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| author | Andreas Rheinhardt <andreas.rheinhardt@gmail.com> | 2020-11-17 23:20:03 +0100 |
|---|---|---|
| committer | Andreas Rheinhardt <andreas.rheinhardt@gmail.com> | 2020-12-08 17:51:47 +0100 |
| commit | 22140374c8980420a3b5c65fcc11d90a04d35946 (patch) | |
| tree | d8a6033b4c4196c309c806d2e1c2b0b5143f296f | |
| parent | 73bc26acb87e0e0ff74bc26bc9d7c54eceeb0145 (diff) | |
| download | ffmpeg-22140374c8980420a3b5c65fcc11d90a04d35946.tar.gz | |
avcodec/mpegaudio_tablegen: Avoid write-only buffers
The mpegaudio_tablegen header contains code to initialize several
tables; it is included in both the fixed as well as the floating point
mpegaudio decoders and some of these tables are only used by the fixed
resp. floating point decoders; yet both types are always initialized,
leaving the compiler to figure out that one of them is unused.
GCC 9.3 fails at this (even with -O3):
$ readelf -s mpegaudiodec_fixed.o|grep _float
28: 0000000000001660 32768 OBJECT LOCAL DEFAULT 4 expval_table_float
An actually unused table (expval_table_fixed/float) of size 32KiB is kept
and initialized (the reason for this is probably that this table is read
from, namely to initialize another table: exp_table_fixed/float; of course
the float resp. fixed tables are not used in the fixed resp. floating point
decoder).
Therefore #ifdef the unneeded tables away.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
| -rw-r--r-- | libavcodec/mpegaudio_tablegen.c | 1 | ||||
| -rw-r--r-- | libavcodec/mpegaudio_tablegen.h | 18 |
2 files changed, 19 insertions, 0 deletions
diff --git a/libavcodec/mpegaudio_tablegen.c b/libavcodec/mpegaudio_tablegen.c index ede7c8e221..ec0d51c67d 100644 --- a/libavcodec/mpegaudio_tablegen.c +++ b/libavcodec/mpegaudio_tablegen.c @@ -22,6 +22,7 @@ #include <stdlib.h> #define CONFIG_HARDCODED_TABLES 0 +#define BUILD_TABLES #include "libavutil/tablegen.h" #include "mpegaudio_tablegen.h" #include "tableprint.h" diff --git a/libavcodec/mpegaudio_tablegen.h b/libavcodec/mpegaudio_tablegen.h index 0b0ea40682..dcc09e37b8 100644 --- a/libavcodec/mpegaudio_tablegen.h +++ b/libavcodec/mpegaudio_tablegen.h @@ -34,10 +34,18 @@ #else static int8_t table_4_3_exp[TABLE_4_3_SIZE]; static uint32_t table_4_3_value[TABLE_4_3_SIZE]; + +#if defined(BUILD_TABLES) || !USE_FLOATS +#define FIXED_TABLE static uint32_t exp_table_fixed[512]; static uint32_t expval_table_fixed[512][16]; +#endif + +#if defined(BUILD_TABLES) || USE_FLOATS +#define FLOAT_TABLE static float exp_table_float[512]; static float expval_table_float[512][16]; +#endif #define FRAC_BITS 23 #define IMDCT_SCALAR 1.759 @@ -79,13 +87,23 @@ static av_cold void mpegaudio_tableinit(void) exp2_val = exp2_base * exp2_lut[exponent & 3] / IMDCT_SCALAR; for (value = 0; value < 16; value++) { double f = pow43_lut[value] * exp2_val; +#ifdef FIXED_TABLE expval_table_fixed[exponent][value] = (f < 0xFFFFFFFF ? llrint(f) : 0xFFFFFFFF); +#endif +#ifdef FLOAT_TABLE expval_table_float[exponent][value] = f; +#endif } +#ifdef FIXED_TABLE exp_table_fixed[exponent] = expval_table_fixed[exponent][1]; +#endif +#ifdef FLOAT_TABLE exp_table_float[exponent] = expval_table_float[exponent][1]; +#endif } } +#undef FLOAT_TABLE +#undef FIXED_TABLE #endif /* CONFIG_HARDCODED_TABLES */ #endif /* AVCODEC_MPEGAUDIO_TABLEGEN_H */ |