Ping. 2012/9/18 Yuri Rumyantsev <ysrum...@gmail.com>: > Hi All, > > Forgot to attch the patch. > > 2012/9/18 Yuri Rumyantsev <ysrum...@gmail.com>: >> Hi All, >> >> This patch aims to fix all stability issues related to using the first >> scheduler in gcc >> for x86 target (there several reported issues related to this problem). >> >> Main idea of this activity is mostly to provide user a possibility to >> safely turn on first scheduler for his codes. In some cases this could >> positively affect performance, especially for in-order Atom. >> >> Below is short description of proposed changes. >> >> Main idea of this patch is to restrict code motion of instructions >> having likely spilled HW registers as their operands - in general >> all these instructions are unloading of incoming function argument >> in the function entry and passing of outgoing function arguments. >> This is essential for correct scheduling since live range of such insns >> is not defined before register allocation phase. >> This done through 2 hooks: >> >> 1. ix86_adjust_priority which sets up the priority of moves from >> likely spilled HW registers to maximum that allows us to schedule >> such insns as soon as possible, i.e. all moves correspondent to >> incoming function arguments will be scheduled at the top of >> function entry and moves correspondent to function return >> value will be scheduled immediately after call. >> 2. ix86_dependencies_evaluation_hook which insert additional >> dependencies for outgoing function arguments passed in likely >> spilled HW registers to avoid their code motion. This is done >> through the following steps: >> - scan the current schedule region to find all call instructions in >> reverse order; >> - find out the first argument that passed in likely spilled HW >> register. Starting from it insert output dependency between it and >> possible previous argument (it does not matter if it passed in likely >> spilled register or not). This is done in add_parameter_dependencies; >> after it all arguments starting from the first one that is passed in >> likely spilled register are pairwise connected through output >> dependency. >> - add dependencies to the first function argument on >> the rest of instructions in the current block (until next call) to avoid >> intra block code motion. >> - to avoid possible interblock code motion we also check if the first >> argument has dependee in another blocks and if so insert dependency to >> the last non-jump set instruction. >> >> This patch was deeply tested on Atom (eembc_2_0, spec2000 in base/peak mode) >> and Big Core (spec2006 in base/peak mode). >> Also gcc full bootstrapping with turned on 1st scheduler by default was done. >> >> Tested for i386 and x86-64, ok for trunk? >> >> ChangeLog: >> >> 2012-09-18 Yuri Rumyantsev <ysrum...@gmail.com> >> >> * config/i386/i386.c (ix86_dep_by_shift_count_body) : Add >> check on reload_completed since it can be invoked before >> register allocation phase in 1st scheduler. >> (ia32_multipass_dfa_lookahead) : Do not use dfa_lookahead for 1st >> Scheduler to save compile time. >> (ix86_sched_reorder) : Do not perform ready list reordering for 1st >> Scheduler to save compile time. >> (insn_is_function_arg) : New function. Returns true if lhs of insn is >> HW function argument register. >> (add_parameter_dependencies) : New function. Add output dependencies >> for chain of function adjacent arguments if only there is a move to >> likely spilled HW registers. Return first argument if at least one >> dependence was added or NULL otherwise. >> (avoid_func_arg_motion) : New function. Add output or anti dependency >> from insn to first_arg to restrict code motion. >> (add_dependee_for_func_arg) : New function. Avoid cross block motion >> of >> function argument through adding dependency from the first non-jump >> insn in bb. >> (ix86_dependencies_evaluation_hook) : New function. Hook for >> schedule1: >> avoid motion of function arguments passed in passed in likely spilled >> HW registers. >> (ix86_adjust_priority) : New function. Hook for schedule1: set >> priority >> of moves from likely spilled HW registers to maximum to schedule them >> as soon as possible. >> (ix86_sched_init_global): Do not perform multipass scheduling for 1st >> Scheduler to save compile time.
i386-fschedule-insn_for_x86.diff
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