[FFmpeg-devel,07/11] cbs: Remove useless initializations

Submitted by Andreas Rheinhardt on May 22, 2019, 1:04 a.m.

Details

Message ID 20190522010441.44257-8-andreas.rheinhardt@gmail.com
State New
Headers show

Commit Message

Andreas Rheinhardt May 22, 2019, 1:04 a.m.
Up until now, a temporary variable was used and initialized every time a
value was read in CBS; if reading turned out to be successfull, this
value was overwritten (without having ever been looked at) with the
value read if reading was successfull; on failure the variable wasn't
touched either. Therefore these initializations can be and have been
removed.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
---
 libavcodec/cbs_av1.c   | 14 +++++++-------
 libavcodec/cbs_h2645.c |  8 ++++----
 libavcodec/cbs_jpeg.c  |  2 +-
 libavcodec/cbs_mpeg2.c |  2 +-
 libavcodec/cbs_vp9.c   |  8 ++++----
 5 files changed, 17 insertions(+), 17 deletions(-)

Comments

Mark Thompson May 28, 2019, 11:12 p.m.
On 22/05/2019 02:04, Andreas Rheinhardt wrote:
> Up until now, a temporary variable was used and initialized every time a
> value was read in CBS; if reading turned out to be successfull, this
> value was overwritten (without having ever been looked at) with the
> value read if reading was successfull; on failure the variable wasn't
> touched either. Therefore these initializations can be and have been
> removed.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
> ---
>  libavcodec/cbs_av1.c   | 14 +++++++-------
>  libavcodec/cbs_h2645.c |  8 ++++----
>  libavcodec/cbs_jpeg.c  |  2 +-
>  libavcodec/cbs_mpeg2.c |  2 +-
>  libavcodec/cbs_vp9.c   |  8 ++++----
>  5 files changed, 17 insertions(+), 17 deletions(-)

IIRC this was from a broken warning in an older compiler (when you get a separate warning for every syntax element it's not particularly helpful to argue that the compiler is wrong).  I'll see if I can dig up the case this happened in, it probably doesn't apply everywhere and might be worth dropping anyway.

- Mark

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diff --git a/libavcodec/cbs_av1.c b/libavcodec/cbs_av1.c
index eb2d03ef43..e31fc0c411 100644
--- a/libavcodec/cbs_av1.c
+++ b/libavcodec/cbs_av1.c
@@ -574,7 +574,7 @@  static size_t cbs_av1_get_payload_bytes_left(GetBitContext *gbc)
 #define RWContext GetBitContext
 
 #define xf(width, name, var, range_min, range_max, subs, ...) do { \
-        uint32_t value = range_min; \
+        uint32_t value; \
         CHECK(ff_cbs_read_unsigned(ctx, rw, width, #name, \
                                    SUBSCRIPTS(subs, __VA_ARGS__), \
                                    &value, range_min, range_max)); \
@@ -582,7 +582,7 @@  static size_t cbs_av1_get_payload_bytes_left(GetBitContext *gbc)
     } while (0)
 
 #define xsu(width, name, var, subs, ...) do { \
-        int32_t value = 0; \
+        int32_t value; \
         CHECK(ff_cbs_read_signed(ctx, rw, width, #name, \
                                  SUBSCRIPTS(subs, __VA_ARGS__), &value, \
                                  MIN_INT_BITS(width), \
@@ -591,27 +591,27 @@  static size_t cbs_av1_get_payload_bytes_left(GetBitContext *gbc)
     } while (0)
 
 #define uvlc(name, range_min, range_max) do { \
-        uint32_t value = range_min; \
+        uint32_t value; \
         CHECK(cbs_av1_read_uvlc(ctx, rw, #name, \
                                 &value, range_min, range_max)); \
         current->name = value; \
     } while (0)
 
 #define ns(max_value, name, subs, ...) do { \
-        uint32_t value = 0; \
+        uint32_t value; \
         CHECK(cbs_av1_read_ns(ctx, rw, max_value, #name, \
                               SUBSCRIPTS(subs, __VA_ARGS__), &value)); \
         current->name = value; \
     } while (0)
 
 #define increment(name, min, max) do { \
-        uint32_t value = 0; \
+        uint32_t value; \
         CHECK(cbs_av1_read_increment(ctx, rw, min, max, #name, &value)); \
         current->name = value; \
     } while (0)
 
 #define subexp(name, max, subs, ...) do { \
-        uint32_t value = 0; \
+        uint32_t value; \
         CHECK(cbs_av1_read_subexp(ctx, rw, max, #name, \
                                   SUBSCRIPTS(subs, __VA_ARGS__), &value)); \
         current->name = value; \
@@ -629,7 +629,7 @@  static size_t cbs_av1_get_payload_bytes_left(GetBitContext *gbc)
     } while (0)
 
