[AMDGPULowerBufferFatPointers] Handle ptrtoaddr by extending the offset

llvm/docs/LangRef.rst

@@ -3147,14 +3147,21 @@ as follows:
 ``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>][:<idx>]``
-    This specifies the *size* of a pointer and its ``<abi>`` and
-    ``<pref>``\erred alignments for address space ``n``.
-    The fourth parameter ``<idx>`` is the size of the
-    index that used for address calculation, which must be less than or equal
-    to the pointer size. If not
-    specified, the default index size is equal to the pointer size. All sizes
-    are in bits. The address space, ``n``, is optional, and if not specified,
+``p[n]:<size>:<abi>[:<pref>[:<idx>]]``
+    This specifies the properties of a pointer in address space ``n``.
+    The ``<size>`` parameter specifies the size of the bitwise representation.
+    For :ref:`non-integral pointers <nointptrtype>` the representation size may
+    be larger than the address width of the underlying address space (e.g. to
+    accommodate additional metadata).
+    The alignment requirements are specified via the ``<abi>`` and
+    ``<pref>``\erred alignments parameters.
+    The fourth parameter ``<idx>`` is the size of the index that used for
+    address calculations such as :ref:`getelementptr <i_getelementptr>`.
+    It must be less than or equal to the pointer size. If not specified, the
+    default index size is equal to the pointer size.
+    The index size also specifies the width of addresses in this address space.
+    All sizes are in bits.
+    The address space, ``n``, is optional, and if not specified,
     denotes the default address space 0. The value of ``n`` must be
     in the range [1,2^24).
 ``i<size>:<abi>[:<pref>]``
@@ -4266,6 +4273,16 @@ address spaces defined in the :ref:`datalayout string<langref_datalayout>`.
 the default globals address space and ``addrspace("P")`` the program address
 space.
 
+The representation of pointers can be different for each address space and does
+not necessarily need to be a plain integer address (e.g. for
+:ref:`non-integral pointers <nointptrtype>`). In addition to a representation
+bits size, pointers in each address space also have an index size which defines
+the bitwidth of indexing operations as well as the size of `integer addresses`
+in this address space. For example, CHERI capabilities are twice the size of the
+underlying addresses to accommodate for additional metadata such as bounds and
+permissions: on a 32-bit system the bitwidth of the pointer representation size
+is 64, but the underlying address width remains 32 bits.
+
 The default address space is number zero.
 
 The semantics of non-zero address spaces are target-specific. Memory
@@ -12396,12 +12413,15 @@ Semantics:
 """"""""""
 
 The '``ptrtoint``' instruction converts ``value`` to integer type
-``ty2`` by interpreting the pointer value as an integer and either
-truncating or zero extending that value to the size of the integer type.
+``ty2`` by interpreting the all pointer representation bits as an integer
+(equivalent to a ``bitcast``) and either truncating or zero extending that value
+to the size of the integer type.
 If ``value`` is smaller than ``ty2`` then a zero extension is done. If
 ``value`` is larger than ``ty2`` then a truncation is done. If they are
 the same size, then nothing is done (*no-op cast*) other than a type
 change.
+The ``ptrtoint`` always :ref:`captures address and provenance <pointercapture>`
+of the pointer argument.
 
 Example:
 """"""""
@@ -12412,6 +12432,61 @@ Example:
       %Y = ptrtoint ptr %P to i64                        ; yields zero extension on 32-bit architecture
       %Z = ptrtoint <4 x ptr> %P to <4 x i64>; yields vector zero extension for a vector of addresses on 32-bit architecture
 
