[Bug target/82267] x32: unnecessary address-size prefixes. Why isn't -maddress-mode=long the default?

[hjl at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82267

--- Comment #3 from hjl at gcc dot gnu.org <hjl at gcc dot gnu.org> ---
Author: hjl
Date: Sun Sep 24 21:37:09 2017
New Revision: 253127

URL: https://gcc.gnu.org/viewcvs?rev=253127&root=gcc&view=rev
Log:
x32: Encode %esp as %rsp to avoid 0x67 prefix

Since the upper 32 bits of stack register are always zero for x32, we
can encode %esp as %rsp to avoid 0x67 prefix in address if there is no
index or base register.

gcc/

        PR target/82267
        * config/i386/i386.c (ix86_print_operand_address_as): Encode
        %esp as %rsp to avoid 0x67 prefix if there is no index or base
        register.

gcc/testsuite/

        PR target/82267
        * gcc.target/i386/pr82267.c: New test.

Added:
    trunk/gcc/testsuite/gcc.target/i386/pr82267.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/i386/i386.c
    trunk/gcc/testsuite/ChangeLog