[all-commits] [llvm/llvm-project] 2f217a: [WebAssembly] Preserve constness for imported glob...

[Changqing Jing via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 2f217a67295c120d7b97c1d8d6df71f35ebbd109
      https://github.com/llvm/llvm-project/commit/2f217a67295c120d7b97c1d8d6df71f35ebbd109
  Author: Changqing  Jing <changqing.jing at bmw.com>
  Date:   2026-06-09 (Tue, 09 Jun 2026)

  Changed paths:
    M llvm/lib/Target/WebAssembly/Utils/WebAssemblyTypeUtilities.cpp
    M llvm/lib/Target/WebAssembly/Utils/WebAssemblyTypeUtilities.h
    M llvm/lib/Target/WebAssembly/WebAssemblyAsmPrinter.cpp
    M llvm/lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp
    A llvm/test/CodeGen/WebAssembly/immutable-global-alias.ll
    A llvm/test/CodeGen/WebAssembly/imported-const-global.ll
    A llvm/test/CodeGen/WebAssembly/invalid-wasm-global-function-alias.ll
    A llvm/test/CodeGen/WebAssembly/invalid-wasm-global-symbol.ll

  Log Message:
  -----------
  [WebAssembly] Preserve constness for imported globals (#199507)

This fixes a WebAssembly backend bug where imported `const` globals lose
their
constness during lowering.

For a source like:

```c++
extern "C" {
  extern const int [[clang::address_space(1)]] imported_g;
  int goo() { return imported_g; }
}
```

In current main branch, the imported_g is lowered to mutable import
global.
```
(module
  (type (;0;) (func (result i32)))
  (import "env" "imported_g" (global (;0;) (mut i32)))
  (func (;0;) (type 0) (result i32)
    global.get 0)
  (table (;0;) 1 1 funcref)
  (memory (;0;) 2)
  (export "memory" (memory 0))
  (export "goo" (func 0))
  (export "__indirect_function_table" (table 0)))

```

The root cause is that wasm global mutability was hard-coded during
symbol
typing, so the backend ignored `GlobalVariable::isConstant()`. This
patch
threads mutability through wasm global symbol typing and derives it from
`!GV->isConstant()`.

Both the asm-printer path and the MCInst-lowering path are updated,
because
either of them may initialize the wasm symbol first.



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