stdio-common: Convert vfprintf and related functions to buffers

vfprintf is entangled with vfwprintf (of course), __printf_fp,
__printf_fphex, __vstrfmon_l_internal, and the strfrom family of
functions.  The latter use the internal snprintf functionality,
so vsnprintf is converted as well.

The simples conversion is __printf_fphex, followed by
__vstrfmon_l_internal and __printf_fp, and finally
__vfprintf_internal and __vfwprintf_internal.  __vsnprintf_internal
and strfrom* are mostly consuming the new interfaces, so they
are comparatively simple.

__printf_fp is a public symbol, so the FILE *-based interface
had to preserved.

The __printf_fp rewrite does not change the actual binary-to-decimal
conversion algorithm, and digits are still not emitted directly to
the target buffer.  However, the staging buffer now uses bytes
instead of wide characters, and one buffer copy is eliminated.

The changes are at least performance-neutral in my testing.
Floating point printing and snprintf improved measurably, so that
this Lua script

  for i=1,5000000 do
      print(i, i * math.pi)
  end

runs about 5% faster for me.  To preserve fprintf performance for
a simple "%d" format, this commit has some logic changes under
LABEL (unsigned_number) to avoid additional function calls.  There
are certainly some very easy performance improvements here: binary,
octal and hexadecimal formatting can easily avoid the temporary work
buffer (the number of digits can be computed ahead-of-time using one
of the __builtin_clz* built-ins). Decimal formatting can use a
specialized version of _itoa_word for base 10.

The existing (inconsistent) width handling between strfmon and printf
is preserved here.  __print_fp_buffer_1 would have to use
__translated_number_width to achieve ISO conformance for printf.

Test expectations in libio/tst-vtables-common.c are adjusted because
the internal staging buffer merges all virtual function calls into
one.

In general, stack buffer usage is greatly reduced, particularly for
unbuffered input streams.  __printf_fp can still use a large buffer
in binary128 mode for %g, though.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

1 files changed, 109 insertions, 151 deletions

diff --git a/stdio-common/printf_fphex.c b/stdio-common/printf_fphex.c
index 5af380da62..1947faba8d 100644
--- a/stdio-common/printf_fphex.c
+++ b/stdio-common/printf_fphex.c
@@ -17,10 +17,12 @@
    <https://www.gnu.org/licenses/>.  */
 
 #include <array_length.h>
+#include <assert.h>
 #include <ctype.h>
 #include <ieee754.h>
 #include <math.h>
 #include <printf.h>
+#include <libioP.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
@@ -30,6 +32,9 @@
 #include <locale/localeinfo.h>
 #include <stdbool.h>
 #include <rounding-mode.h>
+#include <sys/param.h>
+#include <printf_buffer.h>
+#include <errno.h>
 
 #if __HAVE_DISTINCT_FLOAT128
 # include "ieee754_float128.h"
@@ -39,58 +44,11 @@
 		IEEE854_FLOAT128_BIAS)
 #endif
 
-/* #define NDEBUG 1*/		/* Undefine this for debugging assertions.  */
-#include <assert.h>
-
-#include <libioP.h>
-#define PUT(f, s, n) _IO_sputn (f, s, n)
-#define PAD(f, c, n) (wide ? _IO_wpadn (f, c, n) : _IO_padn (f, c, n))
-#undef putc
-#define putc(c, f) (wide \
-		     ? (int)_IO_putwc_unlocked (c, f) : _IO_putc_unlocked (c, f))
-
-
-/* Macros for doing the actual output.  */
-
-#define outchar(ch)							      \
-  do									      \
-    {									      \
-      const int outc = (ch);						      \
-      if (putc (outc, fp) == EOF)					      \
-	return -1;							      \
-      ++done;								      \
-    } while (0)
-
-#define PRINT(ptr, wptr, len)						      \
-  do									      \
-    {									      \
-      size_t outlen = (len);						      \
-      if (wide)								      \
-	while (outlen-- > 0)						      \
-	  outchar (*wptr++);						      \
-      else								      \
-	while (outlen-- > 0)						      \
-	  outchar (*ptr++);						      \
-    } while (0)
-
-#define PADN(ch, len)							      \
-  do									      \
-    {									      \
-      if (PAD (fp, ch, len) != len)					      \
-	return -1;							      \
-      done += len;							      \
-    }									      \
-  while (0)
-
-#ifndef MIN
-# define MIN(a,b) ((a)<(b)?(a):(b))
-#endif
-
-
-int
-__printf_fphex (FILE *fp,
-		const struct printf_info *info,
-		const void *const *args)
+static void
+__printf_fphex_buffer (struct __printf_buffer *buf,
+		       const char *decimal,
+		       const struct printf_info *info,
+		       const void *const *args)
 {
   /* The floating-point value to output.  */
   union
@@ -106,34 +64,19 @@ __printf_fphex (FILE *fp,
   /* This function always uses LC_NUMERIC.  */
   assert (info->extra == 0);
 
