DWARF parsing and writing support using LLVM (#2520)

This imports LLVM code for DWARF handling. That code has the
Apache 2 license like us. It's also the same code used to
emit DWARF in the common toolchain, so it seems like a safe choice.

This adds two passes: --dwarfdump which runs the same code LLVM
runs for llvm-dwarfdump. This shows we can parse it ok, and will
be useful for debugging. And --dwarfupdate writes out the DWARF
sections (unchanged from what we read, so it just roundtrips - for
updating we need #2515).

This puts LLVM in thirdparty which is added here.

All the LLVM code is behind USE_LLVM_DWARF, which is on
by default, but off in JS for now, as it increases code size by 20%.

This current approach imports the LLVM files directly. This is not
how they are intended to be used, so it required a bunch of
local changes - more than I expected actually, for the platform-specific
stuff. For now this seems to work, so it may be good enough, but
in the long term we may want to switch to linking against libllvm.
A downside to doing that is that binaryen users would need to
have an LLVM build, and even in the waterfall builds we'd have a
problem - while we ship LLVM there anyhow, we constantly update
it, which means that binaryen would need to be on latest llvm all
the time too (which otherwise, given DWARF is quite stable, we
might not need to constantly update).

An even larger issue is that as I did this work I learned about how
DWARF works in LLVM, and while the reading code is easy to
reuse, the writing code is trickier. The main code path is heavily
integrated with the MC layer, which we don't have - we might want
to create a "fake MC layer" for that, but it sounds hard. Instead,
there is the YAML path which is used mostly for testing, and which
can convert DWARF to and from YAML and from binary. Using
the non-YAML parts there, we can convert binary DWARF to
the YAML layer's nice Info data, then convert that to binary. This
works, however, this is not the path LLVM uses normally, and it
supports only some basic DWARF sections - I had to add ranges
support, in fact. So if we need more complex things, we may end
up needing to use the MC layer approach, or consider some other
DWARF library. However, hopefully that should not affect the core
binaryen code which just calls a library for DWARF stuff.

