Allow DataLayout to specify addrspace for allocas.

LLVM makes several assumptions about address space 0. However,
alloca is presently constrained to always return this address space.
There's no real way to avoid using alloca, so without this
there is no way to opt out of these assumptions.

The problematic assumptions include:
- That the pointer size used for the stack is the same size as
  the code size pointer, which is also the maximum sized pointer.

- That 0 is an invalid, non-dereferencable pointer value.

These are problems for AMDGPU because alloca is used to
implement the private address space, which uses a 32-bit
index as the pointer value. Other pointers are 64-bit
and behave more like LLVM's notion of generic address
space. By changing the address space used for allocas,
we can change our generic pointer type to be LLVM's generic
pointer type which does have similar properties.

llvm-svn: 299888

Author: arsenm

llvm/docs/LangRef.rst

@@ -1812,6 +1812,9 @@ as follows:
     must be a multiple of 8-bits. If omitted, the natural stack
     alignment defaults to "unspecified", which does not prevent any
     alignment promotions.
+``A<address space>``
+    Specifies the address space of  objects created by '``alloca``'.
+    Defaults to the default address space of 0.
 ``p[n]:<size>:<abi>:<pref>``
     This specifies the *size* of a pointer and its ``<abi>`` and
     ``<pref>``\erred alignments for address space ``n``. All sizes are in
@@ -7192,15 +7195,15 @@ Syntax:
 
 ::
 
-      <result> = alloca [inalloca] <type> [, <ty> <NumElements>] [, align <alignment>]     ; yields type*:result
+      <result> = alloca [inalloca] <type> [, <ty> <NumElements>] [, align <alignment>] [, addrspace(<num>)]     ; yields type addrspace(num)*:result
 
 Overview:
 """""""""
 
 The '``alloca``' instruction allocates memory on the stack frame of the
 currently executing function, to be automatically released when this
 function returns to its caller. The object is always allocated in the
-default address space (address space zero).
+address space for allocas indicated in the datalayout.
 
 Arguments:
 """"""""""

llvm/include/llvm/IR/DataLayout.h

@@ -104,6 +104,7 @@ class DataLayout {
   /// Defaults to false.
   bool BigEndian;
 
+  unsigned AllocaAddrSpace;
   unsigned StackNaturalAlign;
 
   enum ManglingModeT {
@@ -186,6 +187,7 @@ class DataLayout {
     clear();
     StringRepresentation = DL.StringRepresentation;
     BigEndian = DL.isBigEndian();
+    AllocaAddrSpace = DL.AllocaAddrSpace;
     StackNaturalAlign = DL.StackNaturalAlign;
     ManglingMode = DL.ManglingMode;
     LegalIntWidths = DL.LegalIntWidths;
@@ -241,6 +243,7 @@ class DataLayout {
   }
 
   unsigned getStackAlignment() const { return StackNaturalAlign; }
+  unsigned getAllocaAddrSpace() const { return AllocaAddrSpace; }
 
   bool hasMicrosoftFastStdCallMangling() const {
     return ManglingMode == MM_WinCOFFX86;

llvm/include/llvm/IR/IRBuilder.h

@@ -33,6 +33,7 @@
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
 #include "llvm/IR/Operator.h"
 #include "llvm/IR/Type.h"
 #include "llvm/IR/Value.h"
@@ -1089,9 +1090,15 @@ class IRBuilder : public IRBuilderBase, public Inserter {
   // Instruction creation methods: Memory Instructions
   //===--------------------------------------------------------------------===//
 
+  AllocaInst *CreateAlloca(Type *Ty, unsigned AddrSpace,
+                           Value *ArraySize = nullptr, const Twine &Name = "") {
+    return Insert(new AllocaInst(Ty, AddrSpace, ArraySize), Name);
+  }
+
   AllocaInst *CreateAlloca(Type *Ty, Value *ArraySize = nullptr,
                            const Twine &Name = "") {
-    return Insert(new AllocaInst(Ty, ArraySize), Name);
+    const DataLayout &DL = BB->getParent()->getParent()->getDataLayout();
+    return Insert(new AllocaInst(Ty, DL.getAllocaAddrSpace(), ArraySize), Name);
   }
   // \brief Provided to resolve 'CreateLoad(Ptr, "...")' correctly, instead of
   // converting the string to 'bool' for the isVolatile parameter.

llvm/include/llvm/IR/Instructions.h

@@ -67,18 +67,21 @@ class AllocaInst : public UnaryInstruction {
   AllocaInst *cloneImpl() const;
 
 public:
-  explicit AllocaInst(Type *Ty, Value *ArraySize = nullptr,
+  explicit AllocaInst(Type *Ty, unsigned AddrSpace,
+                      Value *ArraySize = nullptr,
                       const Twine &Name = "",
                       Instruction *InsertBefore = nullptr);
-  AllocaInst(Type *Ty, Value *ArraySize,
+  AllocaInst(Type *Ty, unsigned AddrSpace, Value *ArraySize,
              const Twine &Name, BasicBlock *InsertAtEnd);
 
