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[173.197.98.118]) by smtp.gmail.com with ESMTPSA id x10-20020aa79a4a000000b00593eb3a5e44sm102933pfj.37.2023.01.30.12.59.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Jan 2023 12:59:38 -0800 (PST) From: Richard Henderson To: qemu-devel@nongnu.org Cc: peter.maydell@linaro.org, cota@braap.org Subject: [PATCH 00/27] tcg: Simplify temporary usage Date: Mon, 30 Jan 2023 10:59:07 -1000 Message-Id: <20230130205935.1157347-1-richard.henderson@linaro.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::435; envelope-from=richard.henderson@linaro.org; helo=mail-pf1-x435.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Based-on: 20230126043824.54819-1-richard.henderson@linaro.org ("[PATCH v5 00/36] tcg: Support for Int128 with helpers") The biggest pitfall for new users of TCG is the fact that "normal" temporaries die at branches, and we must therefore use a different "local" temporary in that case. The following patch set changes that, so that the "normal" temporary is the one that lives across branches, and there is a special temporary that dies at the end of the extended basic block, and this special case is reserved for tcg internals. TEMP_LOCAL is renamed TEMP_TB, which I believe to be more explicit and less confusing. TEMP_NORMAL is removed entirely. I thought about putting in a proper full-power liveness analysis pass. This would have eliminated the differences between all non-global temporaries, and would have noticed when TEMP_LOCAL finally dies within a translation and avoid any final writeback. But I came to the conclusion that it was too expensive in runtime, and so retaining some distinction in the types was required. In addition, I found that the usage of temps within plugin-gen.c (9 per guest memory operation) meant that we *must* have some form of temp that can be re-used. (There is one x86 instruction which generates 62 memory operations; 62 * 9 == 558, which is larger than our current TCG_MAX_TEMPS.) However I did add a new liveness pass which, with a single pass over the opcode stream, can see that a TEMP_LOCAL is only live within a single extended basic block, and thus may be transformed to TEMP_EBB. With this, and by not recycling TEMP_LOCAL, we can get identical code out of the backend even when changing the front end translators are adjusted to use TEMP_LOCAL for everything. Benchmarking one test case, qemu-arm linux-test, the new liveness pass comes in at about 1.6% on perf, but I can't see any difference in wall clock time before and after the patch set. r~ Richard Henderson (27): tcg: Adjust TCGContext.temps_in_use check accel/tcg: Pass max_insn to gen_intermediate_code by pointer accel/tcg: Use more accurate max_insns for tb_overflow tcg: Remove branch-to-next regardless of reference count tcg: Rename TEMP_LOCAL to TEMP_TB tcg: Add liveness_pass_0 tcg: Remove TEMP_NORMAL tcg: Pass TCGTempKind to tcg_temp_new_internal tcg: Add tcg_temp_ebb_new_{i32,i64,ptr} tcg: Add tcg_gen_movi_ptr tcg: Use tcg_temp_ebb_new_* in tcg/ accel/tcg/plugin: Use tcg_temp_ebb_* accel/tcg/plugin: Tidy plugin_gen_disable_mem_helpers tcg: Don't re-use TEMP_TB temporaries tcg: Change default temp lifetime to TEMP_TB target/arm: Drop copies in gen_sve_{ldr,str} target/arm: Don't use tcg_temp_local_new_* target/cris: Don't use tcg_temp_local_new target/hexagon: Don't use tcg_temp_local_new_* target/hppa: Don't use tcg_temp_local_new target/i386: Don't use tcg_temp_local_new target/mips: Don't use tcg_temp_local_new target/ppc: Don't use tcg_temp_local_new target/xtensa: Don't use tcg_temp_local_new_* exec/gen-icount: Don't use tcg_temp_local_new_i32 tcg: Remove tcg_temp_local_new_*, tcg_const_local_* tcg: Update docs/devel/tcg-ops.rst for temporary changes docs/devel/tcg-ops.rst | 103 ++++---- target/hexagon/idef-parser/README.rst | 4 +- include/exec/gen-icount.h | 8 +- include/exec/translator.h | 4 +- include/tcg/tcg-op.h | 7 +- include/tcg/tcg.h | 64 ++--- target/arm/translate-a64.h | 1 - target/hexagon/gen_tcg.h | 4 +- accel/tcg/plugin-gen.c | 33 +-- accel/tcg/translate-all.c | 2 +- accel/tcg/translator.c | 6 +- target/alpha/translate.c | 2 +- target/arm/translate-a64.c | 6 - target/arm/translate-sve.c | 38 +-- target/arm/translate.c | 8 +- target/avr/translate.c | 2 +- target/cris/translate.c | 8 +- target/hexagon/genptr.c | 16 +- target/hexagon/idef-parser/parser-helpers.c | 4 +- target/hexagon/translate.c | 4 +- target/hppa/translate.c | 5 +- target/i386/tcg/translate.c | 29 +-- target/loongarch/translate.c | 2 +- target/m68k/translate.c | 2 +- target/microblaze/translate.c | 2 +- target/mips/tcg/translate.c | 59 ++--- target/nios2/translate.c | 2 +- target/openrisc/translate.c | 2 +- target/ppc/translate.c | 8 +- target/riscv/translate.c | 2 +- target/rx/translate.c | 2 +- target/s390x/tcg/translate.c | 2 +- target/sh4/translate.c | 2 +- target/sparc/translate.c | 2 +- target/tricore/translate.c | 2 +- target/xtensa/translate.c | 18 +- tcg/optimize.c | 2 +- tcg/tcg-op-gvec.c | 270 ++++++++++---------- tcg/tcg-op.c | 258 +++++++++---------- tcg/tcg.c | 270 +++++++++++--------- target/cris/translate_v10.c.inc | 10 +- target/mips/tcg/nanomips_translate.c.inc | 4 +- target/ppc/translate/spe-impl.c.inc | 8 +- target/ppc/translate/vmx-impl.c.inc | 4 +- target/hexagon/README | 8 +- target/hexagon/gen_tcg_funcs.py | 18 +- 46 files changed, 640 insertions(+), 677 deletions(-)