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, 283 insertions, 0 deletions

diff --git a/third_party/llvm-project/MD5.cpp b/third_party/llvm-project/MD5.cpp
new file mode 100644
index 000000000..9b02f6291
--- /dev/null
+++ b/third_party/llvm-project/MD5.cpp
@@ -0,0 +1,283 @@
+/*
+ * This code is derived from (original license follows):
+ *
+ * This is an OpenSSL-compatible implementation of the RSA Data Security, Inc.
+ * MD5 Message-Digest Algorithm (RFC 1321).
+ *
+ * Homepage:
+ * http://openwall.info/wiki/people/solar/software/public-domain-source-code/md5
+ *
+ * Author:
+ * Alexander Peslyak, better known as Solar Designer <solar at openwall.com>
+ *
+ * This software was written by Alexander Peslyak in 2001.  No copyright is
+ * claimed, and the software is hereby placed in the public domain.
+ * In case this attempt to disclaim copyright and place the software in the
+ * public domain is deemed null and void, then the software is
+ * Copyright (c) 2001 Alexander Peslyak and it is hereby released to the
+ * general public under the following terms:
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted.
+ *
+ * There's ABSOLUTELY NO WARRANTY, express or implied.
+ *
+ * (This is a heavily cut-down "BSD license".)
+ *
+ * This differs from Colin Plumb's older public domain implementation in that
+ * no exactly 32-bit integer data type is required (any 32-bit or wider
+ * unsigned integer data type will do), there's no compile-time endianness
+ * configuration, and the function prototypes match OpenSSL's.  No code from
+ * Colin Plumb's implementation has been reused; this comment merely compares
+ * the properties of the two independent implementations.
+ *
+ * The primary goals of this implementation are portability and ease of use.
+ * It is meant to be fast, but not as fast as possible.  Some known
+ * optimizations are not included to reduce source code size and avoid
+ * compile-time configuration.
+ */
+
+#include "llvm/Support/MD5.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/Format.h"
+#include "llvm/Support/raw_ostream.h"
+#include <array>
+#include <cstdint>
+#include <cstring>
+
+// The basic MD5 functions.
+
+// F and G are optimized compared to their RFC 1321 definitions for
+// architectures that lack an AND-NOT instruction, just like in Colin Plumb's
+// implementation.
+#define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
+#define G(x, y, z) ((y) ^ ((z) & ((x) ^ (y))))
+#define H(x, y, z) ((x) ^ (y) ^ (z))
+#define I(x, y, z) ((y) ^ ((x) | ~(z)))
+
+// The MD5 transformation for all four rounds.
+#define STEP(f, a, b, c, d, x, t, s)                                           \
+  (a) += f((b), (c), (d)) + (x) + (t);                                         \
+  (a) = (((a) << (s)) | (((a) & 0xffffffff) >> (32 - (s))));                   \
+  (a) += (b);
+
+// SET reads 4 input bytes in little-endian byte order and stores them
+// in a properly aligned word in host byte order.
+#define SET(n)                                                                 \
+  (block[(n)] =                                                                \
+       (MD5_u32plus) ptr[(n) * 4] | ((MD5_u32plus) ptr[(n) * 4 + 1] << 8) |    \
+       ((MD5_u32plus) ptr[(n) * 4 + 2] << 16) |                                \
+       ((MD5_u32plus) ptr[(n) * 4 + 3] << 24))
+#define GET(n) (block[(n)])
+
+using namespace llvm;
+
+/// This processes one or more 64-byte data blocks, but does NOT update
+///the bit counters.  There are no alignment requirements.
