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 <a...@arnd.de>
---
Not sure who would be the best person to pick this patch up.
diff --git a/lib/mpi/longlong.h b/lib/mpi/longlong.h
index aac511417ad1..c4dbdb506174 100644
--- a/lib/mpi/longlong.h
+++ b/lib/mpi/longlong.h
@@ -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")
--
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