+.. _i_ptrtoaddr:
+
+'``ptrtoaddr .. to``' Instruction
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Syntax:
+"""""""
+
+::
+
+      <result> = ptrtoaddr <ty> <value> to <ty2>             ; yields ty2
+
+Overview:
+"""""""""
+
+The '``ptrtoaddr``' instruction converts the pointer or a vector of
+pointers ``value`` to the underlying integer address (or vector of integers) of
+type ``ty2``. This is different from :ref:`ptrtoint <i_ptrtoint>` in that it
+only operates on the index bits of the pointer and ignores all other bits.
+
+Arguments:
+""""""""""
+
+The '``ptrtoaddr``' instruction takes a ``value`` to cast, which must be
+a value of type :ref:`pointer <t_pointer>` or a vector of pointers, and a
+type to cast it to ``ty2``, which must be an :ref:`integer <t_integer>` or
+a vector of integers type.
+
+Semantics:
+""""""""""
+
+The '``ptrtoaddr``' instruction converts ``value`` to integer type
+``ty2`` by interpreting the lowest index-width pointer representation bits as an
+integer and either truncating or zero extending that value to the size of the
+integer type.
+If the address of ``value`` is smaller than ``ty2`` then a zero extension is
+done. If the address of ``value`` is larger than ``ty2`` then a truncation is
+done. If the address size and the pointer representation size are the same and
+``value`` and ``ty2`` are the same size, then nothing is done (*no-op cast*)
+other than a type change.
+
+The ``ptrtoaddr`` always :ref:`captures the address (but not provenance) <pointercapture>`
+of the pointer argument.
+
+Example:
+""""""""
+This example assumes pointers in address space 1 are 64 bits in size with an
+address width of 32 bits (``p1:64:64:64:32`` :ref:`datalayout string<langref_datalayout>`)
+.. code-block:: llvm
+
+      %X = ptrtoaddr ptr addrspace(1) %P to i8  ; extracts low 32 bits and truncates
+      %Y = ptrtoaddr ptr addrspace(1) %P to i64 ; extracts low 32 bits and zero extends
+      %Z = ptrtoaddr <4 x ptr addrspace(1)> %P to <4 x i64>; yields vector zero extension of low 32 bits for each pointer
+
+
 .. _i_inttoptr:
 
 '``inttoptr .. to``' Instruction
@@ -12456,6 +12531,9 @@ of the integer ``value``. If ``value`` is larger than the size of a
 pointer then a truncation is done. If ``value`` is smaller than the size
 of a pointer then a zero extension is done. If they are the same size,
 nothing is done (*no-op cast*).
+The behavior is equivalent to a ``bitcast``, however, the resulting value is not
+guaranteed to be dereferenceable (e.g. if the result type is a
+:ref:`non-integral pointers <nointptrtype>`).
 
 Example:
 """"""""

llvm/include/llvm-c/Core.h

@@ -110,6 +110,7 @@ typedef enum {
   LLVMFPTrunc        = 37,
   LLVMFPExt          = 38,
   LLVMPtrToInt       = 39,
+  LLVMPtrToAddr      = 69,
   LLVMIntToPtr       = 40,
   LLVMBitCast        = 41,
   LLVMAddrSpaceCast  = 60,

llvm/include/llvm/Analysis/TargetTransformInfoImpl.h

@@ -732,6 +732,13 @@ class TargetTransformInfoImplBase {
         return 0;
       break;
     }
+    case Instruction::PtrToAddr: {
+      unsigned DstSize = Dst->getScalarSizeInBits();
+      if (DL.isLegalInteger(DstSize) &&
+          DstSize >= DL.getPointerAddressSizeInBits(Src))
+        return 0;
+      break;
+    }
     case Instruction::PtrToInt: {
       unsigned DstSize = Dst->getScalarSizeInBits();
       if (DL.isLegalInteger(DstSize) &&
@@ -1441,6 +1448,7 @@ class TargetTransformInfoImplCRTPBase : public TargetTransformInfoImplBase {
                                                Op2Info, Operands, I);
     }
     case Instruction::IntToPtr:
+    case Instruction::PtrToAddr:
     case Instruction::PtrToInt:
     case Instruction::SIToFP:
     case Instruction::UIToFP:

llvm/include/llvm/AsmParser/LLToken.h

@@ -318,6 +318,7 @@ enum Kind {
   kw_fptoui,
   kw_fptosi,
   kw_inttoptr,
+  kw_ptrtoaddr,
   kw_ptrtoint,
   kw_bitcast,
   kw_addrspacecast,

llvm/include/llvm/Bitcode/LLVMBitCodes.h

@@ -456,7 +456,8 @@ enum CastOpcodes {
   CAST_PTRTOINT = 9,
   CAST_INTTOPTR = 10,
   CAST_BITCAST = 11,
-  CAST_ADDRSPACECAST = 12
+  CAST_ADDRSPACECAST = 12,
+  CAST_PTRTOADDR = 13,
 };
 
