target/arm: Convert T16, Miscellaneous 16-bit instructions

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20190904193059.26202-64-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

target/arm/t16.decode

@@ -211,18 +211,29 @@ REVSH           1011 1010 11 ... ...            @rdm
 # Hints
 
 {
-  YIELD         1011 1111 0001 0000
-  WFE           1011 1111 0010 0000
-  WFI           1011 1111 0011 0000
+  {
+    YIELD       1011 1111 0001 0000
+    WFE         1011 1111 0010 0000
+    WFI         1011 1111 0011 0000
+
+    # TODO: Implement SEV, SEVL; may help SMP performance.
+    # SEV       1011 1111 0100 0000
+    # SEVL      1011 1111 0101 0000
+
+    # The canonical nop has the second nibble as 0000, but the whole of the
+    # rest of the space is a reserved hint, behaves as nop.
+    NOP         1011 1111 ---- 0000
+  }
+  IT            1011 1111 cond_mask:8
+}
 
-  # TODO: Implement SEV, SEVL; may help SMP performance.
-  # SEV         1011 1111 0100 0000
-  # SEVL        1011 1111 0101 0000
+# Miscellaneous 16-bit instructions
 
-  # The canonical nop has the second nibble as 0000, but the whole of the
-  # rest of the space is a reserved hint, behaves as nop.
-  NOP           1011 1111 ---- 0000
-}
+%imm6_9_3       9:1 3:5 !function=times_2
+
+HLT             1011 1010 10 imm:6              &i
+BKPT            1011 1110 imm:8                 &i
+CBZ             1011 nz:1 0.1 ..... rn:3        imm=%imm6_9_3
 
 # Push and Pop
 

target/arm/translate.c

@@ -10196,6 +10196,18 @@ static bool trans_TBH(DisasContext *s, arg_tbranch *a)
     return op_tbranch(s, a, true);
 }
 
+static bool trans_CBZ(DisasContext *s, arg_CBZ *a)
+{
+    TCGv_i32 tmp = load_reg(s, a->rn);
+
+    arm_gen_condlabel(s);
+    tcg_gen_brcondi_i32(a->nz ? TCG_COND_EQ : TCG_COND_NE,
+                        tmp, 0, s->condlabel);
+    tcg_temp_free_i32(tmp);
+    gen_jmp(s, read_pc(s) + a->imm);
+    return true;
+}
+
 /*
  * Supervisor call
  */
@@ -10417,6 +10429,27 @@ static bool trans_PLI(DisasContext *s, arg_PLD *a)
     return ENABLE_ARCH_7;
 }
 
+/*
+ * If-then
+ */
+
+static bool trans_IT(DisasContext *s, arg_IT *a)
+{
+    int cond_mask = a->cond_mask;
+
+    /*
+     * No actual code generated for this insn, just setup state.
+     *
+     * Combinations of firstcond and mask which set up an 0b1111
+     * condition are UNPREDICTABLE; we take the CONSTRAINED
+     * UNPREDICTABLE choice to treat 0b1111 the same as 0b1110,
+     * i.e. both meaning "execute always".
+     */
+    s->condexec_cond = (cond_mask >> 4) & 0xe;
+    s->condexec_mask = cond_mask & 0x1f;
+    return true;
+}
+
 /*
  * Legacy decoder.
  */
@@ -10783,83 +10816,8 @@ static void disas_thumb_insn(DisasContext *s, uint32_t insn)
     case 8: /* load/store halfword immediate offset, in decodetree */
     case 9: /* load/store from stack, in decodetree */
     case 10: /* add PC/SP (immediate), in decodetree */
+    case 11: /* misc, in decodetree */
     case 12: /* load/store multiple, in decodetree */
-        goto illegal_op;
-
-    case 11:
-        /* misc */
-        op = (insn >> 8) & 0xf;
-        switch (op) {
-        case 0: /* add/sub (sp, immediate), in decodetree */
-        case 2: /* sign/zero extend, in decodetree */
-            goto illegal_op;
-
-        case 4: case 5: case 0xc: case 0xd:
-            /* push/pop, in decodetree */
-            goto illegal_op;
-
-        case 1: case 3: case 9: case 11: /* czb */
-            rm = insn & 7;
-            tmp = load_reg(s, rm);
-            arm_gen_condlabel(s);
-            if (insn & (1 << 11))
-                tcg_gen_brcondi_i32(TCG_COND_EQ, tmp, 0, s->condlabel);
-            else
-                tcg_gen_brcondi_i32(TCG_COND_NE, tmp, 0, s->condlabel);
-            tcg_temp_free_i32(tmp);
-            offset = ((insn & 0xf8) >> 2) | (insn & 0x200) >> 3;
-            gen_jmp(s, read_pc(s) + offset);
-            break;
-
-        case 15: /* IT, nop-hint.  */
-            if ((insn & 0xf) == 0) {
-                goto illegal_op; /* nop hint, in decodetree */
-            }
-            /*
-             * IT (If-Then)
-             *
-             * Combinations of firstcond and mask which set up an 0b1111
-             * condition are UNPREDICTABLE; we take the CONSTRAINED
-             * UNPREDICTABLE choice to treat 0b1111 the same as 0b1110,
-             * i.e. both meaning "execute always".
-             */
-            s->condexec_cond = (insn >> 4) & 0xe;
-            s->condexec_mask = insn & 0x1f;
-            /* No actual code generated for this insn, just setup state.  */
-            break;
-
-        case 0xe: /* bkpt */
-        {
-            int imm8 = extract32(insn, 0, 8);
-            ARCH(5);
-            gen_exception_bkpt_insn(s, syn_aa32_bkpt(imm8, true));
-            break;
-        }
-
-        case 0xa: /* rev, and hlt */
-        {
-            int op1 = extract32(insn, 6, 2);
-
-            if (op1 == 2) {
-                /* HLT */
-                int imm6 = extract32(insn, 0, 6);
-
-                gen_hlt(s, imm6);
-                break;
-            }
-
-            /* Otherwise this is rev, in decodetree */
-            goto illegal_op;
-        }
-
-        case 6: /* setend, cps; in decodetree */
-            goto illegal_op;
-
-        default:
-            goto undef;
-        }
-        break;
-
     case 13: /* conditional branch or swi, in decodetree */
         goto illegal_op;
 
@@ -10915,7 +10873,6 @@ static void disas_thumb_insn(DisasContext *s, uint32_t insn)
     }
     return;
 illegal_op:
-undef:
     unallocated_encoding(s);
 }