From 86ea7eeabe30c98bbe1651a51d03cb89776724e7 Mon Sep 17 00:00:00 2001
From: David Brazdil <dbrazdil@google.com>
Date: Tue, 16 Feb 2016 09:26:07 +0000
Subject: Build dominator tree before generating HInstructions

Second CL in the series of merging HGraphBuilder and SsaBuilder. This
patch refactors the builders so that dominator tree can be built
before any HInstructions are generated. This puts the SsaBuilder
removal of HLoadLocals/HStoreLocals straight after HGraphBuilder's
HInstruction generation phase. Next CL will therefore be able to
merge them.

This patch also adds util classes for iterating bytecode and switch
tables which allowed to simplify the code.

Bug: 27894376
Change-Id: Ic425d298b2e6e7980481ed697230b1a0b7904526
---
 compiler/optimizing/graph_checker.cc | 69 +++++++++++++++++++-----------------
 1 file changed, 37 insertions(+), 32 deletions(-)

(limited to 'compiler/optimizing/graph_checker.cc')

diff --git a/compiler/optimizing/graph_checker.cc b/compiler/optimizing/graph_checker.cc
index c790d013b5..9ea4b2dab4 100644
--- a/compiler/optimizing/graph_checker.cc
+++ b/compiler/optimizing/graph_checker.cc
@@ -27,6 +27,21 @@
 
 namespace art {
 
+static bool IsAllowedToJumpToExitBlock(HInstruction* instruction) {
+  return instruction->IsThrow() || instruction->IsReturn() || instruction->IsReturnVoid();
+}
+
+static bool IsExitTryBoundaryIntoExitBlock(HBasicBlock* block) {
+  if (!block->IsSingleTryBoundary()) {
+    return false;
+  }
+
+  HTryBoundary* boundary = block->GetLastInstruction()->AsTryBoundary();
+  return block->GetPredecessors().size() == 1u &&
+         boundary->GetNormalFlowSuccessor()->IsExitBlock() &&
+         !boundary->IsEntry();
+}
+
 void GraphChecker::VisitBasicBlock(HBasicBlock* block) {
   current_block_ = block;
 
@@ -85,28 +100,17 @@ void GraphChecker::VisitBasicBlock(HBasicBlock* block) {
                           block->GetBlockId()));
   }
 
-  // Ensure that only Return(Void) and Throw jump to Exit. An exiting
-  // TryBoundary may be between a Throw and the Exit if the Throw is in a try.
+  // Ensure that only Return(Void) and Throw jump to Exit. An exiting TryBoundary
+  // may be between the instructions if the Throw/Return(Void) is in a try block.
   if (block->IsExitBlock()) {
     for (HBasicBlock* predecessor : block->GetPredecessors()) {
-      if (predecessor->IsSingleTryBoundary()
-          && !predecessor->GetLastInstruction()->AsTryBoundary()->IsEntry()) {
-        HBasicBlock* real_predecessor = predecessor->GetSinglePredecessor();
-        HInstruction* last_instruction = real_predecessor->GetLastInstruction();
-        if (!last_instruction->IsThrow()) {
-          AddError(StringPrintf("Unexpected TryBoundary between %s:%d and Exit.",
-                                last_instruction->DebugName(),
-                                last_instruction->GetId()));
-        }
-      } else {
-        HInstruction* last_instruction = predecessor->GetLastInstruction();
-        if (!last_instruction->IsReturn()
-            && !last_instruction->IsReturnVoid()
-            && !last_instruction->IsThrow()) {
-          AddError(StringPrintf("Unexpected instruction %s:%d jumps into the exit block.",
-                                last_instruction->DebugName(),
-                                last_instruction->GetId()));
-        }
+      HInstruction* last_instruction = IsExitTryBoundaryIntoExitBlock(predecessor) ?
+        predecessor->GetSinglePredecessor()->GetLastInstruction() :
+        predecessor->GetLastInstruction();
+      if (!IsAllowedToJumpToExitBlock(last_instruction)) {
+        AddError(StringPrintf("Unexpected instruction %s:%d jumps into the exit block.",
+                              last_instruction->DebugName(),
+                              last_instruction->GetId()));
       }
     }
   }
@@ -176,16 +180,15 @@ void GraphChecker::VisitBasicBlock(HBasicBlock* block) {
   // predecessors). Exceptional edges are synthesized and hence
   // not accounted for.
   if (block->GetSuccessors().size() > 1) {
-    for (HBasicBlock* successor : block->GetNormalSuccessors()) {
-      if (successor->IsExitBlock() &&
-          block->IsSingleTryBoundary() &&
-          block->GetPredecessors().size() == 1u &&
-          block->GetSinglePredecessor()->GetLastInstruction()->IsThrow()) {
-        // Allowed critical edge Throw->TryBoundary->Exit.
-      } else if (successor->GetPredecessors().size() > 1) {
-        AddError(StringPrintf("Critical edge between blocks %d and %d.",
-                              block->GetBlockId(),
-                              successor->GetBlockId()));
+    if (IsExitTryBoundaryIntoExitBlock(block)) {
+      // Allowed critical edge (Throw/Return/ReturnVoid)->TryBoundary->Exit.
+    } else {
+      for (HBasicBlock* successor : block->GetNormalSuccessors()) {
+        if (successor->GetPredecessors().size() > 1) {
+          AddError(StringPrintf("Critical edge between blocks %d and %d.",
+                                block->GetBlockId(),
+                                successor->GetBlockId()));
+        }
       }
     }
   }
@@ -505,7 +508,8 @@ void GraphChecker::VisitInvokeStaticOrDirect(HInvokeStaticOrDirect* invoke) {
 
 void GraphChecker::VisitReturn(HReturn* ret) {
   VisitInstruction(ret);
-  if (!ret->GetBlock()->GetSingleSuccessor()->IsExitBlock()) {
+  HBasicBlock* successor = ret->GetBlock()->GetSingleSuccessor();
+  if (!successor->IsExitBlock() && !IsExitTryBoundaryIntoExitBlock(successor)) {
     AddError(StringPrintf("%s:%d does not jump to the exit block.",
                           ret->DebugName(),
                           ret->GetId()));
@@ -514,7 +518,8 @@ void GraphChecker::VisitReturn(HReturn* ret) {
 
 void GraphChecker::VisitReturnVoid(HReturnVoid* ret) {
   VisitInstruction(ret);
-  if (!ret->GetBlock()->GetSingleSuccessor()->IsExitBlock()) {
+  HBasicBlock* successor = ret->GetBlock()->GetSingleSuccessor();
+  if (!successor->IsExitBlock() && !IsExitTryBoundaryIntoExitBlock(successor)) {
     AddError(StringPrintf("%s:%d does not jump to the exit block.",
                           ret->DebugName(),
                           ret->GetId()));
-- 
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