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tcg: Restart code generation when we run out of temps

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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 <balaton@eik.bme.hu>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2021-01-23 12:11:17 -10:00
parent 653b87eb36
commit ae30e86661
3 changed files with 25 additions and 4 deletions
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15
accel/tcg/translate-all.c
View file

@ -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:

3
include/tcg/tcg.h
View file

@ -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)

11
tcg/tcg.c
View file

@ -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;