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![James Hogan](/assets/img/avatar_default.png)
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/
43 lines
682 B
C
43 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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