+const uint8_t *MD5::body(ArrayRef<uint8_t> Data) {
+  const uint8_t *ptr;
+  MD5_u32plus a, b, c, d;
+  MD5_u32plus saved_a, saved_b, saved_c, saved_d;
+  unsigned long Size = Data.size();
+
+  ptr = Data.data();
+
+  a = this->a;
+  b = this->b;
+  c = this->c;
+  d = this->d;
+
+  do {
+    saved_a = a;
+    saved_b = b;
+    saved_c = c;
+    saved_d = d;
+
+    // Round 1
+    STEP(F, a, b, c, d, SET(0), 0xd76aa478, 7)
+    STEP(F, d, a, b, c, SET(1), 0xe8c7b756, 12)
+    STEP(F, c, d, a, b, SET(2), 0x242070db, 17)
+    STEP(F, b, c, d, a, SET(3), 0xc1bdceee, 22)
+    STEP(F, a, b, c, d, SET(4), 0xf57c0faf, 7)
+    STEP(F, d, a, b, c, SET(5), 0x4787c62a, 12)
+    STEP(F, c, d, a, b, SET(6), 0xa8304613, 17)
+    STEP(F, b, c, d, a, SET(7), 0xfd469501, 22)
+    STEP(F, a, b, c, d, SET(8), 0x698098d8, 7)
+    STEP(F, d, a, b, c, SET(9), 0x8b44f7af, 12)
+    STEP(F, c, d, a, b, SET(10), 0xffff5bb1, 17)
+    STEP(F, b, c, d, a, SET(11), 0x895cd7be, 22)
+    STEP(F, a, b, c, d, SET(12), 0x6b901122, 7)
+    STEP(F, d, a, b, c, SET(13), 0xfd987193, 12)
+    STEP(F, c, d, a, b, SET(14), 0xa679438e, 17)
+    STEP(F, b, c, d, a, SET(15), 0x49b40821, 22)
+
+    // Round 2
+    STEP(G, a, b, c, d, GET(1), 0xf61e2562, 5)
+    STEP(G, d, a, b, c, GET(6), 0xc040b340, 9)
+    STEP(G, c, d, a, b, GET(11), 0x265e5a51, 14)
+    STEP(G, b, c, d, a, GET(0), 0xe9b6c7aa, 20)
+    STEP(G, a, b, c, d, GET(5), 0xd62f105d, 5)
+    STEP(G, d, a, b, c, GET(10), 0x02441453, 9)
+    STEP(G, c, d, a, b, GET(15), 0xd8a1e681, 14)
+    STEP(G, b, c, d, a, GET(4), 0xe7d3fbc8, 20)
+    STEP(G, a, b, c, d, GET(9), 0x21e1cde6, 5)
+    STEP(G, d, a, b, c, GET(14), 0xc33707d6, 9)
+    STEP(G, c, d, a, b, GET(3), 0xf4d50d87, 14)
+    STEP(G, b, c, d, a, GET(8), 0x455a14ed, 20)
+    STEP(G, a, b, c, d, GET(13), 0xa9e3e905, 5)
+    STEP(G, d, a, b, c, GET(2), 0xfcefa3f8, 9)
+    STEP(G, c, d, a, b, GET(7), 0x676f02d9, 14)
+    STEP(G, b, c, d, a, GET(12), 0x8d2a4c8a, 20)
+
+    // Round 3
+    STEP(H, a, b, c, d, GET(5), 0xfffa3942, 4)
+    STEP(H, d, a, b, c, GET(8), 0x8771f681, 11)
+    STEP(H, c, d, a, b, GET(11), 0x6d9d6122, 16)
+    STEP(H, b, c, d, a, GET(14), 0xfde5380c, 23)
+    STEP(H, a, b, c, d, GET(1), 0xa4beea44, 4)
+    STEP(H, d, a, b, c, GET(4), 0x4bdecfa9, 11)
+    STEP(H, c, d, a, b, GET(7), 0xf6bb4b60, 16)
+    STEP(H, b, c, d, a, GET(10), 0xbebfbc70, 23)
+    STEP(H, a, b, c, d, GET(13), 0x289b7ec6, 4)
+    STEP(H, d, a, b, c, GET(0), 0xeaa127fa, 11)
+    STEP(H, c, d, a, b, GET(3), 0xd4ef3085, 16)
+    STEP(H, b, c, d, a, GET(6), 0x04881d05, 23)
+    STEP(H, a, b, c, d, GET(9), 0xd9d4d039, 4)
+    STEP(H, d, a, b, c, GET(12), 0xe6db99e5, 11)
+    STEP(H, c, d, a, b, GET(15), 0x1fa27cf8, 16)
+    STEP(H, b, c, d, a, GET(2), 0xc4ac5665, 23)
+
+    // Round 4
+    STEP(I, a, b, c, d, GET(0), 0xf4292244, 6)
+    STEP(I, d, a, b, c, GET(7), 0x432aff97, 10)
+    STEP(I, c, d, a, b, GET(14), 0xab9423a7, 15)
+    STEP(I, b, c, d, a, GET(5), 0xfc93a039, 21)
+    STEP(I, a, b, c, d, GET(12), 0x655b59c3, 6)
