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gbdb: change cycle calculation for better performance

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The conditions are hotpath, so pre-calcuate the end cycle count instead of doing it every loop.

I didn't verify that the compiler wasn't doing this anyway, but this won't hurt.
This commit is contained in:
Max Regan
2018-07-01 21:57:25 +00:00
parent c53802495c
commit 01c1c9e393
1 changed files with 4 additions and 5 deletions
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9
src/apps/gbdb.c
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@@ -186,7 +186,7 @@ static void echo(char *arg_list)
static void step(char *arg_list)
{
uint64_t steps, init_steps;
uint64_t steps, end_steps;
char *token;
token = strtok(arg_list, " ");
if (token == NULL) {
@@ -198,15 +198,14 @@ static void step(char *arg_list)
paused = 0;
signal(SIGINT, break_execution_handler);
init_steps = cpu.metrics.retired_instrs;
end_steps = cpu.metrics.retired_instrs + steps;
do {
cycle();
} while (init_steps + steps > cpu.metrics.retired_instrs &&
} while (end_steps > cpu.metrics.retired_instrs &&
!cpu_at_breakpoint() &&
!cpu.halted &&
!paused);
if (init_steps + steps <= cpu.metrics.retired_instrs) {
if (end_steps <= cpu.metrics.retired_instrs) {
gb_log("CPU stopped after %" PRId64 " instructions\n", steps);
} else if (cpu_at_breakpoint()) {
breakpoint_addr_hit(cpu.pc);