On 4/19/25 10:14 AM, Andrew Pinski wrote:
This was noticed when turning memset (with constant size) into a store of an
empty constructor
but can be reproduced without that.
In this case we have the following IR:
```
p_3 = __builtin_malloc (4096);
*p_3 = {};
```
Which we can treat the store as a memset.
So this patch adds the similar optimization as memset/malloc now for
malloc/constructor.
This patch is on top of
https://gcc.gnu.org/pipermail/gcc-patches/2025-April/681439.html
(it calls allow_memset_malloc_to_calloc but that can be removed if that patch
is rejected).
Bootstrapped and tested on x86_64-linux-gnu.
PR tree-optimization/87900
gcc/ChangeLog:
* tree-ssa-strlen.cc (strlen_pass::handle_assign): Add RHS argument.
For empty constructor RHS, see if can combine with a previous malloc
into
a calloc.
(strlen_pass::check_and_optimize_call): Update call to handle_assign;
passing NULL_TREE for RHS.
(strlen_pass::check_and_optimize_stmt): Update call to handle_assign.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/calloc-10.c: New test.
* gcc.dg/tree-ssa/calloc-11.c: New test.
OK once prereq is in and this goes through a fresh bootstrap &
regression test.
jeff
