From f976aa822dd35496e4e936b5802af0d53d39ac95 Mon Sep 17 00:00:00 2001
From: Santiago Aboy Solanes <solanes@google.com>
Date: Fri, 24 Jun 2022 11:16:35 +0100
Subject: Add an environment to the beginning of catch blocks

We can use the HNop to generate an environment for us and start
using the existing environment infrastructure (e.g. EmitEnvironment)
for recording the catch block's environment.

This is done to provide support for try catch inlining since it
requires several environments rather than just the one.

When doing so, we now have a HNop at the beginning of each catch
block. We have to modify code sinking to allow it to sink code
past this HNop because if we don't we will sink code right before
this instruction which will break the invariant of that HNop being
the first instruction of a catch block.

Test: art/test/testrunner/testrunner.py --host --64 --optimizing -b
Change-Id: I16e7b8cad499fd2d6f7415112b46206db8daf544
---
 compiler/optimizing/graph_checker.cc | 36 ++++++++++++++++++++++++------------
 1 file changed, 24 insertions(+), 12 deletions(-)

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

diff --git a/compiler/optimizing/graph_checker.cc b/compiler/optimizing/graph_checker.cc
index eda6363dda..10711510f2 100644
--- a/compiler/optimizing/graph_checker.cc
+++ b/compiler/optimizing/graph_checker.cc
@@ -159,6 +159,24 @@ void GraphChecker::VisitBasicBlock(HBasicBlock* block) {
     }
   }
 
+  // Make sure the first instruction of a catch block is always a Nop that emits an environment.
+  if (block->IsCatchBlock()) {
+    if (!block->GetFirstInstruction()->IsNop()) {
+      AddError(StringPrintf("Block %d doesn't have a Nop as its first instruction.",
+                            current_block_->GetBlockId()));
+    } else {
+      HNop* nop = block->GetFirstInstruction()->AsNop();
+      if (!nop->NeedsEnvironment()) {
+        AddError(
+            StringPrintf("%s:%d is a Nop and the first instruction of block %d, but it doesn't "
+                         "need an environment.",
+                         nop->DebugName(),
+                         nop->GetId(),
+                         current_block_->GetBlockId()));
+      }
+    }
+  }
+
   // Visit this block's list of phis.
   for (HInstructionIterator it(block->GetPhis()); !it.Done(); it.Advance()) {
     HInstruction* current = it.Current();
@@ -342,14 +360,15 @@ void GraphChecker::VisitTryBoundary(HTryBoundary* try_boundary) {
 }
 
 void GraphChecker::VisitLoadException(HLoadException* load) {
-  // Ensure that LoadException is the first instruction in a catch block.
+  // Ensure that LoadException is the second instruction in a catch block. The first one should be a
+  // Nop (checked separately).
   if (!load->GetBlock()->IsCatchBlock()) {
     AddError(StringPrintf("%s:%d is in a non-catch block %d.",
                           load->DebugName(),
                           load->GetId(),
                           load->GetBlock()->GetBlockId()));
-  } else if (load->GetBlock()->GetFirstInstruction() != load) {
-    AddError(StringPrintf("%s:%d is not the first instruction in catch block %d.",
+  } else if (load->GetBlock()->GetFirstInstruction()->GetNext() != load) {
+    AddError(StringPrintf("%s:%d is not the second instruction in catch block %d.",
                           load->DebugName(),
                           load->GetId(),
                           load->GetBlock()->GetBlockId()));
@@ -513,17 +532,10 @@ void GraphChecker::VisitInstruction(HInstruction* instruction) {
                           instruction->GetId(),
                           current_block_->GetBlockId()));
   } else if (instruction->CanThrowIntoCatchBlock()) {
-    // Find the top-level environment. This corresponds to the environment of
-    // the catch block since we do not inline methods with try/catch.
-    HEnvironment* environment = instruction->GetEnvironment();
-    while (environment->GetParent() != nullptr) {
-      environment = environment->GetParent();
-    }
-
-    // Find all catch blocks and test that `instruction` has an environment
-    // value for each one.
+    // Find all catch blocks and test that `instruction` has an environment value for each one.
     const HTryBoundary& entry = instruction->GetBlock()->GetTryCatchInformation()->GetTryEntry();
     for (HBasicBlock* catch_block : entry.GetExceptionHandlers()) {
+      const HEnvironment* environment = catch_block->GetFirstInstruction()->GetEnvironment();
       for (HInstructionIterator phi_it(catch_block->GetPhis()); !phi_it.Done(); phi_it.Advance()) {
         HPhi* catch_phi = phi_it.Current()->AsPhi();
         if (environment->GetInstructionAt(catch_phi->GetRegNumber()) == nullptr) {
-- 
cgit v1.2.3-59-g8ed1b