PR tree-optimization/78257 - missing memcmp optimization with constant arrays

gcc/ChangeLog:

	PR middle-end/78257
	* builtins.c (expand_builtin_memory_copy_args): Rename called function.
	(expand_builtin_stpcpy_1): Remove argument from call.
	(expand_builtin_memcmp): Rename called function.
	(inline_expand_builtin_bytecmp): Same.
	* expr.c (convert_to_bytes): New function.
	(constant_byte_string): New function (formerly string_constant).
	(string_constant): Call constant_byte_string.
	(byte_representation): New function.
	* expr.h (byte_representation): Declare.
	* fold-const-call.c (fold_const_call): Rename called function.
	* fold-const.c (c_getstr): Remove an argument.
	(getbyterep): Define a new function.
	* fold-const.h (c_getstr): Remove an argument.
	(getbyterep): Declare a new function.
	* gimple-fold.c (gimple_fold_builtin_memory_op): Rename callee.
	(gimple_fold_builtin_string_compare): Same.
	(gimple_fold_builtin_memchr): Same.

gcc/testsuite/ChangeLog:

	PR middle-end/78257
	* gcc.dg/memchr.c: New test.
	* gcc.dg/memcmp-2.c: New test.
	* gcc.dg/memcmp-3.c: New test.
	* gcc.dg/memcmp-4.c: New test.

1 files changed, 6 insertions, 2 deletions

diff --git a/gcc/expr.h b/gcc/expr.h
index 725991f..88d55ba 100644
--- a/gcc/expr.h
+++ b/gcc/expr.h
@@ -289,9 +289,13 @@ expand_normal (tree exp)
 }
 
 
-/* Return the tree node and offset if a given argument corresponds to
-   a string constant.  */
+/* Return STRING_CST and set offset, size and decl, if the first
+   argument corresponds to a string constant.  */
 extern tree string_constant (tree, tree *, tree *, tree *);
+/* Similar to string_constant, return a STRING_CST corresponding
+   to the value representation of the first argument if it's
+   a constant.  */
+extern tree byte_representation (tree, tree *, tree *, tree *);
 
 extern enum tree_code maybe_optimize_mod_cmp (enum tree_code, tree *, tree *);