From c52cfb9aa62920136aa0725f28f526a029f47b91 Mon Sep 17 00:00:00 2001
From: Richard Henderson <richard.henderson@linaro.org>
Date: Wed, 20 Nov 2019 12:12:41 -0500
Subject: [PATCH] target/arm: Convert T16 load/store multiple

Backports commit 6e8514ba408f3cc758cd47e2da5475d8684507ec from qemu
---
 qemu/target/arm/t16.decode  |  8 +++++++
 qemu/target/arm/translate.c | 48 +++++++------------------------------
 2 files changed, 17 insertions(+), 39 deletions(-)

diff --git a/qemu/target/arm/t16.decode b/qemu/target/arm/t16.decode
index 71b3e8f0..a7a437f9 100644
--- a/qemu/target/arm/t16.decode
+++ b/qemu/target/arm/t16.decode
@@ -26,6 +26,7 @@
 &ri              !extern rd imm
 &ldst_rr         !extern p w u rn rt rm shimm shtype
 &ldst_ri         !extern p w u rn rt imm
+&ldst_block      !extern rn i b u w list
 
 # Set S if the instruction is outside of an IT block.
 %s               !function=t16_setflags
@@ -109,3 +110,10 @@ LDR_ri          10011 ... ........              @ldst_spec_i rn=13
 ADR             10100 rd:3 ........             imm=%imm8_0x4
 ADD_rri         10101 rd:3 ........ \
                 &s_rri_rot rn=13 s=0 rot=0 imm=%imm8_0x4  # SP
+
+# Load/store multiple
+
+@ldstm          ..... rn:3 list:8               &ldst_block i=1 b=0 u=0 w=1
+
+STM             11000 ... ........              @ldstm
+LDM_t16         11001 ... ........              @ldstm
diff --git a/qemu/target/arm/translate.c b/qemu/target/arm/translate.c
index 23b51c52..dacf6479 100644
--- a/qemu/target/arm/translate.c
+++ b/qemu/target/arm/translate.c
@@ -10426,6 +10426,14 @@ static bool trans_LDM_t32(DisasContext *s, arg_ldst_block *a)
     return do_ldm(s, a, 2);
 }
 
+static bool trans_LDM_t16(DisasContext *s, arg_ldst_block *a)
+{
+    /* Writeback is conditional on the base register not being loaded.  */
+    a->w = !(a->list & (1 << a->rn));
+    /* BitCount(list) < 1 is UNPREDICTABLE */
+    return do_ldm(s, a, 1);
+}
+
 /*
  * Branch, branch with link
  */
@@ -11221,6 +11229,7 @@ static void disas_thumb_insn(DisasContext *s, uint32_t insn)
     case 8: /* load/store halfword immediate offset, in decodetree */
     case 9: /* load/store from stack, in decodetree */
     case 10: /* add PC/SP (immediate), in decodetree */
+    case 12: /* load/store multiple, in decodetree */
         goto illegal_op;
 
     case 11:
@@ -11444,45 +11453,6 @@ static void disas_thumb_insn(DisasContext *s, uint32_t insn)
         }
         break;
 
-    case 12:
-    {
-        /* load/store multiple */
-        TCGv_i32 loaded_var = NULL;
-        rn = (insn >> 8) & 0x7;
-        addr = load_reg(s, rn);
-        for (i = 0; i < 8; i++) {
-            if (insn & (1 << i)) {
-                if (insn & (1 << 11)) {
-                    /* load */
-                    tmp = tcg_temp_new_i32(tcg_ctx);
-                    gen_aa32_ld32u(s, tmp, addr, get_mem_index(s));
-                    if (i == rn) {
-                        loaded_var = tmp;
-                    } else {
-                        store_reg(s, i, tmp);
-                    }
-                } else {
-                    /* store */
-                    tmp = load_reg(s, i);
-                    gen_aa32_st32(s, tmp, addr, get_mem_index(s));
-                    tcg_temp_free_i32(tcg_ctx, tmp);
-                }
-                /* advance to the next address */
-                tcg_gen_addi_i32(tcg_ctx, addr, addr, 4);
-            }
-        }
-        if ((insn & (1 << rn)) == 0) {
-            /* base reg not in list: base register writeback */
-            store_reg(s, rn, addr);
-        } else {
-            /* base reg in list: if load, complete it now */
-            if (insn & (1 << 11)) {
-                store_reg(s, rn, loaded_var);
-            }
-            tcg_temp_free_i32(tcg_ctx, addr);
-        }
-        break;
-    }
     case 13:
         /* conditional branch or swi */
         cond = (insn >> 8) & 0xf;