On Fri, 2006-12-22 at 12:08 -0800, Chris Lattner wrote:
>
> +/// Four bits are used to represent the condition, as follows:
> +/// 0 A > B
> +/// 1 A == B
> +/// 2 A < B
> +/// 3 A and B are signed
> +///
> +/// S<=> Definition S<=> Definition
> +/// 0000 Always false 1000 Alwasy false
> +/// 0001 A u> B 1001 A s> B
> +/// 0010 A == B 1010 A == B
> +/// 0011 A u>= B 1011 A s>= B
> +/// 0100 A u< B 1100 A s< B
> +/// 0101 A != B 1101 A != B
> +/// 0110 A u<= B 1110 A s<= B
> +/// 0111 Always true 1111 Always true
> +///
> +static unsigned getICmpCode(const ICmpInst *ICI) {
>
>
> This table (and it's use) is not correct. It will miscompile:
>
>
> (a <u b) | (a <s b)
>
>
> You really want separate bits for s<, s>, u<, u>. In this case, you'd
> detect that the merged comparison can't be done with a single compare,
> so you give up.
I don't understand. There are separate bits for each of those.
s< = 1100
s> = 1001
u< = 0100
u> = 0001
>
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