From b35635e9423491a29a00feea80db645ada95ab7b Mon Sep 17 00:00:00 2001
From: Chandler Carruth <chandlerc@gmail.com>
Date: Sat, 8 Jan 2011 06:54:40 +0000
Subject: [PATCH] Remove a kludge from analysis based warnings that used to
 detect temporaries with no-return destructors. The CFG now properly supports
 temporaries and implicit destructors which both makes this kludge no longer
 work, and conveniently removes the need for it.

Turn on CFG handling of implicit destructors and initializers. Several
ad-hoc benchmarks don't indicate any measurable performance impact from
growing the CFG, and it fixes real correctness problems with warnings.

As a result of turning on these CFG elements, we started to tickle an
inf-loop in the unreachable code logic used for warnings. The fix is
trivial.

llvm-svn: 123056
---
 clang/lib/Analysis/ReachableCode.cpp     |  5 ++---
 clang/lib/Sema/AnalysisBasedWarnings.cpp | 16 ++--------------
 clang/test/SemaCXX/return-noreturn.cpp   |  7 ++-----
 3 files changed, 6 insertions(+), 22 deletions(-)

diff --git a/clang/lib/Analysis/ReachableCode.cpp b/clang/lib/Analysis/ReachableCode.cpp
index b9585800c9e8..802b990143d4 100644
--- a/clang/lib/Analysis/ReachableCode.cpp
+++ b/clang/lib/Analysis/ReachableCode.cpp
@@ -30,12 +30,11 @@ static SourceLocation GetUnreachableLoc(const CFGBlock &b, SourceRange &R1,
   unsigned sn = 0;
   R1 = R2 = SourceRange();
 
-top:
   if (sn < b.size()) {
     CFGStmt CS = b[sn].getAs<CFGStmt>();
     if (!CS)
-      goto top;
-    
+      return SourceLocation();
+
     S = CS.getStmt(); 
   } else if (b.getTerminator())
     S = b.getTerminator();
diff --git a/clang/lib/Sema/AnalysisBasedWarnings.cpp b/clang/lib/Sema/AnalysisBasedWarnings.cpp
index f4fde40bfba8..20a503d6a56f 100644
--- a/clang/lib/Sema/AnalysisBasedWarnings.cpp
+++ b/clang/lib/Sema/AnalysisBasedWarnings.cpp
@@ -177,19 +177,6 @@ static ControlFlowKind CheckFallThrough(AnalysisContext &AC) {
         }
       }
     }
-    // FIXME: Remove this hack once temporaries and their destructors are
-    // modeled correctly by the CFG.
-    if (ExprWithCleanups *E = dyn_cast<ExprWithCleanups>(S)) {
-      for (unsigned I = 0, N = E->getNumTemporaries(); I != N; ++I) {
-        const FunctionDecl *FD = E->getTemporary(I)->getDestructor();
-        if (FD->hasAttr<NoReturnAttr>() ||
-            FD->getType()->getAs<FunctionType>()->getNoReturnAttr()) {
-          NoReturnEdge = true;
-          HasFakeEdge = true;
-          break;
-        }
-      }
-    }
     // FIXME: Add noreturn message sends.
     if (NoReturnEdge == false)
       HasPlainEdge = true;
@@ -405,7 +392,8 @@ AnalysisBasedWarnings::IssueWarnings(sema::AnalysisBasedWarnings::Policy P,
 
   // Don't generate EH edges for CallExprs as we'd like to avoid the n^2
   // explosion for destrutors that can result and the compile time hit.
-  AnalysisContext AC(D, 0, false);
+  AnalysisContext AC(D, 0, /*useUnoptimizedCFG=*/false, /*addehedges=*/false,
+                     /*addImplicitDtors=*/true, /*addInitializers=*/true);
 
   // Warning: check missing 'return'
   if (P.enableCheckFallThrough) {
diff --git a/clang/test/SemaCXX/return-noreturn.cpp b/clang/test/SemaCXX/return-noreturn.cpp
index dfd548732150..f7072b21771e 100644
--- a/clang/test/SemaCXX/return-noreturn.cpp
+++ b/clang/test/SemaCXX/return-noreturn.cpp
@@ -7,14 +7,11 @@ namespace PR6884 {
     ~abort_struct() __attribute__((noreturn));
   };
 
-  // FIXME: Should either of these actually warn, since the destructor is
-  //  marked noreturn?
-
   int f() {
     abort_struct();
-  } // expected-warning{{control reaches end of non-void function}}
+  }
 
   int f2() {
     abort_struct s;
-  } // expected-warning{{control reaches end of non-void function}}
+  }
 }
-- 
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