[OpenCL] Add LangAS::opencl_private to represent private address space in AST

Currently Clang uses default address space (0) to represent private address space for OpenCL
in AST. There are two issues with this:

Multiple address spaces including private address space cannot be diagnosed.
There is no mangling for default address space. For example, if private int* is emitted as
i32 addrspace(5)* in IR. It is supposed to be mangled as PUAS5i but it is mangled as
Pi instead.

This patch attempts to represent OpenCL private address space explicitly in AST. It adds
a new enum LangAS::opencl_private and adds it to the variable types which are implicitly
private:

automatic variables without address space qualifier

function parameter

pointee type without address space qualifier (OpenCL 1.2 and below)

Differential Revision: https://reviews.llvm.org/D35082

llvm-svn: 315668

Author: yxsamliu

clang/include/clang/Basic/AddressSpaces.h

@@ -25,16 +25,17 @@ namespace LangAS {
 ///
 enum ID {
   // The default value 0 is the value used in QualType for the the situation
-  // where there is no address space qualifier. For most languages, this also
-  // corresponds to the situation where there is no address space qualifier in
-  // the source code, except for OpenCL, where the address space value 0 in
-  // QualType represents private address space in OpenCL source code.
+  // where there is no address space qualifier.
   Default = 0,
 
   // OpenCL specific address spaces.
+  // In OpenCL each l-value must have certain non-default address space, each
+  // r-value must have no address space (i.e. the default address space). The
+  // pointee of a pointer must have non-default address space.
   opencl_global,
   opencl_local,
   opencl_constant,
+  opencl_private,
   opencl_generic,
 
   // CUDA specific address spaces.

clang/lib/AST/ASTContext.cpp

@@ -707,6 +707,7 @@ static const LangAS::Map *getAddressSpaceMap(const TargetInfo &T,
       1, // opencl_global
       3, // opencl_local
       2, // opencl_constant
+      0, // opencl_private
       4, // opencl_generic
       5, // cuda_device
       6, // cuda_constant

clang/lib/AST/Expr.cpp

@@ -3293,20 +3293,20 @@ Expr::isNullPointerConstant(ASTContext &Ctx,
       // Check that it is a cast to void*.
       if (const PointerType *PT = CE->getType()->getAs<PointerType>()) {
         QualType Pointee = PT->getPointeeType();
-        Qualifiers Q = Pointee.getQualifiers();
-        // In OpenCL v2.0 generic address space acts as a placeholder
-        // and should be ignored.
-        bool IsASValid = true;
-        if (Ctx.getLangOpts().OpenCLVersion >= 200) {
-          if (Pointee.getAddressSpace() == LangAS::opencl_generic)
-            Q.removeAddressSpace();
-          else
-            IsASValid = false;
-        }
-
-        if (IsASValid && !Q.hasQualifiers() &&
-            Pointee->isVoidType() &&                      // to void*
-            CE->getSubExpr()->getType()->isIntegerType()) // from int.
+        // Only (void*)0 or equivalent are treated as nullptr. If pointee type
+        // has non-default address space it is not treated as nullptr.
+        // (__generic void*)0 in OpenCL 2.0 should not be treated as nullptr
+        // since it cannot be assigned to a pointer to constant address space.
+        bool PointeeHasDefaultAS =
+            Pointee.getAddressSpace() == LangAS::Default ||
+            (Ctx.getLangOpts().OpenCLVersion >= 200 &&
+             Pointee.getAddressSpace() == LangAS::opencl_generic) ||
+            (Ctx.getLangOpts().OpenCL &&
+             Ctx.getLangOpts().OpenCLVersion < 200 &&
+             Pointee.getAddressSpace() == LangAS::opencl_private);
+
+        if (PointeeHasDefaultAS && Pointee->isVoidType() && // to void*
+            CE->getSubExpr()->getType()->isIntegerType())   // from int.
           return CE->getSubExpr()->isNullPointerConstant(Ctx, NPC);
       }
     }

clang/lib/AST/ItaniumMangle.cpp

@@ -2227,23 +2227,26 @@ void CXXNameMangler::mangleQualifiers(Qualifiers Quals, const DependentAddressSp
     if (Context.getASTContext().addressSpaceMapManglingFor(AS)) {
       //  <target-addrspace> ::= "AS" <address-space-number>
       unsigned TargetAS = Context.getASTContext().getTargetAddressSpace(AS);
-      ASString = "AS" + llvm::utostr(TargetAS);
+      if (TargetAS != 0)
+        ASString = "AS" + llvm::utostr(TargetAS);
     } else {
       switch (AS) {
       default: llvm_unreachable("Not a language specific address space");
-      //  <OpenCL-addrspace> ::= "CL" [ "global" | "local" | "constant |
-      //                                "generic" ]
+      //  <OpenCL-addrspace> ::= "CL" [ "global" | "local" | "constant" |
+      //                                "private"| "generic" ]
       case LangAS::opencl_global:   ASString = "CLglobal";   break;
       case LangAS::opencl_local:    ASString = "CLlocal";    break;
       case LangAS::opencl_constant: ASString = "CLconstant"; break;
+      case LangAS::opencl_private:  ASString = "CLprivate";  break;
       case LangAS::opencl_generic:  ASString = "CLgeneric";  break;
       //  <CUDA-addrspace> ::= "CU" [ "device" | "constant" | "shared" ]
       case LangAS::cuda_device:     ASString = "CUdevice";   break;
       case LangAS::cuda_constant:   ASString = "CUconstant"; break;
       case LangAS::cuda_shared:     ASString = "CUshared";   break;
       }
     }
-    mangleVendorQualifier(ASString);
+    if (!ASString.empty())
+      mangleVendorQualifier(ASString);
   }
 
