diff options
| author | James Hogan <jhogan@kernel.org> | 2017-12-07 07:20:46 +0000 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2018-01-11 14:40:31 +0100 |
| commit | ebabcf17bcd7ce968b1631ebe08236275698f39b (patch) | |
| tree | 6a11781dbc8689ed2e3cba7d3bfddd6343d13163 /arch/mips/lib/libgcc.h | |
| parent | ccf85c744275de0ba40beff0bf9206a094f12e62 (diff) | |
MIPS: Implement __multi3 for GCC7 MIPS64r6 builds
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/
Diffstat (limited to 'arch/mips/lib/libgcc.h')
| -rw-r--r-- | arch/mips/lib/libgcc.h | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/arch/mips/lib/libgcc.h b/arch/mips/lib/libgcc.h index 28002ed90c2c..199a7f96282f 100644 --- a/arch/mips/lib/libgcc.h +++ b/arch/mips/lib/libgcc.h @@ -10,10 +10,18 @@ typedef int word_type __attribute__ ((mode (__word__))); struct DWstruct { int high, low; }; + +struct TWstruct { + long long high, low; +}; #elif defined(__LITTLE_ENDIAN) struct DWstruct { int low, high; }; + +struct TWstruct { + long long low, high; +}; #else #error I feel sick. #endif @@ -23,4 +31,13 @@ typedef union { long long ll; } DWunion; +#if defined(CONFIG_64BIT) && defined(CONFIG_CPU_MIPSR6) +typedef int ti_type __attribute__((mode(TI))); + +typedef union { + struct TWstruct s; + ti_type ti; +} TWunion; +#endif + #endif /* __ASM_LIBGCC_H */ |