| Issue |
170678
|
| Summary |
clang-21 --target=wasm32 -Og miscompilation
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
TerrorJack
|
```c
void f(void) {
int i = -1;
do { i++; } while (i != 0);
}
```
when the above example is compiled with `clang-21 --target=wasm32 -Og`, the resulting object fails validation:
```
error: func 0 failed to validate
Caused by:
0: type mismatch: values remaining on stack at end of block (at offset 0x43)
```
the disassembled wat content points out that `f` is mis-compiled, missing a `drop` instruction:
```wat
(module
(type (;0;) (func))
(import "env" "__linear_memory" (memory (;0;) 0))
(func (;0;) (type 0)
i32.const 0
)
(@custom "linking" (after code) "\02\08\86\80\80\80\00\01\00\04\00\01f")
(@producers
(processed-by "Ubuntu clang" "21.1.7 (++20251127113503+9ed1927442a4-1~exp1~20251127113518.64)")
)
(@custom "target_features" (after code) "\08+\0bbulk-memory+\0fbulk-memory-opt+\16call-indirect-overlong+\0amultivalue+\0fmutable-globals+\13nontrapping-fptoint+\0freference-types+\08sign-ext")
)
```
this issue doesn't reproduce on `clang-22`, so it might be the case that it's a duplicate issue that's been fixed earlier. still reporting this since 21 is the active release at the moment.
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