[libpng17] Port recent changes to ARM support from libpng-1.6.3beta07.

ANNOUNCE

@@ -1,5 +1,5 @@
 
-Libpng 1.7.0beta14 - June 6, 2013
+Libpng 1.7.0beta14 - June 8, 2013
 
 This is not intended to be a public release.  It will be replaced
 within a few weeks by a public version or by another test version.
@@ -304,7 +304,7 @@ Version 1.7.0beta13 [May 12, 2013]
   Added information in the documentation about problems with and fixes for
     the bad CRC and bad iTXt chunk situations.
 
-Version 1.7.0beta14 [June 6, 2013]
+Version 1.7.0beta14 [June 8, 2013]
   Removed a redundant test in png_set_IHDR().
   Added set(CMAKE_CONFIGURATION_TYPES ...) to CMakeLists.txt (Andrew Hundt)
   Deleted set(CMAKE_BUILD_TYPE) block from CMakeLists.txt
@@ -312,6 +312,21 @@ Version 1.7.0beta14 [June 6, 2013]
   Make ARM NEON support work at compile time (not just configure time).
     This moves the test on __ARM_NEON__ into pngconf.h to avoid issues when
     using a compiler that compiles for multiple architectures at one time.
+  Removed PNG_FILTER_OPTIMIZATIONS and PNG_ARM_NEON_SUPPORTED from
+    pnglibconf.h, allowing more of the decisions to be made internally
+    (pngpriv.h) during the compile.  Without this, symbol prefixing is broken
+    under certain circumstances on ARM platforms.  Now only the API parts of
+    the optimizations ('check' vs 'api') are exposed in the public header files
+    except that the new setting PNG_ARM_NEON_OPT documents how libpng makes the
+    decision about whether or not to use the optimizations.
+  Protect symbol prefixing against CC/CPPFLAGS/CFLAGS useage.
+    Previous iOS/Xcode fixes for the ARM NEON optimizations moved the test
+    on __ARM_NEON__ from configure time to compile time.  This breaks symbol
+    prefixing because the definition of the special png_init_filter_functions
+    call was hidden at configure time if the relevant compiler arguments are
+    passed in CFLAGS as opposed to CC.  This change attempts to avoid all
+    the confusion that would result by declaring the init function even when
+    it is not used, so that it will always get prefixed.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

CHANGES

@@ -4592,7 +4592,7 @@ Version 1.7.0beta13 [May 12, 2013]
   Added information in the documentation about problems with and fixes for
     the bad CRC and bad iTXt chunk situations.
 
-Version 1.7.0beta14 [June 6, 2013]
+Version 1.7.0beta14 [June 8, 2013]
   Removed a redundant test in png_set_IHDR().
   Added set(CMAKE_CONFIGURATION_TYPES ...) to CMakeLists.txt (Andrew Hundt)
   Deleted set(CMAKE_BUILD_TYPE) block from CMakeLists.txt
@@ -4600,6 +4600,21 @@ Version 1.7.0beta14 [June 6, 2013]
   Make ARM NEON support work at compile time (not just configure time).
     This moves the test on __ARM_NEON__ into pngconf.h to avoid issues when
     using a compiler that compiles for multiple architectures at one time.
+  Removed PNG_FILTER_OPTIMIZATIONS and PNG_ARM_NEON_SUPPORTED from
+    pnglibconf.h, allowing more of the decisions to be made internally
+    (pngpriv.h) during the compile.  Without this, symbol prefixing is broken
+    under certain circumstances on ARM platforms.  Now only the API parts of
+    the optimizations ('check' vs 'api') are exposed in the public header files
+    except that the new setting PNG_ARM_NEON_OPT documents how libpng makes the
+    decision about whether or not to use the optimizations.
+  Protect symbol prefixing against CC/CPPFLAGS/CFLAGS useage.
+    Previous iOS/Xcode fixes for the ARM NEON optimizations moved the test
+    on __ARM_NEON__ from configure time to compile time.  This breaks symbol
+    prefixing because the definition of the special png_init_filter_functions
+    call was hidden at configure time if the relevant compiler arguments are
+    passed in CFLAGS as opposed to CC.  This change attempts to avoid all
+    the confusion that would result by declaring the init function even when
+    it is not used, so that it will always get prefixed.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

arm/arm_init.c

@@ -16,7 +16,7 @@
 
 #include "../pngpriv.h"
 
-#ifdef PNG_ARM_NEON_SUPPORTED
+#if PNG_ARM_NEON_OPT > 0
 #ifdef PNG_ARM_NEON_CHECK_SUPPORTED /* Do run-time checks */
 #include <signal.h> /* for sig_atomic_t */
 
