Move quickening info logic to its own table

Added a table that is indexed by dex method index. To prevent size
overhead, there is only one slot for each 16 method indices. This
means there is up to 15 loop iterations to get the quickening info
for a method. The quickening infos are now prefixed by a leb
encoded length. This allows methods that aren't quickened to only
have 1.25 bytes of space overhead.

The value was picked arbitrarily, there is little advantage to
increasing the value since the table only takes 1 byte per 4 method
indices currently. JIT benchmarks do not regress with the change.

There is a net space saving from removing 8 bytes from each
quickening info since most scenarios have more quickened methods than
compiled methods.

For getting quick access to the table, a 4 byte preheader was added
to each dex in the vdex file

Removed logic that stored the quickening info in the CodeItem
debug_info_offset field.

The change adds a small quicken table for each method index, this
means that filters that don't quicken will have a slight increase in
size. The worst case scenario is compiling all the methods, this
results in 0.3% larger vdex for this case. The change also disables
deduping since the quicken infos need to be in dex method index
order.

For filters that don't compile most methods like quicken and
speed-profile, there is space savings. For quicken, the vdex is 2%
smaller.

Bug: 71605148
Bug: 63756964
Test: test-art-host

Change-Id: I89cb679538811369c36b6ac8c40ea93135f813cd

1 files changed, 5 insertions, 7 deletions

diff --git a/runtime/dex_to_dex_decompiler.cc b/runtime/dex_to_dex_decompiler.cc
index e1c07baede..7887191713 100644
--- a/runtime/dex_to_dex_decompiler.cc
+++ b/runtime/dex_to_dex_decompiler.cc
@@ -36,8 +36,7 @@ class DexDecompiler {
                 const ArrayRef<const uint8_t>& quickened_info,
                 bool decompile_return_instruction)
     : code_item_accessor_(dex_file, &code_item),
-      quicken_info_(quickened_info.data()),
-      quicken_info_number_of_indices_(QuickenInfoTable::NumberOfIndices(quickened_info.size())),
+      quicken_info_(quickened_info),
       decompile_return_instruction_(decompile_return_instruction) {}
 
   bool Decompile();
@@ -72,7 +71,7 @@ class DexDecompiler {
   }
 
   uint16_t NextIndex() {
-    DCHECK_LT(quicken_index_, quicken_info_number_of_indices_);
+    DCHECK_LT(quicken_index_, quicken_info_.NumIndices());
     const uint16_t ret = quicken_info_.GetData(quicken_index_);
     quicken_index_++;
     return ret;
@@ -80,7 +79,6 @@ class DexDecompiler {
 
   const CodeItemInstructionAccessor code_item_accessor_;
   const QuickenInfoTable quicken_info_;
-  const size_t quicken_info_number_of_indices_;
   const bool decompile_return_instruction_;
 
   size_t quicken_index_ = 0u;
@@ -104,7 +102,7 @@ bool DexDecompiler::Decompile() {
         break;
 
       case Instruction::NOP:
-        if (quicken_info_number_of_indices_ > 0) {
+        if (quicken_info_.NumIndices() > 0) {
           // Only try to decompile NOP if there are more than 0 indices. Not having
           // any index happens when we unquicken a code item that only has
           // RETURN_VOID_NO_BARRIER as quickened instruction.
@@ -181,14 +179,14 @@ bool DexDecompiler::Decompile() {
     }
   }
 
-  if (quicken_index_ != quicken_info_number_of_indices_) {
+  if (quicken_index_ != quicken_info_.NumIndices()) {
     if (quicken_index_ == 0) {
       LOG(WARNING) << "Failed to use any value in quickening info,"
                    << " potentially due to duplicate methods.";
     } else {
       LOG(FATAL) << "Failed to use all values in quickening info."
                  << " Actual: " << std::hex << quicken_index_
-                 << " Expected: " << quicken_info_number_of_indices_;
+                 << " Expected: " << quicken_info_.NumIndices();
       return false;
     }
   }