target/arm: [tcg,a64] Port to translate_insn

Incrementally paves the way towards using the generic instruction translation
loop.

Backports commit 24299c892cbfe29120f051b6b7d0bcf3e0cc8e85 from qemu

qemu/target/arm/translate-a64.c

@@ -11501,6 +11501,9 @@ static int aarch64_tr_init_disas_context(DisasContextBase *dcbase,
     dc->is_ldex = false;
     dc->ss_same_el = (arm_debug_target_el(env) == dc->current_el);
 
+    dc->next_page_start =
+        (dc->base.pc_first & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE;
+
     init_tmp_a64_array(dc);
 
     return max_insns;
@@ -11540,13 +11543,45 @@ static bool aarch64_tr_breakpoint_check(DisasContextBase *dcbase, CPUState *cpu,
     return true;
 }
 
+static void aarch64_tr_translate_insn(DisasContextBase *dcbase, CPUState *cpu)
+{
+    DisasContext *dc = container_of(dcbase, DisasContext, base);
+    CPUARMState *env = cpu->env_ptr;
+
+    if (dc->ss_active && !dc->pstate_ss) {
+        /* Singlestep state is Active-pending.
+         * If we're in this state at the start of a TB then either
+         *  a) we just took an exception to an EL which is being debugged
+         *     and this is the first insn in the exception handler
+         *  b) debug exceptions were masked and we just unmasked them
+         *     without changing EL (eg by clearing PSTATE.D)
+         * In either case we're going to take a swstep exception in the
+         * "did not step an insn" case, and so the syndrome ISV and EX
+         * bits should be zero.
+         */
+        assert(dc->base.num_insns == 1);
+        gen_exception(dc, EXCP_UDEF, syn_swstep(dc->ss_same_el, 0, 0),
+                      default_exception_el(dc));
+        dc->base.is_jmp = DISAS_NORETURN;
+    } else {
+        disas_a64_insn(env, dc);
+    }
+
+    if (dc->base.is_jmp == DISAS_NEXT) {
+        if (dc->ss_active || dc->pc >= dc->next_page_start) {
+            dc->base.is_jmp = DISAS_TOO_MANY;
+        }
+    }
+
+    dc->base.pc_next = dc->pc;
+}
+
 void gen_intermediate_code_a64(DisasContextBase *dcbase, CPUState *cs,
                                TranslationBlock *tb)
 {
     CPUARMState *env = cs->env_ptr;
     TCGContext *tcg_ctx = env->uc->tcg_ctx;
     DisasContext *dc = container_of(dcbase, DisasContext, base);
-    target_ulong next_page_start;
     int max_insns;
     bool block_full = false;
 
@@ -11557,7 +11592,6 @@ void gen_intermediate_code_a64(DisasContextBase *dcbase, CPUState *cs,
     dc->base.num_insns = 0;
     dc->base.singlestep_enabled = cs->singlestep_enabled;
 
-    next_page_start = (dc->base.pc_first & TARGET_PAGE_MASK) + TARGET_PAGE_SIZE;
     max_insns = dc->base.tb->cflags & CF_COUNT_MASK;
     if (max_insns == 0) {
         max_insns = CF_COUNT_MASK;
@@ -11613,41 +11647,24 @@ void gen_intermediate_code_a64(DisasContextBase *dcbase, CPUState *cs,
         //    gen_io_start();
         //}
 
-        if (dc->ss_active && !dc->pstate_ss) {
+        aarch64_tr_translate_insn(&dc->base, cs);
-            /* Singlestep state is Active-pending.
-             * If we're in this state at the start of a TB then either
-             *  a) we just took an exception to an EL which is being debugged
-             *     and this is the first insn in the exception handler
-             *  b) debug exceptions were masked and we just unmasked them
-             *     without changing EL (eg by clearing PSTATE.D)
-             * In either case we're going to take a swstep exception in the
-             * "did not step an insn" case, and so the syndrome ISV and EX
-             * bits should be zero.
-             */
-            assert(dc->base.num_insns == 1);
-            gen_exception(dc, EXCP_UDEF, syn_swstep(dc->ss_same_el, 0, 0),
-                          default_exception_el(dc));
-            dc->base.is_jmp = DISAS_NORETURN;
-            break;
-        }
-
-        disas_a64_insn(env, dc);
 
         if (tcg_check_temp_count()) {
             fprintf(stderr, "TCG temporary leak before "TARGET_FMT_lx"\n",
                     dc->pc);
         }
 
+        if (!dc->base.is_jmp && (tcg_op_buf_full(tcg_ctx) || cs->singlestep_enabled ||
+                            /* Unicorn: commented out: singlestep ||*/ dc->base.num_insns >= max_insns)) {
+            dc->base.is_jmp = DISAS_TOO_MANY;
+        }
+
         /* Translation stops when a conditional branch is encountered.
          * Otherwise the subsequent code could get translated several times.
          * Also stop translation when a page boundary is reached.  This
          * ensures prefetch aborts occur at the right place.
          */
-    } while (!dc->base.is_jmp && !tcg_op_buf_full(tcg_ctx) &&
+    } while (!dc->base.is_jmp);
-             !cs->singlestep_enabled &&
-             !dc->ss_active &&
-             dc->pc < next_page_start &&
-             dc->base.num_insns < max_insns);
 
     /* if too long translation, save this info */
     if (tcg_op_buf_full(tcg_ctx) || dc->base.num_insns >= max_insns) {