[SROA] Adjust to new clang-format style.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202134 91177308-0d34-0410-b5e6-96231b3b80d8
[SROA] Simplify some of the logic to dig out the old pointer value by
using OldPtr more heavily. Lots of this code was written before the
rewriter had an OldPtr member setup ahead of time. There are already
asserts in place that should ensure this doesn't change any
functionality.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202135 91177308-0d34-0410-b5e6-96231b3b80d8
[SROA] Rather than copying the logic for building a name prefix into the
PHI-pointer builder, just copy the builder and clobber the obvious
fields.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202136 91177308-0d34-0410-b5e6-96231b3b80d8
[SROA] Thread the ability to add a pointer-specific name prefix through
the pointer adjustment code. This is the primary code path that creates
totally new instructions in SROA and being able to lump them based on
the pointer value's name for which they were created causes
*significantly* fewer name collisions and general noise in the debug
output. This is particularly significant because it is making it much
harder to track down instability in the output of SROA, as name
de-duplication is a totally harmless form of instability that gets in
the way of seeing real problems.

The new fancy naming scheme tries to dig out the root "pre-SROA" name
for pointer values and associate that all the way through the pointer
formation instructions. Digging out the root is important to prevent the
multiple iterative rounds of SROA from just layering too much cruft on
top of cruft here. We already track the layers of SROAs iteration in the
alloca name prefix. We don't need to duplicate it here.

Should have no functionality change, and shouldn't have any really
measurable impact on NDEBUG builds, as most of the complex logic is
debug-only.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202139 91177308-0d34-0410-b5e6-96231b3b80d8
[SROA] Use the original load name with the SROA-prefixed IRB rather than
just "load". This helps avoid pointless de-duping with order-sensitive
numbers as we already have unique names from the original load. It also
makes the resulting IR quite a bit easier to read.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202140 91177308-0d34-0410-b5e6-96231b3b80d8