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arm: Remove obsolete assembler implementation filter_neon.S

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This file contains hand-coded assembler implementations of the filter
functions for 32-bit Arm platforms.  These are only used when the
compiler doesn't support neon intrinsics (added to GCC 4.3 in 2008) or
is exactly GCC 4.5.4 (released 2012), both of which are sufficiently
unlikely to be true that it's fair to say the assembler is no longer
used.

This commit deletes filter_neon.S and removes the now obsolete
preprocessor logic in pngpriv.h.

Signed-off-by: Bill Roberts <bill.roberts@arm.com>
Signed-off-by: Cosmin Truta <ctruta@gmail.com>
This commit is contained in:
Ross Burton 2023-12-14 20:25:46 +00:00 committed by Cosmin Truta
parent ceed2a3cf6
commit 9e538750d9
6 changed files with 11 additions and 358 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
CMakeLists.txt
View File

@ -153,9 +153,6 @@ if(TARGET_ARCH MATCHES "^(ARM|arm|aarch)")
arm/arm_init.c
arm/filter_neon_intrinsics.c
arm/palette_neon_intrinsics.c)
if(NOT MSVC AND NOT TARGET_ARCH MATCHES "^(ARM64|arm64|aarch64)")
list(APPEND libpng_arm_sources arm/filter_neon.S)
endif()
if(PNG_ARM_NEON STREQUAL "on")
add_definitions(-DPNG_ARM_NEON_OPT=2)
elseif(PNG_ARM_NEON STREQUAL "check")

6
Makefile.am
View File

@ -107,11 +107,9 @@ libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES = png.c pngerror.c\
png.h pngconf.h pngdebug.h pnginfo.h pngpriv.h pngstruct.h pngusr.dfa
if PNG_ARM_NEON
if PNG_ARM_NEON_ASM
libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += arm/filter_neon.S
endif
libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES += arm/arm_init.c\
arm/filter_neon_intrinsics.c arm/palette_neon_intrinsics.c
arm/filter_neon_intrinsics.c \
arm/palette_neon_intrinsics.c
endif
if PNG_MIPS_MSA

56
Makefile.in
View File

@ -108,7 +108,7 @@ host_triplet = @host@
@ENABLE_TOOLS_TRUE@bin_PROGRAMS = pngfix$(EXEEXT) \
@ENABLE_TOOLS_TRUE@ png-fix-itxt$(EXEEXT)
@PNG_ARM_NEON_TRUE@am__append_2 = arm/arm_init.c\
@PNG_ARM_NEON_TRUE@ arm/filter_neon.S arm/filter_neon_intrinsics.c \
@PNG_ARM_NEON_TRUE@ arm/filter_neon_intrinsics.c \
@PNG_ARM_NEON_TRUE@ arm/palette_neon_intrinsics.c
@PNG_MIPS_MSA_TRUE@am__append_3 = mips/mips_init.c\
@ -188,13 +188,13 @@ am__libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_SOURCES_DIST = png.c \
pngrtran.c pngrutil.c pngset.c pngtrans.c pngwio.c pngwrite.c \
pngwtran.c pngwutil.c png.h pngconf.h pngdebug.h pnginfo.h \
pngpriv.h pngstruct.h pngusr.dfa arm/arm_init.c \
arm/filter_neon.S arm/filter_neon_intrinsics.c \
arm/palette_neon_intrinsics.c mips/mips_init.c \
mips/filter_msa_intrinsics.c mips/filter_mmi_inline_assembly.c \
intel/intel_init.c intel/filter_sse2_intrinsics.c \
powerpc/powerpc_init.c powerpc/filter_vsx_intrinsics.c
arm/filter_neon_intrinsics.c arm/palette_neon_intrinsics.c \
mips/mips_init.c mips/filter_msa_intrinsics.c \
mips/filter_mmi_inline_assembly.c intel/intel_init.c \
intel/filter_sse2_intrinsics.c powerpc/powerpc_init.c \
powerpc/filter_vsx_intrinsics.c
am__dirstamp = $(am__leading_dot)dirstamp
@PNG_ARM_NEON_TRUE@am__objects_1 = arm/arm_init.lo arm/filter_neon.lo \
@PNG_ARM_NEON_TRUE@am__objects_1 = arm/arm_init.lo \
@PNG_ARM_NEON_TRUE@ arm/filter_neon_intrinsics.lo \
@PNG_ARM_NEON_TRUE@ arm/palette_neon_intrinsics.lo
@PNG_MIPS_MSA_TRUE@am__objects_2 = mips/mips_init.lo \
@ -312,7 +312,7 @@ am__depfiles_remade = ./$(DEPDIR)/png.Plo ./$(DEPDIR)/pngerror.Plo \
./$(DEPDIR)/pngtest.Po ./$(DEPDIR)/pngtrans.Plo \
./$(DEPDIR)/pngwio.Plo ./$(DEPDIR)/pngwrite.Plo \
./$(DEPDIR)/pngwtran.Plo ./$(DEPDIR)/pngwutil.Plo \
arm/$(DEPDIR)/arm_init.Plo arm/$(DEPDIR)/filter_neon.Plo \
arm/$(DEPDIR)/arm_init.Plo \
arm/$(DEPDIR)/filter_neon_intrinsics.Plo \
arm/$(DEPDIR)/palette_neon_intrinsics.Plo \
contrib/libtests/$(DEPDIR)/pngimage.Po \
@ -333,16 +333,6 @@ am__depfiles_remade = ./$(DEPDIR)/png.Plo ./$(DEPDIR)/pngerror.Plo \
powerpc/$(DEPDIR)/filter_vsx_intrinsics.Plo \
powerpc/$(DEPDIR)/powerpc_init.Plo
am__mv = mv -f
CPPASCOMPILE = $(CCAS) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) \
$(AM_CPPFLAGS) $(CPPFLAGS) $(AM_CCASFLAGS) $(CCASFLAGS)
LTCPPASCOMPILE = $(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) \
$(LIBTOOLFLAGS) --mode=compile $(CCAS) $(DEFS) \
$(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) \
$(AM_CCASFLAGS) $(CCASFLAGS)
AM_V_CPPAS = $(am__v_CPPAS_@AM_V@)
am__v_CPPAS_ = $(am__v_CPPAS_@AM_DEFAULT_V@)
am__v_CPPAS_0 = @echo " CPPAS " $@;
am__v_CPPAS_1 =
COMPILE = $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) \
$(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS)
LTCOMPILE = $(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) \
@ -885,7 +875,7 @@ all: $(BUILT_SOURCES) config.h
$(MAKE) $(AM_MAKEFLAGS) all-am
.SUFFIXES:
.SUFFIXES: .chk .out .S .c .lo .log .o .obj .test .test$(EXEEXT) .trs
.SUFFIXES: .chk .out .c .lo .log .o .obj .test .test$(EXEEXT) .trs
am--refresh: Makefile
@:
$(srcdir)/Makefile.in: @MAINTAINER_MODE_TRUE@ $(srcdir)/Makefile.am $(am__configure_deps)
@ -1049,7 +1039,6 @@ arm/$(DEPDIR)/$(am__dirstamp):
@$(MKDIR_P) arm/$(DEPDIR)
@: > arm/$(DEPDIR)/$(am__dirstamp)
arm/arm_init.lo: arm/$(am__dirstamp) arm/$(DEPDIR)/$(am__dirstamp)
arm/filter_neon.lo: arm/$(am__dirstamp) arm/$(DEPDIR)/$(am__dirstamp)
