Hello,
I have a C++ program (i386 target) which has a piece of inline assembly
with the following constraints:
asm(/* Some asm code */
: "=&rm" (n0), "=&r" (n1), "=&r" (n2)
: "2" (n0), "1" (n1), "g" (n2), "cI" (s)
);
When compiled with g++ 4.1.2 (CXXFLAGS=-O2 -march=pentium4) the operands
%0 and %5 get the same memory address, even though they refer to
distinct variables (n0 and n2). So, is this a bug in g++ 4.1.2 or am I
doing something wrong? g++ 3.4.6 and g++ 4.3.1 generate correct code,
but that does not really prove anything.
In particular I would like to know:
1) Is it allowed to put matching (digit) constraints referring to
different variables? This is what I do with %2. The same register is
used as input for variable n0 and as output for variable n2.
2) Is there a way to specify some kind of 'earlyclobber' (&) modifier
with a memory constraint? How can I prevent gcc from putting an input
variable and an unrelated output variable in the same memory location?
Thank you for your time,
Jeroen Demeyer.
