On 07/19/2018 08:12 PM, Dimitar Dimitrov wrote: > On събота, 23 юни 2018 г. 20:35:23 EEST Jakub Jelinek wrote: >> On Sat, Jun 23, 2018 at 03:26:50PM +0300, Dimitar Dimitrov wrote: >>> I took arm/ldmstm.md as an inspiration. See attached machine description >>> for PRU that requires the increase. I omitted this machine-generated MD >>> file from my first patch set, but per comments will include it in v2. >>> >>> PRU has a total of 32 32-bit registers with flexible subregister >>> addressing. The PRU GCC port represents the register file as 128 >>> individual 8-bit registers. Rationale: >>> http://gcc.gnu.org/ml/gcc/2017-01/msg00217.html >>> >>> Load/store instructions can load anywhere between 1 and 124 consecutive >>> 8-bit registers. The load/store-multiple patterns seem to require >>> const_int_operand offsets for each loaded register, hence the explosion >>> of operands. >> If it is consecutive only, then you could represent those that load a lot of >> registers using wider modes, so represent e.g. that 124 register load as 15 >> DImode loads + 1 SImode. >> >> Jakub > Jeff, Jakub, thank you for raising a concern that increasing MAX_MAX_OPERANDS > is suspicous. > > I think a better approach is to altogether avoid expansion, and instead > declare define_insn. Advantages are that: > - machine description is greatly simplified; > - there is no machine-generated code; > - I don't need to increase MAX_MAX_OPERANDS. > > I'll revise the PRU port and send patch v2. Here is how I intend to implement > the pattern: > > (define_insn "load_multiple" > [(unspec_volatile > [(parallel [(match_operand:QI 0 "register_operand" "=r") > (match_operand:BLK 1 "memory_operand" "m") > (match_operand:VOID 2 "const_int_operand" "i")])] > UNSPECV_LOAD_MULTPLE)] > "" > "lb%B1o\\t%b0, %1, %2" > [(set_attr "type" "ld") > (set_attr "length" "4")]) So my only worry with that is dataflow -- ie, how many registers have their values changed isn't expressed in the pattern in a way that the generic parts of the compiler understand. That's likely to cause some problems.
Jeff
