On 2017-04-15 14:29, Ronald S. Bultje wrote: > Hi, > > On Fri, Apr 14, 2017 at 9:46 PM, James Darnley <jdarn...@obe.tv> wrote: > >> The labels get stripped leading to (slightly) nicer disassembly from >> objdump. >> --- >> libavcodec/x86/h264_idct.asm | 24 ++++++++++++------------ >> 1 file changed, 12 insertions(+), 12 deletions(-) >> >> diff --git a/libavcodec/x86/h264_idct.asm b/libavcodec/x86/h264_idct.asm >> index 878ff02..dde40e9 100644 >> --- a/libavcodec/x86/h264_idct.asm >> +++ b/libavcodec/x86/h264_idct.asm >> @@ -846,7 +846,7 @@ h264_add8x4_idct_sse2: >> %macro add16_sse2_cycle 2 >> movzx r0, word [r4+%2] >> test r0, r0 >> - jz .cycle%1end >> + jz %%skip > > > So I've thought about it some more. I think I'd first need to understand > what you're doing here and why. > > It seems to me that the issue you're trying to address is that when you > look at disassembly (in e.g. a debugger or objdump), it goes from label to > label (where function entry is also a label), and so every function-local > label means disassembly is cut off as a block, right? (Each block then > represents a jump target or loop or something like that.) > > And you don't like that, so you're getting rid of the labels, right?
Yes. I didn't like that because the function I was looking at had (I think) 16 labels showing in objdump output. Strictly speaking, I'm not getting rid of the labels but just changing them into a format that lets STRIP strip them. Make will run STRIP to strip labels that begin ..@ (if configure has determined that your STRIP supports it). Usually I don't have a problem with labels representing a loop (or 2 nested ones) because it makes it easy to see where the code jumps back to. > So, if all of this is correct, then I agree that the output of tools like > debugger/objdump is irritating. In fact, it has irritated me forever in any > codec's DSP functions. But it also seems like we're moving away from a de > facto convention if we don't use dot-labels anymore. If we do it for > h264_idct, we should do it everywhere (for consistency). Is that what > people want? Maybe we should follow convention and fix objdump to include > all dot labels in a block if a CLI option is provided? ... I don't know what to say. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
