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c22ac1df07
Summary: it's often the case when the rules in the SpecialCaseList are of the form hel.o*bar. That gives us a chance to build trigram index to quickly discard 99% of inputs without running a full regex. A similar idea was used in Google Code Search as described in the blog post: https://swtch.com/~rsc/regexp/regexp4.html The check is defeated, if there's at least one regex more complicated than that. In this case, all inputs will go through the regex. That said, the real-world rules are often simple or can be simplied. That considerably speeds up compiling Chromium with CFI and UBSan. As measured on Chromium's content_message_generator.cc: before, CFI: 44 s after, CFI: 23 s after, CFI, no blacklist: 23 s (~1% slower, but 3 runs were unable to show the difference) after, regular compilation to bitcode: 23 s Reviewers: pcc Subscribers: mgorny, llvm-commits Differential Revision: https://reviews.llvm.org/D27188 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@288303 91177308-0d34-0410-b5e6-96231b3b80d8
Design Of lib/System
====================
The software in this directory is designed to completely shield LLVM from any
and all operating system specific functionality. It is not intended to be a
complete operating system wrapper (such as ACE), but only to provide the
functionality necessary to support LLVM.
The software located here, of necessity, has very specific and stringent design
rules. Violation of these rules means that cracks in the shield could form and
the primary goal of the library is defeated. By consistently using this library,
LLVM becomes more easily ported to new platforms since the only thing requiring
porting is this library.
Complete documentation for the library can be found in the file:
llvm/docs/SystemLibrary.html
or at this URL:
http://llvm.org/docs/SystemLibrary.html
While we recommend that you read the more detailed documentation, for the
impatient, here's a high level summary of the library's requirements.
1. No system header files are to be exposed through the interface.
2. Std C++ and Std C header files are okay to be exposed through the interface.
3. No exposed system-specific functions.
4. No exposed system-specific data.
5. Data in lib/System classes must use only simple C++ intrinsic types.
6. Errors are handled by returning "true" and setting an optional std::string
7. Library must not throw any exceptions, period.
8. Interface functions must not have throw() specifications.
9. No duplicate function impementations are permitted within an operating
system class.
To accomplish these requirements, the library has numerous design criteria that
must be satisfied. Here's a high level summary of the library's design criteria:
1. No unused functionality (only what LLVM needs)
2. High-Level Interfaces
3. Use Opaque Classes
4. Common Implementations
5. Multiple Implementations
6. Minimize Memory Allocation
7. No Virtual Methods