Sorry, no need already to bother with the last question, already knew that it is (again) generated automatically from the Machine description file ....
petruk_gile wrote: > > Thanks .. your reply is really helpful ... > > Btw, I checked the MIPS backend at MIPS.c, but I can't find the definition > of some functions such as: > > get_attr_hazard(), gen_hazard_nop (), etc. > > Anyone know where those functions defined? > > > > > Ian Lance Taylor-3 wrote: >> >> petruk_gile <[EMAIL PROTECTED]> writes: >> >>> I'm a pure beginner in GCC, and currently working on a project to >>> implement >>> instruction scheduling for a new DSP processor. This processor doesn't >>> have >>> pipeline interlock, so the compiler HAVE to schedule the instruction >>> without >>> relying on hardware help anymore .... >>> >>> The problem is, I'm a very beginner in GCC. I think the scheduling in >>> GCC is >>> activated by INSN_SCHEDULING variable (in automatically generated file: >>> insn-attr.h), but I don't even know how to activate this variable. >> >> INSN_SCHEDULING will automatically be turned on if you have any >> define_insn_reservation clauses in your CPU.md file. See the >> "Processor pipeline description" documentation in the gcc internals >> manual. >> >> That said, the gcc scheduler unfortunately does not work very well for >> processors which do not have hardware interlocks. The scheduler will >> lay out the instructions more or less optimally. But the scheduler >> has no ability to insert nops when they are required to satisfy >> interlock constraints. >> >> I know of two workable approachs. You can either insert the required >> nops in the TARGET_MACHINE_DEPENDENT_REORG pass or in the >> TARGET_ASM_FUNCTION_PROLOGUE hook. I personally prefer the latter >> approach, as it takes effect after all other instruction rearrangement >> is complete, but there are existing backends which use the former. >> >> For an example of inserting nops in TARGET_MACHINE_DEPENDENT_REORG, >> see the MIPS backend, specifically mips_avoid_hazards. For an example >> of inserting nops in TARGET_ASM_FUNCTION_PROLOGUE, see the FRV >> backend, specifically frv_pack_insns. >> >> Ian >> >> > > -- View this message in context: http://www.nabble.com/How-to-activate-instruction-scheduling-in-GCC--tf4167590.html#a11941887 Sent from the gcc - Dev mailing list archive at Nabble.com.
