i386: Ignore regparm attribute and warn for it in 64-bit mode

The regparm attribute does not affect code generation on x86-64 target.
Despite this, regparm was accepted silently, unlike other calling
convention attributes handled in the ix86_handle_cconv_attribute
function.

Due to lack of diagnostics, Linux kernel attempted to specify regparm(0)
on vmread_error_trampoline declaration, which is supposed to be invoked
with all arguments on stack:
https://lore.kernel.org/all/20220928232015.745948-1-seanjc@google.com/

To produce a warning for regparm in 64-bit mode, simply move the block
that produces diagnostics above the block that handles the regparm
attribute.

gcc/ChangeLog:

	* config/i386/i386-options.cc (ix86_handle_cconv_attribute):
	Move 64-bit mode check before regparm handling.

gcc/testsuite/ChangeLog:

	* g++.dg/abi/regparm1.C: Require ia32 target.
	* gcc.target/i386/20020224-1.c: Likewise.
	* gcc.target/i386/pr103785.c: Use regparm attribute only if
	not in 64-bit mode.
	* gcc.target/i386/pr36533.c: Likewise.
	* gcc.target/i386/pr59099.c: Likewise.
	* gcc.target/i386/sibcall-8.c: Likewise.
	* gcc.target/i386/sw-1.c: Likewise.
	* gcc.target/i386/pr15184-2.c: Fix invalid comment.
	* gcc.target/i386/attributes-ignore.c: New test.

0 files changed, 0 insertions, 0 deletions