[ADT] Replace std::isprint by llvm::isPrint.

The standard library functions ::isprint/std::isprint have platform-
and locale-dependent behavior which makes LLVM's output less
predictable. In particular, regression tests my fail depending on the
implementation of these functions.

Implement llvm::isPrint in StringExtras.h with a standard behavior and
replace all uses of ::isprint/std::isprint by a call it llvm::isPrint.
The function is inlined and does not look up language settings so it
should perform better than the standard library's version.

Such a replacement has already been done for isdigit, isalpha, isxdigit
in r314883. gtest does the same in gtest-printers.cc using the following
justification:

    // Returns true if c is a printable ASCII character.  We test the
    // value of c directly instead of calling isprint(), which is buggy on
    // Windows Mobile.
    inline bool IsPrintableAscii(wchar_t c) {
      return 0x20 <= c && c <= 0x7E;
    }

Similar issues have also been encountered by Julia:
https://github.com/JuliaLang/julia/issues/7416

I noticed the problem myself when on Windows isprint('\t') started to
evaluate to true (see https://stackoverflow.com/questions/51435249) and
thus caused several unit tests to fail. The result of isprint doesn't
seem to be well-defined even for ASCII characters. Therefore I suggest
to replace isprint by a platform-independent version.

Differential Revision: https://reviews.llvm.org/D49680

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@338034 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/ADT/StringExtras.h

@@ -99,6 +99,15 @@ inline bool isASCII(llvm::StringRef S) {
   return true;
 }
 
+/// Checks whether character \p C is printable.
+///
+/// Locale-independent version of the C standard library isprint whose results
+/// may differ on different platforms.
+inline bool isPrint(char C) {
+  unsigned char UC = static_cast<unsigned char>(C);
+  return (0x20 <= UC) && (UC <= 0x7E);
+}
+
 /// Returns the corresponding lowercase character if \p x is uppercase.
 inline char toLower(char x) {
   if (x >= 'A' && x <= 'Z')

include/llvm/Support/raw_ostream.h

@@ -220,7 +220,7 @@ public:
   raw_ostream &write_uuid(const uuid_t UUID);
 
   /// Output \p Str, turning '\\', '\t', '\n', '"', and anything that doesn't
-  /// satisfy std::isprint into an escape sequence.
+  /// satisfy llvm::isPrint into an escape sequence.
   raw_ostream &write_escaped(StringRef Str, bool UseHexEscapes = false);
 
   raw_ostream &write(unsigned char C);

lib/MC/MCAsmStreamer.cpp

@@ -815,7 +815,7 @@ static void PrintQuotedString(StringRef Data, raw_ostream &OS) {
       continue;
     }
 
-    if (isprint((unsigned char)C)) {
+    if (isPrint((unsigned char)C)) {
       OS << (char)C;
       continue;
     }

lib/ProfileData/InstrProfReader.cpp

@@ -129,7 +129,7 @@ bool TextInstrProfReader::hasFormat(const MemoryBuffer &Buffer) {
   StringRef buffer = Buffer.getBufferStart();
   return count == 0 ||
          std::all_of(buffer.begin(), buffer.begin() + count,
-                     [](char c) { return ::isprint(c) || ::isspace(c); });
+                     [](char c) { return isPrint(c) || ::isspace(c); });
 }
 
 // Read the profile variant flag from the header: ":FE" means this is a FE

lib/Support/StringExtras.cpp

@@ -61,7 +61,7 @@ void llvm::SplitString(StringRef Source,
 void llvm::printEscapedString(StringRef Name, raw_ostream &Out) {
   for (unsigned i = 0, e = Name.size(); i != e; ++i) {
     unsigned char C = Name[i];
-    if (isprint(C) && C != '\\' && C != '"')
+    if (isPrint(C) && C != '\\' && C != '"')
       Out << C;
     else
       Out << '\\' << hexdigit(C >> 4) << hexdigit(C & 0x0F);

lib/Support/raw_ostream.cpp

@@ -160,7 +160,7 @@ raw_ostream &raw_ostream::write_escaped(StringRef Str,
       *this << '\\' << '"';
       break;
     default:
-      if (std::isprint(c)) {
+      if (isPrint(c)) {
         *this << c;
         break;
       }
@@ -436,7 +436,7 @@ raw_ostream &raw_ostream::operator<<(const FormattedBytes &FB) {
 
       // Print the ASCII char values for each byte on this line
       for (uint8_t Byte : Line) {
-        if (isprint(Byte))
+        if (isPrint(Byte))
           *this << static_cast<char>(Byte);
         else
           *this << '.';

lib/Support/regengine.inc

@@ -1013,7 +1013,7 @@ pchar(int ch)
 {
 	static char pbuf[10];
 
