meson: Add support for building with precompiled headers

This substantially speeds up building for windows, due to the vast amount of
headers included via windows.h. A cross build from linux targetting mingw goes
from

994.11user 136.43system 0:31.58elapsed 3579%CPU
to
422.41user 89.05system 0:14.35elapsed 3562%CPU

The wins on windows are similar-ish (but I don't have a system at hand just
now for actual numbers). Targetting other operating systems the wins are far
smaller (tested linux, macOS, FreeBSD).

For now precompiled headers are disabled by default, it's not clear how well
they work on all platforms. E.g. on FreeBSD gcc doesn't seem to have working
support, but clang does.

When doing a full build precompiled headers are only beneficial for targets
with multiple .c files, as meson builds a separate precompiled header for each
target (so that different compilation options take effect). This commit
therefore only changes target with at least two .c files to use precompiled
headers.

Because this commit adds b_pch=false to the default_options new build
directories will have precompiled headers disabled by default, however
existing build directories will continue use the default value of b_pch, which
is true.

Note that using precompiled headers with ccache requires setting
CCACHE_SLOPPINESS=pch_defines,time_macros to get hits.

Reviewed-by: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Reviewed-by: Justin Pryzby <pryzby@telsasoft.com>
Discussion: https://postgr.es/m/CA+hUKG+50eOUbN++ocDc0Qnp9Pvmou23DSXu=ZA6fepOcftKqA@mail.gmail.com
Discussion: https://postgr.es/m/c5736f70-bb6d-8d25-e35c-e3d886e4e905@enterprisedb.com
Discussion: https://postgr.es/m/20190826054000.GE7005%40paquier.xyz

32 files changed, 44 insertions, 1 deletions

diff --git a/.cirrus.yml b/.cirrus.yml
index 531cfe96f65..9f2282471a9 100644
--- a/.cirrus.yml
+++ b/.cirrus.yml
@@ -447,7 +447,7 @@ task:
   # Use /DEBUG:FASTLINK to avoid high memory usage during linking
   configure_script: |
     vcvarsall x64
-    meson setup --backend ninja --buildtype debug -Dc_link_args=/DEBUG:FASTLINK -Dcassert=true -Dssl=openssl -Dextra_lib_dirs=c:\openssl\1.1\lib -Dextra_include_dirs=c:\openssl\1.1\include -DTAR=c:/windows/system32/tar.exe -DPG_TEST_EXTRA="%PG_TEST_EXTRA%" build
+    meson setup --backend ninja --buildtype debug -Dc_link_args=/DEBUG:FASTLINK -Dcassert=true -Db_pch=true -Dssl=openssl -Dextra_lib_dirs=c:\openssl\1.1\lib -Dextra_include_dirs=c:\openssl\1.1\include -DTAR=c:/windows/system32/tar.exe -DPG_TEST_EXTRA="%PG_TEST_EXTRA%" build
 
   build_script: |
     vcvarsall x64
diff --git a/contrib/bloom/meson.build b/contrib/bloom/meson.build
index 16f3b83e4d2..163a93c98fb 100644
--- a/contrib/bloom/meson.build
+++ b/contrib/bloom/meson.build
@@ -15,6 +15,7 @@ endif
 
 bloom = shared_module('bloom',
   bloom_sources,
+  c_pch: pch_postgres_h,
   kwargs: contrib_mod_args,
 )
 contrib_targets += bloom
diff --git a/contrib/btree_gist/meson.build b/contrib/btree_gist/meson.build
index e98c91dacc8..bfb7865d213 100644
--- a/contrib/btree_gist/meson.build
+++ b/contrib/btree_gist/meson.build
@@ -33,6 +33,7 @@ endif
 
 btree_gist = shared_module('btree_gist',
   btree_gist_sources,
+  c_pch: pch_postgres_h,
   kwargs: contrib_mod_args,
 )
 contrib_targets += btree_gist
diff --git a/contrib/hstore/meson.build b/contrib/hstore/meson.build
index 2bb26bb772b..a2a4ec36cb0 100644
--- a/contrib/hstore/meson.build
+++ b/contrib/hstore/meson.build
@@ -18,6 +18,7 @@ endif
 
