Re: JIT compiling with LLVM v11 - Mailing list pgsql-hackers

On Sun, Mar 4, 2018 at 8:39 AM, Andres Freund <andres@anarazel.de> wrote:
> On 2018-03-03 09:37:35 -0500, Peter Eisentraut wrote:
>> [discussion of making this work on a Mac]

I tried out your "jit" branch on my macOS 10.13.3 system.  Vendor "cc"
and "c++" are version "Apple LLVM version 9.0.0 (clang-900.0.39.2)".
I used MacPorts (whereas Peter E is using HomeBrew) to install LLVM
with "sudo port install llvm-5.0".

First, I built it like this:

./configure
  --prefix=$HOME/install/postgres \
  --enable-debug --enable-cassert --enable-depend --with-llvm --with-openssl \
  --enable-tap-tests \
  --with-includes="/opt/local/include" --with-libraries="/opt/local/lib" \
  CC="ccache cc" CXX="ccache c++" LLVM_CONFIG=/opt/local/bin/llvm-config-mp-5.0

The build succeeded, initdb ran, the server started up, and then I
tried the sequence Andres showed:

set jit_above_cost = 0;
set client_min_messages=debug2;
SELECT pg_jit_available();

On that last command I got:

DEBUG:  probing availability of llvm for JIT at
/Users/munro/install/postgres/lib/llvmjit.so
DEBUG:  successfully loaded LLVM in current session
DEBUG:  time to opt: 0.001s
DEBUG:  time to emit: 0.034s
ERROR:  failed to JIT: evalexpr_0_0

Looking at the server output I saw:

warning: ignoring debug info with an invalid version (700000003) in
/Users/munro/install/postgres/lib/llvmjit_types.bc
2018-03-05 16:50:05.888 NZDT [14797] ERROR:  failed to JIT: evalexpr_0_0
2018-03-05 16:50:05.888 NZDT [14797] STATEMENT:  SELECT pg_jit_available();

I could see that llvmjit_types.bc had been produced by this command:

/usr/bin/clang -Wno-ignored-attributes -Wno-unknown-warning-option
-Wno-ignored-optimization-argument -Wall -Wmissing-prototypes
-Wpointer-arith -Wdeclaration-after-statement -Wendif-labels
-Wmissing-format-attribute -Wformat-security -fno-strict-aliasing
-fwrapv -Wno-unused-command-line-argument -g -O0 -Wall -Werror  -O1
-I../../../../src/include  -I/opt/local/include -flto=thin -emit-llvm
-c -o pseudotypes.bc pseudotypes.c

So I tried installing a later clang with "sudo port install clang-5.0"
and setting CLANG=/pt/local/bin/clang-mp-5.0.  It builds and uses that
clang to generate the .bc files, but gives the same error, this time
without the "warning" message.

Looking at llvm_get_function(), the function that raises that error, I
see that there are a few different paths here.  I don't have
HAVE_DECL_LLVMORCGETSYMBOLADDRESSIN defined, and I don't have LLVM <
5, so I should be getting the symbol address with
LLVMOrcGetSymbolAddress(llvm_opt0_orc, &addr, mangled) or
LLVMOrcGetSymbolAddress(llvm_opt3_orc, &addr, mangled), but clearly
those are returning NULL.

Not sure what's happening yet...

-- 
Thomas Munro
http://www.enterprisedb.com