-  /* Locale-dependent representation of decimal point. Hexadecimal
-     formatting always using LC_NUMERIC (disregarding info->extra).  */
-  const char *decimal = _NL_CURRENT (LC_NUMERIC, DECIMAL_POINT);
-  wchar_t decimalwc = _NL_CURRENT_WORD (LC_NUMERIC,
-					_NL_NUMERIC_DECIMAL_POINT_WC);
-
-  /* The decimal point character must never be zero.  */
-  assert (*decimal != '\0' && decimalwc != L'\0');
-
   /* "NaN" or "Inf" for the special cases.  */
   const char *special = NULL;
-  const wchar_t *wspecial = NULL;
 
   /* Buffer for the generated number string for the mantissa.  The
      maximal size for the mantissa is 128 bits.  */
   char numbuf[32];
   char *numstr;
   char *numend;
-  wchar_t wnumbuf[32];
-  wchar_t *wnumstr;
-  wchar_t *wnumend;
   int negative;
 
   /* The maximal exponent of two in decimal notation has 5 digits.  */
   char expbuf[5];
   char *expstr;
-  wchar_t wexpbuf[5];
-  wchar_t *wexpstr;
   int expnegative;
   int exponent;
 
@@ -149,12 +92,6 @@ __printf_fphex (FILE *fp,
   /* Width.  */
   int width = info->width;
 
-  /* Number of characters written.  */
-  int done = 0;
-
-  /* Nonzero if this is output on a wide character stream.  */
-  int wide = info->wide;
-
 #define PRINTF_FPHEX_FETCH(FLOAT, VAR)					\
   {									\
     (VAR) = *(const FLOAT *) args[0];					\
@@ -163,30 +100,18 @@ __printf_fphex (FILE *fp,
     if (isnan (VAR))							\
       {									\
 	if (isupper (info->spec))					\
-	  {								\
-	    special = "NAN";						\
-	    wspecial = L"NAN";						\
-	  }								\
+	  special = "NAN";						\
 	else								\
-	  {								\
-	    special = "nan";						\
-	    wspecial = L"nan";						\
-	  }								\
+	  special = "nan";						\
       }									\
     else								\
       {									\
 	if (isinf (VAR))						\
 	  {								\
 	    if (isupper (info->spec))					\
-	      {								\
-		special = "INF";					\
-		wspecial = L"INF";					\
-	      }								\
+	      special = "INF";						\
 	    else							\
-	      {								\
-		special = "inf";					\
-		wspecial = L"inf";					\
-	      }								\
+	      special = "inf";						\
 	  }								\
       }									\
     negative = signbit (VAR);						\
@@ -215,22 +140,22 @@ __printf_fphex (FILE *fp,
 	--width;
       width -= 3;
 
-      if (!info->left && width > 0)
-	PADN (' ', width);
+      if (!info->left)
+	__printf_buffer_pad (buf, ' ', width);
 
       if (negative)
-	outchar ('-');
+	__printf_buffer_putc (buf, '-');
       else if (info->showsign)
-	outchar ('+');
+	__printf_buffer_putc (buf, '+');
       else if (info->space)
-	outchar (' ');
+	__printf_buffer_putc (buf, ' ');
 
-      PRINT (special, wspecial, 3);
+      __printf_buffer_puts (buf, special);
 
-      if (info->left && width > 0)
-	PADN (' ', width);
+      if (info->left)
+	__printf_buffer_pad (buf, ' ', width);
 
