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authorRichard Henderson <richard.henderson@linaro.org>2019-10-23 11:00:57 -0400
committerPeter Maydell <peter.maydell@linaro.org>2019-10-24 17:16:28 +0100
commite979972a6a17baadfcef05952e7523af99489487 (patch)
treeeb43b8cf0570e0677153924dd7fca3be2104b97f
parent37bf16c645e530b2a4434fd5976afbe885137298 (diff)
downloadqemu-arm-e979972a6a17baadfcef05952e7523af99489487.tar.gz
target/arm: Rely on hflags correct in cpu_get_tb_cpu_state
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%. Assertions are retained for --enable-debug-tcg. Tested-by: Alex Bennée <alex.bennee@linaro.org> Reviewed-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org> Message-id: 20191023150057.25731-25-richard.henderson@linaro.org Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
-rw-r--r--target/arm/helper.c9
1 files changed, 6 insertions, 3 deletions
diff --git a/target/arm/helper.c b/target/arm/helper.c
index c55783e540..63815fc4cf 100644
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -11259,12 +11259,15 @@ void HELPER(rebuild_hflags_a64)(CPUARMState *env, int el)
void cpu_get_tb_cpu_state(CPUARMState *env, target_ulong *pc,
target_ulong *cs_base, uint32_t *pflags)
{
- uint32_t flags, pstate_for_ss;
+ uint32_t flags = env->hflags;
+ uint32_t pstate_for_ss;
*cs_base = 0;
- flags = rebuild_hflags_internal(env);
+#ifdef CONFIG_DEBUG_TCG
+ assert(flags == rebuild_hflags_internal(env));
+#endif
- if (is_a64(env)) {
+ if (FIELD_EX32(flags, TBFLAG_ANY, AARCH64_STATE)) {
*pc = env->pc;
if (cpu_isar_feature(aa64_bti, env_archcpu(env))) {
flags = FIELD_DP32(flags, TBFLAG_A64, BTYPE, env->btype);