Revert^2 "DCE SimplifyAlwaysThrowing optimizations"

This reverts commit 026a662dd6bef3e0e5a58478b764c4ddf662a5ec.

Reason for revert: after aosp/2055933 the inliner will return
true if it analyzed a method as "always throwing". This CL now
uses `after_inliner` instead of `after_gvn` and shouldn't make
the LUCI bots red.

Bug: 227316307
Test: art/test/testrunner/testrunner.py --host --64 --optimizing -b
Change-Id: Icbc2678633c289ae6d066185e9b16e9c3674c8d0

2 files changed, 37 insertions, 13 deletions

diff --git a/compiler/optimizing/dead_code_elimination.cc b/compiler/optimizing/dead_code_elimination.cc
index 1dc10948cc..d808f2ca3a 100644
--- a/compiler/optimizing/dead_code_elimination.cc
+++ b/compiler/optimizing/dead_code_elimination.cc
@@ -209,6 +209,9 @@ static bool RemoveNonNullControlDependences(HBasicBlock* block, HBasicBlock* thr
 //
 //           B1
 //          /  \
+//          |   instr_1
+//          |   ...
+//          |   instr_n
 //          |   foo()  // always throws
 //          \   goto B2
 //           \ /
@@ -218,6 +221,9 @@ static bool RemoveNonNullControlDependences(HBasicBlock* block, HBasicBlock* thr
 //
 //           B1
 //          /  \
+//          |  instr_1
+//          |  ...
+//          |  instr_n
 //          |  foo()
 //          |  goto Exit
 //          |   |
@@ -227,10 +233,6 @@ static bool RemoveNonNullControlDependences(HBasicBlock* block, HBasicBlock* thr
 // Removal of the never taken edge to B2 may expose
 // other optimization opportunities, such as code sinking.
 bool HDeadCodeElimination::SimplifyAlwaysThrows() {
-  // Make sure exceptions go to exit.
-  if (graph_->HasTryCatch()) {
-    return false;
-  }
   HBasicBlock* exit = graph_->GetExitBlock();
   if (exit == nullptr) {
     return false;
@@ -240,15 +242,35 @@ bool HDeadCodeElimination::SimplifyAlwaysThrows() {
 
   // Order does not matter, just pick one.
   for (HBasicBlock* block : graph_->GetReversePostOrder()) {
-    HInstruction* first = block->GetFirstInstruction();
+    if (block->GetTryCatchInformation() != nullptr) {
+      // We don't want to perform the simplify always throws optimizations for throws inside of
+      // tries since those throws might not go to the exit block. We do that by checking the
+      // TryCatchInformation of the blocks.
+      //
+      // As a special case the `catch_block` is the first block of the catch and it has
+      // TryCatchInformation. Other blocks in the catch don't have try catch information (as long as
+      // they are not part of an outer try). Knowing if a `catch_block` is part of an outer try is
+      // possible by checking its successors, but other restrictions of the simplify always throws
+      // optimization will block `catch_block` nevertheless (e.g. only one predecessor) so it is not
+      // worth the effort.
+
+      // TODO(solanes): Maybe we can do a `goto catch` if inside of a try catch instead of going to
+      // the exit. If we do so, we have to take into account that we should go to the nearest valid
+      // catch i.e. one that would accept our exception type.
+      continue;
+    }
+
     HInstruction* last = block->GetLastInstruction();
-    // Ensure only one throwing instruction appears before goto.
-    if (first->AlwaysThrows() &&
-        first->GetNext() == last &&
+    HInstruction* prev = last->GetPrevious();
+    if (prev == nullptr) {
+      DCHECK_EQ(block->GetFirstInstruction(), block->GetLastInstruction());
+      continue;
+    }
+
+    if (prev->AlwaysThrows() &&
         last->IsGoto() &&
         block->GetPhis().IsEmpty() &&
         block->GetPredecessors().size() == 1u) {
-      DCHECK_EQ(block->GetSuccessors().size(), 1u);
       HBasicBlock* pred = block->GetSinglePredecessor();
       HBasicBlock* succ = block->GetSingleSuccessor();
       // Ensure no computations are merged through throwing block.
diff --git a/compiler/optimizing/graph_visualizer.cc b/compiler/optimizing/graph_visualizer.cc
index 716fee4d3e..4a6ee13005 100644
--- a/compiler/optimizing/graph_visualizer.cc
+++ b/compiler/optimizing/graph_visualizer.cc
@@ -586,6 +586,10 @@ class HGraphVisualizerPrinter : public HGraphDelegateVisitor {
     StartAttributeStream("kind") << (try_boundary->IsEntry() ? "entry" : "exit");
   }
 
+  void VisitGoto(HGoto* instruction) override {
+    StartAttributeStream("target") << namer_.GetName(instruction->GetBlock()->GetSingleSuccessor());
+  }
+
   void VisitDeoptimize(HDeoptimize* deoptimize) override {
     StartAttributeStream("kind") << deoptimize->GetKind();
   }
@@ -657,10 +661,8 @@ class HGraphVisualizerPrinter : public HGraphDelegateVisitor {
       StartAttributeStream("dex_pc") << "n/a";
     }
     HBasicBlock* block = instruction->GetBlock();
-    if (IsPass(kDebugDumpName)) {
-      // Include block name for logcat use.
-      StartAttributeStream("block") << namer_.GetName(block);
-    }
+    StartAttributeStream("block") << namer_.GetName(block);
+
     instruction->Accept(this);
     if (instruction->HasEnvironment()) {
       StringList envs;