[Qemu-devel] [PULL 09/29] target/arm: Introduce add_reg_for_lit

[Peter Maydell <peter.maydell@linaro.org>]

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

Provide a common routine for the places that require ALIGN(PC, 4)
as the base address as opposed to plain PC.  The two are always
the same for A32, but the difference is meaningful for thumb mode.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-id: 20190807045335.1361-5-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target/arm/translate-vfp.inc.c |  38 ++------
 target/arm/translate.c         | 166 +++++++++++++++------------------
 2 files changed, 82 insertions(+), 122 deletions(-)

diff --git a/target/arm/translate-vfp.inc.c b/target/arm/translate-vfp.inc.c
index 092eb5ec53d..262d4177e50 100644
--- a/target/arm/translate-vfp.inc.c
+++ b/target/arm/translate-vfp.inc.c
@@ -941,14 +941,8 @@ static bool trans_VLDR_VSTR_sp(DisasContext *s, arg_VLDR_VSTR_sp *a)
         offset = -offset;
     }
 
-    if (s->thumb && a->rn == 15) {
-        /* This is actually UNPREDICTABLE */
-        addr = tcg_temp_new_i32();
-        tcg_gen_movi_i32(addr, s->pc & ~2);
-    } else {
-        addr = load_reg(s, a->rn);
-    }
-    tcg_gen_addi_i32(addr, addr, offset);
+    /* For thumb, use of PC is UNPREDICTABLE.  */
+    addr = add_reg_for_lit(s, a->rn, offset);
     tmp = tcg_temp_new_i32();
     if (a->l) {
         gen_aa32_ld32u(s, tmp, addr, get_mem_index(s));
@@ -983,14 +977,8 @@ static bool trans_VLDR_VSTR_dp(DisasContext *s, arg_VLDR_VSTR_dp *a)
         offset = -offset;
     }
 
-    if (s->thumb && a->rn == 15) {
-        /* This is actually UNPREDICTABLE */
-        addr = tcg_temp_new_i32();
-        tcg_gen_movi_i32(addr, s->pc & ~2);
-    } else {
-        addr = load_reg(s, a->rn);
-    }
-    tcg_gen_addi_i32(addr, addr, offset);
+    /* For thumb, use of PC is UNPREDICTABLE.  */
+    addr = add_reg_for_lit(s, a->rn, offset);
     tmp = tcg_temp_new_i64();
     if (a->l) {
         gen_aa32_ld64(s, tmp, addr, get_mem_index(s));
@@ -1029,13 +1017,8 @@ static bool trans_VLDM_VSTM_sp(DisasContext *s, arg_VLDM_VSTM_sp *a)
         return true;
     }
 
-    if (s->thumb && a->rn == 15) {
-        /* This is actually UNPREDICTABLE */
-        addr = tcg_temp_new_i32();
-        tcg_gen_movi_i32(addr, s->pc & ~2);
-    } else {
-        addr = load_reg(s, a->rn);
-    }
+    /* For thumb, use of PC is UNPREDICTABLE.  */
+    addr = add_reg_for_lit(s, a->rn, 0);
     if (a->p) {
         /* pre-decrement */
         tcg_gen_addi_i32(addr, addr, -(a->imm << 2));
@@ -1112,13 +1095,8 @@ static bool trans_VLDM_VSTM_dp(DisasContext *s, arg_VLDM_VSTM_dp *a)
         return true;
     }
 
-    if (s->thumb && a->rn == 15) {
-        /* This is actually UNPREDICTABLE */
-        addr = tcg_temp_new_i32();
-        tcg_gen_movi_i32(addr, s->pc & ~2);
-    } else {
-        addr = load_reg(s, a->rn);
-    }
+    /* For thumb, use of PC is UNPREDICTABLE.  */
+    addr = add_reg_for_lit(s, a->rn, 0);
     if (a->p) {
         /* pre-decrement */
         tcg_gen_addi_i32(addr, addr, -(a->imm << 2));
diff --git a/target/arm/translate.c b/target/arm/translate.c
index 41523c0241f..f481b87f997 100644
--- a/target/arm/translate.c
+++ b/target/arm/translate.c
@@ -220,6 +220,23 @@ static inline TCGv_i32 load_reg(DisasContext *s, int reg)
     return tmp;
 }
 
