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gtk/gtkcssenumvalue.c: Deal with __builtin_popcount on MSVC

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__builtin_popcount is a GCCism that is used to count the number of bits
involved, which means any non GCC/CLang compilers won't like the code,
meaning that on MSVC builds we must implement it ourselves.

We first use __cpuid() to check whether the CPU supports the popcount
instruction, if it does, we use the __popcnt intrinsic, otherwise
(untested, since I don't have a system that does not have the
instruction), we use the suggested hacks at
http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel

https://bugzilla.gnome.org/show_bug.cgi?id=773299
This commit is contained in:
Chun-wei Fan
2017-10-24 16:16:08 +08:00
parent 5b9177f53b
commit 20fc576275
1 changed files with 37 additions and 0 deletions
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37
gtk/gtkcssenumvalue.c
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@@ -24,6 +24,10 @@
#include "gtkstyleproviderprivate.h"
#include "gtksettingsprivate.h"
#ifdef _MSC_VER
# include <intrin.h>
#endif
/* repeated API */
struct _GtkCssValue {
@@ -1429,6 +1433,39 @@ static const GtkCssValueClass GTK_CSS_VALUE_FONT_VARIANT_EAST_ASIAN = {
gtk_css_font_variant_east_asian_value_print
};
#ifdef _MSC_VER
/* __builtin_popcount is a GCC-only function
so we need to define it for ourselves somehow */
static inline guint
__msvc_compat_popcnt (guint32 value)
{
static gssize popcnt_checked = 0;
static gboolean have_popcnt = FALSE;
# if defined (_M_AMD64) || defined (_M_X64) || (_M_IX86)
if (g_once_init_enter (&popcnt_checked))
{
int cpuinfo[4] = {-1};
__cpuid (cpuinfo, 1);
have_popcnt = (cpuinfo[2] & 0x00800000) != 0;
g_once_init_leave (&popcnt_checked, 1);
}
# endif
if (have_popcnt)
return __popcnt (value);
else
/* http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel */
return (((value & 0xfff) * 0x1001001001001ULL & 0x84210842108421ULL) % 0x1f) +
((((value & 0xfff000) >> 12) * 0x1001001001001ULL & 0x84210842108421ULL) % 0x1f) +
(((value >> 24) * 0x1001001001001ULL & 0x84210842108421ULL) % 0x1f);
}
# define __builtin_popcount(v) __msvc_compat_popcnt(v)
#endif
static gboolean
east_asian_value_is_valid (GtkCssFontVariantEastAsian east_asian)
{