Helps #2400

1 files changed, 306 insertions, 0 deletions

diff --git a/third_party/llvm-project/include/llvm/Support/ConvertUTF.h b/third_party/llvm-project/include/llvm/Support/ConvertUTF.h
new file mode 100644
index 000000000..1add18533
--- /dev/null
+++ b/third_party/llvm-project/include/llvm/Support/ConvertUTF.h
@@ -0,0 +1,306 @@
+/*===--- ConvertUTF.h - Universal Character Names conversions ---------------===
+ *
+ * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+ * See https://llvm.org/LICENSE.txt for license information.
+ * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+ *
+ *==------------------------------------------------------------------------==*/
+/*
+ * Copyright 2001-2004 Unicode, Inc.
+ *
+ * Disclaimer
+ *
+ * This source code is provided as is by Unicode, Inc. No claims are
+ * made as to fitness for any particular purpose. No warranties of any
+ * kind are expressed or implied. The recipient agrees to determine
+ * applicability of information provided. If this file has been
+ * purchased on magnetic or optical media from Unicode, Inc., the
+ * sole remedy for any claim will be exchange of defective media
+ * within 90 days of receipt.
+ *
+ * Limitations on Rights to Redistribute This Code
+ *
+ * Unicode, Inc. hereby grants the right to freely use the information
+ * supplied in this file in the creation of products supporting the
+ * Unicode Standard, and to make copies of this file in any form
+ * for internal or external distribution as long as this notice
+ * remains attached.
+ */
+
+/* ---------------------------------------------------------------------
+
+    Conversions between UTF32, UTF-16, and UTF-8.  Header file.
+
+    Several funtions are included here, forming a complete set of
+    conversions between the three formats.  UTF-7 is not included
+    here, but is handled in a separate source file.
+
+    Each of these routines takes pointers to input buffers and output
+    buffers.  The input buffers are const.
+
+    Each routine converts the text between *sourceStart and sourceEnd,
+    putting the result into the buffer between *targetStart and
+    targetEnd. Note: the end pointers are *after* the last item: e.g.
+    *(sourceEnd - 1) is the last item.
+
+    The return result indicates whether the conversion was successful,
+    and if not, whether the problem was in the source or target buffers.
+    (Only the first encountered problem is indicated.)
+
+    After the conversion, *sourceStart and *targetStart are both
+    updated to point to the end of last text successfully converted in
+    the respective buffers.
+
+    Input parameters:
+        sourceStart - pointer to a pointer to the source buffer.
+                The contents of this are modified on return so that
+                it points at the next thing to be converted.
+        targetStart - similarly, pointer to pointer to the target buffer.
+        sourceEnd, targetEnd - respectively pointers to the ends of the
+                two buffers, for overflow checking only.
+
+    These conversion functions take a ConversionFlags argument. When this
+    flag is set to strict, both irregular sequences and isolated surrogates
+    will cause an error.  When the flag is set to lenient, both irregular
+    sequences and isolated surrogates are converted.
+
+    Whether the flag is strict or lenient, all illegal sequences will cause
+    an error return. This includes sequences such as: <F4 90 80 80>, <C0 80>,
+    or <A0> in UTF-8, and values above 0x10FFFF in UTF-32. Conformant code
+    must check for illegal sequences.
+
+    When the flag is set to lenient, characters over 0x10FFFF are converted
+    to the replacement character; otherwise (when the flag is set to strict)
+    they constitute an error.
+
+    Output parameters:
+        The value "sourceIllegal" is returned from some routines if the input
+        sequence is malformed.  When "sourceIllegal" is returned, the source
+        value will point to the illegal value that caused the problem. E.g.,
+        in UTF-8 when a sequence is malformed, it points to the start of the
+        malformed sequence.
+
+    Author: Mark E. Davis, 1994.
+    Rev History: Rick McGowan, fixes & updates May 2001.
+         Fixes & updates, Sept 2001.
+
+------------------------------------------------------------------------ */
+
+#ifndef LLVM_SUPPORT_CONVERTUTF_H
+#define LLVM_SUPPORT_CONVERTUTF_H
+
+#include <cstddef>
+#include <string>
+#include <system_error>
+
+// Wrap everything in namespace llvm so that programs can link with llvm and
+// their own version of the unicode libraries.
+
+namespace llvm {
+
+/* ---------------------------------------------------------------------
+    The following 4 definitions are compiler-specific.
+    The C standard does not guarantee that wchar_t has at least
+    16 bits, so wchar_t is no less portable than unsigned short!
+    All should be unsigned values to avoid sign extension during
+    bit mask & shift operations.
+------------------------------------------------------------------------ */
+
+typedef unsigned int    UTF32;  /* at least 32 bits */
+typedef unsigned short  UTF16;  /* at least 16 bits */
+typedef unsigned char   UTF8;   /* typically 8 bits */
+typedef unsigned char   Boolean; /* 0 or 1 */
+
+/* Some fundamental constants */
+#define UNI_REPLACEMENT_CHAR (UTF32)0x0000FFFD
+#define UNI_MAX_BMP (UTF32)0x0000FFFF
+#define UNI_MAX_UTF16 (UTF32)0x0010FFFF
+#define UNI_MAX_UTF32 (UTF32)0x7FFFFFFF
+#define UNI_MAX_LEGAL_UTF32 (UTF32)0x0010FFFF
+
+#define UNI_MAX_UTF8_BYTES_PER_CODE_POINT 4
+
+#define UNI_UTF16_BYTE_ORDER_MARK_NATIVE  0xFEFF
+#define UNI_UTF16_BYTE_ORDER_MARK_SWAPPED 0xFFFE
+
+typedef enum {
+  conversionOK,           /* conversion successful */
+  sourceExhausted,        /* partial character in source, but hit end */
+  targetExhausted,        /* insuff. room in target for conversion */
+  sourceIllegal           /* source sequence is illegal/malformed */
+} ConversionResult;
+
+typedef enum {
+  strictConversion = 0,
+  lenientConversion
+} ConversionFlags;
+
+ConversionResult ConvertUTF8toUTF16 (