+/*
+ * Create a new temp, REG + OFS, except PC is ALIGN(PC, 4).
+ * This is used for load/store for which use of PC implies (literal),
+ * or ADD that implies ADR.
+ */
+static TCGv_i32 add_reg_for_lit(DisasContext *s, int reg, int ofs)
+{
+    TCGv_i32 tmp = tcg_temp_new_i32();
+
+    if (reg == 15) {
+        tcg_gen_movi_i32(tmp, (read_pc(s) & ~3) + ofs);
+    } else {
+        tcg_gen_addi_i32(tmp, cpu_R[reg], ofs);
+    }
+    return tmp;
+}
+
 /* Set a CPU register.  The source must be a temporary and will be
    marked as dead.  */
 static void store_reg(DisasContext *s, int reg, TCGv_i32 var)
@@ -9457,16 +9474,12 @@ static void disas_thumb2_insn(DisasContext *s, uint32_t insn)
                  */
                 bool wback = extract32(insn, 21, 1);
 
-                if (rn == 15) {
-                    if (insn & (1 << 21)) {
-                        /* UNPREDICTABLE */
-                        goto illegal_op;
-                    }
-                    addr = tcg_temp_new_i32();
-                    tcg_gen_movi_i32(addr, s->pc & ~3);
-                } else {
-                    addr = load_reg(s, rn);
+                if (rn == 15 && (insn & (1 << 21))) {
+                    /* UNPREDICTABLE */
+                    goto illegal_op;
                 }
+
+                addr = add_reg_for_lit(s, rn, 0);
                 offset = (insn & 0xff) * 4;
                 if ((insn & (1 << 23)) == 0) {
                     offset = -offset;
@@ -10667,27 +10680,15 @@ static void disas_thumb2_insn(DisasContext *s, uint32_t insn)
                         store_reg(s, rd, tmp);
                     } else {
                         /* Add/sub 12-bit immediate.  */
-                        if (rn == 15) {
-                            offset = s->pc & ~(uint32_t)3;
-                            if (insn & (1 << 23))
-                                offset -= imm;
-                            else
-                                offset += imm;
-                            tmp = tcg_temp_new_i32();
-                            tcg_gen_movi_i32(tmp, offset);
-                            store_reg(s, rd, tmp);
+                        if (insn & (1 << 23)) {
+                            imm = -imm;
+                        }
+                        tmp = add_reg_for_lit(s, rn, imm);
+                        if (rn == 13 && rd == 13) {
+                            /* ADD SP, SP, imm or SUB SP, SP, imm */
+                            store_sp_checked(s, tmp);
                         } else {
-                            tmp = load_reg(s, rn);
-                            if (insn & (1 << 23))
-                                tcg_gen_subi_i32(tmp, tmp, imm);
-                            else
-                                tcg_gen_addi_i32(tmp, tmp, imm);
-                            if (rn == 13 && rd == 13) {
-                                /* ADD SP, SP, imm or SUB SP, SP, imm */
-                                store_sp_checked(s, tmp);
-                            } else {
-                                store_reg(s, rd, tmp);
-                            }
+                            store_reg(s, rd, tmp);
                         }
                     }
                 }
@@ -10801,61 +10802,53 @@ static void disas_thumb2_insn(DisasContext *s, uint32_t insn)
             }
         }
         memidx = get_mem_index(s);
-        if (rn == 15) {
-            addr = tcg_temp_new_i32();
-            /* PC relative.  */
-            /* s->pc has already been incremented by 4.  */
-            imm = s->pc & 0xfffffffc;
-            if (insn & (1 << 23))
-                imm += insn & 0xfff;
-            else
-                imm -= insn & 0xfff;
-            tcg_gen_movi_i32(addr, imm);
+        imm = insn & 0xfff;
+        if (insn & (1 << 23)) {
+            /* PC relative or Positive offset.  */
+            addr = add_reg_for_lit(s, rn, imm);
+        } else if (rn == 15) {
+            /* PC relative with negative offset.  */
+            addr = add_reg_for_lit(s, rn, -imm);
         } else {
             addr = load_reg(s, rn);
-            if (insn & (1 << 23)) {
-                /* Positive offset.  */
-                imm = insn & 0xfff;
-                tcg_gen_addi_i32(addr, addr, imm);
-            } else {
-                imm = insn & 0xff;
-                switch ((insn >> 8) & 0xf) {
-                case 0x0: /* Shifted Register.  */
-                    shift = (insn >> 4) & 0xf;
-                    if (shift > 3) {
-                        tcg_temp_free_i32(addr);
-                        goto illegal_op;
-                    }
-                    tmp = load_reg(s, rm);
-                    if (shift)
-                        tcg_gen_shli_i32(tmp, tmp, shift);
-                    tcg_gen_add_i32(addr, addr, tmp);
-                    tcg_temp_free_i32(tmp);
-                    break;
-                case 0xc: /* Negative offset.  */
-                    tcg_gen_addi_i32(addr, addr, -imm);
-                    break;
-                case 0xe: /* User privilege.  */
-                    tcg_gen_addi_i32(addr, addr, imm);
-                    memidx = get_a32_user_mem_index(s);
-                    break;
-                case 0x9: /* Post-decrement.  */
-                    imm = -imm;
-                    /* Fall through.  */
-                case 0xb: /* Post-increment.  */
-                    postinc = 1;
-                    writeback = 1;
-                    break;
-                case 0xd: /* Pre-decrement.  */
-                    imm = -imm;
-                    /* Fall through.  */
-                case 0xf: /* Pre-increment.  */
-                    writeback = 1;
-                    break;
-                default:
+            imm = insn & 0xff;
+            switch ((insn >> 8) & 0xf) {
+            case 0x0: /* Shifted Register.  */
+                shift = (insn >> 4) & 0xf;
+                if (shift > 3) {
                     tcg_temp_free_i32(addr);
                     goto illegal_op;
                 }
+                tmp = load_reg(s, rm);
+                if (shift) {
+                    tcg_gen_shli_i32(tmp, tmp, shift);
+                }
+                tcg_gen_add_i32(addr, addr, tmp);
+                tcg_temp_free_i32(tmp);
+                break;
+            case 0xc: /* Negative offset.  */
+                tcg_gen_addi_i32(addr, addr, -imm);
+                break;
+            case 0xe: /* User privilege.  */
+                tcg_gen_addi_i32(addr, addr, imm);
+                memidx = get_a32_user_mem_index(s);
+                break;
+            case 0x9: /* Post-decrement.  */
+                imm = -imm;
+                /* Fall through.  */
+            case 0xb: /* Post-increment.  */
+                postinc = 1;
+                writeback = 1;
+                break;
+            case 0xd: /* Pre-decrement.  */
+                imm = -imm;
+                /* Fall through.  */
+            case 0xf: /* Pre-increment.  */
+                writeback = 1;
+                break;
+            default:
+                tcg_temp_free_i32(addr);
+                goto illegal_op;
             }
         }
 
