[NVPTX] Add support for addrspacecast in global variable initializers, including emitting generic() when casting to address space 0.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205906 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/NVPTX/NVPTXAsmPrinter.cpp

@@ -152,6 +152,21 @@ const MCExpr *nvptx::LowerConstant(const Constant *CV, AsmPrinter &AP) {
                          !AP.MF ? 0 : AP.MF->getFunction()->getParent());
       report_fatal_error(OS.str());
     }
+  case Instruction::AddrSpaceCast: {
+    // Strip any addrspace(1)->addrspace(0) addrspace casts. These will be
+    // handled by the generic() logic in the MCExpr printer
+    PointerType *DstTy            = cast<PointerType>(CE->getType());
+    PointerType *SrcTy            = cast<PointerType>(CE->getOperand(0)->getType());
+    if (SrcTy->getAddressSpace() == 1 && DstTy->getAddressSpace() == 0) {
+      return LowerConstant(cast<const Constant>(CE->getOperand(0)), AP);
+    }
+    std::string S;
+    raw_string_ostream OS(S);
+    OS << "Unsupported expression in static initializer: ";
+    CE->printAsOperand(OS, /*PrintType=*/ false,
+                       !AP.MF ? 0 : AP.MF->getFunction()->getParent());
+    report_fatal_error(OS.str());
+  }
   case Instruction::GetElementPtr: {
     const DataLayout &TD = *AP.TM.getDataLayout();
     // Generate a symbolic expression for the byte address
@@ -1754,13 +1769,35 @@ void NVPTXAsmPrinter::printScalarConstant(const Constant *CPV, raw_ostream &O) {
     return;
   }
   if (const GlobalValue *GVar = dyn_cast<GlobalValue>(CPV)) {
+    PointerType *PTy = dyn_cast<PointerType>(GVar->getType());
+    bool IsNonGenericPointer = false;
+    if (PTy && PTy->getAddressSpace() != 0) {
+      IsNonGenericPointer = true;
+    }
+    if (EmitGeneric && !isa<Function>(CPV) && !IsNonGenericPointer) {
+      O << "generic(";
       O << *getSymbol(GVar);
+      O << ")";
+    } else {
+      O << *getSymbol(GVar);
+    }
     return;
   }
   if (const ConstantExpr *Cexpr = dyn_cast<ConstantExpr>(CPV)) {
     const Value *v = Cexpr->stripPointerCasts();
+    PointerType *PTy = dyn_cast<PointerType>(Cexpr->getType());
+    bool IsNonGenericPointer = false;
+    if (PTy && PTy->getAddressSpace() != 0) {
+      IsNonGenericPointer = true;
+    }
     if (const GlobalValue *GVar = dyn_cast<GlobalValue>(v)) {
+      if (EmitGeneric && !isa<Function>(v) && !IsNonGenericPointer) {
+        O << "generic(";
         O << *getSymbol(GVar);
+        O << ")";
+      } else {
+        O << *getSymbol(GVar);
+      }
       return;
     } else {
       O << *LowerConstant(CPV, *this);

lib/Target/NVPTX/NVPTXAsmPrinter.h

@@ -96,6 +96,7 @@ class LLVM_LIBRARY_VISIBILITY NVPTXAsmPrinter : public AsmPrinter {
     unsigned curpos;
     raw_ostream &O;
     NVPTXAsmPrinter ≈
+    bool EmitGeneric;
 
   public:
     AggBuffer(unsigned _size, raw_ostream &_O, NVPTXAsmPrinter &_AP)
@@ -104,6 +105,7 @@ class LLVM_LIBRARY_VISIBILITY NVPTXAsmPrinter : public AsmPrinter {
       size = _size;
       curpos = 0;
       numSymbols = 0;
+      EmitGeneric = AP.EmitGeneric;
     }
     ~AggBuffer() { delete[] buffer; }
     unsigned addBytes(unsigned char *Ptr, int Num, int Bytes) {
@@ -155,7 +157,18 @@ class LLVM_LIBRARY_VISIBILITY NVPTXAsmPrinter : public AsmPrinter {
             const Value *v = Symbols[nSym];
             if (const GlobalValue *GVar = dyn_cast<GlobalValue>(v)) {
               MCSymbol *Name = AP.getSymbol(GVar);
+              PointerType *PTy = dyn_cast<PointerType>(GVar->getType());
+              bool IsNonGenericPointer = false;
+              if (PTy && PTy->getAddressSpace() != 0) {
+                IsNonGenericPointer = true;
+              }
+              if (EmitGeneric && !isa<Function>(v) && !IsNonGenericPointer) {
+                O << "generic(";
                 O << *Name;
+                O << ")";
+              } else {
+                O << *Name;
+              }
             } else if (const ConstantExpr *Cexpr = dyn_cast<ConstantExpr>(v)) {
               O << *nvptx::LowerConstant(Cexpr, AP);
             } else
@@ -276,12 +289,27 @@ private:
 
   LineReader *reader;
   LineReader *getReader(std::string);
+
+  // Used to control the need to emit .generic() in the initializer of
+  // module scope variables.
+  // Although ptx supports the hybrid mode like the following,
+  //    .global .u32 a;
+  //    .global .u32 b;
+  //    .global .u32 addr[] = {a, generic(b)}
+  // we have difficulty representing the difference in the NVVM IR.
+  //
+  // Since the address value should always be generic in CUDA C and always
+  // be specific in OpenCL, we use this simple control here.
+  //
+  bool EmitGeneric;
+
 public:
   NVPTXAsmPrinter(TargetMachine &TM, MCStreamer &Streamer)
       : AsmPrinter(TM, Streamer),
         nvptxSubtarget(TM.getSubtarget<NVPTXSubtarget>()) {
     CurrentBankselLabelInBasicBlock = "";
     reader = NULL;
+    EmitGeneric = (nvptxSubtarget.getDrvInterface() == NVPTX::CUDA);
   }
 
   ~NVPTXAsmPrinter() {

test/CodeGen/NVPTX/addrspacecast-gvar.ll

@@ -0,0 +1,9 @@
+; RUN: llc < %s -march=nvptx -mcpu=sm_20 | FileCheck %s
+
+; CHECK: .visible .global .align 4 .u32 g = 42;
+; CHECK: .visible .global .align 4 .u32 g2 = generic(g);
+; CHECK: .visible .global .align 4 .u32 g3 = g;
+
+@g = addrspace(1) global i32 42
+@g2 = addrspace(1) global i32* addrspacecast (i32 addrspace(1)* @g to i32*)
+@g3 = addrspace(1) global i32 addrspace(1)* @g