arm/filter_neon_intrinsics.lo: arm/$(am__dirstamp) \
arm/$(DEPDIR)/$(am__dirstamp)
arm/palette_neon_intrinsics.lo: arm/$(am__dirstamp) \
@ -1237,7 +1226,6 @@ distclean-compile:
@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/pngwtran.Plo@am__quote@ # am--include-marker
@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/pngwutil.Plo@am__quote@ # am--include-marker
@AMDEP_TRUE@@am__include@ @am__quote@arm/$(DEPDIR)/arm_init.Plo@am__quote@ # am--include-marker
@AMDEP_TRUE@@am__include@ @am__quote@arm/$(DEPDIR)/filter_neon.Plo@am__quote@ # am--include-marker
@AMDEP_TRUE@@am__include@ @am__quote@arm/$(DEPDIR)/filter_neon_intrinsics.Plo@am__quote@ # am--include-marker
@AMDEP_TRUE@@am__include@ @am__quote@arm/$(DEPDIR)/palette_neon_intrinsics.Plo@am__quote@ # am--include-marker
@AMDEP_TRUE@@am__include@ @am__quote@contrib/libtests/$(DEPDIR)/pngimage.Po@am__quote@ # am--include-marker
@ -1264,30 +1252,6 @@ $(am__depfiles_remade):
am--depfiles: $(am__depfiles_remade)
.S.o:
@am__fastdepCCAS_TRUE@ $(AM_V_CPPAS)depbase=`echo $@ | sed 's|[^/]*$$|$(DEPDIR)/&|;s|\.o$$||'`;\
@am__fastdepCCAS_TRUE@ $(CPPASCOMPILE) -MT $@ -MD -MP -MF $$depbase.Tpo -c -o $@ $< &&\
@am__fastdepCCAS_TRUE@ $(am__mv) $$depbase.Tpo $$depbase.Po
@AMDEP_TRUE@@am__fastdepCCAS_FALSE@ $(AM_V_CPPAS)source='$<' object='$@' libtool=no @AMDEPBACKSLASH@
@AMDEP_TRUE@@am__fastdepCCAS_FALSE@ DEPDIR=$(DEPDIR) $(CCASDEPMODE) $(depcomp) @AMDEPBACKSLASH@
@am__fastdepCCAS_FALSE@ $(AM_V_CPPAS@am__nodep@)$(CPPASCOMPILE) -c -o $@ $<
.S.obj:
@am__fastdepCCAS_TRUE@ $(AM_V_CPPAS)depbase=`echo $@ | sed 's|[^/]*$$|$(DEPDIR)/&|;s|\.obj$$||'`;\
@am__fastdepCCAS_TRUE@ $(CPPASCOMPILE) -MT $@ -MD -MP -MF $$depbase.Tpo -c -o $@ `$(CYGPATH_W) '$<'` &&\
@am__fastdepCCAS_TRUE@ $(am__mv) $$depbase.Tpo $$depbase.Po
@AMDEP_TRUE@@am__fastdepCCAS_FALSE@ $(AM_V_CPPAS)source='$<' object='$@' libtool=no @AMDEPBACKSLASH@
@AMDEP_TRUE@@am__fastdepCCAS_FALSE@ DEPDIR=$(DEPDIR) $(CCASDEPMODE) $(depcomp) @AMDEPBACKSLASH@
@am__fastdepCCAS_FALSE@ $(AM_V_CPPAS@am__nodep@)$(CPPASCOMPILE) -c -o $@ `$(CYGPATH_W) '$<'`
.S.lo:
@am__fastdepCCAS_TRUE@ $(AM_V_CPPAS)depbase=`echo $@ | sed 's|[^/]*$$|$(DEPDIR)/&|;s|\.lo$$||'`;\
@am__fastdepCCAS_TRUE@ $(LTCPPASCOMPILE) -MT $@ -MD -MP -MF $$depbase.Tpo -c -o $@ $< &&\
@am__fastdepCCAS_TRUE@ $(am__mv) $$depbase.Tpo $$depbase.Plo
@AMDEP_TRUE@@am__fastdepCCAS_FALSE@ $(AM_V_CPPAS)source='$<' object='$@' libtool=yes @AMDEPBACKSLASH@
@AMDEP_TRUE@@am__fastdepCCAS_FALSE@ DEPDIR=$(DEPDIR) $(CCASDEPMODE) $(depcomp) @AMDEPBACKSLASH@
@am__fastdepCCAS_FALSE@ $(AM_V_CPPAS@am__nodep@)$(LTCPPASCOMPILE) -c -o $@ $<
.c.o:
@am__fastdepCC_TRUE@ $(AM_V_CC)depbase=`echo $@ | sed 's|[^/]*$$|$(DEPDIR)/&|;s|\.o$$||'`;\
@am__fastdepCC_TRUE@ $(COMPILE) -MT $@ -MD -MP -MF $$depbase.Tpo -c -o $@ $< &&\
@ -2196,7 +2160,6 @@ distclean: distclean-am
-rm -f ./$(DEPDIR)/pngwtran.Plo
-rm -f ./$(DEPDIR)/pngwutil.Plo
-rm -f arm/$(DEPDIR)/arm_init.Plo
-rm -f arm/$(DEPDIR)/filter_neon.Plo
-rm -f arm/$(DEPDIR)/filter_neon_intrinsics.Plo
-rm -f arm/$(DEPDIR)/palette_neon_intrinsics.Plo
-rm -f contrib/libtests/$(DEPDIR)/pngimage.Po
@ -2284,7 +2247,6 @@ maintainer-clean: maintainer-clean-am
-rm -f ./$(DEPDIR)/pngwtran.Plo
-rm -f ./$(DEPDIR)/pngwutil.Plo
-rm -f arm/$(DEPDIR)/arm_init.Plo
-rm -f arm/$(DEPDIR)/filter_neon.Plo
-rm -f arm/$(DEPDIR)/filter_neon_intrinsics.Plo
-rm -f arm/$(DEPDIR)/palette_neon_intrinsics.Plo
-rm -f contrib/libtests/$(DEPDIR)/pngimage.Po