-	if (isprint(ch) || ch == ' ')
+	if (isPrint(ch) || ch == ' ')
 		(void)snprintf(pbuf, sizeof pbuf, "%c", ch);
 	else
 		(void)snprintf(pbuf, sizeof pbuf, "\\%o", ch);

tools/llvm-bcanalyzer/llvm-bcanalyzer.cpp

@@ -699,7 +699,7 @@ static bool ParseBlock(BitstreamCursor &Stream, BitstreamBlockInfo &BlockInfo,
           std::string Str;
           bool ArrayIsPrintable = true;
           for (unsigned j = i - 1, je = Record.size(); j != je; ++j) {
-            if (!isprint(static_cast<unsigned char>(Record[j]))) {
+            if (!isPrint(static_cast<unsigned char>(Record[j]))) {
               ArrayIsPrintable = false;
               break;
             }
@@ -719,7 +719,7 @@ static bool ParseBlock(BitstreamCursor &Stream, BitstreamBlockInfo &BlockInfo,
         } else {
           bool BlobIsPrintable = true;
           for (unsigned i = 0, e = Blob.size(); i != e; ++i)
-            if (!isprint(static_cast<unsigned char>(Blob[i]))) {
+            if (!isPrint(static_cast<unsigned char>(Blob[i]))) {
               BlobIsPrintable = false;
               break;
             }

tools/llvm-objdump/llvm-objdump.cpp

@@ -1651,7 +1651,7 @@ static void DisassembleObject(const ObjectFile *Obj, bool InlineRelocs) {
             }
             Byte = Bytes.slice(Index)[0];
             outs() << format(" %02x", Byte);
-            AsciiData[NumBytes] = isprint(Byte) ? Byte : '.';
+            AsciiData[NumBytes] = isPrint(Byte) ? Byte : '.';
 
             uint8_t IndentOffset = 0;
             NumBytes++;
@@ -1899,7 +1899,7 @@ void llvm::PrintSectionContents(const ObjectFile *Obj) {
       // Print ascii.
       outs() << "  ";
       for (std::size_t i = 0; i < 16 && addr + i < end; ++i) {
-        if (std::isprint(static_cast<unsigned char>(Contents[addr + i]) & 0xFF))
+        if (isPrint(static_cast<unsigned char>(Contents[addr + i]) & 0xFF))
           outs() << Contents[addr + i];
         else
           outs() << ".";

tools/llvm-readobj/ObjDumper.cpp

@@ -29,7 +29,7 @@ ObjDumper::~ObjDumper() {
 
 static void printAsPrintable(raw_ostream &W, const uint8_t *Start, size_t Len) {
   for (size_t i = 0; i < Len; i++)
-    W << (isprint(Start[i]) ? static_cast<char>(Start[i]) : '.');
+    W << (isPrint(Start[i]) ? static_cast<char>(Start[i]) : '.');
 }
 
 static Expected<object::SectionRef>
@@ -138,7 +138,7 @@ void ObjDumper::printSectionAsHex(const object::ObjectFile *Obj,
 
     TmpSecPtr = SecPtr;
     for (i = 0; TmpSecPtr + i < SecEnd && i < 16; ++i)
-      W.startLine() << (isprint(TmpSecPtr[i]) ? static_cast<char>(TmpSecPtr[i])
+      W.startLine() << (isPrint(TmpSecPtr[i]) ? static_cast<char>(TmpSecPtr[i])
                                               : '.');
 
     W.startLine() << '\n';

unittests/ADT/StringExtrasTest.cpp

@@ -13,6 +13,17 @@
 
 using namespace llvm;
 
+TEST(StringExtrasTest, isPrint) {
+  EXPECT_FALSE(isPrint('\0'));
+  EXPECT_FALSE(isPrint('\t'));
+  EXPECT_TRUE(isPrint('0'));
+  EXPECT_TRUE(isPrint('a'));
+  EXPECT_TRUE(isPrint('A'));
+  EXPECT_TRUE(isPrint(' '));
+  EXPECT_TRUE(isPrint('~'));
+  EXPECT_TRUE(isPrint('?'));
+}
+
 TEST(StringExtrasTest, Join) {
   std::vector<std::string> Items;
   EXPECT_EQ("", join(Items.begin(), Items.end(), " <sep> "));
@@ -93,6 +104,13 @@ TEST(StringExtrasTest, printLowerCase) {
   EXPECT_EQ("abcdefg01234.,&!~`'}\"", OS.str());
 }
 
+TEST(StringExtrasTest, printEscapedString) {
+  std::string str;
+  raw_string_ostream OS(str);
+  printEscapedString("ABCdef123&<>\\\"'\t", OS);
+  EXPECT_EQ("ABCdef123&<>\\5C\\22'\\09", OS.str());
+}
+
 TEST(StringExtrasTest, printHTMLEscaped) {
   std::string str;
   raw_string_ostream OS(str);