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/
21 lines
616 B
Makefile
21 lines
616 B
Makefile
# SPDX-License-Identifier: GPL-2.0
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#
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# Makefile for MIPS-specific library files..
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#
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lib-y += bitops.o csum_partial.o delay.o memcpy.o memset.o \
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mips-atomic.o strncpy_user.o \
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strnlen_user.o uncached.o
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obj-y += iomap.o iomap_copy.o
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obj-$(CONFIG_PCI) += iomap-pci.o
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lib-$(CONFIG_GENERIC_CSUM) := $(filter-out csum_partial.o, $(lib-y))
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obj-$(CONFIG_CPU_GENERIC_DUMP_TLB) += dump_tlb.o
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obj-$(CONFIG_CPU_R3000) += r3k_dump_tlb.o
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obj-$(CONFIG_CPU_TX39XX) += r3k_dump_tlb.o
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# libgcc-style stuff needed in the kernel
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obj-y += ashldi3.o ashrdi3.o bswapsi.o bswapdi.o cmpdi2.o lshrdi3.o multi3.o \
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ucmpdi2.o
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