Address additional comments on try-catch CL
Extra documentation of try-catch building.
Change-Id: I5048c5fcb354c76fa4a60c3d8d21dd216bc9f6cd
diff --git a/compiler/optimizing/builder.cc b/compiler/optimizing/builder.cc
index 883c983..54155db 100644
--- a/compiler/optimizing/builder.cc
+++ b/compiler/optimizing/builder.cc
@@ -346,11 +346,19 @@
// Catch blocks are always considered an entry point into the TryItem in
// order to avoid splitting exceptional edges (they might not have been
// created yet). We separate the move-exception (if present) from the
- // rest of the block and insert a TryBoundary after it.
- HInstruction* split_position = try_block->GetFirstInstruction();
- if (split_position->IsLoadException()) {
- DCHECK(split_position->GetNext()->IsStoreLocal());
- split_position = split_position->GetNext()->GetNext();
+ // rest of the block and insert a TryBoundary after it, creating a
+ // landing pad for the exceptional edges.
+ HInstruction* first_insn = try_block->GetFirstInstruction();
+ HInstruction* split_position = nullptr;
+ if (first_insn->IsLoadException()) {
+ // Catch block starts with a LoadException. Split the block after the
+ // StoreLocal that must come after the load.
+ DCHECK(first_insn->GetNext()->IsStoreLocal());
+ split_position = first_insn->GetNext()->GetNext();
+ } else {
+ // Catch block does not obtain the exception. Split at the beginning
+ // to create an empty catch block.
+ split_position = first_insn;
}
DCHECK(split_position != nullptr);
HBasicBlock* catch_block = try_block;
diff --git a/compiler/optimizing/builder.h b/compiler/optimizing/builder.h
index 9744a55..cae762b 100644
--- a/compiler/optimizing/builder.h
+++ b/compiler/optimizing/builder.h
@@ -98,9 +98,19 @@
HBasicBlock* FindBlockStartingAt(int32_t dex_pc) const;
HBasicBlock* FindOrCreateBlockStartingAt(int32_t dex_pc);
+ // Returns whether the dex_pc of `block` lies within the given range.
bool IsBlockInPcRange(HBasicBlock* block, uint32_t dex_pc_start, uint32_t dex_pc_end);
+
+ // Adds new blocks to `branch_targets_` starting at the limits of TryItems and
+ // their exception handlers.
void CreateBlocksForTryCatch(const DexFile::CodeItem& code_item);
+
+ // Splits edges which cross the boundaries of TryItems, inserts TryBoundary
+ // instructions and links them to the corresponding catch blocks.
void InsertTryBoundaryBlocks(const DexFile::CodeItem& code_item);
+
+ // Splits a single edge, inserting a TryBoundary of given `kind` and linking
+ // it to exception handlers of `try_item`.
void SplitTryBoundaryEdge(HBasicBlock* predecessor,
HBasicBlock* successor,
HTryBoundary::BoundaryKind kind,
diff --git a/compiler/optimizing/nodes.h b/compiler/optimizing/nodes.h
index 5c10245..04c3963 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -1957,8 +1957,6 @@
bool IsControlFlow() const OVERRIDE { return true; }
- bool CanThrow() const OVERRIDE { return true; }
-
// Returns the block's non-exceptional successor (index zero).
HBasicBlock* GetNormalFlowSuccessor() const { return GetBlock()->GetSuccessors().Get(0); }