getZExtValue() already return uint64_t.

fixes #152348

SimplifyCFG collapses raw buffer store from a if\else load into a
select.

This change prevents the TargetExtType dx.Rawbuffer from being replace
thus preserving the if\else blocks.

A further change was needed to eliminate the phi node before we process
Intrinsic::dx_resource_getpointer in DXILResourceAccess.cpp

We cannot form phis/selects of token type, so this should be checked
inside canReplaceOperandWithVariable().

This patch replaces SmallSet<T *, N> with SmallPtrSet<T *, N>.  Note
that SmallSet.h "redirects" SmallSet to SmallPtrSet for pointer
element types:

  template <typename PointeeType, unsigned N>
class SmallSet<PointeeType*, N> : public SmallPtrSet<PointeeType*, N>
{};

We only have 140 instances that rely on this "redirection", with the
vast majority of them under llvm/. Since relying on the redirection
doesn't improve readability, this patch replaces SmallSet with
SmallPtrSet for pointer element types.

Now that #149310 has restricted lifetime intrinsics to only work on
allocas, we can also drop the explicit size argument. Instead, the size
is implied by the alloca.

This removes the ability to only mark a prefix of an alloca alive/dead.
We never used that capability, so we should remove the need to handle
that possibility everywhere (though many key places, including stack
coloring, did not actually respect this).

Capture it in the lambdas instead.

This slightly relaxes the invariant established in #149310, by also
allowing the lifetime argument to be poison. This is to support the
typical pattern of RAUWing with poison when removing an instruction.

It's worth noting that this does not require any conservative
assumptions, lifetimes with poison arguments can simply be skipped.

Fixes https://github.com/llvm/llvm-project/issues/151119.

After #149310 this is guaranteed to be an alloca.

This was always undesirable, and after #149310 it is illegal and will
result in a verifier error.

Fix this by moving SimplifyCFG's check for this into
canReplaceOperandWithVariable(), so it's shared with GVNSink.

This is one of the final remaining debug-intrinsic specific codepaths
out there, and pieces of cross-LLVM infrastructure to do with debug
intrinsics.