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LoongArch: Select ARCH_SUPPORTS_INT128 if CC_HAS_INT128

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This allows compiling a full 128-bit product of two 64-bit integers as a
mul/mulh pair, instead of a nasty long sequence of 20+ instructions.

However, after selecting ARCH_SUPPORTS_INT128, when optimizing for size
the compiler generates calls to __ashlti3, __ashrti3, and __lshrti3 for
shifting __int128 values, causing a link failure:

    loongarch64-unknown-linux-gnu-ld: kernel/sched/fair.o: in
    function `mul_u64_u32_shr':
    <PATH>/include/linux/math64.h:161:(.text+0x5e4): undefined
    reference to `__lshrti3'

So provide the implementation of these functions if ARCH_SUPPORTS_INT128.

Closes: https://lore.kernel.org/loongarch/CAAhV-H5EZ=7OF7CSiYyZ8_+wWuenpo=K2WT8-6mAT4CvzUC_4g@mail.gmail.com/
Signed-off-by: Xi Ruoyao <xry111@xry111.site>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
Xi Ruoyao 2024-05-14 12:24:18 +08:00 committed by Huacai Chen
parent 2cce905959
commit 5125d033c8
4 changed files with 65 additions and 0 deletions
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1
arch/loongarch/Kconfig
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@ -57,6 +57,7 @@ config LOONGARCH
select ARCH_SUPPORTS_ACPI
select ARCH_SUPPORTS_ATOMIC_RMW
select ARCH_SUPPORTS_HUGETLBFS
select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
select ARCH_SUPPORTS_LTO_CLANG
select ARCH_SUPPORTS_LTO_CLANG_THIN
select ARCH_SUPPORTS_NUMA_BALANCING

6
arch/loongarch/include/asm/asm-prototypes.h
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@ -6,3 +6,9 @@
#include <asm/page.h>
#include <asm/ftrace.h>
#include <asm-generic/asm-prototypes.h>
#ifdef CONFIG_ARCH_SUPPORTS_INT128
__int128_t __ashlti3(__int128_t a, int b);
__int128_t __ashrti3(__int128_t a, int b);
__int128_t __lshrti3(__int128_t a, int b);
#endif

2
arch/loongarch/lib/Makefile
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@ -6,6 +6,8 @@
lib-y += delay.o memset.o memcpy.o memmove.o \
clear_user.o copy_user.o csum.o dump_tlb.o unaligned.o
obj-$(CONFIG_ARCH_SUPPORTS_INT128) += tishift.o
obj-$(CONFIG_CPU_HAS_LSX) += xor_simd.o xor_simd_glue.o
obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o

56
arch/loongarch/lib/tishift.S Normal file
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@ -0,0 +1,56 @@
/* SPDX-License-Identifier: GPL-2.0-only */
#include <asm/asmmacro.h>
#include <linux/export.h>
#include <linux/linkage.h>
SYM_FUNC_START(__ashlti3)
srli.d t2, a0, 1
nor t3, zero, a2
sll.d t1, a1, a2
srl.d t2, t2, t3
andi t0, a2, 64
sll.d a0, a0, a2
or t1, t2, t1
maskeqz a1, a0, t0
masknez a0, a0, t0
masknez t0, t1, t0
or a1, t0, a1
jr ra
SYM_FUNC_END(__ashlti3)
EXPORT_SYMBOL(__ashlti3)
SYM_FUNC_START(__ashrti3)
nor t3, zero, a2
slli.d t2, a1, 1
srl.d t1, a0, a2
sll.d t2, t2, t3
andi t0, a2, 64
or t1, t2, t1
sra.d a2, a1, a2
srai.d a1, a1, 63
maskeqz a0, a2, t0
maskeqz a1, a1, t0
masknez a2, a2, t0
masknez t0, t1, t0
or a1, a1, a2
or a0, t0, a0
jr ra
SYM_FUNC_END(__ashrti3)
EXPORT_SYMBOL(__ashrti3)
SYM_FUNC_START(__lshrti3)
slli.d t2, a1, 1
nor t3, zero, a2
srl.d t1, a0, a2
sll.d t2, t2, t3
andi t0, a2, 64
srl.d a1, a1, a2
or t1, t2, t1
maskeqz a0, a1, t0
masknez a1, a1, t0
masknez t0, t1, t0
or a0, t0, a0
jr ra
SYM_FUNC_END(__lshrti3)
EXPORT_SYMBOL(__lshrti3)