[compiler] Move OSR entry point calculation into bytecode analysis

Instead of calculating the OSR entry point both in the bytecode analysis
and in the bytecode graph builder, calculate it once in the analysis and
use that calculation in the graph builder.

Old TODO from https://codereview.chromium.org/2558093005.

Change-Id: I071bc622beb55dc5eddaee25ef28e21fc4b477f0
Reviewed-on: https://chromium-review.googlesource.com/485899
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44888}

src/compiler/bytecode-analysis.cc

@@ -90,6 +90,7 @@ BytecodeAnalysis::BytecodeAnalysis(Handle<BytecodeArray> bytecode_array,
       loop_end_index_queue_(zone),
       end_to_header_(zone),
       header_to_info_(zone),
+      osr_entry_point_(-1),
       liveness_map_(bytecode_array->length(), zone) {}
 
 namespace {
@@ -256,7 +257,8 @@ void BytecodeAnalysis::Analyze(BailoutId osr_bailout_id) {
       // Every byte up to and including the last byte within the backwards jump
       // instruction is considered part of the loop, set loop end accordingly.
       int loop_end = current_offset + iterator.current_bytecode_size();
-      PushLoop(iterator.GetJumpTargetOffset(), loop_end);
+      int loop_header = iterator.GetJumpTargetOffset();
+      PushLoop(loop_header, loop_end);
 
       // Normally prefixed bytecodes are treated as if the prefix's offset was
       // the actual bytecode's offset. However, the OSR id is the offset of the
@@ -270,9 +272,10 @@ void BytecodeAnalysis::Analyze(BailoutId osr_bailout_id) {
       DCHECK(!is_osr_loop ||
              iterator.OffsetWithinBytecode(osr_loop_end_offset));
 
-      // OSR "assigns" everything to OSR values on entry into an OSR loop, so we
-      // need to make sure to considered everything to be assigned.
       if (is_osr_loop) {
+        osr_entry_point_ = loop_header;
+        // OSR "assigns" everything to OSR values on entry into an OSR loop, so
+        // we need to make sure to considered everything to be assigned.
         loop_stack_.top().loop_info->assignments().AddAll();
       }
 

src/compiler/bytecode-analysis.h

@@ -80,6 +80,11 @@ class V8_EXPORT_PRIVATE BytecodeAnalysis BASE_EMBEDDED {
   // Get the loop info of the loop header at {header_offset}.
   const LoopInfo& GetLoopInfoFor(int header_offset) const;
 
+  // True if the current analysis has an OSR entry point.
+  bool HasOSREntryPoint() const { return osr_entry_point_ != -1; }
+  // True if {offset} is the OSR entry loop header.
+  bool IsOSREntryPoint(int offset) const { return osr_entry_point_ == offset; }
+
   // Gets the in-liveness for the bytecode at {offset}.
   const BytecodeLivenessState* GetInLivenessFor(int offset) const;
 
@@ -113,6 +118,7 @@ class V8_EXPORT_PRIVATE BytecodeAnalysis BASE_EMBEDDED {
 
   ZoneMap<int, int> end_to_header_;
   ZoneMap<int, LoopInfo> header_to_info_;
+  int osr_entry_point_;
 
   BytecodeLivenessMap liveness_map_;
 

src/compiler/bytecode-graph-builder.cc

@@ -475,7 +475,6 @@ BytecodeGraphBuilder::BytecodeGraphBuilder(
       bytecode_analysis_(nullptr),
       environment_(nullptr),
       osr_ast_id_(osr_ast_id),
-      osr_loop_offset_(-1),
       merge_environments_(local_zone),
       exception_handlers_(local_zone),
       current_exception_handler_(0),
@@ -2380,7 +2379,7 @@ void BytecodeGraphBuilder::MergeControlToLeaveFunction(Node* exit) {
 void BytecodeGraphBuilder::BuildOSRLoopEntryPoint(int current_offset) {
   DCHECK(bytecode_analysis()->IsLoopHeader(current_offset));
 
