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[libpng16] Added a work around for GCC 4.2 optimization bug

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John Bowler 2012-09-06 15:47:49 -05:00 committed by Glenn Randers-Pehrson
parent b257147015
commit 48cbba8e8e
3 changed files with 21 additions and 8 deletions
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1
ANNOUNCE
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@ -514,6 +514,7 @@ Version 1.6.0beta30 [September 6, 2012]
elements of the png_icc_matrix and png_icc_vector types. The accidental
(harmless) 'const' previously applied to the parameters of two of the
functions have also been removed.
Added a work around for GCC 4.2 optimiztion bug
Send comments/corrections/commendations to png-mng-implement at lists.sf.net
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1
CHANGES
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@ -4266,6 +4266,7 @@ Version 1.6.0beta30 [September 6, 2012]
elements of the png_icc_matrix and png_icc_vector types. The accidental
(harmless) 'const' previously applied to the parameters of two of the
functions have also been removed.
Added a work around for GCC 4.2 optimiztion bug
Send comments/corrections/commendations to png-mng-implement at lists.sf.net
(subscription required; visit

27
png.c
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@ -2155,15 +2155,26 @@ png_find_icc_tag(png_const_bytep profile, png_uint_32 tag, png_uint_32p length)
* png_int_32)[], not (const (png_int_32[])), consequently a compiler may object
* to passing a (png_int_32[]) (which does not have const elements).
*/
typedef png_int_32 png_icc_vector[3];
typedef png_int_32 (*PNG_RESTRICT png_icc_vectorrp)[3];
typedef const png_int_32 (*PNG_RESTRICT png_const_icc_vectorrp)[3];
#define png_cpv(vector) png_constcast(const png_icc_vector*,&vector)
#if __GNUC__ == 4 && __GNUC_MINOR__ == 2
/* GCC 4.2 has an optimization bug which means that if this code is compiled
* with any optimization (i.e. not -O0) it somehow manages to make casts to
* png_const_icc_matrixrp not work in some cases and so warns for some
* function calls. This works round the problem without harming optimization
* with other compilers.
*/
# define PNG_ICC_CONST
#else
# define PNG_ICC_CONST const
#endif
typedef png_int_32 png_icc_vector[3];
typedef png_int_32 (*PNG_RESTRICT png_icc_vectorrp)[3];
typedef PNG_ICC_CONST png_int_32 (*PNG_RESTRICT png_const_icc_vectorrp)[3];
#define png_cpv(vector) png_constcast(PNG_ICC_CONST png_icc_vector*,&vector)
typedef png_int_32 png_icc_matrix[3][3];
typedef png_int_32 (*PNG_RESTRICT png_icc_matrixrp)[3][3];
typedef const png_int_32 (*PNG_RESTRICT png_const_icc_matrixrp)[3][3];
#define png_cpm(matrix) png_constcast(const png_icc_matrix*,&matrix)
typedef png_int_32 png_icc_matrix[3][3];
typedef png_int_32 (*PNG_RESTRICT png_icc_matrixrp)[3][3];
typedef PNG_ICC_CONST png_int_32 (*PNG_RESTRICT png_const_icc_matrixrp)[3][3];
#define png_cpm(matrix) png_constcast(PNG_ICC_CONST png_icc_matrix*,&matrix)
/* These two painfully complex routines are to detect under or overflow on
* addition or subtraction of two 32-bit signed integers. There's probably a