-      return done;
+      return;
     }
 
 #if __HAVE_DISTINCT_FLOAT128
@@ -252,26 +177,15 @@ __printf_fphex (FILE *fp,
       zero_mantissa = num == 0;
 
       if (sizeof (unsigned long int) > 6)
-	{
-	  wnumstr = _itowa_word (num, wnumbuf + (sizeof wnumbuf) / sizeof (wchar_t), 16,
-				 info->spec == 'A');
 	  numstr = _itoa_word (num, numbuf + sizeof numbuf, 16,
 			       info->spec == 'A');
-	}
       else
-	{
-	  wnumstr = _itowa (num, wnumbuf + sizeof wnumbuf / sizeof (wchar_t), 16,
-			    info->spec == 'A');
 	  numstr = _itoa (num, numbuf + sizeof numbuf, 16,
 			  info->spec == 'A');
-	}
 
       /* Fill with zeroes.  */
-      while (wnumstr > wnumbuf + (sizeof wnumbuf - 52) / sizeof (wchar_t))
-	{
-	  *--wnumstr = L'0';
-	  *--numstr = '0';
-	}
+      while (numstr > numbuf + (sizeof numbuf - 13))
+	*--numstr = '0';
 
       leading = fpnum.dbl.ieee.exponent == 0 ? '0' : '1';
 
@@ -307,13 +221,9 @@ __printf_fphex (FILE *fp,
   /* Look for trailing zeroes.  */
   if (! zero_mantissa)
     {
-      wnumend = array_end (wnumbuf);
       numend = array_end (numbuf);
-      while (wnumend[-1] == L'0')
-	{
-	  --wnumend;
+      while (numend[-1] == '0')
 	  --numend;
-	}
 
       bool do_round_away = false;
 
@@ -352,7 +262,6 @@ __printf_fphex (FILE *fp,
 		 like in ASCII.  This is true for the rest of GNU, too.  */
 	      if (ch == '9')
 		{
-		  wnumstr[cnt] = (wchar_t) info->spec;
 		  numstr[cnt] = info->spec;	/* This is tricky,
 						   think about it!  */
 		  break;
@@ -360,14 +269,10 @@ __printf_fphex (FILE *fp,
 	      else if (tolower (ch) < 'f')
 		{
 		  ++numstr[cnt];
-		  ++wnumstr[cnt];
 		  break;
 		}
 	      else
-		{
-		  numstr[cnt] = '0';
-		  wnumstr[cnt] = L'0';
-		}
+		numstr[cnt] = '0';
 	    }
 	  if (cnt < 0)
 	    {
@@ -401,13 +306,10 @@ __printf_fphex (FILE *fp,
       if (precision == -1)
 	precision = 0;
       numend = numstr;
-      wnumend = wnumstr;
     }
 
   /* Now we can compute the exponent string.  */
   expstr = _itoa_word (exponent, expbuf + sizeof expbuf, 10, 0);
-  wexpstr = _itowa_word (exponent,
-			 wexpbuf + sizeof wexpbuf / sizeof (wchar_t), 10, 0);
 
   /* Now we have all information to compute the size.  */
   width -= ((negative || info->showsign || info->space)
@@ -421,54 +323,110 @@ __printf_fphex (FILE *fp,
      A special case when the mantissa or the precision is zero and the `#'
      is not given.  In this case we must not print the decimal point.  */
   if (precision > 0 || info->alt)
-    width -= wide ? 1 : strlen (decimal);
+    --width;
 
-  if (!info->left && info->pad != '0' && width > 0)
-    PADN (' ', width);
+  if (!info->left && info->pad != '0')
+    __printf_buffer_pad (buf, ' ', width);
 
   if (negative)
-    outchar ('-');
+    __printf_buffer_putc (buf, '-');
   else if (info->showsign)
-    outchar ('+');
+    __printf_buffer_putc (buf, '+');
   else if (info->space)
-    outchar (' ');
+    __printf_buffer_putc (buf, ' ');
 
-  outchar ('0');
+  __printf_buffer_putc (buf, '0');
   if ('X' - 'A' == 'x' - 'a')
-    outchar (info->spec + ('x' - 'a'));
+    __printf_buffer_putc (buf, info->spec + ('x' - 'a'));
   else
-    outchar (info->spec == 'A' ? 'X' : 'x');
+    __printf_buffer_putc (buf, info->spec == 'A' ? 'X' : 'x');
 
