Merge branch 'master' into dev

ChangeLog.md

@@ -1,3 +1,39 @@
+1.5.1
+=====
+
+### Significant changes relative to 1.5.0:
+
+1. Previously, the undocumented `JSIMD_FORCE*` environment variables could be
+used to force-enable a particular SIMD instruction set if multiple instruction
+sets were available on a particular platform.  On x86 platforms, where CPU
+feature detection is bulletproof and multiple SIMD instruction sets are
+available, it makes sense for those environment variables to allow forcing the
+use of an instruction set only if that instruction set is available.  However,
+since the ARM implementations of libjpeg-turbo can only use one SIMD
+instruction set, and since their feature detection code is less bulletproof
+(parsing /proc/cpuinfo), it makes sense for the `JSIMD_FORCENEON` environment
+variable to bypass the feature detection code and really force the use of NEON
+instructions.  A new environment variable (`JSIMD_FORCEDSPR2`) was introduced
+in the MIPS implementation for the same reasons, and the existing
+`JSIMD_FORCENONE` environment variable was extended to that implementation.
+These environment variables provide a workaround for those attempting to test
+ARM and MIPS builds of libjpeg-turbo in QEMU, which passes through
+/proc/cpuinfo from the host system.
+
+2. libjpeg-turbo previously assumed that AltiVec instructions were always
+available on PowerPC platforms, which led to "illegal instruction" errors when
+running on PowerPC chips that lack AltiVec support (such as the older 7xx/G3
+and newer e5500 series.)  libjpeg-turbo now examines /proc/cpuinfo on
+Linux/Android systems and enables AltiVec instructions only if the CPU supports
+them.  It also now provides two environment variables, `JSIMD_FORCEALTIVEC` and
+`JSIMD_FORCENONE`, to force-enable and force-disable AltiVec instructions in
+environments where /proc/cpuinfo is an unreliable means of CPU feature
+detection (such as when running in QEMU.)  On OS X, libjpeg-turbo continues to
+assume that AltiVec support is always available, which means that libjpeg-turbo
+cannot be used with G3 Macs unless you set the environment variable
+`JSIMD_FORCENONE` to `1`.
+
+
 1.5.0
 =====
 

simd/Makefile.am

@@ -88,19 +88,24 @@ endif
 
 if SIMD_POWERPC
 
-libsimd_la_SOURCES = jsimd_powerpc.c jsimd_altivec.h jcsample.h \
+noinst_LTLIBRARIES += libsimd_altivec.la
+
+libsimd_altivec_la_SOURCES = \
 	jccolor-altivec.c     jcgray-altivec.c      jcsample-altivec.c \
 	jdcolor-altivec.c     jdmerge-altivec.c     jdsample-altivec.c \
 	jfdctfst-altivec.c    jfdctint-altivec.c \
 	jidctfst-altivec.c    jidctint-altivec.c \
 	jquanti-altivec.c
-libsimd_la_CFLAGS = -maltivec
+libsimd_altivec_la_CFLAGS = -maltivec
 
 jccolor-altivec.lo:  jccolext-altivec.c
 jcgray-altivec.lo:   jcgryext-altivec.c
 jdcolor-altivec.lo:  jdcolext-altivec.c
 jdmerge-altivec.lo:  jdmrgext-altivec.c
 
+libsimd_la_SOURCES = jsimd_powerpc.c jsimd_altivec.h jcsample.h
+libsimd_la_LIBADD = libsimd_altivec.la
+
 endif
 
 AM_CPPFLAGS = -I$(top_srcdir)

simd/jsimd_arm.c

@@ -125,7 +125,7 @@ init_simd (void)
   /* Force different settings through environment variables */
   env = getenv("JSIMD_FORCENEON");
   if ((env != NULL) && (strcmp(env, "1") == 0))
-    simd_support &= JSIMD_ARM_NEON;
+    simd_support = JSIMD_ARM_NEON;
   env = getenv("JSIMD_FORCENONE");
   if ((env != NULL) && (strcmp(env, "1") == 0))
     simd_support = 0;

simd/jsimd_arm64.c

@@ -142,7 +142,7 @@ init_simd (void)
   /* Force different settings through environment variables */
   env = getenv("JSIMD_FORCENEON");
   if ((env != NULL) && (strcmp(env, "1") == 0))
-    simd_support &= JSIMD_ARM_NEON;
+    simd_support = JSIMD_ARM_NEON;
   env = getenv("JSIMD_FORCENONE");
   if ((env != NULL) && (strcmp(env, "1") == 0))
     simd_support = 0;

