target/arm: Merge disas_a64_insn into aarch64_tr_translate_insn

It is confusing to have different exits from translation
for various conditions in separate functions.

Merge disas_a64_insn into its only caller.  Standardize
on the "s" name for the DisasContext, as the code from
disas_a64_insn had more instances.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210821195958.41312-3-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

target/arm/translate-a64.c

@@ -14649,113 +14649,6 @@ static bool btype_destination_ok(uint32_t insn, bool bt, int btype)
     return false;
 }
 
-/* C3.1 A64 instruction index by encoding */
-static void disas_a64_insn(CPUARMState *env, DisasContext *s)
-{
-    uint32_t insn;
-
-    s->pc_curr = s->base.pc_next;
-    insn = arm_ldl_code(env, s->base.pc_next, s->sctlr_b);
-    s->insn = insn;
-    s->base.pc_next += 4;
-
-    s->fp_access_checked = false;
-    s->sve_access_checked = false;
-
-    if (s->pstate_il) {
-        /*
-         * Illegal execution state. This has priority over BTI
-         * exceptions, but comes after instruction abort exceptions.
-         */
-        gen_exception_insn(s, s->pc_curr, EXCP_UDEF,
-                           syn_illegalstate(), default_exception_el(s));
-        return;
-    }
-
-    if (dc_isar_feature(aa64_bti, s)) {
-        if (s->base.num_insns == 1) {
-            /*
-             * At the first insn of the TB, compute s->guarded_page.
-             * We delayed computing this until successfully reading
-             * the first insn of the TB, above.  This (mostly) ensures
-             * that the softmmu tlb entry has been populated, and the
-             * page table GP bit is available.
-             *
-             * Note that we need to compute this even if btype == 0,
-             * because this value is used for BR instructions later
-             * where ENV is not available.
-             */
-            s->guarded_page = is_guarded_page(env, s);
-
-            /* First insn can have btype set to non-zero.  */
-            tcg_debug_assert(s->btype >= 0);
-
-            /*
-             * Note that the Branch Target Exception has fairly high
-             * priority -- below debugging exceptions but above most
-             * everything else.  This allows us to handle this now
-             * instead of waiting until the insn is otherwise decoded.
-             */
-            if (s->btype != 0
-                && s->guarded_page
-                && !btype_destination_ok(insn, s->bt, s->btype)) {
-                gen_exception_insn(s, s->pc_curr, EXCP_UDEF,
-                                   syn_btitrap(s->btype),
-                                   default_exception_el(s));
-                return;
-            }
-        } else {
-            /* Not the first insn: btype must be 0.  */
-            tcg_debug_assert(s->btype == 0);
-        }
-    }
-
-    switch (extract32(insn, 25, 4)) {
-    case 0x0: case 0x1: case 0x3: /* UNALLOCATED */
-        unallocated_encoding(s);
-        break;
-    case 0x2:
-        if (!dc_isar_feature(aa64_sve, s) || !disas_sve(s, insn)) {
-            unallocated_encoding(s);
-        }
-        break;
-    case 0x8: case 0x9: /* Data processing - immediate */
-        disas_data_proc_imm(s, insn);
-        break;
-    case 0xa: case 0xb: /* Branch, exception generation and system insns */
-        disas_b_exc_sys(s, insn);
-        break;
-    case 0x4:
-    case 0x6:
-    case 0xc:
-    case 0xe:      /* Loads and stores */
-        disas_ldst(s, insn);
-        break;
-    case 0x5:
-    case 0xd:      /* Data processing - register */
-        disas_data_proc_reg(s, insn);
-        break;
-    case 0x7:
-    case 0xf:      /* Data processing - SIMD and floating point */
-        disas_data_proc_simd_fp(s, insn);
-        break;
-    default:
-        assert(FALSE); /* all 15 cases should be handled above */
-        break;
-    }
-
-    /* if we allocated any temporaries, free them here */
-    free_tmp_a64(s);
-
-    /*
-     * After execution of most insns, btype is reset to 0.
-     * Note that we set btype == -1 when the insn sets btype.
-     */
-    if (s->btype > 0 && s->base.is_jmp != DISAS_NORETURN) {
-        reset_btype(s);
-    }
-}
-
 static void aarch64_tr_init_disas_context(DisasContextBase *dcbase,
                                           CPUState *cpu)
 {
@@ -14857,10 +14750,11 @@ static void aarch64_tr_insn_start(DisasContextBase *dcbase, CPUState *cpu)
 
 static void aarch64_tr_translate_insn(DisasContextBase *dcbase, CPUState *cpu)
 {
-    DisasContext *dc = container_of(dcbase, DisasContext, base);
+    DisasContext *s = container_of(dcbase, DisasContext, base);
     CPUARMState *env = cpu->env_ptr;
+    uint32_t insn;
 