253
arm/filter_neon.S
View File

@ -1,253 +0,0 @@
/* filter_neon.S - NEON optimised filter functions
*
* Copyright (c) 2018 Cosmin Truta
* Copyright (c) 2014,2017 Glenn Randers-Pehrson
* Written by Mans Rullgard, 2011.
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*/
/* This is required to get the symbol renames, which are #defines, and the
* definitions (or not) of PNG_ARM_NEON_OPT and PNG_ARM_NEON_IMPLEMENTATION.
*/
#define PNG_VERSION_INFO_ONLY
#include "../pngpriv.h"
#if (defined(__linux__) || defined(__FreeBSD__)) && defined(__ELF__)
.section .note.GNU-stack,"",%progbits /* mark stack as non-executable */
#endif
#ifdef PNG_READ_SUPPORTED
/* Assembler NEON support - only works for 32-bit ARM (i.e. it does not work for
* ARM64). The code in arm/filter_neon_intrinsics.c supports ARM64, however it
* only works if -mfpu=neon is specified on the GCC command line. See pngpriv.h
* for the logic which sets PNG_USE_ARM_NEON_ASM:
*/
#if PNG_ARM_NEON_IMPLEMENTATION == 2 /* hand-coded assembler */
#if PNG_ARM_NEON_OPT > 0
#ifdef __ELF__
# define ELF
#else
# define ELF @
#endif
.arch armv7-a
.fpu neon
.macro func name, export=0
.macro endfunc
ELF .size \name, . - \name
.endfunc
.purgem endfunc
.endm
.text
/* Explicitly specifying alignment here because some versions of
* GAS don't align code correctly. This is harmless in correctly
* written versions of GAS.
*/
.align 2
.if \export
.global \name
.endif
ELF .type \name, STT_FUNC
.func \name
\name:
.endm
func png_read_filter_row_sub4_neon, export=1
ldr r3, [r0, #4] @ rowbytes
vmov.i8 d3, #0
1:
vld4.32 {d4[],d5[],d6[],d7[]}, [r1,:128]
vadd.u8 d0, d3, d4
vadd.u8 d1, d0, d5
vadd.u8 d2, d1, d6
vadd.u8 d3, d2, d7
vst4.32 {d0[0],d1[0],d2[0],d3[0]},[r1,:128]!
subs r3, r3, #16
bgt 1b
bx lr
endfunc
func png_read_filter_row_sub3_neon, export=1
ldr r3, [r0, #4] @ rowbytes
vmov.i8 d3, #0
mov r0, r1
mov r2, #3
mov r12, #12
vld1.8 {q11}, [r0], r12
1:
vext.8 d5, d22, d23, #3
vadd.u8 d0, d3, d22
vext.8 d6, d22, d23, #6
vadd.u8 d1, d0, d5
vext.8 d7, d23, d23, #1
vld1.8 {q11}, [r0], r12
vst1.32 {d0[0]}, [r1,:32], r2
vadd.u8 d2, d1, d6
vst1.32 {d1[0]}, [r1], r2
vadd.u8 d3, d2, d7
vst1.32 {d2[0]}, [r1], r2
vst1.32 {d3[0]}, [r1], r2
subs r3, r3, #12
bgt 1b
bx lr
endfunc
func png_read_filter_row_up_neon, export=1
ldr r3, [r0, #4] @ rowbytes
1:
vld1.8 {q0}, [r1,:128]
vld1.8 {q1}, [r2,:128]!
vadd.u8 q0, q0, q1
vst1.8 {q0}, [r1,:128]!
subs r3, r3, #16
bgt 1b
bx lr
endfunc
func png_read_filter_row_avg4_neon, export=1
ldr r12, [r0, #4] @ rowbytes
vmov.i8 d3, #0
1:
vld4.32 {d4[],d5[],d6[],d7[]}, [r1,:128]
vld4.32 {d16[],d17[],d18[],d19[]},[r2,:128]!
