| Issue |
75601
|
| Summary |
Missing optimization: @malloc call not conditionally placed inside if branch
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
0xdeafbeef
|
[Alive2 proof](https://alive2.llvm.org/ce/z/c3yvcs)
## Description
The LLVM optimizer does not move the `malloc` call into the conditional branch for a function that conditionally allocates memory based on an input parameter. This optimization is expected to reduce unnecessary allocations when the condition is not met.
## Steps to Reproduce
Consider the following C function `alloc_escape`:
```c
char* alloc_escape(int alloc) {
char* alloced = malloc(10);
if (alloc) {
return alloced;
} else {
free(alloced);
return NULL;
}
}
```
or more opaque rust version:
```rust
pub fn alloc_escape(alloc: bool) -> Option<Vec<u8>> {
let alloced = vec![0; 10];
if alloc {
Some(alloced)
} else {
None
}
}
```
## Expected Behavior
The memory allocation should be moved inside the conditional branch to ensure that it only occurs when necessary, based on the condition.
## Actual Behavior
The memory allocation is not moved into the conditional branch, leading to a pair of unnecessary allocations and deallocations.
Llvm version - 17.0.6
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