   // The ARC ownership qualifiers start with underscores.

clang/lib/AST/TypePrinter.cpp

@@ -1677,16 +1677,19 @@ void Qualifiers::print(raw_ostream &OS, const PrintingPolicy& Policy,
     addSpace = true;
   }
   if (unsigned addrspace = getAddressSpace()) {
-    if (addSpace)
-      OS << ' ';
-    addSpace = true;
-    switch (addrspace) {
+    if (addrspace != LangAS::opencl_private) {
+      if (addSpace)
+        OS << ' ';
+      addSpace = true;
+      switch (addrspace) {
       case LangAS::opencl_global:
         OS << "__global";
         break;
       case LangAS::opencl_local:
         OS << "__local";
         break;
+      case LangAS::opencl_private:
+        break;
       case LangAS::opencl_constant:
       case LangAS::cuda_constant:
         OS << "__constant";
@@ -1705,6 +1708,7 @@ void Qualifiers::print(raw_ostream &OS, const PrintingPolicy& Policy,
         OS << "__attribute__((address_space(";
         OS << addrspace - LangAS::FirstTargetAddressSpace;
         OS << ")))";
+      }
     }
   }
   if (Qualifiers::GC gc = getObjCGCAttr()) {

clang/lib/Basic/Targets/AMDGPU.cpp

@@ -47,6 +47,7 @@ static const LangAS::Map AMDGPUPrivIsZeroDefIsGenMap = {
     1, // opencl_global
     3, // opencl_local
     2, // opencl_constant
+    0, // opencl_private
     4, // opencl_generic
     1, // cuda_device
     2, // cuda_constant
@@ -58,6 +59,7 @@ static const LangAS::Map AMDGPUGenIsZeroDefIsGenMap = {
     1, // opencl_global
     3, // opencl_local
     2, // opencl_constant
+    5, // opencl_private
     0, // opencl_generic
     1, // cuda_device
     2, // cuda_constant
@@ -69,6 +71,7 @@ static const LangAS::Map AMDGPUPrivIsZeroDefIsPrivMap = {
     1, // opencl_global
     3, // opencl_local
     2, // opencl_constant
+    0, // opencl_private
     4, // opencl_generic
     1, // cuda_device
     2, // cuda_constant
@@ -80,6 +83,7 @@ static const LangAS::Map AMDGPUGenIsZeroDefIsPrivMap = {
     1, // opencl_global
     3, // opencl_local
     2, // opencl_constant
+    5, // opencl_private
     0, // opencl_generic
     1, // cuda_device
     2, // cuda_constant

clang/lib/Basic/Targets/NVPTX.h

@@ -28,6 +28,7 @@ static const unsigned NVPTXAddrSpaceMap[] = {
     1, // opencl_global
     3, // opencl_local
     4, // opencl_constant
+    0, // opencl_private
     // FIXME: generic has to be added to the target
     0, // opencl_generic
     1, // cuda_device

clang/lib/Basic/Targets/SPIR.h

@@ -27,6 +27,7 @@ static const unsigned SPIRAddrSpaceMap[] = {
     1, // opencl_global
     3, // opencl_local
     2, // opencl_constant
+    0, // opencl_private
     4, // opencl_generic
     0, // cuda_device
     0, // cuda_constant

clang/lib/Basic/Targets/TCE.h

@@ -35,6 +35,7 @@ static const unsigned TCEOpenCLAddrSpaceMap[] = {
     3, // opencl_global
     4, // opencl_local
     5, // opencl_constant
+    0, // opencl_private
     // FIXME: generic has to be added to the target
     0, // opencl_generic
     0, // cuda_device

clang/lib/CodeGen/CGDecl.cpp

@@ -956,7 +956,9 @@ void CodeGenFunction::EmitLifetimeEnd(llvm::Value *Size, llvm::Value *Addr) {
 CodeGenFunction::AutoVarEmission
 CodeGenFunction::EmitAutoVarAlloca(const VarDecl &D) {
   QualType Ty = D.getType();
-  assert(Ty.getAddressSpace() == LangAS::Default);
+  assert(
+      Ty.getAddressSpace() == LangAS::Default ||
+      (Ty.getAddressSpace() == LangAS::opencl_private && getLangOpts().OpenCL));
 
   AutoVarEmission emission(D);