zig/pulls/361462 files changed, 10 insertions(+), 3 deletions(-)
lib- std
- zig
- llvm
- src
- codegen
lib/std/zig/llvm/Builder.zig+4-1
| ... | ... | @@ -13955,8 +13955,11 @@ pub fn toBitcode(self: *Builder, allocator: Allocator, producer: Producer) bitco |
| 13955 | 13955 | } |
| 13956 | 13956 | |
| 13957 | 13957 | const strtab = alias.global.strtab(self); |
| 13958 | ||
| 13959 | 13958 | const global = alias.global.ptrConst(self); |
| 13959 | ||
| 13960 | // LLVM requires the types to match | |
| 13961 | assert(global.addr_space == alias.aliasee.typeOf(self).pointerAddrSpace(self)); | |
| 13962 | ||
| 13960 | 13963 | try module_block.writeAbbrev(ModuleBlock.Alias{ |
| 13961 | 13964 | .strtab_offset = strtab.offset, |
| 13962 | 13965 | .strtab_size = strtab.size, |
src/codegen/llvm.zig+6-2
| ... | ... | @@ -1661,7 +1661,7 @@ pub const Object = struct { |
| 1661 | 1661 | const alias = try o.builder.addAlias( |
| 1662 | 1662 | exp_name, |
| 1663 | 1663 | llvm_global_ty, |
| 1664 | .default, | |
| 1664 | global_index.ptrConst(&o.builder).addr_space, | |
| 1665 | 1665 | global_index.toConst(), |
| 1666 | 1666 | ); |
| 1667 | 1667 | break :global alias.ptrConst(&o.builder).global; |
| ... | ... | @@ -1673,6 +1673,10 @@ pub const Object = struct { |
| 1673 | 1673 | // We can just repurpose the existing alias. |
| 1674 | 1674 | alias.setAliasee(global_index.toConst(), &o.builder); |
| 1675 | 1675 | alias.ptrConst(&o.builder).global.ptr(&o.builder).type = global_index.typeOf(&o.builder); |
| 1676 | // If the type the alias is pointing to can change, then | |
| 1677 | // it makes sense that we should update the address | |
| 1678 | // space too. | |
| 1679 | alias.ptrConst(&o.builder).global.ptr(&o.builder).addr_space = global_index.ptrConst(&o.builder).addr_space; | |
| 1676 | 1680 | break :global existing_global; |
| 1677 | 1681 | }, |
| 1678 | 1682 | .variable, .function => { |
| ... | ... | @@ -1687,7 +1691,7 @@ pub const Object = struct { |
| 1687 | 1691 | const alias = try o.builder.addAlias( |
| 1688 | 1692 | exp_name, |
| 1689 | 1693 | llvm_global_ty, |
| 1690 | .default, | |
| 1694 | global_index.ptrConst(&o.builder).addr_space, | |
| 1691 | 1695 | global_index.toConst(), |
| 1692 | 1696 | ); |
| 1693 | 1697 | break :global alias.ptrConst(&o.builder).global; |