[llvm] r197740 - Change getStringRepresentation to skip defaults.

[Sean Silva]

On Thu, Dec 19, 2013 at 4:03 PM, Rafael Espindola <
rafael.espindola at gmail.com> wrote:

> Author: rafael
> Date: Thu Dec 19 17:03:03 2013
> New Revision: 197740
>
> URL: http://llvm.org/viewvc/llvm-project?rev=197740&view=rev
> Log:
> Change getStringRepresentation to skip defaults.
>
> I have a pending change for clang to use getStringRepresentation to check
> that its DataLayout is in sync with llvm's.
>

What is the reason that we don't just have a single point of truth for
this? Phrased another way: why is it necessary to maintain these DataLayout
strings independently, once in clang and once in LLVM core?

-- Sean Silva



>
> getStringRepresentation is not called from llvm itself, so far it is mostly
> a debugging aid, so the shorter strings are an independent improvement.
>
> Modified:
>     llvm/trunk/lib/IR/DataLayout.cpp
>
> Modified: llvm/trunk/lib/IR/DataLayout.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/DataLayout.cpp?rev=197740&r1=197739&r2=197740&view=diff
>
> ==============================================================================
> --- llvm/trunk/lib/IR/DataLayout.cpp (original)
> +++ llvm/trunk/lib/IR/DataLayout.cpp Thu Dec 19 17:03:03 2013
> @@ -18,6 +18,7 @@
>
>  #include "llvm/IR/DataLayout.h"
>  #include "llvm/ADT/DenseMap.h"
> +#include "llvm/ADT/STLExtras.h"
>  #include "llvm/IR/Constants.h"
>  #include "llvm/IR/DerivedTypes.h"
>  #include "llvm/IR/Module.h"
> @@ -151,6 +152,21 @@ DataLayout::InvalidPointerElem = { 0U, 0
>  //                       DataLayout Class Implementation
>
>  //===----------------------------------------------------------------------===//
>
> +static LayoutAlignElem DefaultAlignments[] = {
> +  { INTEGER_ALIGN, 1, 1, 1 },    // i1
> +  { INTEGER_ALIGN, 8, 1, 1 },    // i8
> +  { INTEGER_ALIGN, 16, 2, 2 },   // i16
> +  { INTEGER_ALIGN, 32, 4, 4 },   // i32
> +  { INTEGER_ALIGN, 64, 4, 8 },   // i64
> +  { FLOAT_ALIGN, 16, 2, 2 },     // half
> +  { FLOAT_ALIGN, 32, 4, 4 },     // float
> +  { FLOAT_ALIGN, 64, 8, 8 },     // double
> +  { FLOAT_ALIGN, 128, 16, 16 },  // ppcf128, quad, ...
> +  { VECTOR_ALIGN, 64, 8, 8 },    // v2i32, v1i64, ...
> +  { VECTOR_ALIGN, 128, 16, 16 }, // v16i8, v8i16, v4i32, ...
> +  { AGGREGATE_ALIGN, 0, 0, 8 }   // struct
> +};
> +
>  void DataLayout::init(StringRef Desc) {
>    initializeDataLayoutPass(*PassRegistry::getPassRegistry());
>
> @@ -159,18 +175,11 @@ void DataLayout::init(StringRef Desc) {
>    StackNaturalAlign = 0;
>
>    // Default alignments
> -  setAlignment(INTEGER_ALIGN,   1,  1, 1);   // i1
> -  setAlignment(INTEGER_ALIGN,   1,  1, 8);   // i8
> -  setAlignment(INTEGER_ALIGN,   2,  2, 16);  // i16
> -  setAlignment(INTEGER_ALIGN,   4,  4, 32);  // i32
> -  setAlignment(INTEGER_ALIGN,   4,  8, 64);  // i64
> -  setAlignment(FLOAT_ALIGN,     2,  2, 16);  // half
> -  setAlignment(FLOAT_ALIGN,     4,  4, 32);  // float
> -  setAlignment(FLOAT_ALIGN,     8,  8, 64);  // double
> -  setAlignment(FLOAT_ALIGN,    16, 16, 128); // ppcf128, quad, ...
> -  setAlignment(VECTOR_ALIGN,    8,  8, 64);  // v2i32, v1i64, ...
> -  setAlignment(VECTOR_ALIGN,   16, 16, 128); // v16i8, v8i16, v4i32, ...
> -  setAlignment(AGGREGATE_ALIGN, 0,  8,  0);  // struct
> +  for (int I = 0, N = array_lengthof(DefaultAlignments); I < N; ++I) {
> +    LayoutAlignElem &E = DefaultAlignments[I];
> +    setAlignment((AlignTypeEnum)E.AlignType, E.ABIAlign, E.PrefAlign,
> +                 E.TypeBitWidth);
> +  }
>    setPointerAlignment(0, 8, 8, 8);
>
>    parseSpecifier(Desc);
> @@ -483,19 +492,34 @@ std::string DataLayout::getStringReprese
>    for (SmallVectorImpl<unsigned>::iterator asb = addrSpaces.begin(),
>        ase = addrSpaces.end(); asb != ase; ++asb) {
>      const PointerAlignElem &PI = Pointers.find(*asb)->second;
> +
> +    // Skip default.
> +    if (PI.AddressSpace == 0 && PI.ABIAlign == 8 && PI.PrefAlign == 8 &&
> +        PI.TypeByteWidth == 8)
> +      continue;
> +
>      OS << "-p";
>      if (PI.AddressSpace) {
>        OS << PI.AddressSpace;
>      }
> -     OS << ":" << PI.TypeByteWidth*8 << ':' << PI.ABIAlign*8
> -        << ':' << PI.PrefAlign*8;
> +    OS << ":" << PI.TypeByteWidth*8 << ':' << PI.ABIAlign*8;
> +    if (PI.PrefAlign != PI.ABIAlign)
> +      OS << ':' << PI.PrefAlign*8;
>    }
> -  OS << "-S" << StackNaturalAlign*8;
>
> +  LayoutAlignElem *DefaultStart = DefaultAlignments;
> +  LayoutAlignElem *DefaultEnd =
> +      DefaultStart + array_lengthof(DefaultAlignments);
>    for (unsigned i = 0, e = Alignments.size(); i != e; ++i) {
>      const LayoutAlignElem &AI = Alignments[i];
> -    OS << '-' << (char)AI.AlignType << AI.TypeBitWidth << ':'
> -       << AI.ABIAlign*8 << ':' << AI.PrefAlign*8;
> +    if (std::find(DefaultStart, DefaultEnd, AI) != DefaultEnd)
> +      continue;
> +    OS << '-' << (char)AI.AlignType;
> +    if (AI.TypeBitWidth)
> +      OS << AI.TypeBitWidth;
> +    OS << ':' << AI.ABIAlign*8;
> +    if (AI.ABIAlign != AI.PrefAlign)
> +      OS << ':' << AI.PrefAlign*8;
>    }
>
>    if (!LegalIntWidths.empty()) {
> @@ -504,6 +528,10 @@ std::string DataLayout::getStringReprese
>      for (unsigned i = 1, e = LegalIntWidths.size(); i != e; ++i)
>        OS << ':' << (unsigned)LegalIntWidths[i];
>    }
> +
> +  if (StackNaturalAlign)
> +    OS << "-S" << StackNaturalAlign*8;
> +
>    return OS.str();
>  }
>
>
>
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