vhadd.u8 d0, d3, d16
vadd.u8 d0, d0, d4
vhadd.u8 d1, d0, d17
vadd.u8 d1, d1, d5
vhadd.u8 d2, d1, d18
vadd.u8 d2, d2, d6
vhadd.u8 d3, d2, d19
vadd.u8 d3, d3, d7
vst4.32 {d0[0],d1[0],d2[0],d3[0]},[r1,:128]!
subs r12, r12, #16
bgt 1b
bx lr
endfunc
func png_read_filter_row_avg3_neon, export=1
push {r4,lr}
ldr r12, [r0, #4] @ rowbytes
vmov.i8 d3, #0
mov r0, r1
mov r4, #3
mov lr, #12
vld1.8 {q11}, [r0], lr
1:
vld1.8 {q10}, [r2], lr
vext.8 d5, d22, d23, #3
vhadd.u8 d0, d3, d20
vext.8 d17, d20, d21, #3
vadd.u8 d0, d0, d22
vext.8 d6, d22, d23, #6
vhadd.u8 d1, d0, d17
vext.8 d18, d20, d21, #6
vadd.u8 d1, d1, d5
vext.8 d7, d23, d23, #1
vld1.8 {q11}, [r0], lr
vst1.32 {d0[0]}, [r1,:32], r4
vhadd.u8 d2, d1, d18
vst1.32 {d1[0]}, [r1], r4
vext.8 d19, d21, d21, #1
vadd.u8 d2, d2, d6
vhadd.u8 d3, d2, d19
vst1.32 {d2[0]}, [r1], r4
vadd.u8 d3, d3, d7
vst1.32 {d3[0]}, [r1], r4
subs r12, r12, #12
bgt 1b
pop {r4,pc}
endfunc
.macro paeth rx, ra, rb, rc
vaddl.u8 q12, \ra, \rb @ a + b
vaddl.u8 q15, \rc, \rc @ 2*c
vabdl.u8 q13, \rb, \rc @ pa
vabdl.u8 q14, \ra, \rc @ pb
vabd.u16 q15, q12, q15 @ pc
vcle.u16 q12, q13, q14 @ pa <= pb
vcle.u16 q13, q13, q15 @ pa <= pc
vcle.u16 q14, q14, q15 @ pb <= pc
vand q12, q12, q13 @ pa <= pb && pa <= pc
vmovn.u16 d28, q14
vmovn.u16 \rx, q12
vbsl d28, \rb, \rc
vbsl \rx, \ra, d28
.endm
func png_read_filter_row_paeth4_neon, export=1
ldr r12, [r0, #4] @ rowbytes
vmov.i8 d3, #0
vmov.i8 d20, #0
1:
vld4.32 {d4[],d5[],d6[],d7[]}, [r1,:128]
vld4.32 {d16[],d17[],d18[],d19[]},[r2,:128]!
paeth d0, d3, d16, d20
vadd.u8 d0, d0, d4
paeth d1, d0, d17, d16
vadd.u8 d1, d1, d5
paeth d2, d1, d18, d17
vadd.u8 d2, d2, d6
paeth d3, d2, d19, d18
vmov d20, d19
vadd.u8 d3, d3, d7
vst4.32 {d0[0],d1[0],d2[0],d3[0]},[r1,:128]!
subs r12, r12, #16
bgt 1b
bx lr
endfunc
func png_read_filter_row_paeth3_neon, export=1
push {r4,lr}
ldr r12, [r0, #4] @ rowbytes
vmov.i8 d3, #0
vmov.i8 d4, #0
mov r0, r1
mov r4, #3
mov lr, #12
vld1.8 {q11}, [r0], lr
1:
vld1.8 {q10}, [r2], lr
paeth d0, d3, d20, d4
vext.8 d5, d22, d23, #3
vadd.u8 d0, d0, d22
vext.8 d17, d20, d21, #3
paeth d1, d0, d17, d20
vst1.32 {d0[0]}, [r1,:32], r4
vext.8 d6, d22, d23, #6
vadd.u8 d1, d1, d5
vext.8 d18, d20, d21, #6
paeth d2, d1, d18, d17
vext.8 d7, d23, d23, #1
vld1.8 {q11}, [r0], lr
vst1.32 {d1[0]}, [r1], r4
vadd.u8 d2, d2, d6
vext.8 d19, d21, d21, #1
paeth d3, d2, d19, d18
vst1.32 {d2[0]}, [r1], r4
vmov d4, d19
vadd.u8 d3, d3, d7
vst1.32 {d3[0]}, [r1], r4
subs r12, r12, #12
bgt 1b
pop {r4,pc}
endfunc
#endif /* PNG_ARM_NEON_OPT > 0 */
#endif /* PNG_ARM_NEON_IMPLEMENTATION == 2 (assembler) */
#endif /* READ */