-  if (!osr_ast_id_.IsNone() && osr_loop_offset_ == current_offset) {
+  if (bytecode_analysis()->IsOSREntryPoint(current_offset)) {
     // For OSR add a special {OsrLoopEntry} node into the current loop header.
     // It will be turned into a usable entry by the OSR deconstruction.
     Environment* osr_env = environment()->Copy();
@@ -2390,15 +2389,10 @@ void BytecodeGraphBuilder::BuildOSRLoopEntryPoint(int current_offset) {
 }
 
 void BytecodeGraphBuilder::BuildOSRNormalEntryPoint() {
-  if (!osr_ast_id_.IsNone()) {
+  if (bytecode_analysis()->HasOSREntryPoint()) {
     // For OSR add an {OsrNormalEntry} as the the top-level environment start.
     // It will be replaced with {Dead} by the OSR deconstruction.
     NewNode(common()->OsrNormalEntry());
-    // Translate the offset of the jump instruction to the jump target offset of
-    // that instruction so that the derived BailoutId points to the loop header.
-    osr_loop_offset_ =
-        bytecode_analysis()->GetLoopOffsetFor(osr_ast_id_.ToInt());
-    DCHECK(bytecode_analysis()->IsLoopHeader(osr_loop_offset_));
   }
 }
 
@@ -2545,7 +2539,7 @@ Node* BytecodeGraphBuilder::TryBuildSimplifiedLoadNamed(const Operator* op,
   // TODO(mstarzinger,6112): This is a workaround for OSR loop entries being
   // pruned from the graph by a soft-deopt. It can happen that a LoadIC that
   // control-dominates the OSR entry is still in "uninitialized" state.
-  if (!osr_ast_id_.IsNone()) return nullptr;
+  if (bytecode_analysis()->HasOSREntryPoint()) return nullptr;
   Node* effect = environment()->GetEffectDependency();
   Node* control = environment()->GetControlDependency();
   Reduction early_reduction = type_hint_lowering().ReduceLoadNamedOperation(
@@ -2564,7 +2558,7 @@ Node* BytecodeGraphBuilder::TryBuildSimplifiedLoadKeyed(const Operator* op,
   // TODO(mstarzinger,6112): This is a workaround for OSR loop entries being
   // pruned from the graph by a soft-deopt. It can happen that a LoadIC that
   // control-dominates the OSR entry is still in "uninitialized" state.
-  if (!osr_ast_id_.IsNone()) return nullptr;
+  if (bytecode_analysis()->HasOSREntryPoint()) return nullptr;
   Node* effect = environment()->GetEffectDependency();
   Node* control = environment()->GetControlDependency();
   Reduction early_reduction = type_hint_lowering().ReduceLoadKeyedOperation(
@@ -2583,7 +2577,7 @@ Node* BytecodeGraphBuilder::TryBuildSimplifiedStoreNamed(const Operator* op,
   // TODO(mstarzinger,6112): This is a workaround for OSR loop entries being
   // pruned from the graph by a soft-deopt. It can happen that a LoadIC that
   // control-dominates the OSR entry is still in "uninitialized" state.
-  if (!osr_ast_id_.IsNone()) return nullptr;
+  if (bytecode_analysis()->HasOSREntryPoint()) return nullptr;
   Node* effect = environment()->GetEffectDependency();
   Node* control = environment()->GetControlDependency();
   Reduction early_reduction = type_hint_lowering().ReduceStoreNamedOperation(
@@ -2602,7 +2596,7 @@ Node* BytecodeGraphBuilder::TryBuildSimplifiedStoreKeyed(const Operator* op,
   // TODO(mstarzinger,6112): This is a workaround for OSR loop entries being
   // pruned from the graph by a soft-deopt. It can happen that a LoadIC that
   // control-dominates the OSR entry is still in "uninitialized" state.
-  if (!osr_ast_id_.IsNone()) return nullptr;
+  if (bytecode_analysis()->HasOSREntryPoint()) return nullptr;
   Node* effect = environment()->GetEffectDependency();
   Node* control = environment()->GetControlDependency();
   Reduction early_reduction = type_hint_lowering().ReduceStoreKeyedOperation(

src/compiler/bytecode-graph-builder.h

@@ -325,7 +325,6 @@ class BytecodeGraphBuilder {
   const BytecodeAnalysis* bytecode_analysis_;
   Environment* environment_;
   BailoutId osr_ast_id_;
-  int osr_loop_offset_;
 
   // Merge environments are snapshots of the environment at points where the
   // control flow merges. This models a forward data flow propagation of all