Merge used flags so that we don't have to iterate on isUsed. With this change

"clang -cc1 -fsyntax-only" on the preprocessed output of

#define M extern int a;
#define M2 M M
#define M4 M2 M2
#define M8 M4 M4
#define M16 M8 M8
#define M32 M16 M16
#define M64 M32 M32
#define M128 M64 M64
#define M256 M128 M128
#define M512 M256 M256
#define M1024 M512 M512
#define M2048 M1024 M1024
#define M4096 M2048 M2048
#define M8192 M4096 M4096
#define M16384 M8192 M8192
M16384

goes from 2.994s to 1.416s. GCC is at 0.022s, so we still have a long way to go.

llvm-svn: 168519

2 files changed, 5 insertions, 8 deletions

diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index 870b8f11d78..b04c149deee 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -260,14 +260,7 @@ bool Decl::isUsed(bool CheckUsedAttr) const {
   // Check for used attribute.
   if (CheckUsedAttr && hasAttr<UsedAttr>())
     return true;
-  
-  // Check redeclarations. We merge attributes, so we don't need to check
-  // attributes in all redeclarations.
-  for (redecl_iterator I = redecls_begin(), E = redecls_end(); I != E; ++I) {
-    if (I->Used)
-      return true;
-  }
-  
+
   return false; 
 }
 
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 629fccc3064..e48211032f7 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -2388,6 +2388,10 @@ bool Sema::MergeCompatibleFunctionDecls(FunctionDecl *New, FunctionDecl *Old,
   if (Old->isPure())
     New->setPure();
 
+  // Merge "used" flag.
+  if (Old->isUsed(false))
+    New->setUsed();
+
   // Merge attributes from the parameters.  These can mismatch with K&R
   // declarations.
   if (New->getNumParams() == Old->getNumParams())