target/arm: Change gen_goto_tb to work on displacements

In preparation for TARGET_TB_PCREL, reduce reliance on absolute values.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20221020030641.2066807-3-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 27 insertions, 23 deletions

diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
index 60ff753d81..928445a7cb 100644
--- a/target/arm/translate-a64.c
+++ b/target/arm/translate-a64.c
@@ -370,8 +370,10 @@ static inline bool use_goto_tb(DisasContext *s, uint64_t dest)
     return translator_use_goto_tb(&s->base, dest);
 }
 
-static inline void gen_goto_tb(DisasContext *s, int n, uint64_t dest)
+static void gen_goto_tb(DisasContext *s, int n, int64_t diff)
 {
+    uint64_t dest = s->pc_curr + diff;
+
     if (use_goto_tb(s, dest)) {
         tcg_gen_goto_tb(n);
         gen_a64_set_pc_im(dest);
@@ -1354,7 +1356,7 @@ static inline AArch64DecodeFn *lookup_disas_fn(const AArch64DecodeTable *table,
  */
 static void disas_uncond_b_imm(DisasContext *s, uint32_t insn)
 {
-    uint64_t addr = s->pc_curr + sextract32(insn, 0, 26) * 4;
+    int64_t diff = sextract32(insn, 0, 26) * 4;
 
     if (insn & (1U << 31)) {
         /* BL Branch with link */
@@ -1363,7 +1365,7 @@ static void disas_uncond_b_imm(DisasContext *s, uint32_t insn)
 
     /* B Branch / BL Branch with link */
     reset_btype(s);
-    gen_goto_tb(s, 0, addr);
+    gen_goto_tb(s, 0, diff);
 }
 
 /* Compare and branch (immediate)
@@ -1375,14 +1377,14 @@ static void disas_uncond_b_imm(DisasContext *s, uint32_t insn)
 static void disas_comp_b_imm(DisasContext *s, uint32_t insn)
 {
     unsigned int sf, op, rt;
-    uint64_t addr;
+    int64_t diff;
     TCGLabel *label_match;
     TCGv_i64 tcg_cmp;
 
     sf = extract32(insn, 31, 1);
     op = extract32(insn, 24, 1); /* 0: CBZ; 1: CBNZ */
     rt = extract32(insn, 0, 5);
-    addr = s->pc_curr + sextract32(insn, 5, 19) * 4;
+    diff = sextract32(insn, 5, 19) * 4;
 
     tcg_cmp = read_cpu_reg(s, rt, sf);
     label_match = gen_new_label();
@@ -1391,9 +1393,9 @@ static void disas_comp_b_imm(DisasContext *s, uint32_t insn)
     tcg_gen_brcondi_i64(op ? TCG_COND_NE : TCG_COND_EQ,
                         tcg_cmp, 0, label_match);
 
-    gen_goto_tb(s, 0, s->base.pc_next);
+    gen_goto_tb(s, 0, 4);
     gen_set_label(label_match);
-    gen_goto_tb(s, 1, addr);
+    gen_goto_tb(s, 1, diff);
 }
 
 /* Test and branch (immediate)
@@ -1405,13 +1407,13 @@ static void disas_comp_b_imm(DisasContext *s, uint32_t insn)
 static void disas_test_b_imm(DisasContext *s, uint32_t insn)
 {
     unsigned int bit_pos, op, rt;
-    uint64_t addr;
+    int64_t diff;
     TCGLabel *label_match;
     TCGv_i64 tcg_cmp;
 
     bit_pos = (extract32(insn, 31, 1) << 5) | extract32(insn, 19, 5);
     op = extract32(insn, 24, 1); /* 0: TBZ; 1: TBNZ */
-    addr = s->pc_curr + sextract32(insn, 5, 14) * 4;
+    diff = sextract32(insn, 5, 14) * 4;
     rt = extract32(insn, 0, 5);
 
     tcg_cmp = tcg_temp_new_i64();
@@ -1422,9 +1424,9 @@ static void disas_test_b_imm(DisasContext *s, uint32_t insn)
     tcg_gen_brcondi_i64(op ? TCG_COND_NE : TCG_COND_EQ,
                         tcg_cmp, 0, label_match);
     tcg_temp_free_i64(tcg_cmp);
-    gen_goto_tb(s, 0, s->base.pc_next);
+    gen_goto_tb(s, 0, 4);
     gen_set_label(label_match);
-    gen_goto_tb(s, 1, addr);
+    gen_goto_tb(s, 1, diff);
 }
 
