[PULL 21/24] target/arm: Introduce gen_pc_plus_diff for aarch64

[Peter Maydell]

From: Richard Henderson <richard.henderson@linaro.org>

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: 20221020030641.2066807-8-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/arm/translate-a64.c | 41 +++++++++++++++++++++++++++-----------
 1 file changed, 29 insertions(+), 12 deletions(-)

diff --git a/target/arm/translate-a64.c b/target/arm/translate-a64.c
index 713f1a89a4a..c2316352957 100644
--- a/target/arm/translate-a64.c
+++ b/target/arm/translate-a64.c
@@ -140,9 +140,14 @@ static void reset_btype(DisasContext *s)
     }
 }
 
+static void gen_pc_plus_diff(DisasContext *s, TCGv_i64 dest, target_long diff)
+{
+    tcg_gen_movi_i64(dest, s->pc_curr + diff);
+}
+
 void gen_a64_update_pc(DisasContext *s, target_long diff)
 {
-    tcg_gen_movi_i64(cpu_pc, s->pc_curr + diff);
+    gen_pc_plus_diff(s, cpu_pc, diff);
 }
 
 /*
@@ -1360,7 +1365,7 @@ static void disas_uncond_b_imm(DisasContext *s, uint32_t 
insn)
 
     if (insn & (1U << 31)) {
         /* BL Branch with link */
-        tcg_gen_movi_i64(cpu_reg(s, 30), s->base.pc_next);
+        gen_pc_plus_diff(s, cpu_reg(s, 30), curr_insn_len(s));
     }
 
     /* B Branch / BL Branch with link */
@@ -2301,11 +2306,17 @@ static void disas_uncond_b_reg(DisasContext *s, 
uint32_t insn)
         default:
             goto do_unallocated;
         }
-        gen_a64_set_pc(s, dst);
         /* BLR also needs to load return address */
         if (opc == 1) {
-            tcg_gen_movi_i64(cpu_reg(s, 30), s->base.pc_next);
+            TCGv_i64 lr = cpu_reg(s, 30);
+            if (dst == lr) {
+                TCGv_i64 tmp = new_tmp_a64(s);
+                tcg_gen_mov_i64(tmp, dst);
+                dst = tmp;
+            }
+            gen_pc_plus_diff(s, lr, curr_insn_len(s));
         }
+        gen_a64_set_pc(s, dst);
         break;
 
     case 8: /* BRAA */
@@ -2328,11 +2339,17 @@ static void disas_uncond_b_reg(DisasContext *s, 
uint32_t insn)
         } else {
             dst = cpu_reg(s, rn);
         }
-        gen_a64_set_pc(s, dst);
         /* BLRAA also needs to load return address */
         if (opc == 9) {
-            tcg_gen_movi_i64(cpu_reg(s, 30), s->base.pc_next);
+            TCGv_i64 lr = cpu_reg(s, 30);
+            if (dst == lr) {
+                TCGv_i64 tmp = new_tmp_a64(s);
+                tcg_gen_mov_i64(tmp, dst);
+                dst = tmp;
+            }
+            gen_pc_plus_diff(s, lr, curr_insn_len(s));
         }
+        gen_a64_set_pc(s, dst);
         break;
 
     case 4: /* ERET */
@@ -2900,7 +2917,8 @@ static void disas_ld_lit(DisasContext *s, uint32_t insn)
 
     tcg_rt = cpu_reg(s, rt);
 
-    clean_addr = tcg_constant_i64(s->pc_curr + imm);
+    clean_addr = new_tmp_a64(s);
+    gen_pc_plus_diff(s, clean_addr, imm);
     if (is_vector) {
         do_fp_ld(s, rt, clean_addr, size);
     } else {
@@ -4244,23 +4262,22 @@ static void disas_ldst(DisasContext *s, uint32_t insn)
 static void disas_pc_rel_adr(DisasContext *s, uint32_t insn)
 {
     unsigned int page, rd;
-    uint64_t base;
-    uint64_t offset;
+    int64_t offset;
 
     page = extract32(insn, 31, 1);
     /* SignExtend(immhi:immlo) -> offset */
     offset = sextract64(insn, 5, 19);
     offset = offset << 2 | extract32(insn, 29, 2);
     rd = extract32(insn, 0, 5);
-    base = s->pc_curr;
 
     if (page) {
         /* ADRP (page based) */
-        base &= ~0xfff;
         offset <<= 12;
+        /* The page offset is ok for TARGET_TB_PCREL. */
+        offset -= s->pc_curr & 0xfff;
     }
 
-    tcg_gen_movi_i64(cpu_reg(s, rd), base + offset);
+    gen_pc_plus_diff(s, cpu_reg(s, rd), offset);
 }
 
 /*
-- 
2.25.1