于 2020年6月9日 GMT+08:00 下午1:43:58, Shiyou Yin <yinshiyou...@loongson.cn> 写到: >>-----Original Message----- >>From: jiaxun.y...@flygoat.com [mailto:jiaxun.y...@flygoat.com] >>Sent: Tuesday, June 9, 2020 2:03 AM >>To: FFmpeg development discussions and patches; Shiyou Yin; 'FFmpeg >>development discussions and >>patches' >>Subject: Re: [FFmpeg-devel] [PATCH v4 2/4] libavutils: Add parse_r helper for >>MIPS >> >> >> >>于 2020年6月8日 GMT+08:00 下午4:38:58, Shiyou Yin <yinshiyou...@loongson.cn> 写到: >>>>-----Original Message----- >>>>From: ffmpeg-devel-boun...@ffmpeg.org >>>>[mailto:ffmpeg-devel-boun...@ffmpeg.org] On Behalf Of >>>>Jiaxun Yang >>>>Sent: Monday, June 8, 2020 11:30 AM >>>>To: ffmpeg-devel@ffmpeg.org >>>>Cc: yinshi...@loongson.cn; Jiaxun Yang >>>>Subject: [FFmpeg-devel] [PATCH v4 2/4] libavutils: Add parse_r helper for >>>>MIPS >>>> >> >>[...] >> >>>In inline assembler, we can add asmSymbolicName in Input/ Output Operands, >>>format: >>>[ [asmSymbolicName] ] constraint (cExpression) >>>[ [asmSymbolicName] ] constraint (cVariableName) >> >>Could you expand it? >>I'm not really sure how that related to our case. >> >>I'm trying to use raw opcode in inline assembly and I need >>this helper to deal with oprands in raw opcode. >> >>Thanks! >> > >For the raw opcode case, another proposal for your reference. >static uint32_t read_cpucfg_2(uint32_t reg) >{ > register uint32_t input __asm__ ("t0") = reg; > register uint32_t __res __asm__ ("t1") = 0; > __asm__ volatile( > ".insn \n\t" > ".word (0xc9084918) \n\t" > ); > return __res;
Actually this is not always safe. t0 and t1 might be clobbered by compiler optimization. >} I need this helper to ensure the register usage is guarded by compiler's allocation system. > -- Jiaxun Yang _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
