Support unaligned integer loads on ARM and MIPS.

runtime/vm/assembler_arm64.cc

Index: runtime/vm/assembler_arm64.cc
diff --git a/runtime/vm/assembler_arm64.cc b/runtime/vm/assembler_arm64.cc
index 37e9ca3b59bd9031f33498a69ff6d942d3d59efa..cec46518fabd5ff6baa20395ebd3e67a2e7cc383 100644
--- a/runtime/vm/assembler_arm64.cc
+++ b/runtime/vm/assembler_arm64.cc
@@ -1444,6 +1444,18 @@ Address Assembler::ElementAddressForIntIndex(bool is_external,
 }
 
 
+void Assembler::LoadElementAddressForIntIndex(Register address,
+                                              bool is_external,
+                                              intptr_t cid,
+                                              intptr_t index_scale,
+                                              Register array,
+                                              intptr_t index) {
+  const int64_t offset = index * index_scale +
+      (is_external ? 0 : (Instance::DataOffsetFor(cid) - kHeapObjectTag));
+  AddImmediate(address, array, offset);
+}
+
+
 Address Assembler::ElementAddressForRegIndex(bool is_load,
                                              bool is_external,
                                              intptr_t cid,
@@ -1470,6 +1482,102 @@ Address Assembler::ElementAddressForRegIndex(bool is_load,
   return Address(base, offset, Address::Offset, size);
 }
 
+
+void Assembler::LoadElementAddressForRegIndex(Register address,
+                                              bool is_load,
+                                              bool is_external,
+                                              intptr_t cid,
+                                              intptr_t index_scale,
+                                              Register array,
+                                              Register index) {
+  // Note that index is expected smi-tagged, (i.e, LSL 1) for all arrays.
+  const intptr_t shift = Utils::ShiftForPowerOfTwo(index_scale) - kSmiTagShift;
+  const int32_t offset =
+      is_external ? 0 : (Instance::DataOffsetFor(cid) - kHeapObjectTag);
+  if (shift == 0) {
+    add(address, array, Operand(index));
+  } else if (shift < 0) {
+    ASSERT(shift == -1);
+    add(address, array, Operand(index, ASR, 1));
+  } else {
+    add(address, array, Operand(index, LSL, shift));
+  }
+  if (offset != 0) {
+    AddImmediate(address, address, offset);
+  }
+}
+
+
+void Assembler::LoadUnaligned(Register dst, Register addr, Register tmp,
+                              OperandSize sz) {
+  ASSERT(dst != addr);
+  ldr(dst, Address(addr, 0), kUnsignedByte);
+  if (sz == kHalfword) {
+    ldr(tmp, Address(addr, 1), kByte);
+    orr(dst, dst, Operand(tmp, LSL, 8));
+    return;
+  }
+  ldr(tmp, Address(addr, 1), kUnsignedByte);
+  orr(dst, dst, Operand(tmp, LSL, 8));
+  if (sz == kUnsignedHalfword) {
+    return;
+  }
+  ldr(tmp, Address(addr, 2), kUnsignedByte);
+  orr(dst, dst, Operand(tmp, LSL, 16));
+  if (sz == kWord) {
+    ldr(tmp, Address(addr, 3), kByte);
+    orr(dst, dst, Operand(tmp, LSL, 24));
+    return;
+  }
+  ldr(tmp, Address(addr, 3), kUnsignedByte);
+  orr(dst, dst, Operand(tmp, LSL, 24));
+  if (sz == kUnsignedWord) {
+    return;
+  }
+  ldr(tmp, Address(addr, 4), kUnsignedByte);
+  orr(dst, dst, Operand(tmp, LSL, 32));
+  ldr(tmp, Address(addr, 5), kUnsignedByte);
+  orr(dst, dst, Operand(tmp, LSL, 40));
+  ldr(tmp, Address(addr, 6), kUnsignedByte);
+  orr(dst, dst, Operand(tmp, LSL, 48));
+  ldr(tmp, Address(addr, 7), kUnsignedByte);
+  orr(dst, dst, Operand(tmp, LSL, 56));
+  if (sz == kDoubleWord) {
+    return;
+  }
+  UNIMPLEMENTED();
+}
+
+
+void Assembler::StoreUnaligned(Register src, Register addr, Register tmp,
+                               OperandSize sz) {
+  str(src, Address(addr, 0), kUnsignedByte);
+  LsrImmediate(tmp, src, 8);
+  str(tmp, Address(addr, 1), kUnsignedByte);
+  if ((sz == kHalfword) || (sz == kUnsignedHalfword)) {
+    return;
+  }
+  LsrImmediate(tmp, src, 16);
+  str(tmp, Address(addr, 2), kUnsignedByte);
+  LsrImmediate(tmp, src, 24);
+  str(tmp, Address(addr, 3), kUnsignedByte);
+  if ((sz == kWord) || (sz == kUnsignedWord)) {
+    return;
+  }
+  LsrImmediate(tmp, src, 24);
+  str(tmp, Address(addr, 4), kUnsignedByte);
+  LsrImmediate(tmp, src, 32);
+  str(tmp, Address(addr, 5), kUnsignedByte);
+  LsrImmediate(tmp, src, 40);
+  str(tmp, Address(addr, 6), kUnsignedByte);
+  LsrImmediate(tmp, src, 48);
+  str(tmp, Address(addr, 7), kUnsignedByte);
+  if (sz == kDoubleWord) {
+    return;
+  }
+  UNIMPLEMENTED();
+}
+
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM64