Clang changes for alloc_align attribute 

GCC has the alloc_align attribute, which is similar to assume_aligned, except the attribute's parameter is the index of the integer parameter that needs aligning to.

Differential Revision: https://reviews.llvm.org/D29599

llvm-svn: 299117
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index 4a7cc02..ee85e30 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -2465,6 +2465,12 @@
   PeepholeProtection protectFromPeepholes(RValue rvalue);
   void unprotectFromPeepholes(PeepholeProtection protection);
 
+  void EmitAlignmentAssumption(llvm::Value *PtrValue, llvm::Value *Alignment,
+                               llvm::Value *OffsetValue = nullptr) {
+    Builder.CreateAlignmentAssumption(CGM.getDataLayout(), PtrValue, Alignment,
+                                      OffsetValue);
+  }
+
   //===--------------------------------------------------------------------===//
   //                             Statement Emission
   //===--------------------------------------------------------------------===//