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authorPeter Maydell <peter.maydell@linaro.org>2021-07-25 18:44:05 +0100
committerRichard Henderson <richard.henderson@linaro.org>2021-07-26 06:56:03 -1000
commitc8cf47a946200239826e58abc203dcaa4fdbb30c (patch)
tree056644e66875fa1c5eaea710427a61abd34726b0 /accel/tcg/cpu-exec.c
parentdf3a2de51a07089a4a729fe1f792f658df9dade4 (diff)
accel/tcg: Remove unnecessary check on icount_extra in cpu_loop_exec_tb()
In cpu_loop_exec_tb(), we decide whether to look for a TB with exactly insns_left instructions in it using the condition (!cpu->icount_extra && insns_left > 0 && insns_left < tb->icount) The check for icount_extra == 0 is unnecessary, because we just set insns_left = MIN(0xffff, cpu->icount_budget); icount_extra = icount_budget - insns_left; and so icount_extra can only be non-zero if icount_budget > 0xffff and insns_left == 0xffff. But in that case insns_left >= tb->icount because 0xffff is much larger than TCG_MAX_INSNS, so the condition will be false anyway. Remove the unnecessary check, and instead assert: * that we are only going to execute a partial TB here if the icount budget has run out (ie icount_extra == 0) * that the number of insns we're going to execute does fit into the CF_COUNT_MASK Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-Id: <20210725174405.24568-3-peter.maydell@linaro.org> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Diffstat (limited to 'accel/tcg/cpu-exec.c')
-rw-r--r--accel/tcg/cpu-exec.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
index 6e8dc29119..5aa42fbff3 100644
--- a/accel/tcg/cpu-exec.c
+++ b/accel/tcg/cpu-exec.c
@@ -843,7 +843,9 @@ static inline void cpu_loop_exec_tb(CPUState *cpu, TranslationBlock *tb,
* execute we need to ensure we find/generate a TB with exactly
* insns_left instructions in it.
*/
- if (!cpu->icount_extra && insns_left > 0 && insns_left < tb->icount) {
+ if (insns_left > 0 && insns_left < tb->icount) {
+ assert(insns_left <= CF_COUNT_MASK);
+ assert(cpu->icount_extra == 0);
cpu->cflags_next_tb = (tb->cflags & ~CF_COUNT_MASK) | insns_left;
}
#endif