Improve the AST representation of Objective-C @try/@catch/@finally

statements. Instead of the @try having a single @catch, where all of
the @catch's were chained (using an O(n^2) algorithm nonetheless),
@try just holds an array of its @catch blocks. The resulting AST is
slightly more compact (not important) and better represents the actual
language semantics (good).



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@102221 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 36 insertions, 24 deletions

diff --git a/lib/Frontend/PCHReaderStmt.cpp b/lib/Frontend/PCHReaderStmt.cpp
index d253654f7c..cf26b6e237 100644
--- a/lib/Frontend/PCHReaderStmt.cpp
+++ b/lib/Frontend/PCHReaderStmt.cpp
@@ -838,12 +838,11 @@ unsigned PCHStmtReader::VisitObjCForCollectionStmt(ObjCForCollectionStmt *S) {
 
 unsigned PCHStmtReader::VisitObjCAtCatchStmt(ObjCAtCatchStmt *S) {
   VisitStmt(S);
-  S->setCatchBody(cast_or_null<Stmt>(StmtStack[StmtStack.size() - 2]));
-  S->setNextCatchStmt(cast_or_null<Stmt>(StmtStack[StmtStack.size() - 1]));
+  S->setCatchBody(cast_or_null<Stmt>(StmtStack.back()));
   S->setCatchParamDecl(cast_or_null<ParmVarDecl>(Reader.GetDecl(Record[Idx++])));
   S->setAtCatchLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
   S->setRParenLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
-  return 2;
+  return 1;
 }
 
 unsigned PCHStmtReader::VisitObjCAtFinallyStmt(ObjCAtFinallyStmt *S) {
@@ -855,11 +854,21 @@ unsigned PCHStmtReader::VisitObjCAtFinallyStmt(ObjCAtFinallyStmt *S) {
 
 unsigned PCHStmtReader::VisitObjCAtTryStmt(ObjCAtTryStmt *S) {
   VisitStmt(S);
-  S->setTryBody(cast_or_null<Stmt>(StmtStack[StmtStack.size() - 3]));
-  S->setCatchStmts(cast_or_null<Stmt>(StmtStack[StmtStack.size() - 2]));
-  S->setFinallyStmt(cast_or_null<Stmt>(StmtStack[StmtStack.size() - 1]));
+  assert(Record[Idx] == S->getNumCatchStmts());
+  ++Idx;
+  bool HasFinally = Record[Idx++];
+  for (unsigned I = 0, N = S->getNumCatchStmts(); I != N; ++I) {
+    unsigned Offset = StmtStack.size() - N - HasFinally + I;
+    S->setCatchStmt(I, cast_or_null<ObjCAtCatchStmt>(StmtStack[Offset]));
+  }
+
+  unsigned TryOffset
+    = StmtStack.size() - S->getNumCatchStmts() - HasFinally - 1;
+  S->setTryBody(cast_or_null<Stmt>(StmtStack[TryOffset]));
+  if (HasFinally)
+    S->setFinallyStmt(cast_or_null<Stmt>(StmtStack[StmtStack.size() - 1]));
   S->setAtTryLoc(SourceLocation::getFromRawEncoding(Record[Idx++]));
-  return 3;
+  return 1 + S->getNumCatchStmts() + HasFinally;
 }
 
 unsigned PCHStmtReader::VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt *S) {
@@ -1231,7 +1240,9 @@ Stmt *PCHReader::ReadStmt(llvm::BitstreamCursor &Cursor) {
       S = new (Context) ObjCAtFinallyStmt(Empty);
       break;
     case pch::STMT_OBJC_AT_TRY:
-      S = new (Context) ObjCAtTryStmt(Empty);
+      S = ObjCAtTryStmt::CreateEmpty(*Context, 
+                                     Record[PCHStmtReader::NumStmtFields],
+                                     Record[PCHStmtReader::NumStmtFields + 1]);
       break;
     case pch::STMT_OBJC_AT_SYNCHRONIZED:
       S = new (Context) ObjCAtSynchronizedStmt(Empty);
diff --git a/lib/Frontend/PCHWriterStmt.cpp b/lib/Frontend/PCHWriterStmt.cpp
index 9a9539bb54..a0ea5c9553 100644
--- a/lib/Frontend/PCHWriterStmt.cpp
+++ b/lib/Frontend/PCHWriterStmt.cpp
@@ -764,7 +764,6 @@ void PCHStmtWriter::VisitObjCForCollectionStmt(ObjCForCollectionStmt *S) {
 
 void PCHStmtWriter::VisitObjCAtCatchStmt(ObjCAtCatchStmt *S) {
   Writer.WriteSubStmt(S->getCatchBody());
-  Writer.WriteSubStmt(S->getNextCatchStmt());
   Writer.AddDeclRef(S->getCatchParamDecl(), Record);
   Writer.AddSourceLocation(S->getAtCatchLoc(), Record);
   Writer.AddSourceLocation(S->getRParenLoc(), Record);
@@ -778,9 +777,13 @@ void PCHStmtWriter::VisitObjCAtFinallyStmt(ObjCAtFinallyStmt *S) {
 }
 
