@@ -30,13 +30,15 @@ static inline TranslationBlock * tb_lookup(CPUState *cpu,
hash = tb_jmp_cache_hash_func(pc);
tb = qatomic_rcu_read(&cpu->tb_jmp_cache[hash]);
- if (likely(tb &&
- tb->pc == pc &&
- tb->cs_base == cs_base &&
- tb->flags == flags &&
- tb->trace_vcpu_dstate == *cpu->trace_dstate &&
- tb_cflags(tb) == cflags)) {
- return tb;
+ if (likely(tb)) {
+ uint64_t bits = tb->pc ^ pc;
+ bits |= tb->cs_base ^ cs_base;
+ bits |= tb->flags ^ flags;
+ bits |= tb->trace_vcpu_dstate ^ *cpu->trace_dstate;
+ bits |= tb_cflags(tb) ^ cflags;
+ if (!bits) {
+ return tb;
+ }
}
tb = tb_htable_lookup(cpu, pc, cs_base, flags, cflags);
if (tb == NULL) {
Now that everything is nicely aligned instead of a compare and jump just blitz the bits together and test for zero at the end. [AJB: looking at perf I can't see much change. Basically the hotspot seems to be the initial load of the TB parameters. If this reflects the stall of the memory bus loading TB fields I guess this means there isn't much more to be squeezed out here: helper_lookup_tb_ptr() /home/alex/lsrc/qemu.git/builds/arm.all/qemu-system-aarch64 Event: cycles:ppp Percent Disassembly of section .text: 0000000000809c40 <helper_lookup_tb_ptr>: helper_lookup_tb_ptr(): { return ctpop64(arg); } const void *HELPER(lookup_tb_ptr)(CPUArchState *env) { 4.14 push %r13 1.32 push %r12 env_cpu(): * * Return the CPUState associated with the environment. */ static inline CPUState *env_cpu(CPUArchState *env) { return &env_archcpu(env)->parent_obj; 0.47 lea -0x9dc0(%rdi),%r12 helper_lookup_tb_ptr(): 0.80 push %rbp 0.40 mov %rdi,%rbp 0.90 push %rbx 1.59 sub $0x28,%rsp 1.95 mov %fs:0x28,%rax 2.28 mov %rax,0x18(%rsp) 0.51 xor %eax,%eax CPUState *cpu = env_cpu(env); TranslationBlock *tb; target_ulong cs_base, pc; uint32_t flags; cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags); 0.98 lea 0x4(%rsp),%rcx 0.66 lea 0x8(%rsp),%rdx 1.09 lea 0x10(%rsp),%rsi 2.08 → callq cpu_get_tb_cpu_state tb = tb_lookup(cpu, pc, cs_base, flags, curr_cflags(cpu)); 1.19 mov 0x10(%rsp),%rsi 1.03 mov 0x4(%rsp),%r9d deposit32(): uint32_t fieldval) { uint32_t mask; assert(start >= 0 && length > 0 && length <= 32 - start); mask = (~0U >> (32 - length)) << start; return (value & ~mask) | ((fieldval << start) & mask); 2.53 mov -0x1b24(%rbp),%r8d 0.55 lea parallel_cpus,%rdx tb_jmp_cache_hash_func(): } static inline unsigned int tb_jmp_cache_hash_func(target_ulong pc) { target_ulong tmp; tmp = pc ^ (pc >> (TARGET_PAGE_BITS - TB_JMP_PAGE_BITS)); 0.09 mov %rsi,%rdi deposit32(): 0.62 shl $0x18,%r8d curr_cflags(): /* current cflags for hashing/comparison */ static inline uint32_t curr_cflags(CPUState *cpu) { uint32_t cflags = deposit32(0, CF_CLUSTER_SHIFT, 8, cpu->cluster_index); cflags |= parallel_cpus ? CF_PARALLEL : 0; 1.80 mov %r8d,%eax 0.92 or $0x80000,%eax 1.45 cmpb $0x0,(%rdx) 0.84 lea use_icount,%rdx 3.13 cmovne %eax,%r8d cflags |= icount_enabled() ? CF_USE_ICOUNT : 0; 0.62 mov (%rdx),%ecx