DenseMap is the wrong data structure to use for sample records and call
sites. The keys are too large, causing massive core memory growth when
reading profiles.
Before this patch, a 21Mb input profile was causing the compiler to grow
to 3Gb in memory. By switching to std::map, the compiler now grows to
300Mb in memory.
There still are some opportunities for memory footprint reduction. I'll
be looking at those next.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255389 91177308-0d34-0410-b5e6-96231b3b80d8
31b250abad