https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88282
Tamar Christina <tnfchris at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|ASSIGNED |NEW
CC| |vmakarov at gcc dot gnu.org
Assignee|tnfchris at gcc dot gnu.org |unassigned at gcc dot
gnu.org
--- Comment #3 from Tamar Christina <tnfchris at gcc dot gnu.org> ---
This is caused by the change in r266385 for PR87718.
That causes the cost model to go completely off the rail and also changes the
register classes.
Previously out costs were 0 in most cases, now we have large numbers like
65540004.
```
r93 costs: GENERAL_REGS:0 FP_LO_REGS:10000 FP_REGS:10000
POINTER_AND_FP_REGS:10000 MEM:8000
r92 costs: GENERAL_REGS:0 FP_LO_REGS:10000 FP_REGS:10000
POINTER_AND_FP_REGS:10000 MEM:8000
```
was before and now
```
r93 costs: GENERAL_REGS:65540004 FP_LO_REGS:65544004 FP_REGS:65544004
POINTER_AND_FP_REGS:65544004 MEM:8000
r92 costs: TAILCALL_ADDR_REGS:131074004 GENERAL_REGS:131074004
FP_LO_REGS:131074004 FP_REGS:131074004 POINTER_AND_FP_REGS:131074004 MEM:8000
```
The reason this crashes with stack clash enabled is because the alloca code
emits a probe at SP.
The costing now makes it think it has to spill the hard register
Creating newreg=98 from oldreg=92, assigning class GENERAL_REGS to r98
16: sp:DI=r98:DI
REG_DEAD r92:DI
REG_ARGS_SIZE 0
Inserting insn reload before:
27: r98:DI=r92:DI
it can't do it so it crashes in reload.
