target/arm: Convert Table Branch

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20190904193059.26202-41-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 41 insertions, 24 deletions

diff --git a/target/arm/t32.decode b/target/arm/t32.decode
index 11a9a2e..d05673f 100644
--- a/target/arm/t32.decode
+++ b/target/arm/t32.decode
@@ -489,7 +489,7 @@ LDRD_ri_t32      1110 1001 .101 .... .... .... ........    @ldstd_ri8 w=0 p=1
 STRD_ri_t32      1110 1001 .110 .... .... .... ........    @ldstd_ri8 w=1 p=1
 LDRD_ri_t32      1110 1001 .111 .... .... .... ........    @ldstd_ri8 w=1 p=1
 
-# Load/Store Exclusive and Load-Acquire/Store-Release
+# Load/Store Exclusive, Load-Acquire/Store-Release, and Table Branch
 
 @strex_i         .... .... .... rn:4 rt:4 rd:4 .... .... \
                  &strex rt2=15 imm=%imm8x4
@@ -533,6 +533,12 @@ LDA              1110 1000 1101 .... .... 1111 1010 1111      @ldrex_0
 LDAB             1110 1000 1101 .... .... 1111 1000 1111      @ldrex_0
 LDAH             1110 1000 1101 .... .... 1111 1001 1111      @ldrex_0
 
+&tbranch         rn rm
+@tbranch         .... .... .... rn:4 .... .... .... rm:4      &tbranch
+
+TBB              1110 1000 1101 .... 1111 0000 0000 ....      @tbranch
+TBH              1110 1000 1101 .... 1111 0000 0001 ....      @tbranch
+
 # Parallel addition and subtraction
 
 SADD8            1111 1010 1000 .... 1111 .... 0000 ....      @rndm
diff --git a/target/arm/translate.c b/target/arm/translate.c
index 7023ee7..96149ea 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -10081,6 +10081,37 @@ static bool trans_BLX_i(DisasContext *s, arg_BLX_i *a)
     return true;
 }
 
+static bool op_tbranch(DisasContext *s, arg_tbranch *a, bool half)
+{
+    TCGv_i32 addr, tmp;
+
+    tmp = load_reg(s, a->rm);
+    if (half) {
+        tcg_gen_add_i32(tmp, tmp, tmp);
+    }
+    addr = load_reg(s, a->rn);
+    tcg_gen_add_i32(addr, addr, tmp);
+
+    gen_aa32_ld_i32(s, tmp, addr, get_mem_index(s),
+                    half ? MO_UW | s->be_data : MO_UB);
+    tcg_temp_free_i32(addr);
+
+    tcg_gen_add_i32(tmp, tmp, tmp);
+    tcg_gen_addi_i32(tmp, tmp, read_pc(s));
+    store_reg(s, 15, tmp);
+    return true;
+}
+
+static bool trans_TBB(DisasContext *s, arg_tbranch *a)
+{
+    return op_tbranch(s, a, false);
+}
+
+static bool trans_TBH(DisasContext *s, arg_tbranch *a)
+{
+    return op_tbranch(s, a, true);
+}
+
 /*
  * Supervisor call
  */
@@ -10466,9 +10497,7 @@ static bool thumb_insn_is_16bit(DisasContext *s, uint32_t pc, uint32_t insn)
 /* Translate a 32-bit thumb instruction. */
 static void disas_thumb2_insn(DisasContext *s, uint32_t insn)
 {
-    uint32_t rd, rn, rm, rs;
-    TCGv_i32 tmp;
-    TCGv_i32 addr;
+    uint32_t rd, rn, rs;
     int op;
 
     /*
@@ -10514,7 +10543,6 @@ static void disas_thumb2_insn(DisasContext *s, uint32_t insn)
     rn = (insn >> 16) & 0xf;
     rs = (insn >> 12) & 0xf;
     rd = (insn >> 8) & 0xf;
-    rm = insn & 0xf;
     switch ((insn >> 25) & 0xf) {
     case 0: case 1: case 2: case 3:
         /* 16-bit instructions.  Should never happen.  */
@@ -10587,25 +10615,8 @@ static void disas_thumb2_insn(DisasContext *s, uint32_t insn)
                 /* Load/store exclusive, in decodetree */
                 goto illegal_op;
             } else if ((insn & (7 << 5)) == 0) {
-                /* Table Branch.  */
-                addr = load_reg(s, rn);
-                tmp = load_reg(s, rm);
-                tcg_gen_add_i32(addr, addr, tmp);
-                if (insn & (1 << 4)) {
-                    /* tbh */
-                    tcg_gen_add_i32(addr, addr, tmp);
-                    tcg_temp_free_i32(tmp);
-                    tmp = tcg_temp_new_i32();
-                    gen_aa32_ld16u(s, tmp, addr, get_mem_index(s));
-                } else { /* tbb */
-                    tcg_temp_free_i32(tmp);
-                    tmp = tcg_temp_new_i32();
-                    gen_aa32_ld8u(s, tmp, addr, get_mem_index(s));
-                }
-                tcg_temp_free_i32(addr);
-                tcg_gen_shli_i32(tmp, tmp, 1);
-                tcg_gen_addi_i32(tmp, tmp, read_pc(s));
-                store_reg(s, 15, tmp);
+                /* Table Branch, in decodetree */
+                goto illegal_op;
             } else {
                 /* Load/store exclusive, load-acq/store-rel, in decodetree */
                 goto illegal_op;