 hstore = shared_module('hstore',
   hstore_sources,
+  c_pch: pch_postgres_h,
   kwargs: contrib_mod_args,
 )
 contrib_targets += hstore
diff --git a/contrib/pg_trgm/meson.build b/contrib/pg_trgm/meson.build
index c8c7c07b308..839d6c4a7f6 100644
--- a/contrib/pg_trgm/meson.build
+++ b/contrib/pg_trgm/meson.build
@@ -13,6 +13,7 @@ endif
 
 pg_trgm = shared_module('pg_trgm',
   pg_trgm_sources,
+  c_pch: pch_postgres_h,
   kwargs: contrib_mod_args,
 )
 contrib_targets += pg_trgm
diff --git a/contrib/pgcrypto/meson.build b/contrib/pgcrypto/meson.build
index 7fc7bbc7ca1..cc782578b49 100644
--- a/contrib/pgcrypto/meson.build
+++ b/contrib/pgcrypto/meson.build
@@ -78,6 +78,7 @@ endif
 pgcrypto = shared_module('pgcrypto',
   pgcrypto_sources,
   link_with: pgcrypto_link_with,
+  c_pch: pch_postgres_h,
   kwargs: contrib_mod_args + {
     'dependencies': [pgcrypto_deps, contrib_mod_args['dependencies']]
   },
diff --git a/contrib/pgstattuple/meson.build b/contrib/pgstattuple/meson.build
index 05e4cd46a5c..42d0b0e6ce9 100644
--- a/contrib/pgstattuple/meson.build
+++ b/contrib/pgstattuple/meson.build
@@ -12,6 +12,7 @@ endif
 
 pgstattuple = shared_module('pgstattuple',
   pgstattuple_sources,
+  c_pch: pch_postgres_h,
   kwargs: contrib_mod_args,
 )
 contrib_targets += pgstattuple
diff --git a/contrib/sepgsql/meson.build b/contrib/sepgsql/meson.build
index 8bef239e3c2..1ac0fa388ab 100644
--- a/contrib/sepgsql/meson.build
+++ b/contrib/sepgsql/meson.build
@@ -22,6 +22,7 @@ endif
 
 sepgsql = shared_module('sepgsql',
   sepgsql_sources,
+  c_pch: pch_postgres_h,
   kwargs: contrib_mod_args + {
     'dependencies': [selinux, contrib_mod_args['dependencies']],
   }
diff --git a/contrib/xml2/meson.build b/contrib/xml2/meson.build
index 89b0d677516..92ab3368428 100644
--- a/contrib/xml2/meson.build
+++ b/contrib/xml2/meson.build
@@ -15,6 +15,7 @@ endif
 
 xml2 = shared_module('pgxml',
   xml2_sources,
+  c_pch: pch_postgres_h,
   kwargs: contrib_mod_args + {
     'dependencies': [libxml, libxslt, contrib_mod_args['dependencies']],
   },
diff --git a/meson.build b/meson.build
index 25a6fa941cc..f0cb01c0015 100644
--- a/meson.build
+++ b/meson.build
@@ -15,6 +15,7 @@ project('postgresql',
   meson_version: '>=0.54',
   default_options: [
     'warning_level=1', #-Wall equivalent
+    'b_pch=false',
     'buildtype=release',
     # For compatibility with the autoconf build, set a default prefix. This
     # works even on windows, where it's a drive-relative path (i.e. when on
diff --git a/src/backend/meson.build b/src/backend/meson.build
index 6f4cd6ceb09..37562bae132 100644
--- a/src/backend/meson.build
+++ b/src/backend/meson.build
@@ -62,6 +62,7 @@ postgres_lib = static_library('postgres_lib',
   backend_sources + timezone_sources + generated_backend_sources,
   link_whole: backend_link_with,
   dependencies: backend_build_deps,
+  c_pch: pch_postgres_h,
   kwargs: internal_lib_args,
 )
 
@@ -81,6 +82,10 @@ if cc.get_id() == 'msvc'
 
   backend_link_args += '/DEF:@0@'.format(postgres_def.full_path())
   backend_link_depends += postgres_def
+  # Due to the way msvc and meson's precompiled headers implementation
+  # interact, we need to have symbols from the full library available. Could
+  # be restricted to b_pch=true.
+  backend_link_with += postgres_lib
 
 elif host_system == 'aix'
   # The '.' argument leads mkldexport.sh to emit "#! .", which refers to the
diff --git a/src/backend/snowball/meson.build b/src/backend/snowball/meson.build
index 974401d187e..72959fa29d6 100644
--- a/src/backend/snowball/meson.build
+++ b/src/backend/snowball/meson.build
@@ -66,6 +66,7 @@ endif
 
