Re: unexpected RTL

[Georg-Johann Lay <avr at gjlay dot de>]

Florent DEFAY schrieb:
> Hi,
>
> I am working on a new port for a 16bits target, 8 registers.
>
> When compiling libgcc2.c I get this error:
>
> ../../../gcc-4.3.3/libgcc/../gcc/libgcc2.c: In function ‘__mulsi3’:
> ../../../gcc-4.3.3/libgcc/../gcc/libgcc2.c:566: error: insn does not
> satisfy its constraints:
> (insn 122 171 102 ../../../gcc-4.3.3/libgcc/../gcc/libgcc2.c:565 (set
> (mem/c/i:HI (plus:HI (mem/f/c/i:HI (plus:HI (reg/f:HI 5 r5)
>                         (const_int 2 [0x2])) [0 D.2445+0 S2 A16])
>                 (const_int 2 [0x2])) [0 <result>+2 S2 A16])
>         (reg:HI 0 r0)) 5 {movhi} (nil))
> ../../../gcc-4.3.3/libgcc/../gcc/libgcc2.c:566: internal compiler
> error: in final_scan_insn, at final.c:2548
>
>
> According to my GO_IF_LEGITIMATE_ADDRESS, this RTL should not exist.
> Is it possible that there are not enough registers in the machine ?

This macro and some others like REGNO_OK_FOR_BASE_P have two flavours: 
strict (for strict RTL) and non-strict (for non-strict RTL).
Strict versions must disallow pseudos that have no hard regs assigned.

When gcc runs out of regs it puts values in stack slots: the reg is 
replaced with a mem in reload pass.

Georg-Johann