Horton

Re: JIT compiling with LLVM v9.0

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Merlin Moncure <mmoncure@gmail.com>
Cc: Thomas Munro <thomas.munro@enterprisedb.com>, Jeff Davis <pgsql@j-davis.com>, Konstantin Knizhnik <k.knizhnik@postgrespro.ru>, pgsql-hackers@lists.postgresql.org
Date: 2018-02-09T18:58:35Z
Lists: pgsql-hackers 
On 2018-02-09 09:10:25 -0600, Merlin Moncure wrote:
> Question:  when watching the compilation log, I see quite a few files
> being compiled with both O2 and O1, for example:
> 
> clang -Wall -Wmissing-prototypes -Wpointer-arith
> -Wdeclaration-after-statement -Wendif-labels
> -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing
> -fwrapv -Wno-unused-command-line-argument -O2 -O1
> -Wno-ignored-attributes -Wno-unknown-warning-option
> -Wno-ignored-optimization-argument -I../../../../src/include
> -D_GNU_SOURCE -I/home/mmoncure/llvm/include -DLLVM_BUILD_GLOBAL_ISEL
> -D_GNU_SOURCE -D_DEBUG -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS
> -D__STDC_LIMIT_MACROS  -flto=thin -emit-llvm -c -o nbtsort.bc
> nbtsort.c
> 
> Is this intentional?  (didn't check standard compilation, it just jumped out).

It stemms from the following hunk in Makefile.global.in about emitting
bitcode:
# Add -O1 to the options as clang otherwise will emit 'noinline'
# attributes everywhere, making JIT inlining impossible to test in a
# debugging build.
#
# FIXME: While LLVM will re-optimize when emitting code (after
# inlining), it'd be better to only do this if -O0 is specified.
%.bc : CFLAGS +=-O1

%.bc : %.c
	$(COMPILE.c.bc) -o $@ $<

Inspecting the clang source code it's impossible to stop clang from
emitting noinline attributes for every function on -O0.

I think it makes sense to change this to filtering out -O0 and only
adding -O1 if that's not present. :/

Greetings,

Andres Freund

Commits

  1. Improve JIT docs.

  2. Add documentation for the JIT feature.

  3. Add EXPLAIN support for JIT.

  4. Add inlining support to LLVM JIT provider.

  5. JIT tuple deforming in LLVM JIT provider.

  6. Add FIELDNO_* macro designating offset into structs required for JIT.

  7. Add expression compilation support to LLVM JIT provider.

  8. Expand list of synchronized types and functions in LLVM JIT provider.

  9. Add helpers for emitting LLVM IR.

  10. Basic planner and executor integration for JIT.

  11. Debugging and profiling support for LLVM JIT provider.

  12. Support for optimizing and emitting code in LLVM JIT provider.

  13. Add file containing extensions of the LLVM C API.

  14. Basic JIT provider and error handling infrastructure.

  15. Add configure infrastructure (--with-llvm) to enable LLVM support.

  16. Add C++ support to configure.

  17. Add PGAC_PROG_VARCC_VARFLAGS_OPT autoconf macro.

  18. Fix VM buffer pin management in heap_lock_updated_tuple_rec().

  19. Allow tupleslots to have a fixed tupledesc, use in executor nodes.

  20. Expression evaluation based aggregate transition invocation.

  21. Perform slot validity checks in a separate pass over expression.

  22. Rely on executor utils to build targetlist for DML RETURNING.

  23. Refer to OS X as "macOS", except for the port name which is still "darwin".