From 290bff3f3e491e8b523d90cd25637e85ccc863a7 Mon Sep 17 00:00:00 2001
From: Denis Drakhnya <numas13@gmail.com>
Date: Sat, 28 Nov 2020 11:32:50 +0200
Subject: [PATCH] target: e2k: Fix instr return.

---
 target/e2k/helper.c            | 19 +++++++++++++++++++
 target/e2k/helper.h            |  1 +
 target/e2k/translate.c         |  1 -
 target/e2k/translate/control.c | 11 ++++++++---
 4 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/target/e2k/helper.c b/target/e2k/helper.c
index 0578621641..00c0a41dad 100644
--- a/target/e2k/helper.c
+++ b/target/e2k/helper.c
@@ -192,6 +192,25 @@ static inline void do_call(CPUE2KState *env, int wbs, target_ulong pc_next)
     reset_ctprs(env);
 }
 
+uint64_t helper_prep_return(CPUE2KState *env, int ipd)
+{
+    uint64_t pc, ret = 0;
+    void *p;
+
+    if (env->pcsp.index < 32) {
+        helper_raise_exception(env, E2K_EXCP_MAPERR);
+        return 0;
+    }
+
+    p = (void *) env->pcsp.base + env->pcsp.index - 24;
+    memcpy(&pc, p, 8);
+    ret |= deposit64(ret, CTPR_BASE_OFF, CTPR_BASE_LEN, pc);
+    ret |= deposit64(ret, CTPR_TAG_OFF, CTPR_TAG_LEN, CTPR_TAG_RETURN);
+    ret |= deposit64(ret, CTPR_IPD_OFF, CTPR_IPD_LEN, ipd);
+
+    return ret;
+}
+
 void helper_return(CPUE2KState *env)
 {
     uint32_t new_wd_size, new_wd_base, offset;
diff --git a/target/e2k/helper.h b/target/e2k/helper.h
index 1381c11331..e13e331a71 100644
--- a/target/e2k/helper.h
+++ b/target/e2k/helper.h
@@ -1,5 +1,6 @@
 DEF_HELPER_2(raise_exception, noreturn, env, int)
 DEF_HELPER_1(debug, void, env)
+DEF_HELPER_2(prep_return, i64, env, int)
 DEF_HELPER_1(return, void, env)
 DEF_HELPER_4(call, void, env, i64, int, tl)
 DEF_HELPER_2(sxt, i64, i64, i64)
diff --git a/target/e2k/translate.c b/target/e2k/translate.c
index deb59d1bcd..b223209958 100644
--- a/target/e2k/translate.c
+++ b/target/e2k/translate.c
@@ -382,7 +382,6 @@ static inline void do_branch(DisasContext *ctx, target_ulong pc_next)
         gen_goto_ctpr_disp(ctx->ct.u.ctpr);
 
         gen_set_label(l1);
-        // FIXME: gdb does not see IP change
         gen_helper_return(cpu_env);
         tcg_gen_lookup_and_goto_ptr();
         break;
diff --git a/target/e2k/translate/control.c b/target/e2k/translate/control.c
index 34a2b450ba..1e36fd81a3 100644
--- a/target/e2k/translate/control.c
+++ b/target/e2k/translate/control.c
@@ -296,9 +296,14 @@ static void gen_cs0(DisasContext *dc)
            lowermost ones are undefined, while the latter also known as "type"
            field should be filled in with zeroes.  */
         if (type == RETURN) {
-            uint64_t reg = ((uint64_t) CTPR_TAG_RETURN << CTPR_TAG_OFF) |
-                ((uint64_t) ipd << CTPR_IPD_OFF);
-            tcg_gen_movi_tl(e2k_cs.ctprs[ctpr - 1], reg);
+            TCGv_i32 t0 = tcg_const_i32(ipd);
+
+            if (ctpr != 3) {
+                e2k_tr_gen_exception(dc, E2K_EXCP_ILLOPN);
+            }
+
+            gen_helper_prep_return(e2k_cs.ctprs[2], cpu_env, t0);
+            tcg_temp_free_i32(t0);
         }
 
         /* GETTSD has as meaningless `CS0.param' as RETURN. The only