 dict_snowball = shared_module('dict_snowball',
   dict_snowball_sources,
+  c_pch: pch_postgres_h,
   kwargs: pg_mod_args + {
     'include_directories': [stemmer_inc],
   }
diff --git a/src/bin/pg_dump/meson.build b/src/bin/pg_dump/meson.build
index 3527a25c288..e66f632b54e 100644
--- a/src/bin/pg_dump/meson.build
+++ b/src/bin/pg_dump/meson.build
@@ -13,6 +13,7 @@ pg_dump_common_sources = files(
 
 pg_dump_common = static_library('libpgdump_common',
   pg_dump_common_sources,
+  c_pch: pch_postgres_fe_h,
   dependencies: [frontend_code, libpq, zlib],
   kwargs: internal_lib_args,
 )
diff --git a/src/bin/pg_upgrade/meson.build b/src/bin/pg_upgrade/meson.build
index a7b927a45c7..212bc9ce6ef 100644
--- a/src/bin/pg_upgrade/meson.build
+++ b/src/bin/pg_upgrade/meson.build
@@ -24,6 +24,7 @@ endif
 
 pg_upgrade = executable('pg_upgrade',
   pg_upgrade_sources,
+  c_pch: pch_postgres_fe_h,
   dependencies: [frontend_code, libpq],
   kwargs: default_bin_args,
 )
diff --git a/src/bin/pgbench/meson.build b/src/bin/pgbench/meson.build
index 3cc393d17ea..1a3ec5d1295 100644
--- a/src/bin/pgbench/meson.build
+++ b/src/bin/pgbench/meson.build
@@ -27,6 +27,7 @@ pgbench = executable('pgbench',
   pgbench_sources,
   dependencies: [frontend_code, libpq, thread_dep],
   include_directories: include_directories('.'),
+  c_pch: pch_postgres_fe_h,
   c_args: host_system == 'windows' ? ['-DFD_SETSIZE=1024'] : [],
   kwargs: default_bin_args,
 )
diff --git a/src/bin/psql/meson.build b/src/bin/psql/meson.build
index 1264fc19fbd..a4c46bf5385 100644
--- a/src/bin/psql/meson.build
+++ b/src/bin/psql/meson.build
@@ -44,6 +44,7 @@ endif
 
 psql = executable('psql',
   psql_sources,
+  c_pch: pch_postgres_fe_h,
   include_directories: include_directories('.'),
   dependencies: [frontend_code, libpq, readline],
   kwargs: default_bin_args,
diff --git a/src/common/meson.build b/src/common/meson.build
index 23842e1ffef..1c9b8a3a018 100644
--- a/src/common/meson.build
+++ b/src/common/meson.build
@@ -147,6 +147,7 @@ foreach name, opts : pgcommon_variants
     endif
     c_args = opts.get('c_args', []) + common_cflags[cflagname]
     cflag_libs += static_library('libpgcommon@0@_@1@'.format(name, cflagname),
+      c_pch: pch_c_h,
       include_directories: include_directories('.'),
       kwargs: opts + {
         'sources': sources,
@@ -159,6 +160,7 @@ foreach name, opts : pgcommon_variants
 
   lib = static_library('libpgcommon@0@'.format(name),
       link_with: cflag_libs,
+      c_pch: pch_c_h,
       include_directories: include_directories('.'),
       kwargs: opts + {
         'dependencies': opts['dependencies'] + [ssl],
diff --git a/src/fe_utils/meson.build b/src/fe_utils/meson.build
index 3e226c260ac..fe0b801387c 100644
--- a/src/fe_utils/meson.build
+++ b/src/fe_utils/meson.build
@@ -23,6 +23,7 @@ fe_utils_sources += psqlscan
 
 fe_utils = static_library('libpgfeutils',
   fe_utils_sources + generated_headers,
+  c_pch: pch_postgres_fe_h,
   include_directories: [postgres_inc, libpq_inc],
   c_args: host_system == 'windows' ? ['-DFD_SETSIZE=1024'] : [],
   dependencies: frontend_common_code,
diff --git a/src/include/meson.build b/src/include/meson.build
index f2f7d03ff27..35c06c4856a 100644
--- a/src/include/meson.build
+++ b/src/include/meson.build
@@ -114,6 +114,7 @@ install_headers(
 