10
configure.ac
View File

@ -425,16 +425,6 @@ AM_CONDITIONAL([PNG_ARM_NEON],
*) test "$enable_arm_neon" != '' ;;
esac])
# Add the assembler implementation source file. This only works on 32-bit
# ARM and causes problems even if empty on 64-bit ARM.
AM_CONDITIONAL([PNG_ARM_NEON_ASM],
[test "$enable_arm_neon" != 'no' &&
case "$host_cpu" in
arm64*|aarch64*) false ;;
arm*) true ;;
*) test "$enable_arm_neon" != '' ;;
esac])
# MIPS MSA
# ========

41
pngpriv.h
View File

@ -140,47 +140,6 @@
* callbacks to do this.
*/
# define PNG_FILTER_OPTIMIZATIONS png_init_filter_functions_neon
/* By default the 'intrinsics' code in arm/filter_neon_intrinsics.c is used
* if possible - if __ARM_NEON__ is set and the compiler version is not known
* to be broken. This is controlled by PNG_ARM_NEON_IMPLEMENTATION which can
* be:
*
* 1 The intrinsics code (the default with __ARM_NEON__)
* 2 The hand coded assembler (the default without __ARM_NEON__)
*
* It is possible to set PNG_ARM_NEON_IMPLEMENTATION in CPPFLAGS, however
* this is *NOT* supported and may cease to work even after a minor revision
* to libpng. It *is* valid to do this for testing purposes, e.g. speed
* testing or a new compiler, but the results should be communicated to the
* libpng implementation list for incorporation in the next minor release.
*/
# ifndef PNG_ARM_NEON_IMPLEMENTATION
# if defined(__ARM_NEON__) || defined(__ARM_NEON)
# if defined(__clang__)
/* At present it is unknown by the libpng developers which versions
* of clang support the intrinsics, however some or perhaps all
* versions do not work with the assembler so this may be
* irrelevant, so just use the default (do nothing here.)
*/
# elif defined(__GNUC__)
/* GCC 4.5.4 NEON support is known to be broken. 4.6.3 is known to
* work, so if this *is* GCC, or G++, look for a version >4.5
*/
# if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 6)
# define PNG_ARM_NEON_IMPLEMENTATION 2
# endif /* no GNUC support */
# endif /* __GNUC__ */
# else /* !defined __ARM_NEON__ */
/* The 'intrinsics' code simply won't compile without this -mfpu=neon:
*/
# if !defined(__aarch64__) && !defined(_M_ARM64)
/* The assembler code currently does not work on ARM64 */
# define PNG_ARM_NEON_IMPLEMENTATION 2
# endif /* __aarch64__ */
# endif /* __ARM_NEON__ */
# endif /* !PNG_ARM_NEON_IMPLEMENTATION */
# ifndef PNG_ARM_NEON_IMPLEMENTATION
/* Use the intrinsics code by default. */
# define PNG_ARM_NEON_IMPLEMENTATION 1