ARM: Add PostIndex support to Ldrd/Strd macro fallback code....

src/arm/macro-assembler-arm.cc

Index: src/arm/macro-assembler-arm.cc
===================================================================
--- src/arm/macro-assembler-arm.cc	(revision 8354)
+++ src/arm/macro-assembler-arm.cc	(working copy)
@@ -647,19 +647,36 @@
   ASSERT_EQ(0, dst1.code() % 2);
   ASSERT_EQ(dst1.code() + 1, dst2.code());
 
+  // V8 does not use this addressing mode, so the fallback code
+  // below doesn't support it yet.
+  ASSERT((src.am() != PreIndex) && (src.am() != NegPreIndex));
+
   // Generate two ldr instructions if ldrd is not available.
   if (CpuFeatures::IsSupported(ARMv7)) {
     CpuFeatures::Scope scope(ARMv7);
     ldrd(dst1, dst2, src, cond);
   } else {
-    MemOperand src2(src);
-    src2.set_offset(src2.offset() + 4);
-    if (dst1.is(src.rn())) {
-      ldr(dst2, src2, cond);
-      ldr(dst1, src, cond);
-    } else {
-      ldr(dst1, src, cond);
-      ldr(dst2, src2, cond);
+    if ((src.am() == Offset) || (src.am() == NegOffset)) {
+      MemOperand src2(src);
+      src2.set_offset(src2.offset() + 4);
+      if (dst1.is(src.rn())) {
+        ldr(dst2, src2, cond);
+        ldr(dst1, src, cond);
+      } else {
+        ldr(dst1, src, cond);
+        ldr(dst2, src2, cond);
+      }
+    } else {  // PostIndex or NegPostIndex.
+      ASSERT((src.am() == PostIndex) || (src.am() == NegPostIndex));
+      if (dst1.is(src.rn())) {
+        ldr(dst2, MemOperand(src.rn(), 4, Offset), cond);
+        ldr(dst1, src, cond);
+      } else {
+        MemOperand src2(src);
+        src2.set_offset(src2.offset() - 4);
+        ldr(dst1, MemOperand(src.rn(), 4, PostIndex), cond);
+        ldr(dst2, src2, cond);
+      }
     }
   }
 }
@@ -672,15 +689,26 @@
   ASSERT_EQ(0, src1.code() % 2);
   ASSERT_EQ(src1.code() + 1, src2.code());
 
+  // V8 does not use this addressing mode, so the fallback code
+  // below doesn't support it yet.
+  ASSERT((dst.am() != PreIndex) && (dst.am() != NegPreIndex));
+
   // Generate two str instructions if strd is not available.
   if (CpuFeatures::IsSupported(ARMv7)) {
     CpuFeatures::Scope scope(ARMv7);
     strd(src1, src2, dst, cond);
   } else {
     MemOperand dst2(dst);
-    dst2.set_offset(dst2.offset() + 4);
-    str(src1, dst, cond);
-    str(src2, dst2, cond);
+    if ((dst.am() == Offset) || (dst.am() == NegOffset)) {
+      dst2.set_offset(dst2.offset() + 4);
+      str(src1, dst, cond);
+      str(src2, dst2, cond);
+    } else {  // PostIndex or NegPostIndex.
+      ASSERT((dst.am() == PostIndex) || (dst.am() == NegPostIndex));
+      dst2.set_offset(dst2.offset() - 4);
+      str(src1, MemOperand(dst.rn(), 4, PostIndex), cond);
+      str(src2, dst2, cond);
+    }
   }
 }