This patch removes the magic "main" JITDylib from ExecutionEngine. The main
JITDylib was created automatically at ExecutionSession construction time, and
all subsequently created JITDylibs were added to the main JITDylib's
links-against list by default. This saves a couple of lines of boilerplate for
simple JIT setups, but this isn't worth introducing magical behavior for.
ORCv2 clients should now construct their own main JITDylib using
ExecutionSession::createJITDylib and set up its linkages manually using
JITDylib::setSearchOrder (or related methods in JITDylib).
The runAsMain function takes a pointer to a function with a standard C main
signature, int(*)(int, char*[]), and invokes it using the given arguments and
program name. The arguments are copied into writable temporary storage as
required by the C and C++ specifications, so runAsMain safe to use when calling
main functions that modify their arguments in-place.
This patch also uses the new runAsMain function to replace hand-rolled versions
in lli, llvm-jitlink, and the SpeculativeJIT example.
Summary:
This patch introduces, SequenceBBQuery - new heuristic to find likely next callable functions it tries to find the blocks with calls in order of execution sequence of Blocks.
It still uses BlockFrequencyAnalysis to find high frequency blocks. For a handful of hottest blocks (plan to customize), the algorithm traverse and discovered the caller blocks along the way to Entry Basic Block and Exit Basic Block. It uses Block Hint, to stop traversing the already visited blocks in both direction. It implicitly assumes that once the block is visited during discovering entry or exit nodes, revisiting them again does not add much. It also branch probability info (cached result) to traverse only hot edges (planned to customize) from hot blocks. Without BPI, the algorithm mostly return's all the blocks in the CFG with calls.
It also changes the heuristic queries, so they don't maintain states. Hence it is safe to call from multiple threads.
It also implements, new instrumentation to avoid jumping into JIT on every call to the function with the help _orc_speculate.decision.block and _orc_speculate.block.
"Speculator Registration Mechanism is also changed" - kudos to @lhames
Open to review, mostly looking to change implementation of SequeceBBQuery heuristics with good data structure choices.
Reviewers: lhames, dblaikie
Reviewed By: lhames
Subscribers: mgorny, hiraditya, mgrang, llvm-commits, lhames
Tags: #speculative_compilation_in_orc, #llvm
Differential Revision: https://reviews.llvm.org/D66399
llvm-svn: 370092
Now that we've moved to C++14, we no longer need the llvm::make_unique
implementation from STLExtras.h. This patch is a mechanical replacement
of (hopefully) all the llvm::make_unique instances across the monorepo.
llvm-svn: 369013
