target/arm: Convert CBZ, CBNZ to decodetree

Convert the compare-and-branch-immediate insns CBZ and CBNZ to decodetree. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-id: 20230512144106.3608981-15-peter.maydell@linaro.org
qemu · May 18, 2023 · f8977d5 · f8977d5
1 parent 6201b2a
commit f8977d5
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Showing 2 changed files with 11 additions and 20 deletions.
diff --git a/target/arm/tcg/a64.decode b/target/arm/tcg/a64.decode
@@ -113,3 +113,8 @@ EXTR            0 00 100111 0 0 rm:5 0 imm:5 rn:5 rd:5   &extract sf=0
 
 B               0 00101 .......................... @branch
 BL              1 00101 .......................... @branch
+
+%imm19   5:s19 !function=times_4
+&cbz     rt imm sf nz
+
+CBZ             sf:1 011010 nz:1 ................... rt:5 &cbz imm=%imm19
diff --git a/target/arm/tcg/translate-a64.c b/target/arm/tcg/translate-a64.c
@@ -1334,33 +1334,22 @@ static bool trans_BL(DisasContext *s, arg_i *a)
     return true;
 }
 
-/* Compare and branch (immediate)
- *   31  30         25  24  23                  5 4      0
- * +----+-------------+----+---------------------+--------+
- * | sf | 0 1 1 0 1 0 | op |         imm19       |   Rt   |
- * +----+-------------+----+---------------------+--------+
- */
-static void disas_comp_b_imm(DisasContext *s, uint32_t insn)
+
+static bool trans_CBZ(DisasContext *s, arg_cbz *a)
 {
-    unsigned int sf, op, rt;
-    int64_t diff;
     DisasLabel match;
     TCGv_i64 tcg_cmp;
 
-    sf = extract32(insn, 31, 1);
-    op = extract32(insn, 24, 1); /* 0: CBZ; 1: CBNZ */
-    rt = extract32(insn, 0, 5);
-    diff = sextract32(insn, 5, 19) * 4;
-
-    tcg_cmp = read_cpu_reg(s, rt, sf);
+    tcg_cmp = read_cpu_reg(s, a->rt, a->sf);
     reset_btype(s);
 
     match = gen_disas_label(s);
-    tcg_gen_brcondi_i64(op ? TCG_COND_NE : TCG_COND_EQ,
+    tcg_gen_brcondi_i64(a->nz ? TCG_COND_NE : TCG_COND_EQ,
                         tcg_cmp, 0, 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);
+    return true;
 }
 
 /* Test and branch (immediate)
@@ -2408,9 +2397,6 @@ 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 0x1a: case 0x5a: /* Compare & branch (immediate) */
-        disas_comp_b_imm(s, insn);
-        break;
     case 0x1b: case 0x5b: /* Test & branch (immediate) */
         disas_test_b_imm(s, insn);
         break;