On Sun, Aug 18, 2019 at 12:23 AM William Tambe <tambewilliam@xxxxxxxxx> wrote: > > A simpler question from me should have been: > > What should a define_constraint look like to match the following operand ? > (mem/f/c:SI (mem/c:SI (reg/f:SI 0 %sp))) Does your target actually support memory indirect addressing modes? These are uncommon. This looks more like a mistake with REG_OK_STRICT. Before register allocation, we can accept (mem (reg)) where reg is a pseudo reg, assuming it will get allocated to a hard reg later. But during register allocation, we must reject (mem (reg)) where reg is a psuedo-reg, because this means the reg was not allocated to a hard register, and is instead mapped to a stack slot. Once register allocation finished, the (mem (reg)) will be changed to (mem (mem (stack-slot-address)) which is unlikely to be a valid address. You can see this if you look at the RTL dumps. The code that decides whether it is OK to accept a pseudo-reg here is controlled by REG_OK_STRICT. See for instance the definition of REGNO_MODE_OK_FOR_BASE_P in working ports. Or if you defined the TARGET_LEGITIMATE_ADDRESS_P hook, this is controlled by the "strict" argument. In strict mode, you need to reject pseudo-regs, and in non-strict mode you accept pseudo-regs. Jim