 void PCHStmtWriter::VisitObjCAtTryStmt(ObjCAtTryStmt *S) {
+  Record.push_back(S->getNumCatchStmts());
+  Record.push_back(S->getFinallyStmt() != 0);
   Writer.WriteSubStmt(S->getTryBody());
-  Writer.WriteSubStmt(S->getCatchStmts());
-  Writer.WriteSubStmt(S->getFinallyStmt());
+  for (unsigned I = 0, N = S->getNumCatchStmts(); I != N; ++I)
+    Writer.WriteSubStmt(S->getCatchStmt(I));
+  if (S->getFinallyStmt())
+    Writer.WriteSubStmt(S->getFinallyStmt());
   Writer.AddSourceLocation(S->getAtTryLoc(), Record);
   Code = pch::STMT_OBJC_AT_TRY;
 }
diff --git a/lib/Frontend/RewriteObjC.cpp b/lib/Frontend/RewriteObjC.cpp
index 66b8d39c70..fc674354c4 100644
--- a/lib/Frontend/RewriteObjC.cpp
+++ b/lib/Frontend/RewriteObjC.cpp
@@ -1861,8 +1861,7 @@ Stmt *RewriteObjC::RewriteObjCTryStmt(ObjCAtTryStmt *S) {
   assert((*startBuf == '}') && "bogus @try block");
 
   SourceLocation lastCurlyLoc = startLoc;
-  ObjCAtCatchStmt *catchList = S->getCatchStmts();
-  if (catchList) {
+  if (S->getNumCatchStmts()) {
     startLoc = startLoc.getFileLocWithOffset(1);
     buf = " /* @catch begin */ else {\n";
     buf += " id _caught = objc_exception_extract(&_stack);\n";
@@ -1880,26 +1879,27 @@ Stmt *RewriteObjC::RewriteObjCTryStmt(ObjCAtTryStmt *S) {
   }
   bool sawIdTypedCatch = false;
   Stmt *lastCatchBody = 0;
-  while (catchList) {
-    ParmVarDecl *catchDecl = catchList->getCatchParamDecl();
+  for (unsigned I = 0, N = S->getNumCatchStmts(); I != N; ++I) {
+    ObjCAtCatchStmt *Catch = S->getCatchStmt(I);
+    ParmVarDecl *catchDecl = Catch->getCatchParamDecl();
 
-    if (catchList == S->getCatchStmts())
+    if (I == 0)
       buf = "if ("; // we are generating code for the first catch clause
     else
       buf = "else if (";
-    startLoc = catchList->getLocStart();
+    startLoc = Catch->getLocStart();
     startBuf = SM->getCharacterData(startLoc);
 
     assert((*startBuf == '@') && "bogus @catch location");
 
     const char *lParenLoc = strchr(startBuf, '(');
 
-    if (catchList->hasEllipsis()) {
+    if (Catch->hasEllipsis()) {
       // Now rewrite the body...
-      lastCatchBody = catchList->getCatchBody();
+      lastCatchBody = Catch->getCatchBody();
       SourceLocation bodyLoc = lastCatchBody->getLocStart();
       const char *bodyBuf = SM->getCharacterData(bodyLoc);
-      assert(*SM->getCharacterData(catchList->getRParenLoc()) == ')' &&
+      assert(*SM->getCharacterData(Catch->getRParenLoc()) == ')' &&
              "bogus @catch paren location");
       assert((*bodyBuf == '{') && "bogus @catch body location");
 
@@ -1923,8 +1923,8 @@ Stmt *RewriteObjC::RewriteObjCTryStmt(ObjCAtTryStmt *S) {
         }
       }
       // Now rewrite the body...
-      lastCatchBody = catchList->getCatchBody();
-      SourceLocation rParenLoc = catchList->getRParenLoc();
+      lastCatchBody = Catch->getCatchBody();
+      SourceLocation rParenLoc = Catch->getRParenLoc();
       SourceLocation bodyLoc = lastCatchBody->getLocStart();
       const char *bodyBuf = SM->getCharacterData(bodyLoc);
       const char *rParenBuf = SM->getCharacterData(rParenLoc);
@@ -1937,8 +1937,6 @@ Stmt *RewriteObjC::RewriteObjCTryStmt(ObjCAtTryStmt *S) {
     } else {
       assert(false && "@catch rewrite bug");
     }
-    // make sure all the catch bodies get rewritten!
-    catchList = catchList->getNextCatchStmt();
   }
   // Complete the catch list...
   if (lastCatchBody) {