Implement irreducible loop support in optimizing.

So we don't fallback to the interpreter in the presence of
irreducible loops.

Implications:
- A loop pre-header does not necessarily dominate a loop header.
- Non-constant redundant phis will be kept in loop headers, to
  satisfy our linear scan register allocation algorithm.
- while-graph optimizations, such as gvn, licm, lse, and dce
  need to know when they are dealing with irreducible loops.

Change-Id: I2cea8934ce0b40162d215353497c7f77d6c9137e

1 files changed, 5 insertions, 8 deletions

diff --git a/compiler/optimizing/optimizing_compiler.cc b/compiler/optimizing/optimizing_compiler.cc
index 3eb72744ee..cafc6c5440 100644
--- a/compiler/optimizing/optimizing_compiler.cc
+++ b/compiler/optimizing/optimizing_compiler.cc
@@ -777,19 +777,16 @@ CodeGenerator* OptimizingCompiler::TryCompile(ArenaAllocator* arena,
 
     {
       PassScope scope(SsaBuilder::kSsaBuilderPassName, &pass_observer);
-      BuildSsaResult result = graph->TryBuildingSsa(&handles);
-      if (result != kBuildSsaSuccess) {
+      GraphAnalysisResult result = graph->TryBuildingSsa(&handles);
+      if (result != kAnalysisSuccess) {
         switch (result) {
-          case kBuildSsaFailNonNaturalLoop:
-            MaybeRecordStat(MethodCompilationStat::kNotCompiledNonNaturalLoop);
-            break;
-          case kBuildSsaFailThrowCatchLoop:
+          case kAnalysisFailThrowCatchLoop:
             MaybeRecordStat(MethodCompilationStat::kNotCompiledThrowCatchLoop);
             break;
-          case kBuildSsaFailAmbiguousArrayOp:
+          case kAnalysisFailAmbiguousArrayOp:
             MaybeRecordStat(MethodCompilationStat::kNotCompiledAmbiguousArrayOp);
             break;
-          case kBuildSsaSuccess:
+          case kAnalysisSuccess:
             UNREACHABLE();
         }
         pass_observer.SetGraphInBadState();