[Webkit-unassigned] [Bug 163548] Air::IRC doesn't need to have a special-case for uncolored Tmps since they all get colored

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=163548

--- Comment #1 from Filip Pizlo <fpizlo at apple.com> ---
Here's a horrible bug.  Say you have a Patchpoint that late-clobbers all regs followed by a Patchpoint that wants a scratch.  If you do this, the scratch is uncolorable.

We have this bug right now because we don't have callee-save FPRs on x86.  So if you have a CCall or JS call Patchpoint followed by a Patchpoint that wants FP scratches, then the FP scratch will not get colored and it will be left as %xmm0 at the end of IRC.  That may be wrong, if the return value of the CCall or Patchpoint just before was %xmm0, for example.

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