simd/jsimd_mips.c

@@ -2,7 +2,7 @@
  * jsimd_mips.c
  *
  * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
- * Copyright (C) 2009-2011, 2014, D. R. Commander.
+ * Copyright (C) 2009-2011, 2014, 2016, D. R. Commander.
  * Copyright (C) 2013-2014, MIPS Technologies, Inc., California.
  * Copyright (C) 2015, Matthieu Darbois.
  *
@@ -77,6 +77,14 @@ init_simd (void)
   if (!parse_proc_cpuinfo("MIPS 74K"))
     return;
 #endif
+
+  /* Force different settings through environment variables */
+  env = getenv("JSIMD_FORCEDSPR2");
+  if ((env != NULL) && (strcmp(env, "1") == 0))
+    simd_support = JSIMD_MIPS_DSPR2;
+  env = getenv("JSIMD_FORCENONE");
+  if ((env != NULL) && (strcmp(env, "1") == 0))
+    simd_support = 0;
 }
 
 static const int mips_idct_ifast_coefs[4] = {

simd/jsimd_powerpc.c

@@ -2,7 +2,7 @@
  * jsimd_powerpc.c
  *
  * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
- * Copyright (C) 2009-2011, 2014-2015, D. R. Commander.
+ * Copyright (C) 2009-2011, 2014-2016, D. R. Commander.
  * Copyright (C) 2015, Matthieu Darbois.
  *
  * Based on the x86 SIMD extension for IJG JPEG library,
@@ -22,19 +22,106 @@
 #include "../jsimddct.h"
 #include "jsimd.h"
 
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+
 static unsigned int simd_support = ~0;
 
+#if defined(__linux__) || defined(ANDROID) || defined(__ANDROID__)
+
+#define SOMEWHAT_SANE_PROC_CPUINFO_SIZE_LIMIT (1024 * 1024)
+
+LOCAL(int)
+check_feature (char *buffer, char *feature)
+{
+  char *p;
+  if (*feature == 0)
+    return 0;
+  if (strncmp(buffer, "cpu", 3) != 0)
+    return 0;
+  buffer += 3;
+  while (isspace(*buffer))
+    buffer++;
+
+  /* Check if 'feature' is present in the buffer as a separate word */
+  while ((p = strstr(buffer, feature))) {
+    if (p > buffer && !isspace(*(p - 1))) {
+      buffer++;
+      continue;
+    }
+    p += strlen(feature);
+    if (*p != 0 && !isspace(*p)) {
+      buffer++;
+      continue;
+    }
+    return 1;
+  }
+  return 0;
+}
+
+LOCAL(int)
+parse_proc_cpuinfo (int bufsize)
+{
+  char *buffer = (char *)malloc(bufsize);
+  FILE *fd;
+  simd_support = 0;
+
+  if (!buffer)
+    return 0;
+
+  fd = fopen("/proc/cpuinfo", "r");
+  if (fd) {
+    while (fgets(buffer, bufsize, fd)) {
+      if (!strchr(buffer, '\n') && !feof(fd)) {
+        /* "impossible" happened - insufficient size of the buffer! */
+        fclose(fd);
+        free(buffer);
+        return 0;
+      }
+      if (check_feature(buffer, "altivec"))
+        simd_support |= JSIMD_ALTIVEC;
+    }
+    fclose(fd);
+  }
+  free(buffer);
+  return 1;
+}
+
+#endif
+
+/*
+ * Check what SIMD accelerations are supported.
+ *
+ * FIXME: This code is racy under a multi-threaded environment.
+ */
 LOCAL(void)
 init_simd (void)
 {
   char *env = NULL;
+#if !defined(__ALTIVEC__) && (defined(__linux__) || defined(ANDROID) || defined(__ANDROID__))
+  int bufsize = 1024; /* an initial guess for the line buffer size limit */
+#endif
 
   if (simd_support != ~0U)
     return;
 
-  simd_support = JSIMD_ALTIVEC;
+  simd_support = 0;
+
+#if defined(__ALTIVEC__) || defined(__APPLE__)
+  simd_support |= JSIMD_ALTIVEC;
+#elif defined(__linux__) || defined(ANDROID) || defined(__ANDROID__)
+  while (!parse_proc_cpuinfo(bufsize)) {
+    bufsize *= 2;
+    if (bufsize > SOMEWHAT_SANE_PROC_CPUINFO_SIZE_LIMIT)
+      break;
+  }
+#endif
 
   /* Force different settings through environment variables */
+  env = getenv("JSIMD_FORCEALTIVEC");
+  if ((env != NULL) && (strcmp(env, "1") == 0))
+    simd_support = JSIMD_ALTIVEC;
   env = getenv("JSIMD_FORCENONE");
   if ((env != NULL) && (strcmp(env, "1") == 0))
     simd_support = 0;