Add the commandline options -fprofile-instr-generate[=filename] and -profile-instr-use=filename
-fprofile-instr-generate
-- Add instrumentation on branches, switches, and function entry; uses LLVM's InstrProf pass.
-- Link to profile runtime that writes instrumentation counters to a file.
-fprofile-instr-use
-- Read profile data from a file and apply branch weights to branches and switches, and annotate functions with entrycount in LLVM IR.
-- Functions with low or high entrycount are marked with 'cold' or 'inlinehint'.
The only statement type without PGO yet is "try-finally".
A new pragma, `pragma(LDC_profile_instr, [ true | false ])`, is added to selectively disable/enable instrumentation of functions (granularity = whole functions).
The runtime library ldc-profile-rt is a copy of LLVM compiler-rt lib/profile. It has to be exactly in-sync with the LLVM version, and thus we need a copy for each PGO-supported LLVM (>=3.7).
import ldc.profile for a D interface to ldc-profile-rt (for example to reset execution counts after a program startup phase).
The instrumentation data is mainly passed on to LLVM: function-entry counts and branch counts/probabilities. LDC marks functions as hot when "execution count is 30% of the maximum function execution count", and marks functions as cold if their count is 1% of maximum function execution count.
The source of LLVM's llvm-profdata tool is hereby included in LDCs repository (different source for each LLVM version), and the binary is included in the install bin folder.
The executable is named "ldc-profdata" to avoid clashing with llvm-profdata on the same machine. This is needed because profdata executable has to be in-sync with the LLVM version used to build LDC.
Maintenance burden: for trunk LLVM, we have to keep ldc-profile-rt and llvm-profdata in sync. There is no diff with upstream; but because of active development there are the occasional API changes.
This PR removes the command line option which adds the pass names as additional
command line options. This code prevents compiling for AArch64 (since LLVM 3.7)
and ARM (since LLVM 3.8). Recommendation on LLVM list was to use the PassNameParser
only in test tools but not in a production compiler.
It has been a long time since this actually caused problems. If some
start to show up again, we should preferrably come up with a local fix
instead of globally disable everything (which is horrible for -O3 -g
builds).
This approach is easier and requires less code. With some template foo
the BoolOrDefaultAdapter is not required.
This solutions applies to previous LLVM versions, too.
The TargetLibraryInfo class is now a wrapper. The real implementation
is TargetLibraryInfoImpl.
The TargetMachine can be asked for the DataLayout (like in all other
supported versions except 3.6)
Add some of the sanitizer passes to LDC. This is not complete (linking must be
done using clang and the right `-fsanitize=` option) and may not be useful at
all.
If it proves to be usefull then a lot of other options (e.g. blacklist) must be
added.
There might be still some pieces left here and there, and
there is certainly code that could be rewritten in a nicer
way with the 3.0 requirement out of the picture.
I have seen it used several times in benchmarks comparing it
to 'gdc -O3' and 'dmd -O -inline' now, so people apparently
expect it to yield the highest available optimization level.
1. Main include corresponding to .cpp file, if any.
2. DMD and LDC includes.
3. LLVM includes.
4. System includes.
Also updated a few include guards to match the default format.
