From d95ccd58a9fd96880c94ca995b334501738df5e8 Mon Sep 17 00:00:00 2001
From: Zhongxing Xu <xuzhongxing@gmail.com>
Date: Wed, 27 Oct 2010 03:23:10 +0000
Subject: [PATCH] If visiting RHS causes us to finish 'Block', e.g. the RHS is
 a StmtExpr containing a DoStmt, and the LHS doesn't create a new block, then
 we should return RBlock.  Otherwise we'll incorrectly return NULL.

Also relax an assertion in VisitWhileStmt(). Reset 'Block' when it is finished.

llvm-svn: 117436
---
 clang/lib/Analysis/CFG.cpp                 | 11 ++++++++---
 clang/test/Analysis/misc-ps-region-store.m |  6 ++++++
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/clang/lib/Analysis/CFG.cpp b/clang/lib/Analysis/CFG.cpp
index f003879b7a7f..3653500f9257 100644
--- a/clang/lib/Analysis/CFG.cpp
+++ b/clang/lib/Analysis/CFG.cpp
@@ -935,8 +935,12 @@ CFGBlock *CFGBuilder::VisitBinaryOperator(BinaryOperator *B,
     AppendStmt(Block, B, asc);
   }
 
-  Visit(B->getRHS());
-  return Visit(B->getLHS());
+  CFGBlock *RBlock = Visit(B->getRHS());
+  CFGBlock *LBlock = Visit(B->getLHS());
+  // If visiting RHS causes us to finish 'Block', e.g. the RHS is a StmtExpr
+  // containing a DoStmt, and the LHS doesn't create a new block, then we should
+  // return RBlock.  Otherwise we'll incorrectly return NULL.
+  return (LBlock ? LBlock : RBlock);
 }
 
 CFGBlock *CFGBuilder::VisitBlockExpr(BlockExpr *E, AddStmtChoice asc) {
@@ -1736,7 +1740,8 @@ CFGBlock* CFGBuilder::VisitWhileStmt(WhileStmt* W) {
   if (Stmt* C = W->getCond()) {
     Block = ExitConditionBlock;
     EntryConditionBlock = addStmt(C);
-    assert(Block == EntryConditionBlock);
+    // The condition might finish the current 'Block'.
+    Block = EntryConditionBlock;
 
     // If this block contains a condition variable, add both the condition
     // variable and initializer to the CFG.
diff --git a/clang/test/Analysis/misc-ps-region-store.m b/clang/test/Analysis/misc-ps-region-store.m
index 4378e0653652..ed285b422b40 100644
--- a/clang/test/Analysis/misc-ps-region-store.m
+++ b/clang/test/Analysis/misc-ps-region-store.m
@@ -1157,6 +1157,12 @@ pr8141 (void) {
     }
 }
 
+// Don't crash when building the CFG.
+void do_not_crash(int x) {
+  while (x - ({do {} while (0); x; })) {
+  }
+}
+
 // <rdar://problem/8424269> - Handle looking at the size of a VLA in
 // ArrayBoundChecker.  Nothing intelligent (yet); just don't crash.
 typedef struct RDar8424269_A {