From d1643e41ef242ae656f667bf3c8b0324635cefd3 Mon Sep 17 00:00:00 2001
From: buzbee <buzbee@google.com>
Date: Wed, 5 Sep 2012 14:06:51 -0700
Subject: Basic block combine pass

Combine basic blocks terminated by instruction that we have since
proven not to throw.  This change is intended to relieve some of the
computational load for llvm by reducing the number of basic blocks
it has to contend with.

Also:
  Add stats to show how successful check elimination is.
  Restore mechanism to disable some expensive optimization passes when
  compiling large methods.

Change-Id: I7fae22160988cbefb90ea9fb1cc26d7364e8d229
---
 src/compiler/Frontend.cc | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

(limited to 'src/compiler/Frontend.cc')

diff --git a/src/compiler/Frontend.cc b/src/compiler/Frontend.cc
index 8c403c599e..4aa0ac89e9 100644
--- a/src/compiler/Frontend.cc
+++ b/src/compiler/Frontend.cc
@@ -80,6 +80,7 @@ static uint32_t kCompilerDebugFlags = 0 |     // Enable debug/testing modes
   //(1 << kDebugShowMemoryUsage) |
   //(1 << kDebugShowNops) |
   //(1 << kDebugCountOpcodes) |
+  //(1 << kDebugDumpCheckStats) |
 #if defined(ART_USE_QUICK_COMPILER)
   //(1 << kDebugDumpBitcodeFile) |
   //(1 << kDebugVerifyBitcode) |
@@ -315,6 +316,7 @@ void oatDumpCFG(CompilationUnit* cUnit, const char* dirPrefix)
     BasicBlock *bb = (BasicBlock *) oatGrowableListGetElement(blockList,
                                                               blockIdx);
     if (bb == NULL) break;
+    if (bb->blockType == kDead) continue;
     if (bb->blockType == kEntryBlock) {
       fprintf(file, "  entry_%d [shape=Mdiamond];\n", bb->id);
     } else if (bb->blockType == kExitBlock) {
@@ -1049,18 +1051,16 @@ CompiledMethod* oatCompileMethod(Compiler& compiler,
     }
   }
 
-#if defined(ART_USE_QUICK_COMPILER)
-  if (cUnit->genBitcode) {
-    // Bitcode generation requires full dataflow analysis, no qdMode
-    cUnit->qdMode = false;
-  }
-#endif
-
   if (cUnit->qdMode) {
+#if !defined(ART_USE_QUICK_COMPILER)
+    // Bitcode generation requires full dataflow analysis
     cUnit->disableDataflow = true;
+#endif
     // Disable optimization which require dataflow/ssa
     cUnit->disableOpt |=
+#if !defined(ART_USE_QUICK_COMPILER)
         (1 << kNullCheckElimination) |
+#endif
         (1 << kBBOpt) |
         (1 << kPromoteRegs);
     if (cUnit->printMe) {
@@ -1104,9 +1104,16 @@ CompiledMethod* oatCompileMethod(Compiler& compiler,
   /* Perform null check elimination */
   oatMethodNullCheckElimination(cUnit.get());
 
+  /* Combine basic blocks where possible */
+  oatMethodBasicBlockCombine(cUnit.get());
+
   /* Do some basic block optimizations */
   oatMethodBasicBlockOptimization(cUnit.get());
 
+  if (cUnit->enableDebug & (1 << kDebugDumpCheckStats)) {
+    oatDumpCheckStats(cUnit.get());
+  }
+
   oatInitializeRegAlloc(cUnit.get());  // Needs to happen after SSA naming
 
   /* Allocate Registers using simple local allocation scheme */
-- 
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