Add argmemonly attribute.

This change adds new attribute called "argmemonly". Function marked with this attribute can only access memory through it's argument pointers. This attribute directly corresponds to the "OnlyAccessesArgumentPointees" ModRef behaviour in alias analysis.

Differential Revision: http://reviews.llvm.org/D10398

llvm-svn: 241979

6 files changed, 43 insertions, 0 deletions

diff --git a/llvm/include/llvm/Analysis/AliasAnalysis.h b/llvm/include/llvm/Analysis/AliasAnalysis.h
index 57e44876f5c..36f8199a032 100644
--- a/llvm/include/llvm/Analysis/AliasAnalysis.h
+++ b/llvm/include/llvm/Analysis/AliasAnalysis.h
@@ -211,6 +211,8 @@ public:
     /// (if it has any) are non-volatile loads from objects pointed to by its
     /// pointer-typed arguments, with arbitrary offsets.
     ///
+    /// This property corresponds to the LLVM IR 'argmemonly' attribute combined
+    /// with 'readonly' attribute.
     /// This property corresponds to the IntrReadArgMem LLVM intrinsic flag.
     OnlyReadsArgumentPointees = ArgumentPointees | Ref,
 
@@ -218,6 +220,7 @@ public:
     /// function (if it has any) are non-volatile loads and stores from objects
     /// pointed to by its pointer-typed arguments, with arbitrary offsets.
     ///
+    /// This property corresponds to the LLVM IR 'argmemonly' attribute.
     /// This property corresponds to the IntrReadWriteArgMem LLVM intrinsic flag.
     OnlyAccessesArgumentPointees = ArgumentPointees | ModRef,
 
diff --git a/llvm/include/llvm/Bitcode/LLVMBitCodes.h b/llvm/include/llvm/Bitcode/LLVMBitCodes.h
index 605c4172dd8..7130ee75523 100644
--- a/llvm/include/llvm/Bitcode/LLVMBitCodes.h
+++ b/llvm/include/llvm/Bitcode/LLVMBitCodes.h
@@ -407,6 +407,7 @@ namespace bitc {
     ATTR_KIND_DEREFERENCEABLE_OR_NULL = 42,
     ATTR_KIND_CONVERGENT = 43,
     ATTR_KIND_SAFESTACK = 44,
+    ATTR_KIND_ARGMEMONLY = 45
   };
 
   enum ComdatSelectionKindCodes {
diff --git a/llvm/include/llvm/IR/Attributes.h b/llvm/include/llvm/IR/Attributes.h
index 366bf709ab1..4d6d7da1fa5 100644
--- a/llvm/include/llvm/IR/Attributes.h
+++ b/llvm/include/llvm/IR/Attributes.h
@@ -98,6 +98,8 @@ public:
     OptimizeNone,          ///< Function must not be optimized.
     ReadNone,              ///< Function does not access memory
     ReadOnly,              ///< Function only reads from memory
+    ArgMemOnly,            ///< Funciton can access memory only using pointers
+                           ///< based on its arguments.
     Returned,              ///< Return value is always equal to this argument
     ReturnsTwice,          ///< Function can return twice
     SExt,                  ///< Sign extended before/after call
diff --git a/llvm/include/llvm/IR/CallSite.h b/llvm/include/llvm/IR/CallSite.h
index dd2903e807e..2841781e8a9 100644
--- a/llvm/include/llvm/IR/CallSite.h
+++ b/llvm/include/llvm/IR/CallSite.h
@@ -290,6 +290,15 @@ public:
     CALLSITE_DELEGATE_SETTER(setOnlyReadsMemory());
   }
 
+  /// @brief Determine if the call can access memmory only using pointers based
+  /// on its arguments.
+  bool onlyAccessesArgMemory() const {
+    CALLSITE_DELEGATE_GETTER(onlyAccessesArgMemory());
+  }
+  void setOnlyAccessesArgMemory() {
+    CALLSITE_DELEGATE_SETTER(setOnlyAccessesArgMemory());
+  }
+
   /// @brief Determine if the call cannot return.
   bool doesNotReturn() const {
     CALLSITE_DELEGATE_GETTER(doesNotReturn());
diff --git a/llvm/include/llvm/IR/Function.h b/llvm/include/llvm/IR/Function.h
index 02ea056de39..ec9f4cad094 100644
--- a/llvm/include/llvm/IR/Function.h
+++ b/llvm/include/llvm/IR/Function.h
@@ -293,6 +293,16 @@ public:
     addFnAttr(Attribute::ReadOnly);
   }
 
+  /// @brief Determine if the call can access memmory only using pointers based
+  /// on its arguments.
+  bool onlyAccessesArgMemory() const {
+    return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
+                                      Attribute::ArgMemOnly);
+  }
+  void setOnlyAccessesArgMemory() {
+    addFnAttr(Attribute::ArgMemOnly);
+  }
+  
   /// @brief Determine if the function cannot return.
   bool doesNotReturn() const {
     return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
diff --git a/llvm/include/llvm/IR/Instructions.h b/llvm/include/llvm/IR/Instructions.h
index 62723e44c0c..07d5f111b9e 100644
--- a/llvm/include/llvm/IR/Instructions.h
+++ b/llvm/include/llvm/IR/Instructions.h
@@ -1595,6 +1595,15 @@ public:
     addAttribute(AttributeSet::FunctionIndex, Attribute::ReadOnly);
   }
 
+  /// @brief Determine if the call can access memmory only using pointers based
+  /// on its arguments.
+  bool onlyAccessesArgMemory() const {
+    return hasFnAttr(Attribute::ArgMemOnly);
+  }
+  void setOnlyAccessesArgMemory() {
+    addAttribute(AttributeSet::FunctionIndex, Attribute::ArgMemOnly);
+  }
+
   /// \brief Determine if the call cannot return.
   bool doesNotReturn() const { return hasFnAttr(Attribute::NoReturn); }
   void setDoesNotReturn() {
@@ -3364,6 +3373,15 @@ public:
     addAttribute(AttributeSet::FunctionIndex, Attribute::ReadOnly);
   }
 
+  /// @brief Determine if the call access memmory only using it's pointer
+  /// arguments.
+  bool onlyAccessesArgMemory() const {
+    return hasFnAttr(Attribute::ArgMemOnly);
+  }
+  void setOnlyAccessesArgMemory() {
+    addAttribute(AttributeSet::FunctionIndex, Attribute::ArgMemOnly);
+  }
+
   /// \brief Determine if the call cannot return.
   bool doesNotReturn() const { return hasFnAttr(Attribute::NoReturn); }
   void setDoesNotReturn() {