target/arm: Convert conditional branch insns to decodetree

Convert the immediate conditional branch insn B.cond to decodetree. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-id: 20230512144106.3608981-17-peter.maydell@linaro.org
qemu · May 18, 2023 · 484df36 · 484df36
1 parent e505828
commit 484df36
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Showing 2 changed files with 8 additions and 24 deletions.
diff --git a/target/arm/tcg/a64.decode b/target/arm/tcg/a64.decode
@@ -124,3 +124,5 @@ CBZ             sf:1 011010 nz:1 ................... rt:5 &cbz imm=%imm19
 &tbz       rt imm nz bitpos
 
 TBZ             . 011011 nz:1 ..... .............. rt:5 &tbz  imm=%imm14 bitpos=%imm31_19
+
+B_cond          0101010 0 ................... 0 cond:4 imm=%imm19
diff --git a/target/arm/tcg/translate-a64.c b/target/arm/tcg/translate-a64.c
@@ -1371,36 +1371,21 @@ static bool trans_TBZ(DisasContext *s, arg_tbz *a)
     return true;
 }
 
-/* Conditional branch (immediate)
- *  31           25  24  23                  5   4  3    0
- * +---------------+----+---------------------+----+------+
- * | 0 1 0 1 0 1 0 | o1 |         imm19       | o0 | cond |
- * +---------------+----+---------------------+----+------+
- */
-static void disas_cond_b_imm(DisasContext *s, uint32_t insn)
+static bool trans_B_cond(DisasContext *s, arg_B_cond *a)
 {
-    unsigned int cond;
-    int64_t diff;
-
-    if ((insn & (1 << 4)) || (insn & (1 << 24))) {
-        unallocated_encoding(s);
-        return;
-    }
-    diff = sextract32(insn, 5, 19) * 4;
-    cond = extract32(insn, 0, 4);
-
     reset_btype(s);
-    if (cond < 0x0e) {
+    if (a->cond < 0x0e) {
         /* genuinely conditional branches */
         DisasLabel match = gen_disas_label(s);
-        arm_gen_test_cc(cond, match.label);
+        arm_gen_test_cc(a->cond, match.label);
         gen_goto_tb(s, 0, 4);
         set_disas_label(s, match);
-        gen_goto_tb(s, 1, diff);
+        gen_goto_tb(s, 1, a->imm);
     } else {
         /* 0xe and 0xf are both "always" conditions */
-        gen_goto_tb(s, 0, diff);
+        gen_goto_tb(s, 0, a->imm);
     }
+    return true;
 }
 
 /* HINT instruction group, including various allocated HINTs */
@@ -2385,9 +2370,6 @@ static void disas_uncond_b_reg(DisasContext *s, uint32_t insn)
 static void disas_b_exc_sys(DisasContext *s, uint32_t insn)
 {
     switch (extract32(insn, 25, 7)) {
-    case 0x2a: /* Conditional branch (immediate) */
-        disas_cond_b_imm(s, insn);
-        break;
     case 0x6a: /* Exception generation / System */
         if (insn & (1 << 24)) {
             if (extract32(insn, 22, 2) == 0) {