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author | James Hogan <jhogan@kernel.org> | 2017-12-07 07:20:46 +0000 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-03-03 10:19:46 +0100 |
commit | cacdb0162489b42f6b46e132b4d08860aa9a07c9 (patch) | |
tree | 2ea3db577ac159519fb7464ac450af9a97c20942 /firmware/ess | |
parent | 37d866a9e5656b2c4e32817a8cb0ff212ad227e9 (diff) | |
download | linux-stable-cacdb0162489b42f6b46e132b4d08860aa9a07c9.tar.gz linux-stable-cacdb0162489b42f6b46e132b4d08860aa9a07c9.tar.bz2 linux-stable-cacdb0162489b42f6b46e132b4d08860aa9a07c9.zip |
MIPS: Implement __multi3 for GCC7 MIPS64r6 builds
commit ebabcf17bcd7ce968b1631ebe08236275698f39b upstream.
GCC7 is a bit too eager to generate suboptimal __multi3 calls (128bit
multiply with 128bit result) for MIPS64r6 builds, even in code which
doesn't explicitly use 128bit types, such as the following:
unsigned long func(unsigned long a, unsigned long b)
{
return a > (~0UL) / b;
}
Which GCC rearanges to:
return (unsigned __int128)a * (unsigned __int128)b > 0xffffffffffffffff;
Therefore implement __multi3, but only for MIPS64r6 with GCC7 as under
normal circumstances we wouldn't expect any calls to __multi3 to be
generated from kernel code.
Reported-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: James Hogan <jhogan@kernel.org>
Tested-by: Waldemar Brodkorb <wbx@openadk.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Maciej W. Rozycki <macro@mips.com>
Cc: Matthew Fortune <matthew.fortune@mips.com>
Cc: Florian Fainelli <florian@openwrt.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/17890/
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'firmware/ess')
0 files changed, 0 insertions, 0 deletions