builtins: Move the character difference into result instead of reassigning result [PR109086]

expand_simple_binop() is allowed to allocate a new pseudo-register and
return it, instead of forcing the result into the provided
pseudo-register.  This can cause a problem when we expand the unrolled
loop for __builtin_strcmp: the compiler always generates code for all n
iterations of the loop, so "result" will be an alias of the
pseudo-register allocated and used in the last iteration; but at runtime
the loop can break early, causing this pseudo-register uninitialized.

Emit a move instruction in the iteration to force the difference into
one register which has been allocated before the loop, to avoid this
issue.

gcc/ChangeLog:

	PR other/109086
	* builtins.cc (inline_string_cmp): Force the character
	difference into "result" pseudo-register, instead of reassign
	the pseudo-register.

0 files changed, 0 insertions, 0 deletions