[Bug inline-asm/68843] New: ICE with "u" input constraint

[bernd.edlinger at hotmail dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68843

            Bug ID: 68843
           Summary: ICE with "u" input constraint
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: inline-asm
          Assignee: unassigned at gcc dot gnu.org
          Reporter: bernd.edlinger at hotmail dot de
  Target Milestone: ---

Hi,

I have just played a bit with 80x87 fpu register constraints, and found an ICE:

cat t1.c
double test()
{
  double x,y;
  asm ("# %0 %1 %2" : "=&t" (x) : "f" (x), "u" (y));
  return x;
}

gcc -O -S t1.c
t1.c: In function 'test':
t1.c:6:1: internal compiler error: in change_stack, at reg-stack.c:2522
 }
 ^

0xa934a3 change_stack
        ../../gcc-trunk/gcc/reg-stack.c:2522
0xa93b62 subst_asm_stack_regs
        ../../gcc-trunk/gcc/reg-stack.c:2125
0xa95ead subst_stack_regs
        ../../gcc-trunk/gcc/reg-stack.c:2302
0xa960ed convert_regs_1
        ../../gcc-trunk/gcc/reg-stack.c:2951
0xa960ed convert_regs_2
        ../../gcc-trunk/gcc/reg-stack.c:3086
0xa96f5a convert_regs
        ../../gcc-trunk/gcc/reg-stack.c:3121
0xa96f5a reg_to_stack
        ../../gcc-trunk/gcc/reg-stack.c:3250
0xa96f5a rest_of_handle_stack_regs
        ../../gcc-trunk/gcc/reg-stack.c:3305
0xa96f5a execute
        ../../gcc-trunk/gcc/reg-stack.c:3336
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.

and same result for:

cat t2.c
double test()
{
  double x,y;
  asm ("# %0 %1 %2" : "=&r" (x) : "r" (x), "u" (y));
  return x;
}