ARM: 9029/1: Make iwmmxt.S support Clang's integrated assembler

commit 3c9f5708 upstream

This patch replaces 6 IWMMXT instructions Clang's integrated assembler
does not support in iwmmxt.S using macros, while making sure GNU
assembler still emit the same instructions. This should be easier than
providing full IWMMXT support in Clang.  This is one of the last bits of
kernel code that could be compiled but not assembled with clang. Once
all of it works with IAS, we no longer need to special-case 32-bit Arm
in Kbuild, or turn off CONFIG_IWMMXT when build-testing.

"Intel Wireless MMX Technology - Developer Guide - August, 2002" should
be referenced for the encoding schemes of these extensions.

Link: https://github.com/ClangBuiltLinux/linux/issues/975



Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Suggested-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Jian Cai <jiancai@google.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>