On 7/17/21 10:30 AM, Peter Maydell wrote:
On Mon, 12 Jul 2021 at 16:42, Richard Henderson
<richard.hender...@linaro.org> wrote:
The space reserved for CF_COUNT_MASK was overly large.
Reduce to free up cflags bits and eliminate an extra test.
Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
include/exec/exec-all.h | 4 +++-
accel/tcg/translate-all.c | 5 ++---
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
index 754f4130c9..dfe82ed19c 100644
--- a/include/exec/exec-all.h
+++ b/include/exec/exec-all.h
@@ -492,7 +492,9 @@ struct TranslationBlock {
target_ulong cs_base; /* CS base for this block */
uint32_t flags; /* flags defining in which context the code was generated
*/
uint32_t cflags; /* compile flags */
-#define CF_COUNT_MASK 0x00007fff
+
+/* Note that TCG_MAX_INSNS is 512; we validate this match elsewhere. */
+#define CF_COUNT_MASK 0x000001ff
#define CF_LAST_IO 0x00008000 /* Last insn may be an IO access. */
#define CF_MEMI_ONLY 0x00010000 /* Only instrument memory ops */
#define CF_USE_ICOUNT 0x00020000
diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
index 4df26de858..997e44c73b 100644
--- a/accel/tcg/translate-all.c
+++ b/accel/tcg/translate-all.c
@@ -1430,9 +1430,8 @@ TranslationBlock *tb_gen_code(CPUState *cpu,
if (max_insns == 0) {
max_insns = CF_COUNT_MASK;
}
- if (max_insns > TCG_MAX_INSNS) {
- max_insns = TCG_MAX_INSNS;
- }
+ QEMU_BUILD_BUG_ON(CF_COUNT_MASK + 1 != TCG_MAX_INSNS);
+
Previously we would allow max_insns = TCG_MAX_INSNS (512).
Now we only allow it to be 511...
Hmm. Well, 0 is supposed to map to "max", currently written as
max_insns = cflags & CF_COUNT_MASK;
if (max_insns == 0) {
max_insns = CF_COUNT_MASK;
}
I could just as easily map 0 -> TCG_MAX_INSNS instead.
r~