+  const UTF8** sourceStart, const UTF8* sourceEnd,
+  UTF16** targetStart, UTF16* targetEnd, ConversionFlags flags);
+
+/**
+ * Convert a partial UTF8 sequence to UTF32.  If the sequence ends in an
+ * incomplete code unit sequence, returns \c sourceExhausted.
+ */
+ConversionResult ConvertUTF8toUTF32Partial(
+  const UTF8** sourceStart, const UTF8* sourceEnd,
+  UTF32** targetStart, UTF32* targetEnd, ConversionFlags flags);
+
+/**
+ * Convert a partial UTF8 sequence to UTF32.  If the sequence ends in an
+ * incomplete code unit sequence, returns \c sourceIllegal.
+ */
+ConversionResult ConvertUTF8toUTF32(
+  const UTF8** sourceStart, const UTF8* sourceEnd,
+  UTF32** targetStart, UTF32* targetEnd, ConversionFlags flags);
+
+ConversionResult ConvertUTF16toUTF8 (
+  const UTF16** sourceStart, const UTF16* sourceEnd,
+  UTF8** targetStart, UTF8* targetEnd, ConversionFlags flags);
+
+ConversionResult ConvertUTF32toUTF8 (
+  const UTF32** sourceStart, const UTF32* sourceEnd,
+  UTF8** targetStart, UTF8* targetEnd, ConversionFlags flags);
+
+ConversionResult ConvertUTF16toUTF32 (
+  const UTF16** sourceStart, const UTF16* sourceEnd,
+  UTF32** targetStart, UTF32* targetEnd, ConversionFlags flags);
+
+ConversionResult ConvertUTF32toUTF16 (
+  const UTF32** sourceStart, const UTF32* sourceEnd,
+  UTF16** targetStart, UTF16* targetEnd, ConversionFlags flags);
+
+Boolean isLegalUTF8Sequence(const UTF8 *source, const UTF8 *sourceEnd);
+
+Boolean isLegalUTF8String(const UTF8 **source, const UTF8 *sourceEnd);
+
+unsigned getNumBytesForUTF8(UTF8 firstByte);
+
+/*************************************************************************/
+/* Below are LLVM-specific wrappers of the functions above. */
+
+template <typename T> class ArrayRef;
+template <typename T> class SmallVectorImpl;
+class StringRef;
+
+/**
+ * Convert an UTF8 StringRef to UTF8, UTF16, or UTF32 depending on
+ * WideCharWidth. The converted data is written to ResultPtr, which needs to
+ * point to at least WideCharWidth * (Source.Size() + 1) bytes. On success,
+ * ResultPtr will point one after the end of the copied string. On failure,
+ * ResultPtr will not be changed, and ErrorPtr will be set to the location of
+ * the first character which could not be converted.
+ * \return true on success.
+ */
+bool ConvertUTF8toWide(unsigned WideCharWidth, llvm::StringRef Source,
+                       char *&ResultPtr, const UTF8 *&ErrorPtr);
+
+/**
+* Converts a UTF-8 StringRef to a std::wstring.
+* \return true on success.
+*/
+bool ConvertUTF8toWide(llvm::StringRef Source, std::wstring &Result);
+
+/**
+* Converts a UTF-8 C-string to a std::wstring.
+* \return true on success.
+*/
+bool ConvertUTF8toWide(const char *Source, std::wstring &Result);
+
+/**
+* Converts a std::wstring to a UTF-8 encoded std::string.
+* \return true on success.
+*/
+bool convertWideToUTF8(const std::wstring &Source, std::string &Result);
+
+
+/**
+ * Convert an Unicode code point to UTF8 sequence.
+ *
+ * \param Source a Unicode code point.
+ * \param [in,out] ResultPtr pointer to the output buffer, needs to be at least
+ * \c UNI_MAX_UTF8_BYTES_PER_CODE_POINT bytes.  On success \c ResultPtr is
+ * updated one past end of the converted sequence.
+ *
+ * \returns true on success.
+ */
+bool ConvertCodePointToUTF8(unsigned Source, char *&ResultPtr);
+
+/**
+ * Convert the first UTF8 sequence in the given source buffer to a UTF32
+ * code point.
+ *
+ * \param [in,out] source A pointer to the source buffer. If the conversion
+ * succeeds, this pointer will be updated to point to the byte just past the
+ * end of the converted sequence.
+ * \param sourceEnd A pointer just past the end of the source buffer.
+ * \param [out] target The converted code
+ * \param flags Whether the conversion is strict or lenient.
+ *
+ * \returns conversionOK on success
+ *
+ * \sa ConvertUTF8toUTF32
+ */
+inline ConversionResult convertUTF8Sequence(const UTF8 **source,
+                                            const UTF8 *sourceEnd,
+                                            UTF32 *target,
+                                            ConversionFlags flags) {
+  if (*source == sourceEnd)
+    return sourceExhausted;
+  unsigned size = getNumBytesForUTF8(**source);
+  if ((ptrdiff_t)size > sourceEnd - *source)
+    return sourceExhausted;
+  return ConvertUTF8toUTF32(source, *source + size, &target, target + 1, flags);
+}
+
+/**
+ * Returns true if a blob of text starts with a UTF-16 big or little endian byte
+ * order mark.
+ */
+bool hasUTF16ByteOrderMark(ArrayRef<char> SrcBytes);
+
+/**
+ * Converts a stream of raw bytes assumed to be UTF16 into a UTF8 std::string.
+ *
+ * \param [in] SrcBytes A buffer of what is assumed to be UTF-16 encoded text.
+ * \param [out] Out Converted UTF-8 is stored here on success.
+ * \returns true on success
+ */
+bool convertUTF16ToUTF8String(ArrayRef<char> SrcBytes, std::string &Out);
+
+/**
+* Converts a UTF16 string into a UTF8 std::string.
+*
+* \param [in] Src A buffer of UTF-16 encoded text.
+* \param [out] Out Converted UTF-8 is stored here on success.
+* \returns true on success
+*/
+bool convertUTF16ToUTF8String(ArrayRef<UTF16> Src, std::string &Out);
+
+/**
+ * Converts a UTF-8 string into a UTF-16 string with native endianness.
+ *
+ * \returns true on success
+ */
+bool convertUTF8ToUTF16String(StringRef SrcUTF8,
+                              SmallVectorImpl<UTF16> &DstUTF16);
+
+#if defined(_WIN32)
+namespace sys {
+namespace windows {
+std::error_code UTF8ToUTF16(StringRef utf8, SmallVectorImpl<wchar_t> &utf16);
+/// Convert to UTF16 from the current code page used in the system
+std::error_code CurCPToUTF16(StringRef utf8, SmallVectorImpl<wchar_t> &utf16);
+std::error_code UTF16ToUTF8(const wchar_t *utf16, size_t utf16_len,
+                            SmallVectorImpl<char> &utf8);
+/// Convert from UTF16 to the current code page used in the system
+std::error_code UTF16ToCurCP(const wchar_t *utf16, size_t utf16_len,
+                             SmallVectorImpl<char> &utf8);
+} // namespace windows
+} // namespace sys
+#endif
+
+} /* end namespace llvm */
+
+#endif