Move and rewrite bit loading/storing methods.

Move bit loading/storing methods to BitMemoryRegion and rewrite them.

Enforce natural alignment of the data pointer in BitMemoryRegion.
This probably would not be reasonable in MemoryRegion, but it is
fine here since the BitMemoryRegion already has extra bit offset.
The alignment makes it possible to simplify and optimize the methods.

This makes the stackmap reading code 33% faster.
(measured by the time needed to verify all stackmap fields on ARM).

Test: m -j40 test-art-host-gtest
Change-Id: I00be8052969a6056b262df4cd2066ffd86043196

1 files changed, 7 insertions, 5 deletions

diff --git a/compiler/optimizing/stack_map_stream.cc b/compiler/optimizing/stack_map_stream.cc
index 7010e3f380..bf7c5542ef 100644
--- a/compiler/optimizing/stack_map_stream.cc
+++ b/compiler/optimizing/stack_map_stream.cc
@@ -427,10 +427,11 @@ void StackMapStream::FillInCodeInfo(MemoryRegion region) {
   if (stack_mask_bits > 0) {
     size_t stack_mask_bytes = RoundUp(stack_mask_bits, kBitsPerByte) / kBitsPerByte;
     for (size_t i = 0; i < encoding.stack_mask.num_entries; ++i) {
-      MemoryRegion source(&stack_masks_[i * stack_mask_bytes], stack_mask_bytes);
-      BitMemoryRegion stack_mask = code_info.GetStackMask(i, encoding);
-      for (size_t bit_index = 0; bit_index < stack_mask_bits; ++bit_index) {
-        stack_mask.StoreBit(bit_index, source.LoadBit(bit_index));
+      BitMemoryRegion src(MemoryRegion(&stack_masks_[i * stack_mask_bytes], stack_mask_bytes));
+      BitMemoryRegion dst = code_info.GetStackMask(i, encoding);
+      for (size_t bit_index = 0; bit_index < stack_mask_bits; bit_index += BitSizeOf<uint32_t>()) {
+        size_t num_bits = std::min<size_t>(stack_mask_bits - bit_index, BitSizeOf<uint32_t>());
+        dst.StoreBits(bit_index, src.LoadBits(bit_index, num_bits), num_bits);
       }
     }
   }
@@ -600,8 +601,9 @@ size_t StackMapStream::PrepareStackMasks(size_t entry_size_in_bits) {
   for (StackMapEntry& stack_map : stack_maps_) {
     size_t index = dedup.size();
     MemoryRegion stack_mask(stack_masks_.data() + index * byte_entry_size, byte_entry_size);
+    BitMemoryRegion stack_mask_bits(stack_mask);
     for (size_t i = 0; i < entry_size_in_bits; i++) {
-      stack_mask.StoreBit(i, stack_map.sp_mask != nullptr && stack_map.sp_mask->IsBitSet(i));
+      stack_mask_bits.StoreBit(i, stack_map.sp_mask != nullptr && stack_map.sp_mask->IsBitSet(i));
     }
     stack_map.stack_mask_index = dedup.emplace(stack_mask, index).first->second;
   }