On Sun, Jan 24, 2021 at 08:11:22AM -1000, Richard Henderson wrote: > Some large translation blocks can generate so many unique > constants that we run out of temps to hold them. In this > case, longjmp back to the start of code generation and > restart with a smaller translation block. > > Buglink: https://bugs.launchpad.net/bugs/1912065 > Tested-by: BALATON Zoltan <bala...@eik.bme.hu> > Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org> > Signed-off-by: Richard Henderson <richard.hender...@linaro.org> > --- > include/tcg/tcg.h | 3 +++ > accel/tcg/translate-all.c | 15 ++++++++++++++- > tcg/tcg.c | 11 ++++++++--- > 3 files changed, 25 insertions(+), 4 deletions(-) > > diff --git a/include/tcg/tcg.h b/include/tcg/tcg.h > index c5a9d65d5f..0f0695e90d 100644 > --- a/include/tcg/tcg.h > +++ b/include/tcg/tcg.h > @@ -680,6 +680,9 @@ struct TCGContext { > > uint16_t gen_insn_end_off[TCG_MAX_INSNS]; > target_ulong gen_insn_data[TCG_MAX_INSNS][TARGET_INSN_START_WORDS]; > + > + /* Exit to translator on overflow. */ > + sigjmp_buf jmp_trans; > }; > > static inline bool temp_readonly(TCGTemp *ts) > diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c > index d09c187e0f..81d4c83f22 100644 > --- a/accel/tcg/translate-all.c > +++ b/accel/tcg/translate-all.c > @@ -1926,11 +1926,17 @@ TranslationBlock *tb_gen_code(CPUState *cpu, > ti = profile_getclock(); > #endif > > + gen_code_size = sigsetjmp(tcg_ctx->jmp_trans, 0); > + if (unlikely(gen_code_size != 0)) { > + goto error_return; > + } > + > tcg_func_start(tcg_ctx); > > tcg_ctx->cpu = env_cpu(env); > gen_intermediate_code(cpu, tb, max_insns); > tcg_ctx->cpu = NULL; > + max_insns = tb->icount; > > trace_translate_block(tb, tb->pc, tb->tc.ptr); > > @@ -1955,6 +1961,7 @@ TranslationBlock *tb_gen_code(CPUState *cpu, > > gen_code_size = tcg_gen_code(tcg_ctx, tb); > if (unlikely(gen_code_size < 0)) { > + error_return: > switch (gen_code_size) { > case -1: > /* > @@ -1966,6 +1973,9 @@ TranslationBlock *tb_gen_code(CPUState *cpu, > * flush the TBs, allocate a new TB, re-initialize it per > * above, and re-do the actual code generation. > */ > + qemu_log_mask(CPU_LOG_TB_OP | CPU_LOG_TB_OP_OPT, > + "Restarting code generation for " > + "code_gen_buffer overflow\n"); > goto buffer_overflow; > > case -2: > @@ -1978,9 +1988,12 @@ TranslationBlock *tb_gen_code(CPUState *cpu, > * Try again with half as many insns as we attempted this time. > * If a single insn overflows, there's a bug somewhere... > */ > - max_insns = tb->icount; > assert(max_insns > 1); > max_insns /= 2; > + qemu_log_mask(CPU_LOG_TB_OP | CPU_LOG_TB_OP_OPT, > + "Restarting code generation with " > + "smaller translation block (max %d insns)\n", > + max_insns); > goto tb_overflow; > > default: > diff --git a/tcg/tcg.c b/tcg/tcg.c > index 67b08f708d..9e1b0d73c7 100644 > --- a/tcg/tcg.c > +++ b/tcg/tcg.c > @@ -1205,18 +1205,23 @@ void tcg_func_start(TCGContext *s) > QSIMPLEQ_INIT(&s->labels); > } > > -static inline TCGTemp *tcg_temp_alloc(TCGContext *s) > +static TCGTemp *tcg_temp_alloc(TCGContext *s) > { > int n = s->nb_temps++; > - tcg_debug_assert(n < TCG_MAX_TEMPS); > + > + if (n >= TCG_MAX_TEMPS) { > + /* Signal overflow, starting over with fewer guest insns. */ > + siglongjmp(s->jmp_trans, -2); > + } > return memset(&s->temps[n], 0, sizeof(TCGTemp)); > } > > -static inline TCGTemp *tcg_global_alloc(TCGContext *s) > +static TCGTemp *tcg_global_alloc(TCGContext *s) > { > TCGTemp *ts; > > tcg_debug_assert(s->nb_globals == s->nb_temps); > + tcg_debug_assert(s->nb_globals < TCG_MAX_TEMPS); > s->nb_globals++; > ts = tcg_temp_alloc(s); > ts->kind = TEMP_GLOBAL; > -- > 2.25.1 > >
Hi Richard, Thanks for providing the fix. Tested-by: Roman Bolshakov <r.bolsha...@yadro.com> Regards, Roman
