Fix push/pop instruction selection and encoding.

1) Thumb 'push' can handle lr and 'pop' can handle pc, so make use of them.
2) Thumb2 push was incorrectly encoded as stmia, which should be stmdb
instead.

None of the above affect the code that we currently ship.

Change-Id: I89ab46b032a3d562355c2cc3bc05fe308ba40957

1 files changed, 11 insertions, 5 deletions

diff --git a/vm/compiler/codegen/arm/ArchUtility.c b/vm/compiler/codegen/arm/ArchUtility.c
index 95b96c496..7a4d307b5 100644
--- a/vm/compiler/codegen/arm/ArchUtility.c
+++ b/vm/compiler/codegen/arm/ArchUtility.c
@@ -25,18 +25,24 @@ static char *shiftNames[4] = {
     "ror"};
 
 /* Decode and print a ARM register name */
-static char * decodeRegList(int vector, char *buf)
+static char * decodeRegList(ArmOpcode opcode, int vector, char *buf)
 {
     int i;
     bool printed = false;
     buf[0] = 0;
-    for (i = 0; i < 8; i++, vector >>= 1) {
+    for (i = 0; i < 16; i++, vector >>= 1) {
         if (vector & 0x1) {
+            int regId = i;
+            if (opcode == kThumbPush && i == 8) {
+                regId = rlr;
+            } else if (opcode == kThumbPop && i == 8) {
+                regId = rpc;
+            }
             if (printed) {
-                sprintf(buf + strlen(buf), ", r%d", i);
+                sprintf(buf + strlen(buf), ", r%d", regId);
             } else {
                 printed = true;
-                sprintf(buf, "r%d", i);
+                sprintf(buf, "r%d", regId);
             }
         }
     }
@@ -209,7 +215,7 @@ static void buildInsnString(char *fmt, ArmLIR *lir, char* buf,
                        strcpy(tbuf, "see above");
                        break;
                    case 'R':
-                       decodeRegList(operand, tbuf);
+                       decodeRegList(lir->opcode, operand, tbuf);
                        break;
                    default:
                        strcpy(tbuf,"DecodeError");