Update llvm/clang to trunk r126547.

There are several bugfixes in this update, but the most important one is
to ensure __start_ and __stop_ symbols for linker sets and kernel module
metadata are always emitted in object files:

  http://llvm.org/bugs/show_bug.cgi?id=9292

Before this fix, if you compiled kernel modules with clang, they would
not be properly processed by kldxref, and if they had any dependencies,
the kernel would fail to load those.  Another problem occurred when
attempting to mount a tmpfs filesystem, which would result in 'operation
not supported by device'.

1 files changed, 52 insertions, 26 deletions

diff --git a/contrib/llvm/tools/clang/lib/Sema/AnalysisBasedWarnings.cpp b/contrib/llvm/tools/clang/lib/Sema/AnalysisBasedWarnings.cpp
index 63f561d..6a42224 100644
--- a/contrib/llvm/tools/clang/lib/Sema/AnalysisBasedWarnings.cpp
+++ b/contrib/llvm/tools/clang/lib/Sema/AnalysisBasedWarnings.cpp
@@ -15,6 +15,7 @@
 
 #include "clang/Sema/AnalysisBasedWarnings.h"
 #include "clang/Sema/SemaInternal.h"
+#include "clang/Sema/ScopeInfo.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/AST/DeclObjC.h"
@@ -26,6 +27,8 @@
 #include "clang/Analysis/AnalysisContext.h"
 #include "clang/Analysis/CFG.h"
 #include "clang/Analysis/Analyses/ReachableCode.h"
+#include "clang/Analysis/Analyses/CFGReachabilityAnalysis.h"
+#include "clang/Analysis/CFGStmtMap.h"
 #include "clang/Analysis/Analyses/UninitializedValuesV2.h"
 #include "llvm/ADT/BitVector.h"
 #include "llvm/Support/Casting.h"
@@ -289,7 +292,7 @@ struct CheckFallThroughDiagnostics {
 /// of a noreturn function.  We assume that functions and blocks not marked
 /// noreturn will return.
 static void CheckFallThroughForBody(Sema &S, const Decl *D, const Stmt *Body,
-                                    QualType BlockTy,
+                                    const BlockExpr *blkExpr,
                                     const CheckFallThroughDiagnostics& CD,
                                     AnalysisContext &AC) {
 
@@ -306,6 +309,7 @@ static void CheckFallThroughForBody(Sema &S, const Decl *D, const Stmt *Body,
     HasNoReturn = MD->hasAttr<NoReturnAttr>();
   }
   else if (isa<BlockDecl>(D)) {
+    QualType BlockTy = blkExpr->getType();
     if (const FunctionType *FT =
           BlockTy->getPointeeType()->getAs<FunctionType>()) {
       if (FT->getResultType()->isVoidType())
@@ -477,11 +481,20 @@ clang::sema::AnalysisBasedWarnings::AnalysisBasedWarnings(Sema &s) : S(s) {
         Diagnostic::Ignored);
 }
 
+static void flushDiagnostics(Sema &S, sema::FunctionScopeInfo *fscope) {
+  for (llvm::SmallVectorImpl<sema::PossiblyUnreachableDiag>::iterator
+       i = fscope->PossiblyUnreachableDiags.begin(),
+       e = fscope->PossiblyUnreachableDiags.end();
+       i != e; ++i) {
+    const sema::PossiblyUnreachableDiag &D = *i;
+    S.Diag(D.Loc, D.PD);
+  }
+}
+
 void clang::sema::
 AnalysisBasedWarnings::IssueWarnings(sema::AnalysisBasedWarnings::Policy P,
-                                     const Decl *D, QualType BlockTy) {
-
-  assert(BlockTy.isNull() || isa<BlockDecl>(D));
+                                     sema::FunctionScopeInfo *fscope,
+                                     const Decl *D, const BlockExpr *blkExpr) {
 
