This is the payoff.
>From perf record -g data of ubuntu 18 boot and shutdown:
BEFORE:
- 23.02% 2.82% qemu-system-aar [.] helper_lookup_tb_ptr
- 20.22% helper_lookup_tb_ptr
+ 10.05% tb_htable_lookup
- 9.13% cpu_get_tb_cpu_state
3.20% aa64_va_parameters_both
0.55% fp_exception_el
- 11.66% 4.74% qemu-system-aar [.] cpu_get_tb_cpu_state
- 6.96% cpu_get_tb_cpu_state
3.63% aa64_va_parameters_both
0.60% fp_exception_el
0.53% sve_exception_el
AFTER:
- 16.40% 3.40% qemu-system-aar [.] helper_lookup_tb_ptr
- 13.03% helper_lookup_tb_ptr
+ 11.19% tb_htable_lookup
0.55% cpu_get_tb_cpu_state
0.98% 0.71% qemu-system-aar [.] cpu_get_tb_cpu_state
0.87% 0.24% qemu-system-aar [.] rebuild_hflags_a64
Before, helper_lookup_tb_ptr is the second hottest function in the
application, consuming almost a quarter of the runtime. Within the
entire execution, cpu_get_tb_cpu_state consumes about 12%.
After, helper_lookup_tb_ptr has dropped to the fourth hottest function,
with consumption dropping to a sixth of the runtime. Within the
entire execution, cpu_get_tb_cpu_state has dropped below 1%, and the
supporting function to rebuild hflags also consumes about 1%.
Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
target/arm/helper.c | 9 ++-------
1 file changed, 2 insertions(+), 7 deletions(-)
diff --git a/target/arm/helper.c b/target/arm/helper.c
index 3c8724883d..1bdb87267e 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -13894,21 +13894,16 @@ void HELPER(rebuild_hflags_a64)(CPUARMState *env,
uint32_t el)
void cpu_get_tb_cpu_state(CPUARMState *env, target_ulong *pc,
target_ulong *cs_base, uint32_t *pflags)
{
- int current_el = arm_current_el(env);
- uint32_t flags;
+ uint32_t flags = env->hflags;
uint32_t pstate_for_ss;
*cs_base = 0;
- if (is_a64(env)) {
+ if (FIELD_EX32(flags, TBFLAG_ANY, AARCH64_STATE)) {
*pc = env->pc;
- flags = rebuild_hflags_a64(env, current_el);
- assert(flags == env->hflags);
flags = FIELD_DP32(flags, TBFLAG_A64, BTYPE, env->btype);
pstate_for_ss = env->pstate;
} else {
*pc = env->regs[15];
- flags = rebuild_hflags_a32(env, current_el);
- assert(flags == env->hflags);
flags = FIELD_DP32(flags, TBFLAG_A32, THUMB, env->thumb);
flags = FIELD_DP32(flags, TBFLAG_A32, CONDEXEC, env->condexec_bits);
pstate_for_ss = env->uncached_cpsr;
--
2.17.1