-  if (!info->left && info->pad == '0' && width > 0)
-    PADN ('0', width);
+  if (!info->left && info->pad == '0')
+    __printf_buffer_pad (buf, '0', width);
 
-  outchar (leading);
+  __printf_buffer_putc (buf, leading);
 
   if (precision > 0 || info->alt)
-    {
-      const wchar_t *wtmp = &decimalwc;
-      PRINT (decimal, wtmp, wide ? 1 : strlen (decimal));
-    }
+    __printf_buffer_puts (buf, decimal);
 
   if (precision > 0)
     {
       ssize_t tofill = precision - (numend - numstr);
-      PRINT (numstr, wnumstr, MIN (numend - numstr, precision));
-      if (tofill > 0)
-	PADN ('0', tofill);
+      __printf_buffer_write (buf, numstr, MIN (numend - numstr, precision));
+      __printf_buffer_pad (buf, '0', tofill);
     }
 
   if ('P' - 'A' == 'p' - 'a')
-    outchar (info->spec + ('p' - 'a'));
+    __printf_buffer_putc (buf, info->spec + ('p' - 'a'));
   else
-    outchar (info->spec == 'A' ? 'P' : 'p');
+    __printf_buffer_putc (buf, info->spec == 'A' ? 'P' : 'p');
+
+  __printf_buffer_putc (buf, expnegative ? '-' : '+');
+
+  __printf_buffer_write (buf, expstr, (expbuf + sizeof expbuf) - expstr);
+
+  if (info->left && info->pad != '0')
+    __printf_buffer_pad (buf, info->pad, width);
+}
+
+void
+__printf_fphex_l_buffer (struct __printf_buffer *buf, locale_t loc,
+			 const struct printf_info *info,
+			 const void *const *args)
+{
+  __printf_fphex_buffer (buf, _nl_lookup (loc, LC_NUMERIC, DECIMAL_POINT),
+			 info, args);
+}
 
-  outchar (expnegative ? '-' : '+');
 
-  PRINT (expstr, wexpstr, (expbuf + sizeof expbuf) - expstr);
+/* The wide buffer version is implemented by translating the output of
+   the multibyte verison.  */
 
-  if (info->left && info->pad != '0' && width > 0)
-    PADN (info->pad, width);
+struct __printf_buffer_fphex_to_wide
+{
+  struct __printf_buffer base;
+  wchar_t decimalwc;
+  struct __wprintf_buffer *next;
+  char untranslated[PRINTF_BUFFER_SIZE_DIGITS];
+};
+
+/* Translate to wide characters, rewriting "." to the actual decimal
+   point.  */
+void
+__printf_buffer_flush_fphex_to_wide (struct __printf_buffer_fphex_to_wide *buf)
+{
+  /* No need to adjust buf->base.written, only buf->next->written matters.  */
+  for (char *p = buf->untranslated; p < buf->base.write_ptr; ++p)
+    {
+      /* wchar_t overlaps with char in the ASCII range.  */
+      wchar_t ch = *p;
+      if (ch == L'.')
+	ch = buf->decimalwc;
+      __wprintf_buffer_putc (buf->next, ch);
+    }
 
-  return done;
+  if (!__wprintf_buffer_has_failed (buf->next))
+    buf->base.write_ptr = buf->untranslated;
+  else
+    __printf_buffer_mark_failed (&buf->base);
+}
+
+void
+__wprintf_fphex_l_buffer (struct __wprintf_buffer *next, locale_t loc,
+			  const struct printf_info *info,
+			  const void *const *args)
+{
+  struct __printf_buffer_fphex_to_wide buf;
+  __printf_buffer_init (&buf.base, buf.untranslated, sizeof (buf.untranslated),
+			__printf_buffer_mode_fphex_to_wide);
+  buf.decimalwc = _nl_lookup_word (loc, LC_NUMERIC,
+				   _NL_NUMERIC_DECIMAL_POINT_WC);
+  buf.next = next;
+  __printf_fphex_buffer (&buf.base, ".", info, args);
+  if (__printf_buffer_has_failed (&buf.base))
+    {
+      __wprintf_buffer_mark_failed (buf.next);
+      return;
+    }
+  __printf_buffer_flush_fphex_to_wide (&buf);
 }