-  AllocaInst(Type *Ty, const Twine &Name, Instruction *InsertBefore = nullptr);
-  AllocaInst(Type *Ty, const Twine &Name, BasicBlock *InsertAtEnd);
+  AllocaInst(Type *Ty, unsigned AddrSpace,
+             const Twine &Name, Instruction *InsertBefore = nullptr);
+  AllocaInst(Type *Ty, unsigned AddrSpace,
+             const Twine &Name, BasicBlock *InsertAtEnd);
 
-  AllocaInst(Type *Ty, Value *ArraySize, unsigned Align,
+  AllocaInst(Type *Ty, unsigned AddrSpace, Value *ArraySize, unsigned Align,
              const Twine &Name = "", Instruction *InsertBefore = nullptr);
-  AllocaInst(Type *Ty, Value *ArraySize, unsigned Align,
+  AllocaInst(Type *Ty, unsigned AddrSpace, Value *ArraySize, unsigned Align,
              const Twine &Name, BasicBlock *InsertAtEnd);
 
   // Out of line virtual method, so the vtable, etc. has a home.

llvm/lib/AsmParser/LLParser.cpp

@@ -1852,6 +1852,34 @@ bool LLParser::ParseOptionalCommaAlign(unsigned &Alignment,
   return false;
 }
 
+/// ParseOptionalCommaAddrSpace
+///   ::=
+///   ::= ',' addrspace(1)
+///
+/// This returns with AteExtraComma set to true if it ate an excess comma at the
+/// end.
+bool LLParser::ParseOptionalCommaAddrSpace(unsigned &AddrSpace,
+                                           LocTy &Loc,
+                                           bool &AteExtraComma) {
+  AteExtraComma = false;
+  while (EatIfPresent(lltok::comma)) {
+    // Metadata at the end is an early exit.
+    if (Lex.getKind() == lltok::MetadataVar) {
+      AteExtraComma = true;
+      return false;
+    }
+
+    Loc = Lex.getLoc();
+    if (Lex.getKind() != lltok::kw_addrspace)
+      return Error(Lex.getLoc(), "expected metadata or 'addrspace'");
+
+    if (ParseOptionalAddrSpace(AddrSpace))
+      return true;
+  }
+
+  return false;
+}
+
 bool LLParser::parseAllocSizeArguments(unsigned &BaseSizeArg,
                                        Optional<unsigned> &HowManyArg) {
   Lex.Lex();
@@ -6033,8 +6061,9 @@ bool LLParser::ParseCall(Instruction *&Inst, PerFunctionState &PFS,
 ///       (',' 'align' i32)?
 int LLParser::ParseAlloc(Instruction *&Inst, PerFunctionState &PFS) {
   Value *Size = nullptr;
-  LocTy SizeLoc, TyLoc;
+  LocTy SizeLoc, TyLoc, ASLoc;
   unsigned Alignment = 0;
+  unsigned AddrSpace = 0;
   Type *Ty = nullptr;
 
   bool IsInAlloca = EatIfPresent(lltok::kw_inalloca);
@@ -6048,20 +6077,36 @@ int LLParser::ParseAlloc(Instruction *&Inst, PerFunctionState &PFS) {
   bool AteExtraComma = false;
   if (EatIfPresent(lltok::comma)) {
     if (Lex.getKind() == lltok::kw_align) {
-      if (ParseOptionalAlignment(Alignment)) return true;
+      if (ParseOptionalAlignment(Alignment))
+        return true;
+      if (ParseOptionalCommaAddrSpace(AddrSpace, ASLoc, AteExtraComma))
+        return true;
+    } else if (Lex.getKind() == lltok::kw_addrspace) {
+      ASLoc = Lex.getLoc();
+      if (ParseOptionalAddrSpace(AddrSpace))
+        return true;
     } else if (Lex.getKind() == lltok::MetadataVar) {
       AteExtraComma = true;
     } else {
       if (ParseTypeAndValue(Size, SizeLoc, PFS) ||
-          ParseOptionalCommaAlign(Alignment, AteExtraComma))
+          ParseOptionalCommaAlign(Alignment, AteExtraComma) ||
+          (!AteExtraComma &&
+           ParseOptionalCommaAddrSpace(AddrSpace, ASLoc, AteExtraComma)))
         return true;
     }
   }
 
   if (Size && !Size->getType()->isIntegerTy())
     return Error(SizeLoc, "element count must have integer type");
 
