[PATCH] llvm.noalias - Add IRBuilder support

[hfinkel at anl.gov]

Hi chandlerc, reames,

This is part of the series started by D9375, and adds functions in IRBuilder to create the llvm.noalias intrinsics (this is used by later patches).

There is a workaround for some kinds of pointers we can't currently mangle. I don't think this is worth fixing in the mangling code because soon we'll have only an opaque pointer type and this will be irrelevant.

http://reviews.llvm.org/D9378

Files:
  include/llvm/IR/IRBuilder.h
  lib/IR/IRBuilder.cpp

Index: include/llvm/IR/IRBuilder.h
===================================================================
--- include/llvm/IR/IRBuilder.h
+++ include/llvm/IR/IRBuilder.h
@@ -445,6 +445,9 @@
   /// assume that the provided condition will be true.
   CallInst *CreateAssumption(Value *Cond);
 
+  /// \brief Create an noalias intrinsic.
+  Instruction *CreateNoAlias(Value *Ptr, MDNode *ScopeTag);
+
   /// \brief Create a call to the experimental.gc.statepoint intrinsic to
   /// start a new statepoint sequence.
   CallInst *CreateGCStatepoint(Value *ActualCallee,
Index: lib/IR/IRBuilder.cpp
===================================================================
--- lib/IR/IRBuilder.cpp
+++ lib/IR/IRBuilder.cpp
@@ -17,6 +17,7 @@
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Metadata.h"
 using namespace llvm;
 
 /// CreateGlobalString - Make a new global variable with an initializer that
@@ -185,6 +186,33 @@
   return createCallHelper(FnAssume, Ops, this);
 }
 
+Instruction *IRBuilderBase::CreateNoAlias(Value *Ptr, MDNode *ScopeTag) {
+  // FIXME: We can currently mangle just about everything, but not literal
+  // structs (for those, bitcast to i8*).
+  Value *CPtr = Ptr;
+  if (StructType* STyp =
+        dyn_cast<StructType>(CPtr->getType()->getPointerElementType())) {
+    if (STyp->isLiteral())
+      CPtr = getCastedInt8PtrValue(CPtr);
+  }
+
+  Type *Types[] = { CPtr->getType() };
+  Value *Ops[] = { CPtr, MetadataAsValue::get(Context, ScopeTag) };
+  Module *M = BB->getParent()->getParent();
+  Value *FnNoAlias = Intrinsic::getDeclaration(M, Intrinsic::noalias, Types);
+  Instruction *Ret = createCallHelper(FnNoAlias, Ops, this);
+  cast<CallInst>(Ret)->setDoesNotThrow();
+
+  if (Ret->getType() != Ptr->getType()) {
+    BitCastInst *BCI = new BitCastInst(Ret, Ptr->getType(), "");
+    BB->getInstList().insert(InsertPt, BCI);
+    SetInstDebugLocation(BCI);
+    Ret = BCI;
+  }
+
+  return Ret;
+}
+
 /// Create a call to a Masked Load intrinsic.
 /// Ptr      - the base pointer for the load
 /// Align    - alignment of the source location

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