From 7fead31dbee1a1349d360eff7b56dc6571449443 Mon Sep 17 00:00:00 2001
From: Jordy Rose <jediknil@belkadan.com>
Date: Thu, 9 Jun 2011 05:44:04 +0000
Subject: [PATCH] [analyzer] Ignore parentheses around block-level expressions
 when computing liveness. Fixes the other half of PR8962.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@132769 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Analysis/LiveVariables.cpp | 16 +++++++++++++---
 test/Analysis/misc-ps.c        | 12 ++++++++++++
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/lib/Analysis/LiveVariables.cpp b/lib/Analysis/LiveVariables.cpp
index 303dc0f604..0fe87e8719 100644
--- a/lib/Analysis/LiveVariables.cpp
+++ b/lib/Analysis/LiveVariables.cpp
@@ -142,8 +142,12 @@ void TransferFuncs::Visit(Stmt *S) {
     if (AD.Observer)
       AD.Observer->ObserveStmt(S, currentBlock, AD, LiveState);
 
-    if (getCFG().isBlkExpr(S))
-      LiveState(S, AD) = Dead;
+    if (getCFG().isBlkExpr(S)) {
+      if (Expr *E = dyn_cast<Expr>(S)) 
+        LiveState(E->IgnoreParens(), AD) = Dead;
+      else
+        LiveState(S, AD) = Dead;
+    }
 
     StmtVisitor<TransferFuncs,void>::Visit(S);
   }
@@ -157,7 +161,10 @@ void TransferFuncs::Visit(Stmt *S) {
   }
   else {
     // For block-level expressions, mark that they are live.
-    LiveState(S,AD) = Alive;
+    if (Expr *E = dyn_cast<Expr>(S)) 
+      LiveState(E->IgnoreParens(), AD) = Alive;
+    else
+      LiveState(S, AD) = Alive;
   }
 }
   
@@ -174,6 +181,9 @@ void TransferFuncs::VisitTerminator(CFGBlock* B) {
     return;
 
   assert (getCFG().isBlkExpr(E));
+
+  if (const Expr *Ex = dyn_cast<Expr>(E))
+    E = Ex->IgnoreParens();
   LiveState(E, AD) = Alive;
 }
 
diff --git a/test/Analysis/misc-ps.c b/test/Analysis/misc-ps.c
index 0729ce2f77..84992c6bb2 100644
--- a/test/Analysis/misc-ps.c
+++ b/test/Analysis/misc-ps.c
@@ -50,3 +50,15 @@ int PR8962_b (int *t) {
   return *t; // expected-warning {{null pointer}}
 }
 
+int PR8962_c (int *t) {
+  // If the last element in a StmtExpr was a ParenExpr, it's still live
+  if (({ (t ? (_Bool)0 : (_Bool)1); })) return 0;
+  return *t; // no-warning
+}
+
+int PR8962_d (int *t) {
+  // If the last element in a StmtExpr is an __extension__, it's still live
+  if (({ __extension__(t ? (_Bool)0 : (_Bool)1); })) return 0;
+  return *t; // no-warning
+}
+
-- 
2.40.0