Enhance Sema::DiagRuntimeBehavior() to delay some diagnostics to see if the related code is reachable. This suppresses some

diagnostics that occur in unreachable code (e.g., -Warray-bound).

We only pay the cost of doing the reachability analysis when we issue one of these diagnostics.

llvm-svn: 126290

1 files changed, 12 insertions, 1 deletions

diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
index 0827597abdf..0c39e132539 100644
--- a/clang/lib/Sema/Sema.cpp
+++ b/clang/lib/Sema/Sema.cpp
@@ -48,6 +48,7 @@ void FunctionScopeInfo::Clear() {
   SwitchStack.clear();
   Returns.clear();
   ErrorTrap.reset();
+  PossiblyUnreachableDiags.clear();
 }
 
 BlockScopeInfo::~BlockScopeInfo() { }
@@ -639,9 +640,19 @@ void Sema::PopFunctionOrBlockScope(const AnalysisBasedWarnings::Policy *WP,
   // Issue any analysis-based warnings.
   if (WP && D)
     AnalysisWarnings.IssueWarnings(*WP, Scope, D, blkExpr);
+  else {
+    for (llvm::SmallVectorImpl<sema::PossiblyUnreachableDiag>::iterator
+         i = Scope->PossiblyUnreachableDiags.begin(),
+         e = Scope->PossiblyUnreachableDiags.end();
+         i != e; ++i) {
+      const sema::PossiblyUnreachableDiag &D = *i;
+      Diag(D.Loc, D.PD);
+    }
+  }
 
-  if (FunctionScopes.back() != Scope)
+  if (FunctionScopes.back() != Scope) {
     delete Scope;
+  }
 }
 
 /// \brief Determine whether any errors occurred within this function/method/