helper_lookup_tb_ptr(): 0.60 mov 0x8(%rsp),%rdx 1.95 mov %r8d,%eax 0.60 or $0x20000,%eax 0.45 test %ecx,%ecx 3.70 cmovne %eax,%r8d tb_jmp_cache_hash_func(): 0.47 lea target_page,%rax 0.55 mov 0x4(%rax),%ecx 0.55 sub $0x6,%ecx 3.17 shr %cl,%rdi 0.53 xor %rsi,%rdi return (((tmp >> (TARGET_PAGE_BITS - TB_JMP_PAGE_BITS)) & TB_JMP_PAGE_MASK) 1.74 mov %rdi,%rax | (tmp & TB_JMP_ADDR_MASK)); 0.50 and $0x3f,%edi return (((tmp >> (TARGET_PAGE_BITS - TB_JMP_PAGE_BITS)) & TB_JMP_PAGE_MASK) 2.85 shr %cl,%rax 0.31 and $0xfc0,%eax | (tmp & TB_JMP_ADDR_MASK)); 0.36 or %edi,%eax tb_lookup(): /* we should never be trying to look up an INVALID tb */ tcg_debug_assert(!(cflags & CF_INVALID)); hash = tb_jmp_cache_hash_func(pc); tb = qatomic_rcu_read(&cpu->tb_jmp_cache[hash]); 2.26 lea 0x210(%r12,%rax,8),%r13 5.86 mov 0x0(%r13),%rbx if (likely(tb)) { 0.38 test %rbx,%rbx 0.00 ↓ je e7 uint64_t bits = tb->pc ^ pc; 6.77 mov (%rbx),%rax bits |= tb->cs_base ^ cs_base; 0.75 mov 0x8(%rbx),%rcx uint64_t bits = tb->pc ^ pc; 1.67 xor %rsi,%rax bits |= tb->cs_base ^ cs_base; 0.83 xor %rdx,%rcx 0.95 or %rax,%rcx bits |= tb->flags ^ flags; 0.05 mov %r9d,%eax 1.63 xor 0x10(%rbx),%eax 2.26 or %rax,%rcx bits |= tb->trace_vcpu_dstate ^ *cpu->trace_dstate; 0.08 mov 0x18(%rbx),%eax 0.55 xor -0x1b38(%rbp),%rax 2.45 or %rcx,%rax tb_cflags(): return qatomic_read(&tb->cflags); 0.13 mov 0x14(%rbx),%ecx tb_lookup(): bits |= tb_cflags(tb) ^ cflags; 0.22 xor %r8d,%ecx if (!bits) { 3.34 or %rax,%rcx 3.69 ↓ je fe return tb; } } tb = tb_htable_lookup(cpu, pc, cs_base, flags, cflags); 0.21 e7: mov %r9d,%ecx mov %r12,%rdi 0.20 → callq tb_htable_lookup 0.00 mov %rax,%rbx if (tb == NULL) { 0.02 test %rax,%rax ↓ je 130 return NULL; } qatomic_set(&cpu->tb_jmp_cache[hash], tb); 0.10 mov %rax,0x0(%r13) helper_lookup_tb_ptr(): if (tb == NULL) { return tcg_code_gen_epilogue; } qemu_log_mask_and_addr(CPU_LOG_EXEC, pc, 0.40 fe: lea qemu_loglevel,%rax 0.16 testb $0x20,(%rax) 0.14 ↓ jne 140 "Chain %d: %p [" TARGET_FMT_lx "/" TARGET_FMT_lx "/%#x] %s\n", cpu->cpu_index, tb->tc.ptr, cs_base, pc, flags, lookup_symbol(pc)); return tb->tc.ptr; 1.69 10a: mov 0x20(%rbx),%rax } 0.18 10e: mov 0x18(%rsp),%rsi 0.34 xor %fs:0x28,%rsi 0.50 ↓ jne 188 4.48 add $0x28,%rsp 0.27 pop %rbx 0.10 pop %rbp 0.30 pop %r12 4.56 pop %r13 0.20 ← retq nop return tcg_code_gen_epilogue; 130: lea tcg_code_gen_epilogue,%rax mov (%rax),%rax ↑ jmp 10e nop qemu_log_mask_and_addr(CPU_LOG_EXEC, pc, 140: mov 0x10(%rsp),%rdi → callq qemu_log_in_addr_range test %al,%al ↑ je 10a mov 0x10(%rsp),%rdi → callq lookup_symbol sub $0x8,%rsp mov 0x20(%rbx),%rdx mov -0x1b28(%rbp),%esi push %rax mov 0x14(%rsp),%r9d lea __PRETTY_FUNCTION__.30436+0x10,%rdi xor %eax,%eax mov 0x20(%rsp),%r8 mov 0x18(%rsp),%rcx → callq qemu_log pop %rax pop %rdx ↑ jmp 10a } 188: → callq __stack_chk_fail@plt ] Signed-off-by: Alex Bennée <alex.bennee@linaro.org> --- include/exec/tb-lookup.h | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-)