target: [tcg] Use a generic enum for DISAS_ values

Used later. An enum makes expected values explicit and
bounds the value space of switches.

Backports commit 77fc6f5e28667634916f114ae04c6029cd7b9c45 from qemu

qemu/include/exec/exec-all.h

@@ -35,36 +35,6 @@ typedef abi_ulong tb_page_addr_t;
 typedef ram_addr_t tb_page_addr_t;
 #endif
 
-/* DisasContext is_jmp field values
- *
- * is_jmp starts as DISAS_NEXT. The translator will keep processing
- * instructions until an exit condition is reached. If we reach the
- * exit condition and is_jmp is still DISAS_NEXT (because of some
- * other condition) we simply "jump" to the next address.
- * The remaining exit cases are:
- *
- *   DISAS_JUMP    - Only the PC was modified dynamically (e.g computed)
- *   DISAS_TB_JUMP - Only the PC was modified statically (e.g. branch)
- *
- * In these cases as long as the PC is updated we can chain to the
- * next TB either by exiting the loop or looking up the next TB via
- * the loookup helper.
- *
- *   DISAS_UPDATE  - CPU State was modified dynamically
- *
- * This covers any other CPU state which necessities us exiting the
- * TCG code to the main run-loop. Typically this includes anything
- * that might change the interrupt state.
- *
- * Individual translators may define additional exit cases to deal
- * with per-target special conditions.
- */
-#define DISAS_NEXT    0 /* next instruction can be analyzed */
-#define DISAS_JUMP    1 /* only pc was modified dynamically */
-#define DISAS_TB_JUMP 2 /* only pc was modified statically */
-#define DISAS_UPDATE  3 /* cpu state was modified dynamically */
-#define DISAS_NORETURN 4 /* the tb has already been exited */
-
 #include "qemu/log.h"
 
 void gen_intermediate_code(CPUState *cpu, struct TranslationBlock *tb);

qemu/include/exec/translator.h

@@ -0,0 +1,40 @@
+/*
+ * Generic intermediate code generation.
+ *
+ * Copyright (C) 2016-2017 Lluís Vilanova <vilanova@ac.upc.edu>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef EXEC__TRANSLATOR_H
+#define EXEC__TRANSLATOR_H
+
+/**
+ * DisasJumpType:
+ * @DISAS_NEXT: Next instruction in program order.
+ * @DISAS_TOO_MANY: Too many instructions translated.
+ * @DISAS_NORETURN: Following code is dead.
+ * @DISAS_TARGET_*: Start of target-specific conditions.
+ *
+ * What instruction to disassemble next.
+ */
+typedef enum DisasJumpType {
+    DISAS_NEXT,
+    DISAS_TOO_MANY,
+    DISAS_NORETURN,
+    DISAS_TARGET_0,
+    DISAS_TARGET_1,
+    DISAS_TARGET_2,
+    DISAS_TARGET_3,
+    DISAS_TARGET_4,
+    DISAS_TARGET_5,
+    DISAS_TARGET_6,
+    DISAS_TARGET_7,
+    DISAS_TARGET_8,
+    DISAS_TARGET_9,
+    DISAS_TARGET_10,
+    DISAS_TARGET_11,
+} DisasJumpType;
+
+#endif  /* EXEC__TRANSLATOR_H */

qemu/target/arm/translate.c

@@ -4283,7 +4283,7 @@ static void gen_goto_tb(DisasContext *s, int n, target_ulong dest)
         gen_set_pc_im(s, dest);
         gen_goto_ptr(s);
     }
-    s->is_jmp = DISAS_TB_JUMP;
+    s->is_jmp = DISAS_NORETURN;
 }
 
 static inline void gen_jmp(DisasContext *s, uint32_t dest)
@@ -4295,7 +4295,6 @@ static inline void gen_jmp(DisasContext *s, uint32_t dest)
         gen_bx_im(s, dest);
     } else {
         gen_goto_tb(s, 0, dest);
-        s->is_jmp = DISAS_TB_JUMP;
     }
 }
 

qemu/target/arm/translate.h

@@ -1,6 +1,8 @@
 #ifndef TARGET_ARM_TRANSLATE_H
 #define TARGET_ARM_TRANSLATE_H
 
+#include "exec/translator.h"
+
 /* internal defines */
 typedef struct DisasContext {
     target_ulong pc;
@@ -119,28 +121,31 @@ static void disas_set_insn_syndrome(DisasContext *s, uint32_t syn)
 }
 