 /// UnaryOpcodes - These are values used in the bitcode files to encode which

llvm/include/llvm/CodeGen/GlobalISel/IRTranslator.h

@@ -486,6 +486,9 @@ class IRTranslator : public MachineFunctionPass {
   bool translatePtrToInt(const User &U, MachineIRBuilder &MIRBuilder) {
     return translateCast(TargetOpcode::G_PTRTOINT, U, MIRBuilder);
   }
+  bool translatePtrToAddr(const User &U, MachineIRBuilder &MIRBuilder) {
+    return translatePtrToInt(U, MIRBuilder);
+  }
   bool translateTrunc(const User &U, MachineIRBuilder &MIRBuilder) {
     return translateCast(TargetOpcode::G_TRUNC, U, MIRBuilder);
   }

llvm/include/llvm/IR/DataLayout.h

@@ -324,16 +324,38 @@ class DataLayout {
   /// the backends/clients are updated.
   Align getPointerPrefAlignment(unsigned AS = 0) const;
 
-  /// Layout pointer size in bytes, rounded up to a whole
-  /// number of bytes.
+  /// The pointer representation size in bytes, rounded up to a whole number of
+  /// bytes. The difference between this function and getPointerAddressSize() is
+  /// this one returns the size of the entire pointer type (this includes
+  /// metadata bits for fat pointers) and the latter only returns the number of
+  /// address bits.
+  /// \sa DataLayout::getPointerAddressSizeInBits
   /// FIXME: The defaults need to be removed once all of
   /// the backends/clients are updated.
   unsigned getPointerSize(unsigned AS = 0) const;
 
-  // Index size in bytes used for address calculation,
-  /// rounded up to a whole number of bytes.
+  /// The index size in bytes used for address calculation, rounded up to a
+  /// whole number of bytes. This not only defines the size used in
+  /// getelementptr operations, but also the size of addresses in this \p AS.
+  /// For example, a 64-bit CHERI-enabled target has 128-bit pointers of which
+  /// only 64 are used to represent the address and the remaining ones are used
+  /// for metadata such as bounds and access permissions. In this case
+  /// getPointerSize() returns 16, but getIndexSize() returns 8.
+  /// To help with code understanding, the alias getPointerAddressSize() can be
+  /// used instead of getIndexSize() to clarify that an address width is needed.
   unsigned getIndexSize(unsigned AS) const;
 
+  /// The integral size of a pointer in a given address space in bytes, which
+  /// is defined to be the same as getIndexSize(). This exists as a separate
+  /// function to make it clearer when reading code that the size of an address
+  /// is being requested. While targets exist where index size and the
+  /// underlying address width are not identical (e.g. AMDGPU fat pointers with
+  /// 48-bit addresses and 32-bit offsets indexing), there is currently no need
+  /// to differentiate these properties in LLVM.
+  /// \sa DataLayout::getIndexSize
+  /// \sa DataLayout::getPointerAddressSizeInBits
+  unsigned getPointerAddressSize(unsigned AS) const { return getIndexSize(AS); }
+
   /// Return the address spaces containing non-integral pointers.  Pointers in
   /// this address space don't have a well-defined bitwise representation.
   SmallVector<unsigned, 8> getNonIntegralAddressSpaces() const {
@@ -358,29 +380,53 @@ class DataLayout {
     return PTy && isNonIntegralPointerType(PTy);
   }
 
-  /// Layout pointer size, in bits
+  /// The size in bits of the pointer representation in a given address space.
+  /// This is not necessarily the same as the integer address of a pointer (e.g.
+  /// for fat pointers).
+  /// \sa DataLayout::getPointerAddressSizeInBits()
   /// FIXME: The defaults need to be removed once all of
   /// the backends/clients are updated.
   unsigned getPointerSizeInBits(unsigned AS = 0) const {
     return getPointerSpec(AS).BitWidth;
   }
 