@@ -216,4 +216,4 @@ png_init_filter_functions_neon(png_structp pp, unsigned int bpp)
           png_read_filter_row_paeth4_neon;
    }
 }
-#endif /* PNG_ARM_NEON_SUPPORTED */
+#endif /* PNG_ARM_NEON_OPT > 0 */

arm/filter_neon.S

@@ -11,7 +11,7 @@
  */
 
 /* This is required to get the symbol renames, which are #defines, and also
- * includes the definition (or not) of PNG_ARM_NEON_SUPPORTED.
+ * includes the definition (or not) of PNG_ARM_NEON_OPT.
  */
 #define PNG_VERSION_INFO_ONLY
 #include "../pngpriv.h"
@@ -20,7 +20,7 @@
 .section .note.GNU-stack,"",%progbits /* mark stack as non-executable */
 #endif
 
-#ifdef PNG_ARM_NEON_SUPPORTED
+#if PNG_ARM_NEON_OPT > 0
 
 #ifdef __ELF__
 #   define ELF
@@ -232,4 +232,4 @@ func    png_read_filter_row_paeth3_neon, export=1
 
         pop             {r4,pc}
 endfunc
-#endif /* PNG_ARM_NEON_SUPPORTED */
+#endif /* PNG_ARM_NEON_OPT > 0 */

configure.ac

@@ -352,7 +352,7 @@ AC_ARG_ENABLE([arm-neon],
    [case "$enableval" in
       no|off)
          # disable the default enabling on __ARM_NEON__ systems:
-         AC_DEFINE([PNG_ARM_NEON_NOT_SUPPORTED], [],
+         AC_DEFINE([PNG_ARM_NEON_OPT], [0],
                    [Disable ARM Neon optimizations])
          # Prevent inclusion of the assembler files below:
          enable_arm_neon=no;;
@@ -363,8 +363,11 @@ AC_ARG_ENABLE([arm-neon],
          AC_DEFINE([PNG_ARM_NEON_API_SUPPORTED], [],
                    [Turn on ARM Neon optimizations at run-time]);;
       yes|on)
-         AC_DEFINE([PNG_ARM_NEON_SUPPORTED], [],
+         AC_DEFINE([PNG_ARM_NEON_OPT], [2],
-                   [Enable ARM Neon optimizations]);;
+                   [Enable ARM Neon optimizations])
+         AC_MSG_WARN([--enable-arm-neon: please specify 'check' or 'api', if]
+            [you want the optimizations unconditionally pass -mfpu=neon]
+            [to the compiler.]);;
       *)
          AC_MSG_ERROR([--enable-arm-neon=${enable_arm_neon}: invalid value])
    esac])

pngconf.h

@@ -1,7 +1,7 @@
 
 /* pngconf.h - machine configurable file for libpng
  *
- * libpng version 1.7.0beta14 - June 6, 2013
+ * libpng version 1.7.0beta14 - June 8, 2013
  *
  * Copyright (c) 1998-2013 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -194,30 +194,6 @@
  *                PNG_USE_DLL is set.
  */
 
-/* Compile time options.
- * =====================
- * In a multi-arch build the compiler may compile the code several times for the
- * same object module, producing different codes for different architectures.
- * When this happens configure-time setting of the target host options cannot be
- * done and this interferes with the handling of the ARM NEON optimizations, and
- * possibly other similiar optimizations.  Put additional tests here; in general
- * this is needed when the same option can be changed at both compile time and
- * run time depending on the target OS (i.e. iOS vs Android.)
- */
-#ifdef __ARM_NEON__
-   /* If the default below causes problems set PNG_ARM_NEON_NOT_SUPPORTED either
-    * by passing --enable-arm-neon=no to configure or setting it in some other
-    * way when pnglibconf.h is built.
-    */
-#  if (!defined PNG_ARM_NEON_SUPPORTED) && (!defined PNG_ARM_NEON_NOT_SUPPORTED)
-#     define PNG_ARM_NEON_SUPPORTED
-#  endif
-#endif
-
-#if (defined PNG_ARM_NEON_SUPPORTED) && (defined PNG_ARM_NEON_NOT_SUPPORTED)
-#  error configuration: ARM_NEON cannot both be supported and disabled
-#endif
-
 /* System specific discovery.
  * ==========================
  * This code is used at build time to find PNG_IMPEXP, the API settings