   // We avoid doing analysis-based warnings when there are errors for
   // two reasons:
@@ -491,9 +504,6 @@ AnalysisBasedWarnings::IssueWarnings(sema::AnalysisBasedWarnings::Policy P,
   //     time.
   Diagnostic &Diags = S.getDiagnostics();
 
-  if (Diags.hasErrorOccurred() || Diags.hasFatalErrorOccurred())
-    return;
-
   // Do not do any analysis for declarations in system headers if we are
   // going to just ignore them.
   if (Diags.getSuppressSystemWarnings() &&
@@ -504,6 +514,12 @@ AnalysisBasedWarnings::IssueWarnings(sema::AnalysisBasedWarnings::Policy P,
   if (cast<DeclContext>(D)->isDependentContext())
     return;
 
+  if (Diags.hasErrorOccurred() || Diags.hasFatalErrorOccurred()) {
+    // Flush out any possibly unreachable diagnostics.
+    flushDiagnostics(S, fscope);
+    return;
+  }
+  
   const Stmt *Body = D->getBody();
   assert(Body);
 
@@ -512,12 +528,40 @@ AnalysisBasedWarnings::IssueWarnings(sema::AnalysisBasedWarnings::Policy P,
   AnalysisContext AC(D, 0, /*useUnoptimizedCFG=*/false, /*addehedges=*/false,
                      /*addImplicitDtors=*/true, /*addInitializers=*/true);
 
+  // Emit delayed diagnostics.
+  if (!fscope->PossiblyUnreachableDiags.empty()) {
+    bool analyzed = false;
+    if (CFGReachabilityAnalysis *cra = AC.getCFGReachablityAnalysis())
+      if (CFGStmtMap *csm = AC.getCFGStmtMap()) {
+        analyzed = true;
+        for (llvm::SmallVectorImpl<sema::PossiblyUnreachableDiag>::iterator
+             i = fscope->PossiblyUnreachableDiags.begin(),
+             e = fscope->PossiblyUnreachableDiags.end();
+             i != e; ++i) {
+          const sema::PossiblyUnreachableDiag &D = *i;
+          if (const CFGBlock *blk = csm->getBlock(D.stmt)) {
+            // Can this block be reached from the entrance?
+            if (cra->isReachable(&AC.getCFG()->getEntry(), blk))
+              S.Diag(D.Loc, D.PD);
+          }
+          else {
+            // Emit the warning anyway if we cannot map to a basic block.
+            S.Diag(D.Loc, D.PD);
+          }
+        }
+      }
+
+    if (!analyzed)
+      flushDiagnostics(S, fscope);
+  }
+  
+  
   // Warning: check missing 'return'
   if (P.enableCheckFallThrough) {
     const CheckFallThroughDiagnostics &CD =
       (isa<BlockDecl>(D) ? CheckFallThroughDiagnostics::MakeForBlock()
                          : CheckFallThroughDiagnostics::MakeForFunction(D));
-    CheckFallThroughForBody(S, D, Body, BlockTy, CD, AC);
+    CheckFallThroughForBody(S, D, Body, blkExpr, CD, AC);
   }
 
   // Warning: check for unreachable code
@@ -550,21 +594,3 @@ AnalysisBasedWarnings::IssueWarnings(sema::AnalysisBasedWarnings::Policy P,
     }
   }
 }
-
-void clang::sema::
-AnalysisBasedWarnings::IssueWarnings(sema::AnalysisBasedWarnings::Policy P,
-                                     const BlockExpr *E) {
-  return IssueWarnings(P, E->getBlockDecl(), E->getType());
-}
-
-void clang::sema::
-AnalysisBasedWarnings::IssueWarnings(sema::AnalysisBasedWarnings::Policy P,
-                                     const ObjCMethodDecl *D) {
-  return IssueWarnings(P, D, QualType());
-}
-
-void clang::sema::
-AnalysisBasedWarnings::IssueWarnings(sema::AnalysisBasedWarnings::Policy P,
-                                     const FunctionDecl *D) {
-  return IssueWarnings(P, D, QualType());
-}