Commit first round work of PR1373. "noalias" is now fully supported in

VMCore, BitCode, and Assembly. Documentation and test case paramattrs.ll
updated also.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37432 91177308-0d34-0410-b5e6-96231b3b80d8

docs/LangRef.html

@@ -784,6 +784,9 @@ a power of 2.</p>
     <dt><tt>sret</tt></dt>
     <dd>This indicates that the parameter specifies the address of a structure
     that is the return value of the function in the source program.</dd>
+    <dt><tt>noalias</tt></dt>
+    <dd>This indicates that the parameter not alias any other object or any 
+    other "noalias" objects during the function call.
     <dt><tt>noreturn</tt></dt>
     <dd>This function attribute indicates that the function never returns. This
     indicates to LLVM that every call to this function should be treated as if

include/llvm/ParameterAttributes.h

@@ -35,7 +35,8 @@ enum Attributes {
   NoReturn   = 1 << 2, ///< mark the function as not returning
   InReg      = 1 << 3, ///< force argument to be passed in register
   StructRet  = 1 << 4, ///< hidden pointer to structure to return
-  NoUnwind   = 1 << 5  ///< Function doesn't unwind stack
+  NoUnwind   = 1 << 5, ///< Function doesn't unwind stack
+  NoAlias    = 1 << 6  ///< Considered to not alias after call.
 };
 
 }

lib/AsmParser/Lexer.l

@@ -229,6 +229,7 @@ inreg           { return INREG; }
 sret            { return SRET;  }
 nounwind        { return NOUNWIND; }
 noreturn        { return NORETURN; }
+noalias         { return NOALIAS; }
 
 void            { RET_TY(Type::VoidTy,  VOID);  }
 float           { RET_TY(Type::FloatTy, FLOAT); }

lib/AsmParser/llvmAsmParser.y

@@ -1101,7 +1101,7 @@ Module *llvm::RunVMAsmParser(const char * AsmString, Module * M) {
 %token <OtherOpVal> EXTRACTELEMENT INSERTELEMENT SHUFFLEVECTOR
 
 // Function Attributes
-%token NORETURN INREG SRET NOUNWIND
+%token NORETURN INREG SRET NOUNWIND NOALIAS
 
 // Visibility Styles
 %token DEFAULT HIDDEN PROTECTED
@@ -1224,10 +1224,11 @@ OptCallingConv : /*empty*/          { $$ = CallingConv::C; } |
                   CHECK_FOR_ERROR
                  };
 
-ParamAttr     : ZEXT  { $$ = ParamAttr::ZExt;      }
+ParamAttr     : ZEXT    { $$ = ParamAttr::ZExt;      }
-              | SEXT  { $$ = ParamAttr::SExt;      }
+              | SEXT    { $$ = ParamAttr::SExt;      }
-              | INREG { $$ = ParamAttr::InReg;     }
+              | INREG   { $$ = ParamAttr::InReg;     }
-              | SRET  { $$ = ParamAttr::StructRet; }
+              | SRET    { $$ = ParamAttr::StructRet; }
+              | NOALIAS { $$ = ParamAttr::NoAlias;   }
               ;
 
 OptParamAttrs : /* empty */  { $$ = ParamAttr::None; }

lib/VMCore/Function.cpp

@@ -99,6 +99,8 @@ ParamAttrsList::getParamAttrsText(uint16_t Attrs) {
     Result += "nounwind ";
   if (Attrs & ParamAttr::InReg)
     Result += "inreg ";
+  if (Attrs & ParamAttr::NoAlias)
+    Result += "noalias ";
   if (Attrs & ParamAttr::StructRet)
     Result += "sret ";  
   return Result;

test/Feature/paramattrs.ll

@@ -8,6 +8,8 @@
 declare i16 @"test"(i16 sext %arg) sext 
 declare i8 @"test2" (i16 zext %a2) zext 
 
+declare i32 @"test3"(i32* noalias %p)
+
 declare void @exit(i32) noreturn nounwind
 
 define i32 @main(i32 %argc, i8 **%argv) nounwind inreg {

tools/llvm2cpp/CppWriter.cpp

@@ -473,6 +473,8 @@ CppWriter::printTypeInternal(const Type* Ty) {
             Out << " | ParamAttr::SExt";
           if (attrs & ParamAttr::ZExt)
             Out << " | ParamAttr::ZExt";
+          if (attrs & ParamAttr::NoAlias)
+            Out << " | ParamAttr::NoAlias";
           if (attrs & ParamAttr::StructRet)
             Out << " | ParamAttr::StructRet";
           if (attrs & ParamAttr::InReg)