On 4/17/25 11:50 AM, Andrew Pinski wrote:
The case here is we have:
```
char buf[32] = {};
void* ret = aaa();
__builtin_memcpy(ret, buf, 32);
```
And buf does not escape. But we don't prop the zeroing from buf to the memcpy
statement
because optimize_memcpy_to_memset only looks back one statement. This can be
fixed to look back
until we get an statement that may clobber the reference. If we get a phi
node, then we don't do
anything.
Bootstrapped and tested on x86_64-linux-gnu.
PR tree-optimization/118947
gcc/ChangeLog:
* gimple-fold.cc (optimize_memcpy_to_memset): Walk back until we get a
statement that may clobber the read.
gcc/testsuite/ChangeLog:
* gcc.dg/pr118947-1.c: New test.
OK
jeff
