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ebabcf17bc
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/
44 lines
682 B
C
44 lines
682 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __ASM_LIBGCC_H
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#define __ASM_LIBGCC_H
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#include <asm/byteorder.h>
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typedef int word_type __attribute__ ((mode (__word__)));
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#ifdef __BIG_ENDIAN
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struct DWstruct {
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int high, low;
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};
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struct TWstruct {
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long long high, low;
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};
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#elif defined(__LITTLE_ENDIAN)
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struct DWstruct {
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int low, high;
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};
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struct TWstruct {
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long long low, high;
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};
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#else
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#error I feel sick.
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#endif
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typedef union {
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struct DWstruct s;
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long long ll;
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} DWunion;
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#if defined(CONFIG_64BIT) && defined(CONFIG_CPU_MIPSR6)
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typedef int ti_type __attribute__((mode(TI)));
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typedef union {
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struct TWstruct s;
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ti_type ti;
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} TWunion;
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#endif
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#endif /* __ASM_LIBGCC_H */
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