With:
int
f1 (void)
{
int x = 4, y;
__asm__ volatile ("imull %3\n\tshrdl %%cl,%1,%0"
: "+a,a" (x), "=d,d" (y)
: "%0,0" (x), "m,r" (8), "c,c" (2));
return x;
}
int
f2 (void)
{
int x = 4, y;
__asm__ volatile ("imull %3\n\tshrdl %%cl,%1,%0"
: "=a,a" (x), "=d,d" (y)
: "%0,0" (x), "m,r" (8), "c,c" (2));
return x;
}
int
f3 (void)
{
int x = 4, y;
__asm__ volatile ("imull %2\n\tshrdl %%cl,%1,%0"
: "+a,a" (x), "=d,d" (y)
: "m,r" (8), "c,c" (2));
return x;
}
int
f4 (void)
{
int x = 4, y;
__asm__ volatile ("imull %3\n\tshrdl %%cl,%1,%0"
: "+a" (x), "=d" (y)
: "%0" (x), "r" (8), "c" (2));
return x;
}
int
f5 (void)
{
int x = 4, y;
__asm__ volatile ("imull %3\n\tshrdl %%cl,%1,%0"
: "=a" (x), "=d" (y)
: "%0" (x), "r" (8), "c" (2));
return x;
}
int
f6 (void)
{
int x = 4, y;
__asm__ volatile ("imull %2\n\tshrdl %%cl,%1,%0"
: "+a" (x), "=d" (y)
: "r" (8), "c" (2));
return x;
}
GCC 3.2.3 and 3.4.3 error on f4:
iasm.c:35: error: inconsistent operand constraints in an `asm'
while GCC 4 errors on f1 and f3:
iasm.c: In function `f1':
iasm.c:5: error: operand constraints for `asm' differ in number of alternatives
iasm.c: In function `f3':
iasm.c:25: error: operand constraints for `asm' differ in number of alternatives
This certainly seems to be inconsistent. Either using %0 matching +a
is valid or not but I don't see anything wrong on f3.
If : "+a" (x) : "%0" (x) is invalid, then both f1 and f4 should fail and
all others pass, if it is valid, I think all functions ought to pass.
--
Summary: Bogus differ in number of alternatives error
Product: gcc
Version: 4.0.0
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: inline-asm
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: jakub at gcc dot gnu dot org
CC: gcc-bugs at gcc dot gnu dot org
GCC target triplet: i386-linux
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20314