-  /// Size in bits of index used for address calculation in getelementptr.
+  /// The size in bits of indices used for address calculation in getelementptr
+  /// and for addresses in the given AS. See getIndexSize() for more
+  /// information.
+  /// \sa DataLayout::getPointerAddressSizeInBits()
   unsigned getIndexSizeInBits(unsigned AS) const {
     return getPointerSpec(AS).IndexBitWidth;
   }
 
-  /// Layout pointer size, in bits, based on the type.  If this function is
+  /// The size in bits of an address in for the given AS. This is defined to
+  /// return the same value as getIndexSizeInBits() since there is currently no
+  /// target that requires these two properties to have different values. See
+  /// getIndexSize() for more information.
+  /// \sa DataLayout::getIndexSizeInBits()
+  unsigned getPointerAddressSizeInBits(unsigned AS) const {
+    return getIndexSizeInBits(AS);
+  }
+
+  /// The pointer representation size in bits for this type. If this function is
   /// called with a pointer type, then the type size of the pointer is returned.
   /// If this function is called with a vector of pointers, then the type size
   /// of the pointer is returned.  This should only be called with a pointer or
   /// vector of pointers.
   unsigned getPointerTypeSizeInBits(Type *) const;
 
-  /// Layout size of the index used in GEP calculation.
+  /// The size in bits of the index used in GEP calculation for this type.
   /// The function should be called with pointer or vector of pointers type.
+  /// This is defined to return the same value as getPointerAddressSizeInBits(),
+  /// but separate functions exist for code clarity.
   unsigned getIndexTypeSizeInBits(Type *Ty) const;
 
+  /// The size in bits of an address for this type.
+  /// This is defined to return the same value as getIndexTypeSizeInBits(),
+  /// but separate functions exist for code clarity.
+  unsigned getPointerAddressSizeInBits(Type *Ty) const {
+    return getIndexTypeSizeInBits(Ty);
+  }
+
   unsigned getPointerTypeSize(Type *Ty) const {
     return getPointerTypeSizeInBits(Ty) / 8;
   }

llvm/include/llvm/IR/InstVisitor.h

@@ -183,6 +183,7 @@ class InstVisitor {
   RetTy visitUIToFPInst(UIToFPInst &I)            { DELEGATE(CastInst);}
   RetTy visitSIToFPInst(SIToFPInst &I)            { DELEGATE(CastInst);}
   RetTy visitPtrToIntInst(PtrToIntInst &I)        { DELEGATE(CastInst);}
+  RetTy visitPtrToAddrInst(PtrToAddrInst &I)      { DELEGATE(PtrToIntInst);}
   RetTy visitIntToPtrInst(IntToPtrInst &I)        { DELEGATE(CastInst);}
   RetTy visitBitCastInst(BitCastInst &I)          { DELEGATE(CastInst);}
   RetTy visitAddrSpaceCastInst(AddrSpaceCastInst &I) { DELEGATE(CastInst);}

llvm/include/llvm/IR/Instruction.def

@@ -190,35 +190,36 @@ HANDLE_CAST_INST(43, UIToFP  , UIToFPInst  )  // UInt -> floating point
 HANDLE_CAST_INST(44, SIToFP  , SIToFPInst  )  // SInt -> floating point
 HANDLE_CAST_INST(45, FPTrunc , FPTruncInst )  // Truncate floating point
 HANDLE_CAST_INST(46, FPExt   , FPExtInst   )  // Extend floating point
-HANDLE_CAST_INST(47, PtrToInt, PtrToIntInst)  // Pointer -> Integer
-HANDLE_CAST_INST(48, IntToPtr, IntToPtrInst)  // Integer -> Pointer
-HANDLE_CAST_INST(49, BitCast , BitCastInst )  // Type cast
-HANDLE_CAST_INST(50, AddrSpaceCast, AddrSpaceCastInst)  // addrspace cast
-  LAST_CAST_INST(50)
+HANDLE_CAST_INST(47, PtrToInt, PtrToIntInst)  // Pointer -> Integer (bitcast)
+HANDLE_CAST_INST(48, PtrToAddr, PtrToAddrInst) // Pointer -> Address
+HANDLE_CAST_INST(49, IntToPtr, IntToPtrInst)  // Integer -> Pointer
+HANDLE_CAST_INST(50, BitCast , BitCastInst )  // Type cast
+HANDLE_CAST_INST(51, AddrSpaceCast, AddrSpaceCastInst)  // addrspace cast
+  LAST_CAST_INST(51)
 