+    STEP(I, d, a, b, c, GET(3), 0x8f0ccc92, 10)
+    STEP(I, c, d, a, b, GET(10), 0xffeff47d, 15)
+    STEP(I, b, c, d, a, GET(1), 0x85845dd1, 21)
+    STEP(I, a, b, c, d, GET(8), 0x6fa87e4f, 6)
+    STEP(I, d, a, b, c, GET(15), 0xfe2ce6e0, 10)
+    STEP(I, c, d, a, b, GET(6), 0xa3014314, 15)
+    STEP(I, b, c, d, a, GET(13), 0x4e0811a1, 21)
+    STEP(I, a, b, c, d, GET(4), 0xf7537e82, 6)
+    STEP(I, d, a, b, c, GET(11), 0xbd3af235, 10)
+    STEP(I, c, d, a, b, GET(2), 0x2ad7d2bb, 15)
+    STEP(I, b, c, d, a, GET(9), 0xeb86d391, 21)
+
+    a += saved_a;
+    b += saved_b;
+    c += saved_c;
+    d += saved_d;
+
+    ptr += 64;
+  } while (Size -= 64);
+
+  this->a = a;
+  this->b = b;
+  this->c = c;
+  this->d = d;
+
+  return ptr;
+}
+
+MD5::MD5() = default;
+
+/// Incrementally add the bytes in \p Data to the hash.
+void MD5::update(ArrayRef<uint8_t> Data) {
+  MD5_u32plus saved_lo;
+  unsigned long used, free;
+  const uint8_t *Ptr = Data.data();
+  unsigned long Size = Data.size();
+
+  saved_lo = lo;
+  if ((lo = (saved_lo + Size) & 0x1fffffff) < saved_lo)
+    hi++;
+  hi += Size >> 29;
+
+  used = saved_lo & 0x3f;
+
+  if (used) {
+    free = 64 - used;
+
+    if (Size < free) {
+      memcpy(&buffer[used], Ptr, Size);
+      return;
+    }
+
+    memcpy(&buffer[used], Ptr, free);
+    Ptr = Ptr + free;
+    Size -= free;
+    body(makeArrayRef(buffer, 64));
+  }
+
+  if (Size >= 64) {
+    Ptr = body(makeArrayRef(Ptr, Size & ~(unsigned long) 0x3f));
+    Size &= 0x3f;
+  }
+
+  memcpy(buffer, Ptr, Size);
+}
+
+/// Add the bytes in the StringRef \p Str to the hash.
+// Note that this isn't a string and so this won't include any trailing NULL
+// bytes.
+void MD5::update(StringRef Str) {
+  ArrayRef<uint8_t> SVal((const uint8_t *)Str.data(), Str.size());
+  update(SVal);
+}
+
+/// Finish the hash and place the resulting hash into \p result.
+/// \param Result is assumed to be a minimum of 16-bytes in size.
+void MD5::final(MD5Result &Result) {
+  unsigned long used, free;
+
+  used = lo & 0x3f;
+
+  buffer[used++] = 0x80;
+
+  free = 64 - used;
+
+  if (free < 8) {
+    memset(&buffer[used], 0, free);
+    body(makeArrayRef(buffer, 64));
+    used = 0;
+    free = 64;
+  }
+
+  memset(&buffer[used], 0, free - 8);
+
+  lo <<= 3;
+  support::endian::write32le(&buffer[56], lo);
+  support::endian::write32le(&buffer[60], hi);
+
+  body(makeArrayRef(buffer, 64));
+
+  support::endian::write32le(&Result[0], a);
+  support::endian::write32le(&Result[4], b);
+  support::endian::write32le(&Result[8], c);
+  support::endian::write32le(&Result[12], d);
+}
+
+SmallString<32> MD5::MD5Result::digest() const {
+  SmallString<32> Str;
+  raw_svector_ostream Res(Str);
+  for (int i = 0; i < 16; ++i)
+    Res << format("%.2x", Bytes[i]);
+  return Str;
+}
+
+void MD5::stringifyResult(MD5Result &Result, SmallString<32> &Str) {
+  Str = Result.digest();
+}
+
+std::array<uint8_t, 16> MD5::hash(ArrayRef<uint8_t> Data) {
+  MD5 Hash;
+  Hash.update(Data);
+  MD5::MD5Result Res;
+  Hash.final(Res);
+
+  return Res;
+}