Emit lifetime.start / lifetime.end markers for unnamed temporary objects.

This will give more information to the optimizers so that they can reuse stack slots
and reduce stack usage.

llvm-svn: 218865

1 files changed, 27 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index 2709a36..a4171a0 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -444,6 +444,23 @@ public:
     new (Buffer + sizeof(Header)) T(a0, a1, a2, a3);
   }
 
+  /// \brief Queue a cleanup to be pushed after finishing the current
+  /// full-expression.
+  template <class T, class A0, class A1>
+  void pushCleanupAfterFullExpr(CleanupKind Kind, A0 a0, A1 a1) {
+    assert(!isInConditionalBranch() && "can't defer conditional cleanup");
+
+    LifetimeExtendedCleanupHeader Header = { sizeof(T), Kind };
+
+    size_t OldSize = LifetimeExtendedCleanupStack.size();
+    LifetimeExtendedCleanupStack.resize(
+        LifetimeExtendedCleanupStack.size() + sizeof(Header) + Header.Size);
+
+    char *Buffer = &LifetimeExtendedCleanupStack[OldSize];
+    new (Buffer) LifetimeExtendedCleanupHeader(Header);
+    new (Buffer + sizeof(Header)) T(a0, a1);
+  }
+
   /// Set up the last cleaup that was pushed as a conditional
   /// full-expression cleanup.
   void initFullExprCleanup();
@@ -596,6 +613,10 @@ public:
   void PopCleanupBlocks(EHScopeStack::stable_iterator OldCleanupStackSize,
                         size_t OldLifetimeExtendedStackSize);
 
+  /// \brief Moves deferred cleanups from lifetime-extended variables from
+  /// the given position on top of the stack
+  void MoveDeferedCleanups(size_t OldLifetimeExtendedSize);
+
   void ResolveBranchFixups(llvm::BasicBlock *Target);
 
   /// The given basic block lies in the current EH scope, but may be a
@@ -1112,6 +1133,9 @@ public:
   void pushLifetimeExtendedDestroy(CleanupKind kind, llvm::Value *addr,
                                    QualType type, Destroyer *destroyer,
                                    bool useEHCleanupForArray);
+  void pushLifetimeEndMarker(StorageDuration SD,
+                             llvm::Value *ReferenceTemporary,
+                             llvm::Value *SizeForLifeTimeMarkers);
   void pushStackRestore(CleanupKind kind, llvm::Value *SPMem);
   void emitDestroy(llvm::Value *addr, QualType type, Destroyer *destroyer,
                    bool useEHCleanupForArray);
@@ -1715,6 +1739,9 @@ public:
   void EmitCXXTemporary(const CXXTemporary *Temporary, QualType TempType,
                         llvm::Value *Ptr);
 
+  llvm::Value *EmitLifetimeStart(uint64_t Size, llvm::Value *Addr);
+  void EmitLifetimeEnd(llvm::Value *Size, llvm::Value *Addr);
+
   llvm::Value *EmitCXXNewExpr(const CXXNewExpr *E);
   void EmitCXXDeleteExpr(const CXXDeleteExpr *E);