accel/tcg: Reduce CF_COUNT_MASK to match TCG_MAX_INSNS

The space reserved for CF_COUNT_MASK was overly large.
Reduce to free up cflags bits and eliminate an extra test.

Tested-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20210717221851.2124573-2-richard.henderson@linaro.org>

diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
index 4df26de..5cc01d6 100644 (file)
--- a/accel/tcg/translate-all.c
+++ b/accel/tcg/translate-all.c
@@ -1428,11 +1428,10 @@ TranslationBlock *tb_gen_code(CPUState *cpu,
 
     max_insns = cflags & CF_COUNT_MASK;
     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);
+
     if (cpu->singlestep_enabled || singlestep) {
         max_insns = 1;
     }

diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
index 754f413..dfe82ed 100644 (file)
--- 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