GCC modified for the FreeChainXenon project
7ad308bd4c
PPX stands for Push-Pop Acceleration. PUSH/PUSH2 and its corresponding POP can be marked with a 1-bit hint to indicate that the POP reads the value written by the PUSH from the stack. The processor tracks these marked instructions internally and fast-forwards register data between matching PUSH and POP instructions, without going through memory or through the training loop of the Fast Store Forwarding Predictor (FSFP). This feature can also be adopted to PUSH2/POP2. For GCC, we emit explicit suffix 'p' (paired) to indicate the push/pop pair are marked with PPX hint. To separate form original push/pop, we add an UNSPEC on top of those PUSH/POP patterns. In the first implementation we only emit them under prologue/epilogue when saving/restoring callee-saved registers to make sure push/pop are paired. So an extra flag was added to check if PPX insns can be emitted for those register save/restore interfaces. The PPX hint is purely a performance hint. If the 'p' suffix is not emitted for paired push/pop, the PPX optimization will be disabled, while program sematic will not be affected at all. gcc/ChangeLog: * config/i386/i386-expand.h (gen_push): Add default bool parameter. (gen_pop): Likewise. * config/i386/i386-opts.h (enum apx_features): Add apx_ppx, add it to apx_all. * config/i386/i386.cc (ix86_emit_restore_reg_using_pop): Add ppx_p parameter for function declaration. (gen_push2): Add ppx_p parameter, emit push2p if ppx_p is true. (gen_push): Likewise. (ix86_emit_restore_reg_using_pop2): Likewise for pop2p. (ix86_emit_save_regs): Emit pushp/push2p under TARGET_APX_PPX. (ix86_emit_restore_reg_using_pop): Add ppx_p, emit popp insn and adjust cfi when ppx_p is ture. (ix86_emit_restore_reg_using_pop2): Add ppx_p and parse to its callee. (ix86_emit_restore_regs_using_pop2): Likewise. (ix86_expand_epilogue): Parse TARGET_APX_PPX to ix86_emit_restore_reg_using_pop. * config/i386/i386.h (TARGET_APX_PPX): New. * config/i386/i386.md (UNSPEC_APX_PPX): New unspec. (pushp_di): New define_insn. (popp_di): Likewise. (push2p_di): Likewise. (pop2p_di): Likewise. * config/i386/i386.opt: Add apx_ppx enum. gcc/testsuite/ChangeLog: * gcc.target/i386/apx-interrupt-1.c: Adjust option to restrict them under certain subfeatures. * gcc.target/i386/apx-push2pop2-1.c: Likewise. * gcc.target/i386/apx-push2pop2_force_drap-1.c: Likewise. * gcc.target/i386/apx-push2pop2_interrupt-1.c: Likewise. * gcc.target/i386/apx-ppx-1.c: New test. |
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| .github | ||
| c++tools | ||
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| Makefile.def | ||
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| ylwrap | ||
This directory contains the GNU Compiler Collection (GCC). The GNU Compiler Collection is free software. See the files whose names start with COPYING for copying permission. The manuals, and some of the runtime libraries, are under different terms; see the individual source files for details. The directory INSTALL contains copies of the installation information as HTML and plain text. The source of this information is gcc/doc/install.texi. The installation information includes details of what is included in the GCC sources and what files GCC installs. See the file gcc/doc/gcc.texi (together with other files that it includes) for usage and porting information. An online readable version of the manual is in the files gcc/doc/gcc.info*. See http://gcc.gnu.org/bugs/ for how to report bugs usefully. Copyright years on GCC source files may be listed using range notation, e.g., 1987-2012, indicating that every year in the range, inclusive, is a copyrightable year that could otherwise be listed individually.