Dataflow analysis rework

Rework key portions of the dataflow analysis code to avoid the
massive slowdowns we're seeing with methods containing more than
20,000 basic blocks.

Add a somewhat hacky lookup cache in front of findBlock.  Later
we'll want to rework the "GrowableList" mechanism to incorporate
this properly.

Add memory to the bit vector utilities to speed up the iterators
for large sparse vectors. (Similarly, in the future we'll want
to include a rewrite of the home-grown bit-vector manipluation
utilites to be better with large ones).

With this CL, compilation speed on the degenerate cases is > 10x
faster.  Compilation of typically-sized methods will see a smallish
improvement.

Change-Id: I7f086c1229dd4fe62f0a5fc361234bf204ebc2b1

1 files changed, 2 insertions, 0 deletions

diff --git a/src/compiler/Compiler.h b/src/compiler/Compiler.h
index ac5e0c9b46..24bc8af169 100644
--- a/src/compiler/Compiler.h
+++ b/src/compiler/Compiler.h
@@ -54,6 +54,7 @@ enum debugControlVector {
     kDebugSlowestFieldPath,
     kDebugSlowestStringPath,
     kDebugExerciseResolveMethod,
+    kDebugVerifyDataflow,
 };
 
 extern uint32_t compilerDebugFlags;
@@ -91,6 +92,7 @@ typedef enum DataFlowAnalysisMode {
     kPreOrderDFSTraversal,      // Depth-First-Search / Pre-Order
     kPostOrderDFSTraversal,     // Depth-First-Search / Post-Order
     kPostOrderDOMTraversal,     // Dominator tree / Post-Order
+    kReversePostOrderTraversal, // Depth-First-Search / reverse Post-Order
 } DataFlowAnalysisMode;
 
 struct CompilationUnit;