https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112748
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
So, do we want something like
--- gcc/gimple-fold.cc.jj 2023-11-02 12:15:12.205998817 +0100
+++ gcc/gimple-fold.cc 2023-11-30 20:24:01.092095623 +0100
@@ -5083,12 +5083,16 @@ gimple_fold_builtin (gimple_stmt_iterato
return gimple_fold_builtin_bzero (gsi);
case BUILT_IN_MEMSET:
+ if (!optimize)
+ return false;
return gimple_fold_builtin_memset (gsi,
gimple_call_arg (stmt, 1),
gimple_call_arg (stmt, 2));
case BUILT_IN_MEMCPY:
case BUILT_IN_MEMPCPY:
case BUILT_IN_MEMMOVE:
+ if (!optimize)
+ return false;
return gimple_fold_builtin_memory_op (gsi, gimple_call_arg (stmt, 0),
gimple_call_arg (stmt, 1), fcode);
case BUILT_IN_SPRINTF_CHK:
(and repeat for many other builtins)?
I'm afraid we can't do if (!optimize) return false; for all builtins in
gimple_fold_builtin, because some builtins by design must be always folded and
never expand. E.g. __builtin_clear_padding,
__builtin_{clz,ctz,clrsb,ffs,popcount,parity}g,
__builtin_{add,sub,mul}_overflow{,_p} and many others.
expand_builtin has
/* When not optimizing, generate calls to library functions for a certain
set of builtins. */
if (!optimize
&& !called_as_built_in (fndecl)
&& fcode != BUILT_IN_FORK
&& fcode != BUILT_IN_EXECL
&& fcode != BUILT_IN_EXECV
&& fcode != BUILT_IN_EXECLP
&& fcode != BUILT_IN_EXECLE
&& fcode != BUILT_IN_EXECVP
&& fcode != BUILT_IN_EXECVE
&& fcode != BUILT_IN_CLEAR_CACHE
&& !ALLOCA_FUNCTION_CODE_P (fcode)
&& fcode != BUILT_IN_FREE
&& (fcode != BUILT_IN_MEMSET
|| !(flag_inline_stringops & ILSOP_MEMSET))
&& (fcode != BUILT_IN_MEMCPY
|| !(flag_inline_stringops & ILSOP_MEMCPY))
&& (fcode != BUILT_IN_MEMMOVE
|| !(flag_inline_stringops & ILSOP_MEMMOVE))
&& (fcode != BUILT_IN_MEMCMP
|| !(flag_inline_stringops & ILSOP_MEMCMP)))
return expand_call (exp, target, ignore);
Perhaps just a general
if (!optimize && !called_as_built_in (fndecl))
return false;
at the start of gimple_fold_builtin? Or do we want to let some exceptions?
Do we also apply GIMPLE match.pd simplification at -O0?
