target/arm: Convert unconditional branch immediate to decodetree

Convert the unconditional branch immediate insns B and BL to decodetree. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-id: 20230512144106.3608981-14-peter.maydell@linaro.org
qemu · May 18, 2023 · 6201b2a · 6201b2a
1 parent 4240fb6
commit 6201b2a
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Showing 2 changed files with 19 additions and 19 deletions.
diff --git a/target/arm/tcg/a64.decode b/target/arm/tcg/a64.decode
@@ -21,6 +21,7 @@
 
 &ri              rd imm
 &rri_sf          rd rn imm sf
+&i               imm
 
 
 ### Data Processing - Immediate
@@ -104,3 +105,11 @@ UBFM            . 10 100110 . ...... ...... ..... ..... @bitfield_32
 
 EXTR            1 00 100111 1 0 rm:5 imm:6 rn:5 rd:5     &extract sf=1
 EXTR            0 00 100111 0 0 rm:5 0 imm:5 rn:5 rd:5   &extract sf=0
+
+# Branches
+
+%imm26   0:s26 !function=times_4
+@branch         . ..... .......................... &i imm=%imm26
+
+B               0 00101 .......................... @branch
+BL              1 00101 .......................... @branch
diff --git a/target/arm/tcg/translate-a64.c b/target/arm/tcg/translate-a64.c
@@ -1319,24 +1319,19 @@ static inline AArch64DecodeFn *lookup_disas_fn(const AArch64DecodeTable *table,
  * match up with those in the manual.
  */
 
-/* Unconditional branch (immediate)
- *   31  30       26 25                                  0
- * +----+-----------+-------------------------------------+
- * | op | 0 0 1 0 1 |                 imm26               |
- * +----+-----------+-------------------------------------+
- */
-static void disas_uncond_b_imm(DisasContext *s, uint32_t insn)
+static bool trans_B(DisasContext *s, arg_i *a)
 {
-    int64_t diff = sextract32(insn, 0, 26) * 4;
-
-    if (insn & (1U << 31)) {
-        /* BL Branch with link */
-        gen_pc_plus_diff(s, cpu_reg(s, 30), curr_insn_len(s));
-    }
+    reset_btype(s);
+    gen_goto_tb(s, 0, a->imm);
+    return true;
+}
 
-    /* B Branch / BL Branch with link */
+static bool trans_BL(DisasContext *s, arg_i *a)
+{
+    gen_pc_plus_diff(s, cpu_reg(s, 30), curr_insn_len(s));
     reset_btype(s);
-    gen_goto_tb(s, 0, diff);
+    gen_goto_tb(s, 0, a->imm);
+    return true;
 }
 
 /* Compare and branch (immediate)
@@ -2413,10 +2408,6 @@ 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 0x0a: case 0x0b:
-    case 0x4a: case 0x4b: /* Unconditional branch (immediate) */
-        disas_uncond_b_imm(s, insn);
-        break;
     case 0x1a: case 0x5a: /* Compare & branch (immediate) */
         disas_comp_b_imm(s, insn);
         break;