[IR][ARM] Add function pointer alignment to datalayout

Use this feature to fix a bug on ARM where 4 byte alignment is
incorrectly assumed.

Differential Revision: https://reviews.llvm.org/D57335

llvm-svn: 355522

1 files changed, 23 insertions, 0 deletions

diff --git a/llvm/include/llvm/IR/DataLayout.h b/llvm/include/llvm/IR/DataLayout.h
index 869b27b1fda..05c72f10d30 100644
--- a/llvm/include/llvm/IR/DataLayout.h
+++ b/llvm/include/llvm/IR/DataLayout.h
@@ -108,6 +108,13 @@ struct PointerAlignElem {
 /// generating LLVM IR is required to generate the right target data for the
 /// target being codegen'd to.
 class DataLayout {
+public:
+  enum class FunctionPtrAlignType {
+    /// The function pointer alignment is independent of the function alignment.
+    Independent,
+    /// The function pointer alignment is a multiple of the function alignment.
+    MultipleOfFunctionAlign,
+  };
 private:
   /// Defaults to false.
   bool BigEndian;
@@ -116,6 +123,9 @@ private:
   unsigned StackNaturalAlign;
   unsigned ProgramAddrSpace;
 
+  unsigned FunctionPtrAlign;
+  FunctionPtrAlignType TheFunctionPtrAlignType;
+
   enum ManglingModeT {
     MM_None,
     MM_ELF,
@@ -199,6 +209,8 @@ public:
     BigEndian = DL.isBigEndian();
     AllocaAddrSpace = DL.AllocaAddrSpace;
     StackNaturalAlign = DL.StackNaturalAlign;
+    FunctionPtrAlign = DL.FunctionPtrAlign;
+    TheFunctionPtrAlignType = DL.TheFunctionPtrAlignType;
     ProgramAddrSpace = DL.ProgramAddrSpace;
     ManglingMode = DL.ManglingMode;
     LegalIntWidths = DL.LegalIntWidths;
@@ -256,6 +268,17 @@ public:
   unsigned getStackAlignment() const { return StackNaturalAlign; }
   unsigned getAllocaAddrSpace() const { return AllocaAddrSpace; }
 
+  /// Returns the alignment of function pointers, which may or may not be
+  /// related to the alignment of functions.
+  /// \see getFunctionPtrAlignType
+  unsigned getFunctionPtrAlign() const { return FunctionPtrAlign; }
+
+  /// Return the type of function pointer alignment.
+  /// \see getFunctionPtrAlign
+  FunctionPtrAlignType getFunctionPtrAlignType() const {
+    return TheFunctionPtrAlignType;
+  }
+
   unsigned getProgramAddressSpace() const { return ProgramAddrSpace; }
 
   bool hasMicrosoftFastStdCallMangling() const {