pngpriv.h

@@ -125,6 +125,46 @@
 
 #endif /* VERSION_INFO_ONLY */
 
+/* Compile time options.
+ * =====================
+ * In a multi-arch build the compiler may compile the code several times for the
+ * same object module, producing different binaries for different architectures.
+ * When this happens configure-time setting of the target host options cannot be
+ * done and this interferes with the handling of the ARM NEON optimizations, and
+ * possibly other similiar optimizations.  Put additional tests here; in general
+ * this is needed when the same option can be changed at both compile time and
+ * run time depending on the target OS (i.e. iOS vs Android.)
+ *
+ * NOTE: symbol prefixing does not pass $(CFLAGS) to the preprocessor, because
+ * this is not possible with certain compilers (Oracle SUN OS CC), as a result
+ * it is necessary to ensure that all extern functions that *might* be used
+ * regardless of $(CFLAGS) get declared in this file.  The test on __ARM_NEON__
+ * below is one example of this behavior because it is controlled by the
+ * presence or not of -mfpu=neon on the GCC command line, it is possible to do
+ * this in $(CC), e.g. "CC=gcc -mfpu=neon", but people who build libpng rarely
+ * do this.
+ */
+#ifndef PNG_ARM_NEON_OPT
+   /* ARM NEON optimizations are being controlled by the compiler settings,
+    * typically the target FPU.  If the FPU has been set to NEON (-mfpu=neon
+    * with GCC) then the compiler will define __ARM_NEON__ and we can rely
+    * unconditionally on NEON instructions not crashing, otherwise we must
+    * disable use of NEON instructions:
+    */
+#  ifdef __ARM_NEON__
+#     define PNG_ARM_NEON_OPT 2
+#  else
+#     define PNG_ARM_NEON_OPT 0
+#  endif
+#endif
+
+#if PNG_ARM_NEON_OPT > 0
+   /* NEON optimizations are to be at least considered by libpng, enable the
+    * callbacks to do this.
+    */
+#  define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_neon
+#endif
+
 /* Is this a build of a DLL where compilation of the object modules requires
  * different preprocessor settings to those required for a simple library?  If
  * so PNG_BUILD_DLL must be set.
@@ -1848,14 +1888,22 @@ PNG_INTERNAL_FUNCTION(void, png_image_free, (png_imagep image), PNG_EMPTY);
 
 #endif /* SIMPLIFIED READ/WRITE */
 
+/* These are initialization functions for hardware specific PNG filter
+ * optimizations; list these here then select the appropriate one at compile
+ * time using the macro PNG_FILTER_OPTIMIZATIONS.  If the macro is not defined
+ * the generic code is used.
+ */
 #ifdef PNG_FILTER_OPTIMIZATIONS
 PNG_INTERNAL_FUNCTION(void, PNG_FILTER_OPTIMIZATIONS, (png_structrp png_ptr,
-    unsigned int bpp), PNG_EMPTY);
+   unsigned int bpp), PNG_EMPTY);
-   /* This is the initialization function for hardware specific optimizations,
+   /* Just declare the optimization that will be used */
-    * one implementation (for ARM NEON machines) is contained in
+#else
-    * arm/filter_neon.c.  It need not be defined - the generic code will be used
+   /* List *all* the possible optimizations here - this branch is required if
-    * if not.
+    * the builder of libpng passes the definition of PNG_FILTER_OPTIMIZATIONS in
+    * CFLAGS in place of CPPFLAGS *and* uses symbol prefixing.
     */
+PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_neon,
+   (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
 #endif
 
 /* Maintainer: Put new private prototypes here ^ */

scripts/pnglibconf.dfa

@@ -126,7 +126,7 @@ logunsupported = 1
 #
 # If you create a private DLL you need to define the following
 # macros in the file 'pngusr.h' and set -DPNG_USER_CONFIG for
-# compilation (i.e. in CFLAGS.)
+# compilation (i.e. in CPPFLAGS.)
 # #define PNG_USER_PRIVATEBUILD \
 #     <Describes by whom and why this version of the DLL was built>
 #  e.g. #define PNG_USER_PRIVATEBUILD "Build by MyCompany for xyz reasons."
@@ -216,35 +216,41 @@ setting ZLIB_HEADER default <zlib.h>
 # include the file too, so that the defaults below are known
 @#  include <zlib.h>
 
-# This setting allows a hardware or configuration specific filter optimization
-# function to be specified, the argument is the name of the filter initializaion
-# function to use.
-
-setting FILTER_OPTIMIZATIONS
-
 # Implementation specific control of the optimizations, enabled by those
 # hardware or software options that need it (typically when run-time choices
 # must be made by the user)
 option SET_OPTION disabled
 