 subdir('catalog')
 subdir('nodes')
+subdir('pch')
 subdir('storage')
 subdir('utils')
 
diff --git a/src/include/pch/c_pch.h b/src/include/pch/c_pch.h
new file mode 100644
index 00000000000..f40c757ca62
--- /dev/null
+++ b/src/include/pch/c_pch.h
@@ -0,0 +1 @@
+#include "c.h"
diff --git a/src/include/pch/meson.build b/src/include/pch/meson.build
new file mode 100644
index 00000000000..2bcec49c3a2
--- /dev/null
+++ b/src/include/pch/meson.build
@@ -0,0 +1,4 @@
+# See https://github.com/mesonbuild/meson/issues/10338
+pch_c_h = meson.source_root() / meson.current_source_dir() / 'c_pch.h'
+pch_postgres_h = meson.source_root() / meson.current_source_dir() / 'postgres_pch.h'
+pch_postgres_fe_h = meson.source_root() / meson.current_source_dir() / 'postgres_fe_pch.h'
diff --git a/src/include/pch/postgres_fe_pch.h b/src/include/pch/postgres_fe_pch.h
new file mode 100644
index 00000000000..f3ea20912d3
--- /dev/null
+++ b/src/include/pch/postgres_fe_pch.h
@@ -0,0 +1 @@
+#include "postgres_fe.h"
diff --git a/src/include/pch/postgres_pch.h b/src/include/pch/postgres_pch.h
new file mode 100644
index 00000000000..71b2f35f76b
--- /dev/null
+++ b/src/include/pch/postgres_pch.h
@@ -0,0 +1 @@
+#include "postgres.h"
diff --git a/src/interfaces/ecpg/ecpglib/meson.build b/src/interfaces/ecpg/ecpglib/meson.build
index 7e6e6fbf5c0..2d07da1ff4c 100644
--- a/src/interfaces/ecpg/ecpglib/meson.build
+++ b/src/interfaces/ecpg/ecpglib/meson.build
@@ -27,6 +27,7 @@ ecpglib_st = static_library('libecpg',
   ecpglib_sources,
   include_directories: ecpglib_inc,
   c_args: ecpglib_c_args,
+  c_pch: pch_postgres_fe_h,
   dependencies: [frontend_stlib_code, thread_dep, libpq],
   link_with: [ecpg_pgtypes_st],
   kwargs: default_lib_args,
@@ -37,6 +38,7 @@ ecpglib_so = shared_library('libecpg',
   ecpglib_sources + ecpglib_so_sources,
   include_directories: ecpglib_inc,
   c_args: ecpglib_c_args,
+  c_pch: pch_postgres_fe_h,
   dependencies: [frontend_shlib_code, libpq, thread_dep],
   link_with: ecpg_pgtypes_so,
   soversion: host_system != 'windows' ? '6' : '',
diff --git a/src/interfaces/ecpg/pgtypeslib/meson.build b/src/interfaces/ecpg/pgtypeslib/meson.build
index 530dd2c602d..d7e1a94d24d 100644
--- a/src/interfaces/ecpg/pgtypeslib/meson.build
+++ b/src/interfaces/ecpg/pgtypeslib/meson.build
@@ -23,6 +23,7 @@ ecpg_pgtypes_st = static_library('libpgtypes',
   ecpg_pgtypes_sources,
   include_directories: ecpg_pgtypes_inc,
   c_args: ecpg_pgtypes_c_args,
+  c_pch: pch_postgres_fe_h,
   dependencies: frontend_stlib_code,
   kwargs: default_lib_args,
 )
@@ -32,6 +33,7 @@ ecpg_pgtypes_so = shared_library('libpgtypes',
   ecpg_pgtypes_sources + ecpg_pgtypes_so_sources,
   include_directories: ecpg_pgtypes_inc,
   c_args: ecpg_pgtypes_c_args,
+  c_pch: pch_postgres_fe_h,
   dependencies: frontend_shlib_code,
   version: '3.' + pg_version_major.to_string(),
   soversion: host_system != 'windows' ? '3' : '',
diff --git a/src/interfaces/ecpg/preproc/meson.build b/src/interfaces/ecpg/preproc/meson.build
index 74876f039c9..3d42ee439ff 100644
--- a/src/interfaces/ecpg/preproc/meson.build
+++ b/src/interfaces/ecpg/preproc/meson.build
@@ -102,6 +102,7 @@ endif
 ecpg_exe = executable('ecpg',
   ecpg_sources,
   include_directories: ['.', ecpg_inc, postgres_inc, libpq_inc],
+  c_pch: pch_postgres_fe_h,
   dependencies: [frontend_code],
   kwargs: default_bin_args,
 )
diff --git a/src/interfaces/libpq/meson.build b/src/interfaces/libpq/meson.build
index 533b2e6f773..8e696f1183c 100644
--- a/src/interfaces/libpq/meson.build
+++ b/src/interfaces/libpq/meson.build
@@ -58,6 +58,7 @@ libpq_st = static_library('libpq',
   libpq_sources,
   include_directories: [libpq_inc],
   c_args: libpq_c_args,
+  c_pch: pch_postgres_fe_h,
   dependencies: [frontend_stlib_code, libpq_deps],
   kwargs: default_lib_args,
 )
@@ -66,6 +67,7 @@ libpq_so = shared_library('libpq',
   libpq_sources + libpq_so_sources,
   include_directories: [libpq_inc, postgres_inc],
   c_args: libpq_c_args,
+  c_pch: pch_postgres_fe_h,
   version: '5.' + pg_version_major.to_string(),
   soversion: host_system != 'windows' ? '5' : '',
   darwin_versions: ['5', '5.' + pg_version_major.to_string()],
diff --git a/src/pl/plperl/meson.build b/src/pl/plperl/meson.build
index 535660085dd..cd3894e6a73 100644
--- a/src/pl/plperl/meson.build
+++ b/src/pl/plperl/meson.build
@@ -45,6 +45,7 @@ endif
 
