[Qemu-devel] [PATCH v3 15/69] target/arm: Convert BX, BXJ, BLX (register)

[Richard Henderson <richard.henderson@linaro.org>]

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/translate.c | 78 ++++++++++++++++++++----------------------
 target/arm/a32.decode  |  7 ++++
 target/arm/t32.decode  |  2 ++
 3 files changed, 47 insertions(+), 40 deletions(-)

diff --git a/target/arm/translate.c b/target/arm/translate.c
index c2420ff45e..d60e859624 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -8432,6 +8432,38 @@ static bool trans_MSR_v7m(DisasContext *s, arg_MSR_v7m *a)
     return true;
 }
 
+static bool trans_BX(DisasContext *s, arg_BX *a)
+{
+    if (!ENABLE_ARCH_4T) {
+        return false;
+    }
+    gen_bx(s, load_reg(s, a->rm));
+    return true;
+}
+
+static bool trans_BXJ(DisasContext *s, arg_BXJ *a)
+{
+    if (!ENABLE_ARCH_5J || arm_dc_feature(s, ARM_FEATURE_M)) {
+        return false;
+    }
+    /* Trivial implementation equivalent to bx.  */
+    gen_bx(s, load_reg(s, a->rm));
+    return true;
+}
+
+static bool trans_BLX_r(DisasContext *s, arg_BLX_r *a)
+{
+    TCGv_i32 tmp;
+
+    if (!ENABLE_ARCH_5) {
+        return false;
+    }
+    tmp = load_reg(s, a->rm);
+    tcg_gen_movi_i32(cpu_R[14], s->base.pc_next | s->thumb);
+    gen_bx(s, tmp);
+    return true;
+}
+
 /*
  * Legacy decoder.
  */
@@ -8721,12 +8753,7 @@ static void disas_arm_insn(DisasContext *s, unsigned int insn)
             /* All done in decodetree.  Illegal ops already signalled.  */
             g_assert_not_reached();
         case 0x1:
-            if (op1 == 1) {
-                /* branch/exchange thumb (bx).  */
-                ARCH(4T);
-                tmp = load_reg(s, rm);
-                gen_bx(s, tmp);
-            } else if (op1 == 3) {
+            if (op1 == 3) {
                 /* clz */
                 ARCH(5);
                 rd = (insn >> 12) & 0xf;
@@ -8737,30 +8764,9 @@ static void disas_arm_insn(DisasContext *s, unsigned int insn)
                 goto illegal_op;
             }
             break;
-        case 0x2:
-            if (op1 == 1) {
-                ARCH(5J); /* bxj */
-                /* Trivial implementation equivalent to bx.  */
-                tmp = load_reg(s, rm);
-                gen_bx(s, tmp);
-            } else {
-                goto illegal_op;
-            }
-            break;
-        case 0x3:
-            if (op1 != 1)
-              goto illegal_op;
-
-            ARCH(5);
-            /* branch link/exchange thumb (blx) */
-            tmp = load_reg(s, rm);
-            tmp2 = tcg_temp_new_i32();
-            tcg_gen_movi_i32(tmp2, s->base.pc_next);
-            store_reg(s, 14, tmp2);
-            gen_bx(s, tmp);
-            break;
-        case 0x4:
-            /* crc32 */
+        case 0x2: /* bxj */
+        case 0x3: /* blx */
+        case 0x4: /* crc32 */
             /* All done in decodetree.  Illegal ops reach here.  */
             goto illegal_op;
         case 0x5:
@@ -10578,16 +10584,8 @@ static void disas_thumb2_insn(DisasContext *s, uint32_t insn)
                             goto illegal_op;
                         }
                         break;
-                    case 4: /* bxj */
-                        /* Trivial implementation equivalent to bx.
-                         * This instruction doesn't exist at all for M-profile.
-                         */
-                        if (arm_dc_feature(s, ARM_FEATURE_M)) {
-                            goto illegal_op;
-                        }
-                        tmp = load_reg(s, rn);
-                        gen_bx(s, tmp);
-                        break;
+                    case 4: /* bxj, in decodetree */
+                        goto illegal_op;
                     case 5: /* Exception return.  */
                         if (IS_USER(s)) {
                             goto illegal_op;
diff --git a/target/arm/a32.decode b/target/arm/a32.decode
index a8ef435b15..6cb9c16e2f 100644
--- a/target/arm/a32.decode
+++ b/target/arm/a32.decode
@@ -29,6 +29,7 @@
 &s_rrrr          s rd rn rm ra
 &rrrr            rd rn rm ra
 &rrr             rd rn rm
+&r               rm
 &msr_reg         rn r mask
 &mrs_reg         rd r
 &msr_bank        rn r sysm
@@ -195,8 +196,14 @@ CRC32CW          .... 0001 0100 .... .... 0010 0100 ....      @rndm
 
 %sysm            8:1 16:4
 
+@rm              ---- .... .... .... .... .... .... rm:4      &r
+
 MRS_bank         ---- 0001 0 r:1 00 .... rd:4 001. 0000 0000  &mrs_bank %sysm
 MSR_bank         ---- 0001 0 r:1 10 .... 1111 001. 0000 rn:4  &msr_bank %sysm
 
 MRS_reg          ---- 0001 0 r:1 00 1111   rd:4 0000 0000 0000  &mrs_reg
 MSR_reg          ---- 0001 0 r:1 10 mask:4 1111 0000 0000 rn:4  &msr_reg
+
+BX               .... 0001 0010 1111 1111 1111 0001 ....      @rm
+BXJ              .... 0001 0010 1111 1111 1111 0010 ....      @rm
+BLX_r            .... 0001 0010 1111 1111 1111 0011 ....      @rm
diff --git a/target/arm/t32.decode b/target/arm/t32.decode
index 261db100ff..337706ebbe 100644
--- a/target/arm/t32.decode
+++ b/target/arm/t32.decode
@@ -26,6 +26,7 @@
 &s_rrrr          !extern s rd rn rm ra
 &rrrr            !extern rd rn rm ra
 &rrr             !extern rd rn rm
+&r               !extern rm
 &msr_reg         !extern rn r mask
 &mrs_reg         !extern rd r
 &msr_bank        !extern rn r sysm
@@ -211,4 +212,5 @@ CRC32CW          1111 1010 1101 .... 1111 .... 1010 ....      @rndm
     MSR_reg      1111 0011 100 r:1 rn:4 1000 mask:4 0000 0000  &msr_reg
     MSR_v7m      1111 0011 100 0   rn:4 1000 mask:2 00 sysm:8
   }
+  BXJ            1111 0011 1100 rm:4 1000 1111 0000 0000      &r
 }
-- 
2.17.1