cpu: Move icount_decr to CPUNegativeOffsetState

Amusingly, we had already ignored the comment to keep this value
at the end of CPUState.  This restores the minimum negative offset
from TCG_AREG0 for code generation.

For the couple of uses within qom/cpu.c, without NEED_CPU_H, add
a pointer from the CPUState object to the IcountDecr object within
CPUNegativeOffsetState.

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 18 insertions, 22 deletions

diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index 98e12d9..5ee0046 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -232,17 +232,25 @@ typedef struct CPUClass {
     bool gdb_stop_before_watchpoint;
 } CPUClass;
 
+/*
+ * Low 16 bits: number of cycles left, used only in icount mode.
+ * High 16 bits: Set to -1 to force TCG to stop executing linked TBs
+ * for this CPU and return to its top level loop (even in non-icount mode).
+ * This allows a single read-compare-cbranch-write sequence to test
+ * for both decrementer underflow and exceptions.
+ */
+typedef union IcountDecr {
+    uint32_t u32;
+    struct {
 #ifdef HOST_WORDS_BIGENDIAN
-typedef struct icount_decr_u16 {
-    uint16_t high;
-    uint16_t low;
-} icount_decr_u16;
+        uint16_t high;
+        uint16_t low;
 #else
-typedef struct icount_decr_u16 {
-    uint16_t low;
-    uint16_t high;
-} icount_decr_u16;
+        uint16_t low;
+        uint16_t high;
 #endif
+    } u16;
+} IcountDecr;
 
 typedef struct CPUBreakpoint {
     vaddr pc;
@@ -314,11 +322,6 @@ struct qemu_work_item;
  * @crash_occurred: Indicates the OS reported a crash (panic) for this CPU
  * @singlestep_enabled: Flags for single-stepping.
  * @icount_extra: Instructions until next timer event.
- * @icount_decr: Low 16 bits: number of cycles left, only used in icount mode.
- * High 16 bits: Set to -1 to force TCG to stop executing linked TBs for this
- * CPU and return to its top level loop (even in non-icount mode).
- * This allows a single read-compare-cbranch-write sequence to test
- * for both decrementer underflow and exceptions.
  * @can_do_io: Nonzero if memory-mapped IO is safe. Deterministic execution
  * requires that IO only be performed on the last instruction of a TB
  * so that interrupts take effect immediately.
@@ -328,6 +331,7 @@ struct qemu_work_item;
  * @as: Pointer to the first AddressSpace, for the convenience of targets which
  *      only have a single AddressSpace
  * @env_ptr: Pointer to subclass-specific CPUArchState field.
+ * @icount_decr_ptr: Pointer to IcountDecr field within subclass.
  * @gdb_regs: Additional GDB registers.
  * @gdb_num_regs: Number of total registers accessible to GDB.
  * @gdb_num_g_regs: Number of registers in GDB 'g' packets.
@@ -387,6 +391,7 @@ struct CPUState {
     MemoryRegion *memory;
 
     void *env_ptr; /* CPUArchState */
+    IcountDecr *icount_decr_ptr;
 
     /* Accessed in parallel; all accesses must be atomic */
     struct TranslationBlock *tb_jmp_cache[TB_JMP_CACHE_SIZE];
@@ -441,15 +446,6 @@ struct CPUState {
 
     bool ignore_memory_transaction_failures;
 
-    /* Note that this is accessed at the start of every TB via a negative
-       offset from AREG0.  Leave this field at the end so as to make the
-       (absolute value) offset as small as possible.  This reduces code
-       size, especially for hosts without large memory offsets.  */
-    union {
-        uint32_t u32;
-        icount_decr_u16 u16;
-    } icount_decr;
-
     struct hax_vcpu_state *hax_vcpu;
 
     int hvf_fd;