 /* Conditional branch (immediate)
@@ -1436,13 +1438,13 @@ static void disas_test_b_imm(DisasContext *s, uint32_t insn)
 static void disas_cond_b_imm(DisasContext *s, uint32_t insn)
 {
     unsigned int cond;
-    uint64_t addr;
+    int64_t diff;
 
     if ((insn & (1 << 4)) || (insn & (1 << 24))) {
         unallocated_encoding(s);
         return;
     }
-    addr = s->pc_curr + sextract32(insn, 5, 19) * 4;
+    diff = sextract32(insn, 5, 19) * 4;
     cond = extract32(insn, 0, 4);
 
     reset_btype(s);
@@ -1450,12 +1452,12 @@ static void disas_cond_b_imm(DisasContext *s, uint32_t insn)
         /* genuinely conditional branches */
         TCGLabel *label_match = gen_new_label();
         arm_gen_test_cc(cond, label_match);
-        gen_goto_tb(s, 0, s->base.pc_next);
+        gen_goto_tb(s, 0, 4);
         gen_set_label(label_match);
-        gen_goto_tb(s, 1, addr);
+        gen_goto_tb(s, 1, diff);
     } else {
         /* 0xe and 0xf are both "always" conditions */
-        gen_goto_tb(s, 0, addr);
+        gen_goto_tb(s, 0, diff);
     }
 }
 
@@ -1629,7 +1631,7 @@ static void handle_sync(DisasContext *s, uint32_t insn,
          * any pending interrupts immediately.
          */
         reset_btype(s);
-        gen_goto_tb(s, 0, s->base.pc_next);
+        gen_goto_tb(s, 0, 4);
         return;
 
     case 7: /* SB */
@@ -1641,7 +1643,7 @@ static void handle_sync(DisasContext *s, uint32_t insn,
          * MB and end the TB instead.
          */
         tcg_gen_mb(TCG_MO_ALL | TCG_BAR_SC);
-        gen_goto_tb(s, 0, s->base.pc_next);
+        gen_goto_tb(s, 0, 4);
         return;
 
     default:
@@ -14946,7 +14948,7 @@ static void aarch64_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
         switch (dc->base.is_jmp) {
         case DISAS_NEXT:
         case DISAS_TOO_MANY:
-            gen_goto_tb(dc, 1, dc->base.pc_next);
+            gen_goto_tb(dc, 1, 4);
             break;
         default:
         case DISAS_UPDATE_EXIT:
diff --git a/target/arm/translate.c b/target/arm/translate.c
index 5752b7af5c..ae30c26ca4 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -2590,8 +2590,10 @@ static void gen_goto_ptr(void)
  * cpu_loop_exec. Any live exit_requests will be processed as we
  * enter the next TB.
  */
-static void gen_goto_tb(DisasContext *s, int n, target_ulong dest)
+static void gen_goto_tb(DisasContext *s, int n, int diff)
 {
+    target_ulong dest = s->pc_curr + diff;
+
     if (translator_use_goto_tb(&s->base, dest)) {
         tcg_gen_goto_tb(n);
         gen_set_pc_im(s, dest);
@@ -2625,7 +2627,7 @@ static inline void gen_jmp_tb(DisasContext *s, uint32_t dest, int tbno)
          *    gen_jmp();
          * on the second call to gen_jmp().
          */
-        gen_goto_tb(s, tbno, dest);
+        gen_goto_tb(s, tbno, dest - s->pc_curr);
         break;
     case DISAS_UPDATE_NOCHAIN:
     case DISAS_UPDATE_EXIT:
@@ -9793,7 +9795,7 @@ static void arm_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
         switch (dc->base.is_jmp) {
         case DISAS_NEXT:
         case DISAS_TOO_MANY:
-            gen_goto_tb(dc, 1, dc->base.pc_next);
+            gen_goto_tb(dc, 1, curr_insn_len(dc));
             break;
         case DISAS_UPDATE_NOCHAIN:
             gen_set_pc_im(dc, dc->base.pc_next);
@@ -9845,7 +9847,7 @@ static void arm_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
             gen_set_pc_im(dc, dc->base.pc_next);
             gen_singlestep_exception(dc);
         } else {
-            gen_goto_tb(dc, 1, dc->base.pc_next);
+            gen_goto_tb(dc, 1, curr_insn_len(dc));
         }
     }
 }