From: Yousong Zhou <yszhou4tech@gmail.com>
Date: Sat, 26 Sep 2015 05:41:43 +0000 (+0800)
Subject: MIPS: UAPI: Ignore __arch_swab{16,32,64} when using MIPS16
X-Git-Tag: omap-for-v4.3/fixes-rc5~15^2~1
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=71a0a72456b48de972d7ed613b06a22a3aa9057f;p=pandora-kernel.git

MIPS: UAPI: Ignore __arch_swab{16,32,64} when using MIPS16

Some GCC versions (e.g. 4.8.3) can incorrectly inline a function with
MIPS32 instructions into another function with MIPS16 code [1], causing
the assembler to genereate incorrect binary code or fail right away
complaining about unrecognized opcode.

In the case of __arch_swab{16,32}, when inlined by the compiler with
flags `-mips32r2 -mips16 -Os', the assembler can fail with the following
error.

    {standard input}:79: Error: unrecognized opcode `wsbh $2,$2'

For performance concerns and to workaround the issue already existing in
older compilers, just ignore these 2 functions when compiling with
mips16 enabled.

 [1] Inlining nomips16 function into mips16 function can result in
     undefined builtins, https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55777

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11241/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
---

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