[PATCH] Replace uint64_t representation of Features with FeatureBitset (std::bitset) in a few more places

[Michael Kuperstein]

Hm. I've read the patch more carefully, and I'm actually somewhat confused now.

Each target has two enumerations:

1. SubtargetFeatureFlag  - this is used, I think, only by the AsmParser, and has elements that look like Feature_HasAVX512.

This one still lives in a regular bitfield, not a bitset, so the elements of the enum are of them form "1 << C". 
If I'm not mistaken, ComputeAvailableFeatures() returns a set of these values.

2. A nameless enum used everywhere else, which has elements that look like X86::FeatureAVX512.

I've changed this enum in my original patch, and now these are ordinal values (1, 2, 3... etc.), instead of powers of 2.

Now, it looks like what you did was to change everything that used bitfields containing SubtargetFeatureFlag to use a FeatureBitset instead. But the values themselves are still powers of 2, so you are still bound by the limits of the underlying type.

Is that right? If it is, then what is the goal of this patch?
If not, then I misunderstood the patch. Could you explain again what it's trying to achieve?


http://reviews.llvm.org/D10542

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