 plperl = shared_module('plperl',
   plperl_sources,
+  c_pch: pch_postgres_h,
   include_directories: [plperl_inc, postgres_inc],
   kwargs: pg_mod_args + {
     'dependencies': [perl_dep, pg_mod_args['dependencies']],
diff --git a/src/pl/plpgsql/src/meson.build b/src/pl/plpgsql/src/meson.build
index c46c0a1da2a..27b2f5ef529 100644
--- a/src/pl/plpgsql/src/meson.build
+++ b/src/pl/plpgsql/src/meson.build
@@ -48,6 +48,7 @@ endif
 
 plpgsql = shared_module('plpgsql',
   plpgsql_sources,
+  c_pch: pch_postgres_h,
   include_directories: include_directories('.'),
   kwargs: pg_mod_args,
 )
diff --git a/src/pl/plpython/meson.build b/src/pl/plpython/meson.build
index 40888386b5f..7bd683580e8 100644
--- a/src/pl/plpython/meson.build
+++ b/src/pl/plpython/meson.build
@@ -36,6 +36,7 @@ endif
 
 plpython = shared_module('plpython3',
   plpython_sources,
+  c_pch: pch_postgres_h,
   include_directories: [plpython_inc, postgres_inc],
   kwargs: pg_mod_args + {
     'dependencies': [python3_dep, pg_mod_args['dependencies']],
diff --git a/src/pl/tcl/meson.build b/src/pl/tcl/meson.build
index f09bb14c950..7a708776c99 100644
--- a/src/pl/tcl/meson.build
+++ b/src/pl/tcl/meson.build
@@ -22,6 +22,7 @@ endif
 
 pltcl = shared_module('pltcl',
   pltcl_sources,
+  c_pch: pch_postgres_h,
   include_directories: [include_directories('.'), postgres_inc],
   kwargs: pg_mod_args + {
     'dependencies': [tcl_dep, pg_mod_args['dependencies']],
diff --git a/src/port/meson.build b/src/port/meson.build
index ced2e014db8..c2222696f1b 100644
--- a/src/port/meson.build
+++ b/src/port/meson.build
@@ -161,6 +161,7 @@ foreach name, opts : pgport_variants
     c_args = opts.get('c_args', []) + pgport_cflags[cflagname]
     cflag_libs += static_library('libpgport@0@_@1@'.format(name, cflagname),
       sources,
+      c_pch: pch_c_h,
       kwargs: opts + {
         'c_args': c_args,
         'build_by_default': false,
@@ -172,6 +173,7 @@ foreach name, opts : pgport_variants
   lib = static_library('libpgport@0@'.format(name),
       pgport_sources,
       link_with: cflag_libs,
+      c_pch: pch_c_h,
       kwargs: opts + {
         'dependencies': opts['dependencies'] + [ssl],
       }