compiler: relocate ID encoding utilities to gofrontend

    
    Relocate the code that encodes/sanitizes identifiers to make them
    assembler-friendly, moving it from the back end to the front end; the
    decisions about when to encode an identifier and the calls to the
    encoding helpers now take place entirely in gofrontend.
    
    Reviewed-on: https://go-review.googlesource.com/33424

	* go-gcc.cc (char_needs_encoding): Remove.
	(needs_encoding, fetch_utf8_char, encode_id): Remove.
	(Gcc_backend::global_variable): Add asm_name parameter.  Don't
	compute asm_name here.
	(Gcc_backend::implicit_variable): Likewise.
	(Gcc_backend::implicit_variable_reference): Likewise.
	(Gcc_backend::immutable_struct): Likewise.
	(Gcc_backend::immutable_struct_reference): Likewise.
	* Make-lang.in (GO_OBJS): Add go/go-encode-id.o.

From-SVN: r242726

1 files changed, 113 insertions, 0 deletions

diff --git a/gcc/go/gofrontend/go-encode-id.cc b/gcc/go/gofrontend/go-encode-id.cc
new file mode 100644
index 0000000..978f208
--- /dev/null
+++ b/gcc/go/gofrontend/go-encode-id.cc
@@ -0,0 +1,113 @@
+// go-encode-id.cc -- Go identifier encoding hooks
+
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "go-location.h"
+#include "go-linemap.h"
+#include "go-encode-id.h"
+
+// Return whether the character c is OK to use in the assembler.
+
+static bool
+char_needs_encoding(char c)
+{
+  switch (c)
+    {
+    case 'A': case 'B': case 'C': case 'D': case 'E': case 'F':
+    case 'G': case 'H': case 'I': case 'J': case 'K': case 'L':
+    case 'M': case 'N': case 'O': case 'P': case 'Q': case 'R':
+    case 'S': case 'T': case 'U': case 'V': case 'W': case 'X':
+    case 'Y': case 'Z':
+    case 'a': case 'b': case 'c': case 'd': case 'e': case 'f':
+    case 'g': case 'h': case 'i': case 'j': case 'k': case 'l':
+    case 'm': case 'n': case 'o': case 'p': case 'q': case 'r':
+    case 's': case 't': case 'u': case 'v': case 'w': case 'x':
+    case 'y': case 'z':
+    case '0': case '1': case '2': case '3': case '4':
+    case '5': case '6': case '7': case '8': case '9':
+    case '_': case '.': case '$': case '/':
+      return false;
+    default:
+      return true;
+    }
+}
+
+// Return whether the identifier needs to be translated because it
+// contains non-ASCII characters.
+
+bool
+go_id_needs_encoding(const std::string& str)
+{
+  for (std::string::const_iterator p = str.begin();
+       p != str.end();
+       ++p)
+    if (char_needs_encoding(*p))
+      return true;
+  return false;
+}
+
+// Pull the next UTF-8 character out of P and store it in *PC.  Return
+// the number of bytes read.
+
+static size_t
+fetch_utf8_char(const char* p, unsigned int* pc)
+{
+  unsigned char c = *p;
+  if ((c & 0x80) == 0)
+    {
+      *pc = c;
+      return 1;
+    }
+  size_t len = 0;
+  while ((c & 0x80) != 0)
+    {
+      ++len;
+      c <<= 1;
+    }
+  unsigned int rc = *p & ((1 << (7 - len)) - 1);
+  for (size_t i = 1; i < len; i++)
+    {
+      unsigned int u = p[i];
+      rc <<= 6;
+      rc |= u & 0x3f;
+    }
+  *pc = rc;
+  return len;
+}
+
+// Encode an identifier using ASCII characters.
+
+std::string
+go_encode_id(const std::string &id)
+{
+  std::string ret;
+  const char* p = id.c_str();
+  const char* pend = p + id.length();
+  while (p < pend)
+    {
+      unsigned int c;
+      size_t len = fetch_utf8_char(p, &c);
+      if (len == 1 && !char_needs_encoding(c))
+        ret += c;
+      else
+        {
+          ret += "$U";
+          char buf[30];
+          snprintf(buf, sizeof buf, "%x", c);
+          ret += buf;
+          ret += "$";
+        }
+      p += len;
+    }
+  return ret;
+}
+
+std::string
+go_selectively_encode_id(const std::string &id)
+{
+  if (go_id_needs_encoding(id))
+    return go_encode_id(id);
+  return std::string();
+}