target/openrisc: Tidy ppc/npc implementation

The NPC SPR is really only supposed to be used for FPGA debugging.
It contains the same contents as PC, unless one plays games.  Follow
the or1ksim implementation in flushing delayed branch state when it
is changed.

The PPC SPR need not be updated every instruction, merely when we
exit the TB or attempt to read its contents.

Signed-off-by: Richard Henderson <rth@twiddle.net>

1 files changed, 11 insertions, 18 deletions

diff --git a/target/openrisc/translate.c b/target/openrisc/translate.c
index cda84b6..10f0633 100644
--- a/target/openrisc/translate.c
+++ b/target/openrisc/translate.c
@@ -39,7 +39,7 @@
 
 typedef struct DisasContext {
     TranslationBlock *tb;
-    target_ulong pc, ppc, npc;
+    target_ulong pc;
     uint32_t tb_flags, synced_flags, flags;
     uint32_t is_jmp;
     uint32_t mem_idx;
@@ -52,7 +52,6 @@ static TCGv cpu_sr;
 static TCGv cpu_R[32];
 static TCGv cpu_pc;
 static TCGv jmp_pc;            /* l.jr/l.jalr temp pc */
-static TCGv cpu_npc;
 static TCGv cpu_ppc;
 static TCGv cpu_sr_f;           /* bf/bnf, F flag taken */
 static TCGv cpu_sr_cy;          /* carry (unsigned overflow) */
@@ -83,8 +82,6 @@ void openrisc_translate_init(void)
                                        "flags");
     cpu_pc = tcg_global_mem_new(cpu_env,
                                 offsetof(CPUOpenRISCState, pc), "pc");
-    cpu_npc = tcg_global_mem_new(cpu_env,
-                                 offsetof(CPUOpenRISCState, npc), "npc");
     cpu_ppc = tcg_global_mem_new(cpu_env,
                                  offsetof(CPUOpenRISCState, ppc), "ppc");
     jmp_pc = tcg_global_mem_new(cpu_env,
@@ -1514,7 +1511,6 @@ void gen_intermediate_code(CPUOpenRISCState *env, struct TranslationBlock *tb)
     dc->tb = tb;
 
     dc->is_jmp = DISAS_NEXT;
-    dc->ppc = pc_start;
     dc->pc = pc_start;
     dc->flags = cpu->env.cpucfgr;
     dc->mem_idx = cpu_mmu_index(&cpu->env, false);
@@ -1543,7 +1539,7 @@ void gen_intermediate_code(CPUOpenRISCState *env, struct TranslationBlock *tb)
     gen_tb_start(tb);
 
     do {
-        tcg_gen_insn_start(dc->pc);
+        tcg_gen_insn_start(dc->pc, num_insns != 0);
         num_insns++;
 
         if (unlikely(cpu_breakpoint_test(cs, dc->pc, BP_ANY))) {
@@ -1561,12 +1557,9 @@ void gen_intermediate_code(CPUOpenRISCState *env, struct TranslationBlock *tb)
         if (num_insns == max_insns && (tb->cflags & CF_LAST_IO)) {
             gen_io_start();
         }
-        dc->ppc = dc->pc - 4;
-        dc->npc = dc->pc + 4;
-        tcg_gen_movi_tl(cpu_ppc, dc->ppc);
-        tcg_gen_movi_tl(cpu_npc, dc->npc);
         disas_openrisc_insn(dc, cpu);
-        dc->pc = dc->npc;
+        dc->pc = dc->pc + 4;
+
         /* delay slot */
         if (dc->delayed_branch) {
             dc->delayed_branch--;
@@ -1574,10 +1567,8 @@ void gen_intermediate_code(CPUOpenRISCState *env, struct TranslationBlock *tb)
                 dc->tb_flags &= ~D_FLAG;
                 gen_sync_flags(dc);
                 tcg_gen_mov_tl(cpu_pc, jmp_pc);
-                tcg_gen_mov_tl(cpu_npc, jmp_pc);
-                tcg_gen_movi_tl(jmp_pc, 0);
-                tcg_gen_exit_tb(0);
-                dc->is_jmp = DISAS_JUMP;
+                tcg_gen_discard_tl(jmp_pc);
+                dc->is_jmp = DISAS_UPDATE;
                 break;
             }
         }
@@ -1591,14 +1582,13 @@ void gen_intermediate_code(CPUOpenRISCState *env, struct TranslationBlock *tb)
     if (tb->cflags & CF_LAST_IO) {
         gen_io_end();
     }
+
+    tcg_gen_movi_tl(cpu_ppc, dc->pc - 4);
     if (dc->is_jmp == DISAS_NEXT) {
         dc->is_jmp = DISAS_UPDATE;
         tcg_gen_movi_tl(cpu_pc, dc->pc);
     }
     if (unlikely(cs->singlestep_enabled)) {
-        if (dc->is_jmp == DISAS_NEXT) {
-            tcg_gen_movi_tl(cpu_pc, dc->pc);
-        }
         gen_exception(dc, EXCP_DEBUG);
     } else {
         switch (dc->is_jmp) {
@@ -1651,4 +1641,7 @@ void restore_state_to_opc(CPUOpenRISCState *env, TranslationBlock *tb,
                           target_ulong *data)
 {
     env->pc = data[0];
+    if (data[1]) {
+        env->ppc = env->pc - 4;
+    }
 }