 #define leb128(name) do { \
-        uint64_t value = 0; \
+        uint64_t value; \
         CHECK(cbs_av1_read_leb128(ctx, rw, #name, &value)); \
         current->name = value; \
     } while (0)
diff --git a/libavcodec/cbs_h2645.c b/libavcodec/cbs_h2645.c
index 319202fc48..8655d8015e 100644
--- a/libavcodec/cbs_h2645.c
+++ b/libavcodec/cbs_h2645.c
@@ -290,28 +290,28 @@  static int cbs_write_se_golomb(CodedBitstreamContext *ctx, PutBitContext *pbc,
 #define RWContext GetBitContext
 
 #define xu(width, name, var, range_min, range_max, subs, ...) do { \
-        uint32_t value = range_min; \
+        uint32_t value; \
         CHECK(ff_cbs_read_unsigned(ctx, rw, width, #name, \
                                    SUBSCRIPTS(subs, __VA_ARGS__), \
                                    &value, range_min, range_max)); \
         var = value; \
     } while (0)
 #define xue(name, var, range_min, range_max, subs, ...) do { \
-        uint32_t value = range_min; \
+        uint32_t value; \
         CHECK(cbs_read_ue_golomb(ctx, rw, #name, \
                                  SUBSCRIPTS(subs, __VA_ARGS__), \
                                  &value, range_min, range_max)); \
         var = value; \
     } while (0)
 #define xi(width, name, var, range_min, range_max, subs, ...) do { \
-        int32_t value = range_min; \
+        int32_t value; \
         CHECK(ff_cbs_read_signed(ctx, rw, width, #name, \
                                  SUBSCRIPTS(subs, __VA_ARGS__), \
                                  &value, range_min, range_max)); \
         var = value; \
     } while (0)
 #define xse(name, var, range_min, range_max, subs, ...) do { \
-        int32_t value = range_min; \
+        int32_t value; \
         CHECK(cbs_read_se_golomb(ctx, rw, #name, \
                                  SUBSCRIPTS(subs, __VA_ARGS__), \
                                  &value, range_min, range_max)); \
diff --git a/libavcodec/cbs_jpeg.c b/libavcodec/cbs_jpeg.c
index b74747cbbf..f7e5454d82 100644
--- a/libavcodec/cbs_jpeg.c
+++ b/libavcodec/cbs_jpeg.c
@@ -45,7 +45,7 @@ 
 #define FUNC(name) cbs_jpeg_read_ ## name
 
 #define xu(width, name, range_min, range_max, subs, ...) do { \
-        uint32_t value = range_min; \
+        uint32_t value; \
         CHECK(ff_cbs_read_unsigned(ctx, rw, width, #name, \
                                    SUBSCRIPTS(subs, __VA_ARGS__), \
                                    &value, range_min, range_max)); \
diff --git a/libavcodec/cbs_mpeg2.c b/libavcodec/cbs_mpeg2.c
index df2e818f07..0110dc0e03 100644
--- a/libavcodec/cbs_mpeg2.c
+++ b/libavcodec/cbs_mpeg2.c
@@ -57,7 +57,7 @@ 
 #define RWContext GetBitContext
 
 #define xui(width, name, var, range_min, range_max, subs, ...) do { \
-        uint32_t value = 0; \
+        uint32_t value; \
         CHECK(ff_cbs_read_unsigned(ctx, rw, width, #name, \
                                    SUBSCRIPTS(subs, __VA_ARGS__), \
                                    &value, range_min, range_max)); \
diff --git a/libavcodec/cbs_vp9.c b/libavcodec/cbs_vp9.c
index 0b5f137ed8..fea0c8f17e 100644
--- a/libavcodec/cbs_vp9.c
+++ b/libavcodec/cbs_vp9.c
@@ -267,14 +267,14 @@  static int cbs_vp9_write_le(CodedBitstreamContext *ctx, PutBitContext *pbc,
 #define RWContext GetBitContext
 
 #define xf(width, name, var, subs, ...) do { \
-        uint32_t value = 0; \
+        uint32_t value; \
         CHECK(ff_cbs_read_unsigned(ctx, rw, width, #name, \
                                    SUBSCRIPTS(subs, __VA_ARGS__), \
                                    &value, 0, (1 << width) - 1)); \
         var = value; \
     } while (0)
 #define xs(width, name, var, subs, ...) do { \
-        int32_t value = 0; \
+        int32_t value; \
         CHECK(cbs_vp9_read_s(ctx, rw, width, #name, \
                              SUBSCRIPTS(subs, __VA_ARGS__), &value)); \
         var = value; \
@@ -282,7 +282,7 @@  static int cbs_vp9_write_le(CodedBitstreamContext *ctx, PutBitContext *pbc,
 
 
 #define increment(name, min, max) do { \
-        uint32_t value = 0; \
+        uint32_t value; \
         CHECK(cbs_vp9_read_increment(ctx, rw, min, max, #name, &value)); \
         current->name = value; \
     } while (0)
@@ -315,7 +315,7 @@  static int cbs_vp9_write_le(CodedBitstreamContext *ctx, PutBitContext *pbc,
     } while (0)
 
 #define fixed(width, name, value) do { \
-        av_unused uint32_t fixed_value = value; \
+        av_unused uint32_t fixed_value; \
         CHECK(ff_cbs_read_unsigned(ctx, rw, width, #name, \
                                    0, &fixed_value, value, value)); \
     } while (0)