- FIRST_FUNCLETPAD_INST(51)
-HANDLE_FUNCLETPAD_INST(51, CleanupPad, CleanupPadInst)
-HANDLE_FUNCLETPAD_INST(52, CatchPad  , CatchPadInst)
-  LAST_FUNCLETPAD_INST(52)
+ FIRST_FUNCLETPAD_INST(52)
+HANDLE_FUNCLETPAD_INST(52, CleanupPad, CleanupPadInst)
+HANDLE_FUNCLETPAD_INST(53, CatchPad  , CatchPadInst)
+  LAST_FUNCLETPAD_INST(53)
 
 // Other operators...
- FIRST_OTHER_INST(53)
-HANDLE_OTHER_INST(53, ICmp   , ICmpInst   )  // Integer comparison instruction
-HANDLE_OTHER_INST(54, FCmp   , FCmpInst   )  // Floating point comparison instr.
-HANDLE_OTHER_INST(55, PHI    , PHINode    )  // PHI node instruction
-HANDLE_OTHER_INST(56, Call   , CallInst   )  // Call a function
-HANDLE_OTHER_INST(57, Select , SelectInst )  // select instruction
-HANDLE_USER_INST (58, UserOp1, Instruction)  // May be used internally in a pass
-HANDLE_USER_INST (59, UserOp2, Instruction)  // Internal to passes only
-HANDLE_OTHER_INST(60, VAArg  , VAArgInst  )  // vaarg instruction
-HANDLE_OTHER_INST(61, ExtractElement, ExtractElementInst)// extract from vector
-HANDLE_OTHER_INST(62, InsertElement, InsertElementInst)  // insert into vector
-HANDLE_OTHER_INST(63, ShuffleVector, ShuffleVectorInst)  // shuffle two vectors.
-HANDLE_OTHER_INST(64, ExtractValue, ExtractValueInst)// extract from aggregate
-HANDLE_OTHER_INST(65, InsertValue, InsertValueInst)  // insert into aggregate
-HANDLE_OTHER_INST(66, LandingPad, LandingPadInst)  // Landing pad instruction.
-HANDLE_OTHER_INST(67, Freeze, FreezeInst) // Freeze instruction.
-  LAST_OTHER_INST(67)
+ FIRST_OTHER_INST(54)
+HANDLE_OTHER_INST(54, ICmp   , ICmpInst   )  // Integer comparison instruction
+HANDLE_OTHER_INST(55, FCmp   , FCmpInst   )  // Floating point comparison instr.
+HANDLE_OTHER_INST(56, PHI    , PHINode    )  // PHI node instruction
+HANDLE_OTHER_INST(57, Call   , CallInst   )  // Call a function
+HANDLE_OTHER_INST(58, Select , SelectInst )  // select instruction
+HANDLE_USER_INST (59, UserOp1, Instruction)  // May be used internally in a pass
+HANDLE_USER_INST (60, UserOp2, Instruction)  // Internal to passes only
+HANDLE_OTHER_INST(61, VAArg  , VAArgInst  )  // vaarg instruction
+HANDLE_OTHER_INST(62, ExtractElement, ExtractElementInst)// extract from vector
+HANDLE_OTHER_INST(63, InsertElement, InsertElementInst)  // insert into vector
+HANDLE_OTHER_INST(64, ShuffleVector, ShuffleVectorInst)  // shuffle two vectors.
+HANDLE_OTHER_INST(65, ExtractValue, ExtractValueInst)// extract from aggregate
+HANDLE_OTHER_INST(66, InsertValue, InsertValueInst)  // insert into aggregate
+HANDLE_OTHER_INST(67, LandingPad, LandingPadInst)  // Landing pad instruction.
+HANDLE_OTHER_INST(68, Freeze, FreezeInst) // Freeze instruction.
+  LAST_OTHER_INST(68)
 
 #undef  FIRST_TERM_INST
 #undef HANDLE_TERM_INST