-    if (dc->ss_active && !dc->pstate_ss) {
+    if (s->ss_active && !s->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
@@ -14871,14 +14765,114 @@ static void aarch64_tr_translate_insn(DisasContextBase *dcbase, CPUState *cpu)
          * "did not step an insn" case, and so the syndrome ISV and EX
          * bits should be zero.
          */
-        assert(dc->base.num_insns == 1);
-        gen_swstep_exception(dc, 0, 0);
-        dc->base.is_jmp = DISAS_NORETURN;
-    } else {
-        disas_a64_insn(env, dc);
+        assert(s->base.num_insns == 1);
+        gen_swstep_exception(s, 0, 0);
+        s->base.is_jmp = DISAS_NORETURN;
+        return;
+    }
+
+    s->pc_curr = s->base.pc_next;
+    insn = arm_ldl_code(env, s->base.pc_next, s->sctlr_b);
+    s->insn = insn;
+    s->base.pc_next += 4;
+
+    s->fp_access_checked = false;
+    s->sve_access_checked = false;
+
+    if (s->pstate_il) {
+        /*
+         * Illegal execution state. This has priority over BTI
+         * exceptions, but comes after instruction abort exceptions.
+         */
+        gen_exception_insn(s, s->pc_curr, EXCP_UDEF,
+                           syn_illegalstate(), default_exception_el(s));
+        return;
+    }
+
+    if (dc_isar_feature(aa64_bti, s)) {
+        if (s->base.num_insns == 1) {
+            /*
+             * At the first insn of the TB, compute s->guarded_page.
+             * We delayed computing this until successfully reading
+             * the first insn of the TB, above.  This (mostly) ensures
+             * that the softmmu tlb entry has been populated, and the
+             * page table GP bit is available.
+             *
+             * Note that we need to compute this even if btype == 0,
+             * because this value is used for BR instructions later
+             * where ENV is not available.
+             */
+            s->guarded_page = is_guarded_page(env, s);
+
+            /* First insn can have btype set to non-zero.  */
+            tcg_debug_assert(s->btype >= 0);
+
+            /*
+             * Note that the Branch Target Exception has fairly high
+             * priority -- below debugging exceptions but above most
+             * everything else.  This allows us to handle this now
+             * instead of waiting until the insn is otherwise decoded.
+             */
+            if (s->btype != 0
+                && s->guarded_page
+                && !btype_destination_ok(insn, s->bt, s->btype)) {
+                gen_exception_insn(s, s->pc_curr, EXCP_UDEF,
+                                   syn_btitrap(s->btype),
+                                   default_exception_el(s));
+                return;
+            }
+        } else {
+            /* Not the first insn: btype must be 0.  */
+            tcg_debug_assert(s->btype == 0);
+        }
+    }
+
+    switch (extract32(insn, 25, 4)) {
+    case 0x0: case 0x1: case 0x3: /* UNALLOCATED */
+        unallocated_encoding(s);
+        break;
+    case 0x2:
+        if (!dc_isar_feature(aa64_sve, s) || !disas_sve(s, insn)) {
+            unallocated_encoding(s);
+        }
+        break;
+    case 0x8: case 0x9: /* Data processing - immediate */
+        disas_data_proc_imm(s, insn);
+        break;
+    case 0xa: case 0xb: /* Branch, exception generation and system insns */
+        disas_b_exc_sys(s, insn);
+        break;
+    case 0x4:
+    case 0x6:
+    case 0xc:
+    case 0xe:      /* Loads and stores */
+        disas_ldst(s, insn);
+        break;
+    case 0x5:
+    case 0xd:      /* Data processing - register */
+        disas_data_proc_reg(s, insn);
+        break;
+    case 0x7:
+    case 0xf:      /* Data processing - SIMD and floating point */
+        disas_data_proc_simd_fp(s, insn);
+        break;
+    default:
+        assert(FALSE); /* all 15 cases should be handled above */
+        break;
+    }
+
+    /* if we allocated any temporaries, free them here */
+    free_tmp_a64(s);
+
+    /*
+     * After execution of most insns, btype is reset to 0.
+     * Note that we set btype == -1 when the insn sets btype.
+     */
+    if (s->btype > 0 && s->base.is_jmp != DISAS_NORETURN) {
+        reset_btype(s);
     }
 
-    translator_loop_temp_check(&dc->base);
+    translator_loop_temp_check(&s->base);
 }
 
 static void aarch64_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)