llvm · Mar 10, 2017
diff --git a/‎llvm/include/llvm/Transforms/Utils/VNCoercion.h
+96 b/‎llvm/include/llvm/Transforms/Utils/VNCoercion.h
+96
@@ -0,0 +1,96 @@
+//===- VNCoercion.h - Value Numbering Coercion Utilities --------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+/// \file / This file provides routines used by LLVM's value numbering passes to
+/// perform various forms of value extraction from memory when the types are not
+/// identical.  For example, given
+///
+/// store i32 8, i32 *%foo
+/// %a = bitcast i32 *%foo to i16
+/// %val = load i16, i16 *%a
+///
+/// It possible to extract the value of the load of %a from the store to %foo.
+/// These routines know how to tell whether they can do that (the analyze*
+/// routines), and can also insert the necessary IR to do it (the get*
+/// routines).
+
+#ifndef LLVM_TRANSFORMS_UTILS_VNCOERCION_H
+#define LLVM_TRANSFORMS_UTILS_VNCOERCION_H
+#include "llvm/IR/IRBuilder.h"
+
+namespace llvm {
+class Function;
+class StoreInst;
+class LoadInst;
+class MemIntrinsic;
+class Instruction;
+class Value;
+class Type;
+class DataLayout;
+namespace VNCoercion {
+/// Return true if CoerceAvailableValueToLoadType would succeed if it was
+/// called.
+bool canCoerceMustAliasedValueToLoad(Value *StoredVal, Type *LoadTy,
+                                     const DataLayout &DL);
+
+/// If we saw a store of a value to memory, and then a load from a must-aliased
+/// pointer of a different type, try to coerce the stored value to the loaded
+/// type.  LoadedTy is the type of the load we want to replace.  IRB is
+/// IRBuilder used to insert new instructions.
+///
+/// If we can't do it, return null.
+Value *coerceAvailableValueToLoadType(Value *StoredVal, Type *LoadedTy,
+                                      IRBuilder<> &IRB, const DataLayout &DL);
+
+/// This function determines whether a value for the pointer LoadPtr can be
+/// extracted from the store at DepSI.
+///
+/// On success, it returns the offset into DepSI that extraction would start.
+/// On failure, it returns -1.
+int analyzeLoadFromClobberingStore(Type *LoadTy, Value *LoadPtr,
+                                   StoreInst *DepSI);
+
+/// This function determines whether a value for the pointer LoadPtr can be
+/// extracted from the load at DepLI.
+///
+/// On success, it returns the offset into DepLI that extraction would start.
+/// On failure, it returns -1.
+int analyzeLoadFromClobberingLoad(Type *LoadTy, Value *LoadPtr, LoadInst *DepLI,
+                                  const DataLayout &DL);
+
+/// This function determines whether a value for the pointer LoadPtr can be
+/// extracted from the memory intrinsic at DepMI.
+///
+/// On success, it returns the offset into DepMI that extraction would start.
+/// On failure, it returns -1.
+int analyzeLoadFromClobberingMemInst(Type *LoadTy, Value *LoadPtr,
+                                     MemIntrinsic *DepMI, const DataLayout &DL);
+
+/// If analyzeLoadFromClobberingStore returned an offset, this function can be
+/// used to actually perform the extraction of the bits from the store. It
+/// inserts instructions to do so at InsertPt, and returns the extracted value.
+Value *getStoreValueForLoad(Value *SrcVal, unsigned Offset, Type *LoadTy,
+                            Instruction *InsertPt, const DataLayout &DL);
+
+/// If analyzeLoadFromClobberingLoad returned an offset, this function can be
+/// used to actually perform the extraction of the bits from the load, including
+/// any necessary load widening.  It inserts instructions to do so at InsertPt,
+/// and returns the extracted value.
+Value *getLoadValueForLoad(LoadInst *SrcVal, unsigned Offset, Type *LoadTy,
+                           Instruction *InsertPt);
+
+/// If analyzeLoadFromClobberingMemInst returned an offset, this function can be
+/// used to actually perform the extraction of the bits from the memory
+/// intrinsic.  It inserts instructions to do so at InsertPt, and returns the
+/// extracted value.
+Value *getMemInstValueForLoad(MemIntrinsic *SrcInst, unsigned Offset,
+                              Type *LoadTy, Instruction *InsertPt,
+                              const DataLayout &DL);
+}
+}
+#endif