[PULL 19/23] accel/tcg: remove CF_NOCACHE and special cases

["Alex Bennée" <alex.bennee@linaro.org>]

Now we no longer generate CF_NOCACHE blocks we can remove a bunch of
the special case handling for them. While we are at it we can remove
the unused tb->orig_tb field and save a few bytes on the TB structure.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210213130325.14781-20-alex.bennee@linaro.org>

diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
index d30c7a84f6..665fe68607 100644
--- a/include/exec/exec-all.h
+++ b/include/exec/exec-all.h
@@ -454,7 +454,6 @@ struct TranslationBlock {
     uint32_t cflags;    /* compile flags */
 #define CF_COUNT_MASK  0x00007fff
 #define CF_LAST_IO     0x00008000 /* Last insn may be an IO access.  */
-#define CF_NOCACHE     0x00010000 /* To be freed after execution */
 #define CF_USE_ICOUNT  0x00020000
 #define CF_INVALID     0x00040000 /* TB is stale. Set with @jmp_lock held */
 #define CF_PARALLEL    0x00080000 /* Generate code for a parallel context */
@@ -469,8 +468,6 @@ struct TranslationBlock {
 
     struct tb_tc tc;
 
-    /* original tb when cflags has CF_NOCACHE */
-    struct TranslationBlock *orig_tb;
     /* first and second physical page containing code. The lower bit
        of the pointer tells the index in page_next[].
        The list is protected by the TB's page('s) lock(s) */
diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
index 72b3c663c5..464b3c3394 100644
--- a/accel/tcg/translate-all.c
+++ b/accel/tcg/translate-all.c
@@ -410,12 +410,6 @@ bool cpu_restore_state(CPUState *cpu, uintptr_t host_pc, bool will_exit)
         TranslationBlock *tb = tcg_tb_lookup(host_pc);
         if (tb) {
             cpu_restore_state_from_tb(cpu, tb, host_pc, will_exit);
-            if (tb_cflags(tb) & CF_NOCACHE) {
-                /* one-shot translation, invalidate it immediately */
-                tb_phys_invalidate(tb, -1);
-                tcg_tb_remove(tb);
-                tb_destroy(tb);
-            }
             return true;
         }
     }
@@ -1634,8 +1628,7 @@ static void do_tb_phys_invalidate(TranslationBlock *tb, bool rm_from_page_list)
     phys_pc = tb->page_addr[0] + (tb->pc & ~TARGET_PAGE_MASK);
     h = tb_hash_func(phys_pc, tb->pc, tb->flags, tb_cflags(tb) & CF_HASH_MASK,
                      tb->trace_vcpu_dstate);
-    if (!(tb->cflags & CF_NOCACHE) &&
-        !qht_remove(&tb_ctx.htable, tb, h)) {
+    if (!qht_remove(&tb_ctx.htable, tb, h)) {
         return;
     }
 
@@ -1796,6 +1789,8 @@ tb_link_page(TranslationBlock *tb, tb_page_addr_t phys_pc,
 {
     PageDesc *p;
     PageDesc *p2 = NULL;
+    void *existing_tb = NULL;
+    uint32_t h;
 
     assert_memory_lock();
 
@@ -1815,25 +1810,20 @@ tb_link_page(TranslationBlock *tb, tb_page_addr_t phys_pc,
         tb->page_addr[1] = -1;
     }
 
-    if (!(tb->cflags & CF_NOCACHE)) {
-        void *existing_tb = NULL;
-        uint32_t h;
-
-        /* add in the hash table */
-        h = tb_hash_func(phys_pc, tb->pc, tb->flags, tb->cflags & CF_HASH_MASK,
-                         tb->trace_vcpu_dstate);
-        qht_insert(&tb_ctx.htable, tb, h, &existing_tb);
+    /* add in the hash table */
+    h = tb_hash_func(phys_pc, tb->pc, tb->flags, tb->cflags & CF_HASH_MASK,
+                     tb->trace_vcpu_dstate);
+    qht_insert(&tb_ctx.htable, tb, h, &existing_tb);
 
-        /* remove TB from the page(s) if we couldn't insert it */
-        if (unlikely(existing_tb)) {
-            tb_page_remove(p, tb);
-            invalidate_page_bitmap(p);
-            if (p2) {
-                tb_page_remove(p2, tb);
-                invalidate_page_bitmap(p2);
-            }
-            tb = existing_tb;
+    /* remove TB from the page(s) if we couldn't insert it */
+    if (unlikely(existing_tb)) {
+        tb_page_remove(p, tb);
+        invalidate_page_bitmap(p);
+        if (p2) {
+            tb_page_remove(p2, tb);
+            invalidate_page_bitmap(p2);
         }
+        tb = existing_tb;
     }
 
     if (p2 && p2 != p) {
@@ -1906,7 +1896,6 @@ TranslationBlock *tb_gen_code(CPUState *cpu,
     tb->cs_base = cs_base;
     tb->flags = flags;
     tb->cflags = cflags;
-    tb->orig_tb = NULL;
     tb->trace_vcpu_dstate = *cpu->trace_dstate;
     tcg_ctx->tb_cflags = cflags;
  tb_overflow:
@@ -2445,16 +2434,6 @@ void cpu_io_recompile(CPUState *cpu, uintptr_t retaddr)
     /* Generate a new TB executing the I/O insn.  */
     cpu->cflags_next_tb = curr_cflags() | CF_LAST_IO | n;
 
-    if (tb_cflags(tb) & CF_NOCACHE) {
-        if (tb->orig_tb) {
-            /* Invalidate original TB if this TB was generated in
-             * cpu_exec_nocache() */
-            tb_phys_invalidate(tb->orig_tb, -1);
-        }
-        tcg_tb_remove(tb);
-        tb_destroy(tb);
-    }
-
     qemu_log_mask_and_addr(CPU_LOG_EXEC, tb->pc,
                            "cpu_io_recompile: rewound execution of TB to "
                            TARGET_FMT_lx "\n", tb->pc);
-- 
2.20.1