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James Hogan
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 <[email protected]>
Signed-off-by: James Hogan <[email protected]>
Tested-by: Waldemar Brodkorb <[email protected]>
Cc: Ralf Baechle <[email protected]>
Cc: Maciej W. Rozycki <[email protected]>
Cc: Matthew Fortune <[email protected]>
Cc: Florian Fainelli <[email protected]>
Cc: [email protected]
Patchwork: https://patchwork.linux-mips.org/patch/17890/