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[97.113.8.179]) by smtp.gmail.com with ESMTPSA id e19-v6sm29558264pfb.153.2018.10.07.13.31.51 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Sun, 07 Oct 2018 13:31:52 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Date: Sun, 7 Oct 2018 13:31:50 -0700 Message-Id: <20181007203150.23550-1-richard.henderson@linaro.org> X-Mailer: git-send-email 2.17.1 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2607:f8b0:4864:20::542 Subject: [Qemu-devel] [PATCH] tcg: Implement CPU_LOG_TB_NOCHAIN during expansion X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: alex.bennee@linaro.org Errors-To: qemu-devel-bounces+patch=linaro.org@nongnu.org Sender: "Qemu-devel" Rather than test NOCHAIN before linking, do not emit the goto_tb opcode at all. We already do this for goto_ptr. Previously, nochain seemed more or less a hack to debug code gen. But there's a real use case when it comes to tracing, so spend a little more effort on what we produce. Signed-off-by: Richard Henderson --- accel/tcg/cpu-exec.c | 2 +- tcg/tcg-op.c | 9 ++++++++- 2 files changed, 9 insertions(+), 2 deletions(-) -- 2.17.1 diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c index 6bcb6d99bd..870027d435 100644 --- a/accel/tcg/cpu-exec.c +++ b/accel/tcg/cpu-exec.c @@ -416,7 +416,7 @@ static inline TranslationBlock *tb_find(CPUState *cpu, } #endif /* See if we can patch the calling TB. */ - if (last_tb && !qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) { + if (last_tb) { tb_add_jump(last_tb, tb_exit, tb); } return tb; diff --git a/tcg/tcg-op.c b/tcg/tcg-op.c index daa416a143..7a8015c5a9 100644 --- a/tcg/tcg-op.c +++ b/tcg/tcg-op.c @@ -2586,6 +2586,10 @@ void tcg_gen_exit_tb(TranslationBlock *tb, unsigned idx) seen this numbered exit before, via tcg_gen_goto_tb. */ tcg_debug_assert(tcg_ctx->goto_tb_issue_mask & (1 << idx)); #endif + /* When not chaining, exit without indicating a link. */ + if (qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) { + val = 0; + } } else { /* This is an exit via the exitreq label. */ tcg_debug_assert(idx == TB_EXIT_REQUESTED); @@ -2603,7 +2607,10 @@ void tcg_gen_goto_tb(unsigned idx) tcg_debug_assert((tcg_ctx->goto_tb_issue_mask & (1 << idx)) == 0); tcg_ctx->goto_tb_issue_mask |= 1 << idx; #endif - tcg_gen_op1i(INDEX_op_goto_tb, idx); + /* When not chaining, we simply fall through to the "fallback" exit. */ + if (!qemu_loglevel_mask(CPU_LOG_TB_NOCHAIN)) { + tcg_gen_op1i(INDEX_op_goto_tb, idx); + } } void tcg_gen_lookup_and_goto_ptr(void)