[FFmpeg-devel] llvm failure : don't do undefined shift

matthieu castet castet.matthieu
Thu Aug 20 19:52:25 CEST 2009


the put_bits can be called with
	unsigned int bit_buf = 0;
	int bit_left = 32;
	int n = 32;
	unsigned int value = 0x1ba;

in the case of ALT_BITSTREAM_WRITER and BITSTREAM_WRITER_LE is not defined, we
will do "bit_buf<<=bit_left;"
But sizeof(bit_buf) == 32 and bit_left==32, and we are in a undefined 

I don't know how to fix this, I only found strange that we have "if (n <
bit_left) {" instead of "if (n <= bit_left) {"


[1] C99 standard, ?6.5.7
If the value of the right operand is negative or is
greater than or equal to the width of the promoted 
left operand, the behavior is undefined.

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