Compute some Debug Info Metadata hash key partially (NFC)
Summary:
This patch changes the computation of the hash key for DISubprogram to
be computed on a small subset of the fields. The hash is computed a
lot faster, but there might be more collision in the table.
However by carefully selecting the fields, colisions should be rare.
Using `opt` to load the IR for FastISelEmitter.cpp.o, with this patch:
- DISubprogram::getImpl() goes from 28ms to 15ms.
- DICompositeType::getImpl() goes from 6ms to 2ms
- DIDerivedType::getImpl() goes from 18 to 12ms
Reviewers: dexonsmith
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D16571
From: Mehdi Amini <mehdi.amini@apple.com>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@263866
91177308-0d34-0410-b5e6-
96231b3b80d8