 /* target-specific extra values for is_jmp */
+/* is_jmp field values */
+#define DISAS_JUMP      DISAS_TARGET_0 /* only pc was modified dynamically */
+#define DISAS_UPDATE    DISAS_TARGET_1 /* cpu state was modified dynamically */
 /* These instructions trap after executing, so the A32/T32 decoder must
  * defer them until after the conditional execution state has been updated.
  * WFI also needs special handling when single-stepping.
  */
-#define DISAS_WFI 5
-#define DISAS_SWI 6
+#define DISAS_WFI       DISAS_TARGET_2
+#define DISAS_SWI       DISAS_TARGET_3
 /* WFE */
-#define DISAS_WFE 7
-#define DISAS_HVC 8
-#define DISAS_SMC 9
-#define DISAS_YIELD 10
+#define DISAS_WFE       DISAS_TARGET_4
+#define DISAS_HVC       DISAS_TARGET_5
+#define DISAS_SMC       DISAS_TARGET_6
+#define DISAS_YIELD     DISAS_TARGET_7
 /* M profile branch which might be an exception return (and so needs
  * custom end-of-TB code)
  */
-#define DISAS_BX_EXCRET 11
+#define DISAS_BX_EXCRET DISAS_TARGET_8
 /* For instructions which want an immediate exit to the main loop,
  * as opposed to attempting to use lookup_and_goto_ptr. Unlike
  * DISAS_UPDATE this doesn't write the PC on exiting the translation
  * loop so you need to ensure something (gen_a64_set_pc_im or runtime
  * helper) has done so before we reach return from cpu_tb_exec.
  */
-#define DISAS_EXIT 12
+#define DISAS_EXIT      DISAS_TARGET_9
 
 #ifdef TARGET_AARCH64
 void a64_translate_init(struct uc_struct *uc);

qemu/target/i386/translate.c

@@ -25,13 +25,13 @@
 #include "exec/exec-all.h"
 #include "tcg-op.h"
 #include "exec/cpu_ldst.h"
+#include "exec/translator.h"
+
 #include "exec/helper-proto.h"
 #include "exec/helper-gen.h"
 
 #include "uc_priv.h"
 
-#define DISAS_TOO_MANY 5
-
 #define PREFIX_REPZ   0x01
 #define PREFIX_REPNZ  0x02
 #define PREFIX_LOCK   0x04
@@ -5045,7 +5045,7 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
         gen_update_cc_op(s);
         gen_jmp_im(s, pc_start - s->cs_base);
         gen_helper_hlt(tcg_ctx, cpu_env, tcg_const_i32(tcg_ctx, s->pc - pc_start));
-        s->is_jmp = DISAS_TB_JUMP;
+        s->is_jmp = DISAS_NORETURN;
         return s->pc;
     }
 
@@ -9245,7 +9245,7 @@ void gen_intermediate_code(CPUState *cs, TranslationBlock *tb)
         gen_tb_start(tcg_ctx);
         gen_jmp_im(dc, tb->pc - tb->cs_base);
         gen_helper_hlt(tcg_ctx, tcg_ctx->cpu_env, tcg_const_i32(tcg_ctx, 0));
-        dc->is_jmp = DISAS_TB_JUMP;
+        dc->is_jmp = DISAS_NORETURN;
         goto done_generating;
     }
 

qemu/target/m68k/translate.c

@@ -24,6 +24,7 @@
 #include "tcg-op.h"
 #include "qemu/log.h"
 #include "exec/cpu_ldst.h"
+#include "exec/translator.h"
 
 #include "exec/helper-proto.h"
 #include "exec/helper-gen.h"
@@ -158,7 +159,11 @@ static void do_writebacks(DisasContext *s)
     }
 }
 
-#define DISAS_JUMP_NEXT 4
+/* is_jmp field values */
+#define DISAS_JUMP      DISAS_TARGET_0 /* only pc was modified dynamically */
+#define DISAS_UPDATE    DISAS_TARGET_1 /* cpu state was modified dynamically */
+#define DISAS_TB_JUMP   DISAS_TARGET_2 /* only pc was modified statically */
+#define DISAS_JUMP_NEXT DISAS_TARGET_3
 
 #if defined(CONFIG_USER_ONLY)
 #define IS_USER(s) 1