-  AllocaInst *AI = new AllocaInst(Ty, Size, Alignment);
+  const DataLayout &DL = M->getDataLayout();
+  unsigned AS = DL.getAllocaAddrSpace();
+  if (AS != AddrSpace) {
+    // TODO: In the future it should be possible to specify addrspace per-alloca.
+    return Error(ASLoc, "address space must match datalayout");
+  }
+
+  AllocaInst *AI = new AllocaInst(Ty, AS, Size, Alignment);
   AI->setUsedWithInAlloca(IsInAlloca);
   AI->setSwiftError(IsSwiftError);
   Inst = AI;

llvm/lib/AsmParser/LLParser.h

@@ -246,6 +246,8 @@ namespace llvm {
     bool ParseOrdering(AtomicOrdering &Ordering);
     bool ParseOptionalStackAlignment(unsigned &Alignment);
     bool ParseOptionalCommaAlign(unsigned &Alignment, bool &AteExtraComma);
+    bool ParseOptionalCommaAddrSpace(unsigned &AddrSpace, LocTy &Loc,
+                                     bool &AteExtraComma);
     bool ParseOptionalCommaInAlloca(bool &IsInAlloca);
     bool parseAllocSizeArguments(unsigned &ElemSizeArg,
                                  Optional<unsigned> &HowManyArg);

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -4006,7 +4006,12 @@ Error BitcodeReader::parseFunctionBody(Function *F) {
       }
       if (!Ty || !Size)
         return error("Invalid record");
-      AllocaInst *AI = new AllocaInst(Ty, Size, Align);
+
+      // FIXME: Make this an optional field.
+      const DataLayout &DL = TheModule->getDataLayout();
+      unsigned AS = DL.getAllocaAddrSpace();
+
+      AllocaInst *AI = new AllocaInst(Ty, AS, Size, Align);
       AI->setUsedWithInAlloca(InAlloca);
       AI->setSwiftError(SwiftError);
       I = AI;

llvm/lib/CodeGen/SjLjEHPrepare.cpp

@@ -175,8 +175,8 @@ Value *SjLjEHPrepare::setupFunctionContext(Function &F,
   // because the value needs to be added to the global context list.
   auto &DL = F.getParent()->getDataLayout();
   unsigned Align = DL.getPrefTypeAlignment(FunctionContextTy);
-  FuncCtx = new AllocaInst(FunctionContextTy, nullptr, Align, "fn_context",
-                           &EntryBB->front());
+  FuncCtx = new AllocaInst(FunctionContextTy, DL.getAllocaAddrSpace(),
+                           nullptr, Align, "fn_context", &EntryBB->front());
 
   // Fill in the function context structure.
   for (LandingPadInst *LPI : LPads) {

llvm/lib/CodeGen/WinEHPrepare.cpp

@@ -86,6 +86,7 @@ class WinEHPrepare : public FunctionPass {
   // All fields are reset by runOnFunction.
   EHPersonality Personality = EHPersonality::Unknown;
 
+  const DataLayout *DL = nullptr;
   DenseMap<BasicBlock *, ColorVector> BlockColors;
   MapVector<BasicBlock *, std::vector<BasicBlock *>> FuncletBlocks;
 };
@@ -111,6 +112,7 @@ bool WinEHPrepare::runOnFunction(Function &Fn) {
   if (!isFuncletEHPersonality(Personality))
     return false;
 
+  DL = &Fn.getParent()->getDataLayout();
   return prepareExplicitEH(Fn);
 }
 
@@ -1070,7 +1072,7 @@ AllocaInst *WinEHPrepare::insertPHILoads(PHINode *PN, Function &F) {
   if (!isa<TerminatorInst>(EHPad)) {
     // If the EHPad isn't a terminator, then we can insert a load in this block
     // that will dominate all uses.
-    SpillSlot = new AllocaInst(PN->getType(), nullptr,
+    SpillSlot = new AllocaInst(PN->getType(), DL->getAllocaAddrSpace(), nullptr,
                                Twine(PN->getName(), ".wineh.spillslot"),
                                &F.getEntryBlock().front());
     Value *V = new LoadInst(SpillSlot, Twine(PN->getName(), ".wineh.reload"),
@@ -1157,7 +1159,7 @@ void WinEHPrepare::replaceUseWithLoad(Value *V, Use &U, AllocaInst *&SpillSlot,
                                       Function &F) {
   // Lazilly create the spill slot.
   if (!SpillSlot)
-    SpillSlot = new AllocaInst(V->getType(), nullptr,
+    SpillSlot = new AllocaInst(V->getType(), DL->getAllocaAddrSpace(), nullptr,
                                Twine(V->getName(), ".wineh.spillslot"),
                                &F.getEntryBlock().front());
 

llvm/lib/IR/AsmWriter.cpp

@@ -3117,6 +3117,12 @@ void AssemblyWriter::printInstruction(const Instruction &I) {
     if (AI->getAlignment()) {
       Out << ", align " << AI->getAlignment();
     }
+
+    unsigned AddrSpace = AI->getType()->getAddressSpace();
+    if (AddrSpace != 0) {
+      Out << ", addrspace(" << AddrSpace << ')';
+    }
+
   } else if (isa<CastInst>(I)) {
     if (Operand) {
       Out << ' ';