Ian Lance Taylor wrote:
"Thomas A.M. Bernard" <[EMAIL PROTECTED]> writes:
I guess I am missing something here. I've tried the following as Paolo
suggested,
(define_insn "setallocate"
[(unspec_volatile:DI [(match_operand:DI 0 "general_operand" "r")]
UNSPEC_ALLOCATE)]
""
"allocate %0\t\t#TCB_INSTRUCTIONS" [(set_attr "type" "multi")])
When flag -O0 is on, everything's fine. But when flag -O1 is engaged,
the instruction is still omitted. Something missing ?
The only that gcc will remove an unspec_volatile instruction is if it
is on a code path which is never executed.
Look at the RTL dump files (from, e.g., -fdump-rtl-all), see where it
is disappearing, and why.
With this pattern for setallocate, when the flag -O1 is engaged, the
instruction is already omitted just at the expansion. As Ian mentioned,
I suspect the problem comes from the fact that the compiler thinks this
code path won't be executed. I presume this should be done at the CFG
level. I added in CFG a "node" which describes 'setallocate' Any clue to
say explicitly this will be executed in any case ?
Thanks,
Thomas