-# These options are specific to the ARM NEON hardware optimizations:
+# These options are specific to the ARM NEON hardware optimizations.  At present
+# these optimizations depend on GCC specific pre-processing of an assembler (.S)
+# file so they probably won't work with other compilers.
 #
-# ARM_NEON: the optimization itself
+# ARM_NEON_OPT: unset: check at compile time (__ARM_NEON__ must be defined by
-# ARM_NEON_NOT: disable the optimization even on systems that apparently support
+#                      the compiler, typically as a result of specifying
-#               it (where the compiler defines __ARM_NEON__).
+#                      CC="gcc -mfpu=neon".)
-# ARM_NEON_API: allow the optimization to be switched on with png_set_hardware
+#                   0: disable (even if the CPU has a NEON FPU.)
-# ARM_NEON_CHECK: compile a run-time check to see if Neon extensions are
+#                   1: check at run time (via ARM_NEON_{API,CHECK})
-setting ZLIB_VERNUM default @ZLIB_VERNUM
+#                   2: switch on unconditionally (inadvisable - instead pass
-#                 supported, this is poorly supported and deprectated - use the
+#                      -mfpu=neon to GCC in CC)
-#                 png_set_hardware API.
+#           When building libpng avoid using any setting other than '0'; '1' is
-option ARM_NEON disabled,
+#           set automatically when either 'API' or 'CHECK' are configured in,
-   sets FILTER_OPTIMIZATIONS png_init_filter_functions_neon
+#           '2' should not be necessary as -mfpu=neon will achieve the same
-option ARM_NEON_NOT disabled
+#           effect as well as applying NEON optimizations to the rest of the
-option ARM_NEON_API disabled enables SET_OPTION ARM_NEON
+#           libpng code.
-option ARM_NEON_CHECK disabled enables ARM_NEON
+#           NOTE: any setting other than '0' requires ALIGNED_MEMORY
+# ARM_NEON_API:   (PNG_ARM_NEON == 1) allow the optimization to be switched on
+#                 with png_set_option
+# ARM_NEON_CHECK: (PNG_ARM_NEON == 1) compile a run-time check to see if Neon
+#                 extensions are supported, this is poorly supported and
+#                 deprectated - use the png_set_option API.
+setting ARM_NEON_OPT
+option ARM_NEON_API disabled requires ALIGNED_MEMORY enables SET_OPTION,
+   sets ARM_NEON_OPT 1
+option ARM_NEON_CHECK disabled requires ALIGNED_MEMORY,
+   sets ARM_NEON_OPT 1
 
 # These settings configure the default compression level (0-9) and 'strategy';
-# strategy is as defined by the implementors of zlib, it describes the input
+# strategy is as defined by the implementors of zlib. It describes the input
 # data and modifies the zlib parameters in an attempt to optimize the balance
 # between search and huffman encoding in the zlib algorithms.  The defaults are
 # the zlib.h defaults - the apparently recursive definition does not arise
@@ -253,6 +259,7 @@ option ARM_NEON_CHECK disabled enables ARM_NEON
 # The TEXT values are the defaults when writing compressed text (all forms)
 
 # The '@' here means to substitute the value when pnglibconf.h is built
+setting ZLIB_VERNUM default @ZLIB_VERNUM
 setting Z_DEFAULT_COMPRESSION default @Z_DEFAULT_COMPRESSION
 # TODO: why aren't these Z_RLE; zlib.h says that Z_RLE, specifically, is
 # appropriate for PNG images, maybe it doesn't exist in all versions?

scripts/pnglibconf.h.prebuilt

@@ -2,7 +2,7 @@
 
 /* pnglibconf.h - library build configuration */
 
-/* Libpng version 1.7.0beta14 - May 13, 2013 */
+/* Libpng version 1.7.0beta14 - June 8, 2013 */
 
 /* Copyright (c) 1998-2013 Glenn Randers-Pehrson */
 
@@ -20,7 +20,6 @@
 #define PNG_ALIGNED_MEMORY_SUPPORTED
 /*#undef PNG_ARM_NEON_API_SUPPORTED*/
 /*#undef PNG_ARM_NEON_CHECK_SUPPORTED*/
-/*#undef PNG_ARM_NEON_SUPPORTED*/
 #define PNG_BENIGN_ERRORS_SUPPORTED
 #define PNG_BENIGN_READ_ERRORS_SUPPORTED
 /*#undef PNG_BENIGN_WRITE_ERRORS_SUPPORTED*/