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lib/mpi: avoid assembler warning 

A wrapper around the umull assembly instruction might reuse
the input register as an output, which is undefined on
some ARM machines, as pointed out by this assembler warning:

  CC      lib/mpi/generic_mpih-mul1.o
/tmp/ccxJuxIy.s: Assembler messages:
/tmp/ccxJuxIy.s:53: rdhi, rdlo and rm must all be different
  CC      lib/mpi/generic_mpih-mul2.o
/tmp/ccI0scAD.s: Assembler messages:
/tmp/ccI0scAD.s:53: rdhi, rdlo and rm must all be different
  CC      lib/mpi/generic_mpih-mul3.o
/tmp/ccMvVQcp.s: Assembler messages:
/tmp/ccMvVQcp.s:53: rdhi, rdlo and rm must all be different

This changes the constraints to force different registers to
be used as output.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Arnd Bergmann 2016-02-26 13:46:26 +01:00 committed by Herbert Xu
parent 1879f40af7
commit c5d552487b
1 changed files with 1 additions and 1 deletions
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2
lib/mpi/longlong.h
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@ -216,7 +216,7 @@ extern UDItype __udiv_qrnnd(UDItype *, UDItype, UDItype, UDItype);
__asm__ ("%@ Inlined umul_ppmm\n" \
"umull %r1, %r0, %r2, %r3" \
: "=&r" ((USItype)(xh)), \
"=r" ((USItype)(xl)) \
"=&r" ((USItype)(xl)) \
: "r" ((USItype)(a)), \
"r" ((USItype)(b)) \
: "r0", "r1")