Separate indirectbrusers/guy-david/separate-indirectbr

4 files changed, 29 insertions, 26 deletions

diff --git a/clang/lib/Analysis/CFG.cpp b/clang/lib/Analysis/CFG.cpp
index d960d51..5d41a4c 100644
--- a/clang/lib/Analysis/CFG.cpp
+++ b/clang/lib/Analysis/CFG.cpp
@@ -545,6 +545,9 @@ class CFGBuilder {
   using LabelSetTy = llvm::SmallSetVector<LabelDecl *, 8>;
   LabelSetTy AddressTakenLabels;
 
+  // A list of indirect goto dispatch blocks (one per indirect goto statement).
+  std::vector<CFGBlock *> IndirectGotoBlocks;
+
   // Information about the currently visited C++ object construction site.
   // This is set in the construction trigger and read when the constructor
   // or a function that returns an object by value is being visited.
@@ -1751,8 +1754,8 @@ std::unique_ptr<CFG> CFGBuilder::buildCFG(const Decl *D, Stmt *Statement) {
     }
   }
 
-  // Add successors to the Indirect Goto Dispatch block (if we have one).
-  if (CFGBlock *B = cfg->getIndirectGotoBlock())
+  // Add successors to the Indirect Goto Dispatch blocks (one per indirect goto statement).  
+  for (CFGBlock *B : IndirectGotoBlocks) {
     for (LabelDecl *LD : AddressTakenLabels) {
       // Lookup the target block.
       LabelMapTy::iterator LI = LabelMap.find(LD);
@@ -1763,6 +1766,7 @@ std::unique_ptr<CFG> CFGBuilder::buildCFG(const Decl *D, Stmt *Statement) {
 
       addSuccessor(B, LI->second.block);
     }
+  }
 
   // Create an empty entry block that has no predecessors.
   cfg->setEntry(createBlock());
@@ -5028,13 +5032,8 @@ CFGBlock *CFGBuilder::VisitConstantExpr(ConstantExpr *E, AddStmtChoice asc) {
 }
 
 CFGBlock *CFGBuilder::VisitIndirectGotoStmt(IndirectGotoStmt *I) {
-  // Lazily create the indirect-goto dispatch block if there isn't one already.
-  CFGBlock *IBlock = cfg->getIndirectGotoBlock();
-
-  if (!IBlock) {
-    IBlock = createBlock(false);
-    cfg->setIndirectGotoBlock(IBlock);
-  }
+  // Create a new indirect-goto dispatch block for each statement.
+  CFGBlock *IBlock = createBlock(false);
 
   // IndirectGoto is a control-flow statement.  Thus we stop processing the
   // current block and create a new one.
@@ -5044,6 +5043,10 @@ CFGBlock *CFGBuilder::VisitIndirectGotoStmt(IndirectGotoStmt *I) {
   Block = createBlock(false);
   Block->setTerminator(I);
   addSuccessor(Block, IBlock);
+  
+  // Store this dispatch block so we can connect it to labels later
+  IndirectGotoBlocks.push_back(IBlock);
+  
   return addStmt(I->getTarget());
 }
 
diff --git a/clang/lib/CodeGen/CGStmt.cpp b/clang/lib/CodeGen/CGStmt.cpp
index 031ef73..9d19cdb 100644
--- a/clang/lib/CodeGen/CGStmt.cpp
+++ b/clang/lib/CodeGen/CGStmt.cpp
@@ -858,21 +858,17 @@ void CodeGenFunction::EmitIndirectGotoStmt(const IndirectGotoStmt &S) {
     return;
   }
 
-  // Ensure that we have an i8* for our PHI node.
+  // Ensure that we have an i8* for the indirect branch.
   llvm::Value *V = Builder.CreateBitCast(EmitScalarExpr(S.getTarget()),
                                          Int8PtrTy, "addr");
-  llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
-
-  // Get the basic block for the indirect goto.
-  llvm::BasicBlock *IndGotoBB = GetIndirectGotoBlock();
 
-  // The first instruction in the block has to be the PHI for the switch dest,
-  // add an entry for this branch.
-  cast<llvm::PHINode>(IndGotoBB->begin())->addIncoming(V, CurBB);
+  // Create a new indirect branch instruction for this statement
+  llvm::IndirectBrInst *IndBr = Builder.CreateIndirectBr(V);
 
-  EmitBranch(IndGotoBB);
-  if (CurBB && CurBB->getTerminator())
-    addInstToCurrentSourceAtom(CurBB->getTerminator(), nullptr);
+  // Add all address-taken labels as possible destinations
+  for (llvm::BasicBlock *BB : AddressTakenLabels) {
+    IndBr->addDestination(BB);
+  }
 }
 
 void CodeGenFunction::EmitIfStmt(const IfStmt &S) {
diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
index b2fe917..73a604f 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -2287,14 +2287,13 @@ CodeGenFunction::EmitNullInitialization(Address DestPtr, QualType Ty) {
 }
 
 llvm::BlockAddress *CodeGenFunction::GetAddrOfLabel(const LabelDecl *L) {
-  // Make sure that there is a block for the indirect goto.
-  if (!IndirectBranch)
-    GetIndirectGotoBlock();
-
   llvm::BasicBlock *BB = getJumpDestForLabel(L).getBlock();
 
-  // Make sure the indirect branch includes all of the address-taken blocks.
-  IndirectBranch->addDestination(BB);
+  // Keep track of this address-taken label for indirect goto statements
+  if (llvm::find(AddressTakenLabels, BB) == AddressTakenLabels.end()) {
+    AddressTakenLabels.push_back(BB);
+  }
+
   return llvm::BlockAddress::get(CurFn->getType(), BB);
 }
 
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index c02ac18..fea0a46 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -1527,6 +1527,11 @@ private:
   /// codegen'd as a jump to the IndirectBranch's basic block.
   llvm::IndirectBrInst *IndirectBranch = nullptr;
 
+  /// AddressTakenLabels - Collection of address-taken labels for indirect gotos.
+  /// Each indirect goto statement will create its own indirectbr instruction
+  /// with all these labels as possible destinations.
+  llvm::SmallVector<llvm::BasicBlock *, 8> AddressTakenLabels;
+
   /// LocalDeclMap - This keeps track of the LLVM allocas or globals for local C
   /// decls.
   DeclMapTy LocalDeclMap;