On Feb 13, 2007, at 9:52 PM, Chris Lattner wrote:
> Generalize TargetData strings, to support more interesting forms of
> data.
> Patch by Scott Michel.
Scott,
> Index: llvm/include/llvm/Target/TargetData.h
> diff -u llvm/include/llvm/Target/TargetData.h:1.53 llvm/include/
> llvm/Target/TargetData.h:1.54
> --- llvm/include/llvm/Target/TargetData.h:1.53 Sat Feb 10 14:37:40
> 2007
> +++ llvm/include/llvm/Target/TargetData.h Tue Feb 13 23:52:16 2007
> @@ -22,6 +22,8 @@
>
> #include "llvm/Pass.h"
> #include "llvm/Support/DataTypes.h"
> +#include "llvm/ADT/SmallVector.h"
> +#include <string>
>
> namespace llvm {
>
> @@ -31,45 +33,96 @@
> class StructLayout;
> class GlobalVariable;
>
> -class TargetData : public ImmutablePass {
> - bool LittleEndian; // Defaults to false
> +/// Enum used to categorize the alignment types stored by
> TargetAlignElem
> +enum AlignTypeEnum {
> + INTEGER_ALIGN = 'i', ///< Integer type alignment
> + PACKED_ALIGN = 'v', ///< Vector type alignment
> + FLOAT_ALIGN = 'f', ///< Floating point type
> alignment
> + AGGREGATE_ALIGN = 'a' ///< Aggregate alignment
> +};
> +/// Target alignment element.
> +///
> +/// Stores the alignment data associated with a given alignment
> type (pointer,
> +/// integer, packed/vector, float) and type bit width.
> +///
> +/// @note The unusual order of elements in the structure attempts
> to reduce
> +/// padding and make the structure slightly more cache friendly.
> +struct TargetAlignElem {
> + unsigned char AlignType; //< Alignment type
> (AlignTypeEnum)
This should be:
AlignTypeEnum AlignType : 8;
> + unsigned char ABIAlign; //< ABI alignment for this
> type/bitw
> + unsigned char PrefAlign; //< Pref. alignment for this
> type/bitw
> + short TypeBitWidth; //< Type bit width
> +
> + /// Initializer
> + static TargetAlignElem get(AlignTypeEnum align_type, unsigned
> char abi_align,
> + unsigned char pref_align, short
> bit_width);
> + /// Less-than predicate
> + bool operator<(const TargetAlignElem &rhs) const;
> + /// Equality predicate
> + bool operator==(const TargetAlignElem &rhs) const;
> + /// output stream operator
> + std::ostream &dump(std::ostream &os) const;
> +};
>
> - // ABI alignments
> - unsigned char BoolABIAlignment; // Defaults to 1 byte
> - unsigned char ByteABIAlignment; // Defaults to 1 byte
> - unsigned char ShortABIAlignment; // Defaults to 2 bytes
> - unsigned char IntABIAlignment; // Defaults to 4 bytes
> - unsigned char LongABIAlignment; // Defaults to 8 bytes
> - unsigned char FloatABIAlignment; // Defaults to 4 bytes
> - unsigned char DoubleABIAlignment; // Defaults to 8 bytes
> - unsigned char PointerMemSize; // Defaults to 8 bytes
> - unsigned char PointerABIAlignment; // Defaults to 8 bytes
> -
> - // Preferred stack/global type alignments
> - unsigned char BoolPrefAlignment; // Defaults to BoolABIAlignment
> - unsigned char BytePrefAlignment; // Defaults to ByteABIAlignment
> - unsigned char ShortPrefAlignment; // Defaults to
> ShortABIAlignment
> - unsigned char IntPrefAlignment; // Defaults to IntABIAlignment
> - unsigned char LongPrefAlignment; // Defaults to LongABIAlignment
> - unsigned char FloatPrefAlignment; // Defaults to
> FloatABIAlignment
> - unsigned char DoublePrefAlignment; // Defaults to
> DoubleABIAlignment
> - unsigned char PointerPrefAlignment; // Defaults to
> PointerABIAlignment
> - unsigned char AggMinPrefAlignment; // Defaults to 0 bytes
> +//! TargetAlignElem output stream inserter
> +/*!
> + @sa TargetAlignElem::dump()
> + */
> +std::ostream &operator<<(std::ostream &os, const TargetAlignElem
> &elem);
> +
> +class TargetData : public ImmutablePass {
> +private:
> + bool LittleEndian; ///< Defaults to false
> + unsigned char PointerMemSize; ///< Pointer size in bytes
> + unsigned char PointerABIAlign; ///< Pointer ABI alignment
> + unsigned char PointerPrefAlign; ///< Pointer preferred
> global alignment
'Pointer preferred global alignment' ?
global what?
> +
> + //! Where the primitive type alignment data is stored.
> + /*!
> + @sa init().
> + @note Could support multiple size pointer alignments, e.g., 32-
> bit pointers
> + vs. 64-bit pointers by extending TargetAlignment, but for now,
> we don't.
> + */
> + SmallVector<TargetAlignElem, 16> Alignments;
> + //! Alignment iterator shorthand
> + typedef SmallVector<TargetAlignElem, 16>::iterator align_iterator;
I don't think the elements in 'Alignments' should ever be mutable
through iterators. I'd suggest using:
typedef SmallVector<TargetAlignElem, 16>::const_iterator
align_iterator;
> + //! Invalid alignment.
> + /*!
> + This member is a signal that a requested alignment type and
> bit width were
> + not found in the SmallVector.
> + */
> + static const TargetAlignElem InvalidAlignmentElem;
> +
> + //! Set/initialize target alignments
> + void setAlignment(AlignTypeEnum align_type, unsigned char
> abi_align,
> + unsigned char pref_align, short bit_width);
> + //! Get TargetAlignElem from alignment type and bit width
> + const TargetAlignElem &getAlignment(AlignTypeEnum, short) const;
Please give these arguments names to indicate what they are.
> + //! Internal helper method that returns requested alignment for
> type.
> + unsigned char getAlignment(const Type *Ty, bool abi_or_pref) const;
abi_or_pref doesn't indicate what 'true' means. Should this be an
enum with two values?
> - /// Parse a target data layout string and initialize TargetData
> members.
> - ///
> - /// Parse a target data layout string, initializing the various
> TargetData
> - /// members along the way. A TargetData specification string
> looks like
> - /// "E-p:64:64-d:64-f:32-l:64-i:32-s:16-b:8-B:8" and specifies the
> - /// target's endianess, the ABI alignments of various data types
> and
> - /// the size of pointers.
The format of this string should be described somewhere. Perhaps in
LangRef.html?
-Chris
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