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| author | Duncan P. N. Exon Smith <dexonsmith@apple.com> | 2015-12-10 17:56:06 +0000 |
|---|---|---|
| committer | Duncan P. N. Exon Smith <dexonsmith@apple.com> | 2015-12-10 17:56:06 +0000 |
| commit | 836f0ddb600f1e43dde312280c392c7ecc92c088 (patch) | |
| tree | 0862c602b989f4769cd0e006ec7e0ecec90e5d6b /lldb/packages/Python/lldbsuite/test/python_api/process/main.cpp | |
| parent | bff0a21b57c698403452694b925079de9e2d0868 (diff) | |
| download | bcm5719-llvm-836f0ddb600f1e43dde312280c392c7ecc92c088.tar.gz bcm5719-llvm-836f0ddb600f1e43dde312280c392c7ecc92c088.zip | |
Verifier: Avoid quadratic checking of aggregates for bad bitcasts
Avoid O(N^2) behaviour when checking for bad bitcasts in `ConstantExpr`s
buried inside of aggregate initializers to `GlobalVariable`s. I've:
- centralized the "visited" set for recursing through `ConstantExpr`s so
that expressions are only visited once per Verifier run,
- removed the duplicate logic for the stack visit, and
- avoided recursing into other `GlobalValue`s.
This recovers roughly a 100x time difference in clang compiles of a
particular input file (filled with large cross-referencing tables) that
depends on whether `-disable-llvm-verifier` is on. This slowdown was
caused by r187506, which introduced these checks.
Now, avoiding `-disable-llvm-verifier` only causes a 2x slowdown for
this case.
(Interestingly, dumping the textual IR for this file starts at least
50GB of global variable initializers (I don't know the total, since I
killed the dump)...)
llvm-svn: 255269
Diffstat (limited to 'lldb/packages/Python/lldbsuite/test/python_api/process/main.cpp')
0 files changed, 0 insertions, 0 deletions