@@ -11051,10 +11044,7 @@ static void disas_thumb_insn(DisasContext *s, uint32_t insn)
         if (insn & (1 << 11)) {
             rd = (insn >> 8) & 7;
             /* load pc-relative.  Bit 1 of PC is ignored.  */
-            val = read_pc(s) + ((insn & 0xff) * 4);
-            val &= ~(uint32_t)2;
-            addr = tcg_temp_new_i32();
-            tcg_gen_movi_i32(addr, val);
+            addr = add_reg_for_lit(s, 15, (insn & 0xff) * 4);
             tmp = tcg_temp_new_i32();
             gen_aa32_ld32u_iss(s, tmp, addr, get_mem_index(s),
                                rd | ISSIs16Bit);
@@ -11432,16 +11422,8 @@ static void disas_thumb_insn(DisasContext *s, uint32_t insn)
          *  - Add PC/SP (immediate)
          */
         rd = (insn >> 8) & 7;
-        if (insn & (1 << 11)) {
-            /* SP */
-            tmp = load_reg(s, 13);
-        } else {
-            /* PC. bit 1 is ignored.  */
-            tmp = tcg_temp_new_i32();
-            tcg_gen_movi_i32(tmp, read_pc(s) & ~(uint32_t)2);
-        }
         val = (insn & 0xff) * 4;
-        tcg_gen_addi_i32(tmp, tmp, val);
+        tmp = add_reg_for_lit(s, insn & (1 << 11) ? 13 : 15, val);
         store_reg(s, rd, tmp);
         break;
 
-- 
2.20.1