Cap number of threads on 32bit platforms (#1729382)

Also drop %_lto_cflags macro (reverted upstream) before people
start adapting its use.

0001-Drop-_lto_cflags-macro-afterall.patch

@@ -0,0 +1,50 @@
+From 7faf8eda1358f8a877b9b3d6e1197b814e80b50b Mon Sep 17 00:00:00 2001
+Message-Id: <7faf8eda1358f8a877b9b3d6e1197b814e80b50b.1566557361.git.pmatilai@redhat.com>
+From: Panu Matilainen <pmatilai@redhat.com>
+Date: Tue, 13 Aug 2019 16:26:31 +0300
+Subject: [PATCH] Drop %_lto_cflags macro afterall
+
+This was only added in commit 2bb7b0cf066c97a9d92eb0bf59618896000cb29d,
+but turns out that this kind of usage is bad for build reproducability
+because the system-specific CPU count gets recorded RPMTAG_OPTFLAGS
+and the resulting binaries too (depending on gcc flags).
+In addition, gcc upstream has decided to make -flto default to
+autodetected parallelism. Since -flto can be overridden with
+by simply appending -fno-lto for the packages that need to disable it,
+there's no practical need for us to provide such a macro for disabling
+either.
+---
+ macros.in   | 2 +-
+ platform.in | 3 ---
+ 2 files changed, 1 insertion(+), 4 deletions(-)
+
+diff --git a/macros.in b/macros.in
+index 633d5ca6e..b7da4ea2f 100644
+--- a/macros.in
++++ b/macros.in
+@@ -1025,7 +1025,7 @@ package or when debugging this package.\
+ %build_fflags %{optflags} %{?_fmoddir:-I%{_fmoddir}}
+ 
+ # Link editor flags.  This is usually called LDFLAGS in makefiles.
+-#%build_ldflags -Wl,-z,relro %{?_lto_cflags}
++#%build_ldflags -Wl,-z,relro
+ 
+ # Expands to shell code to seot the compiler/linker environment
+ # variables CFLAGS, CXXFLAGS, FFLAGS, FCFLAGS, LDFLAGS if they have
+diff --git a/platform.in b/platform.in
+index e1efc42b0..db6d2382f 100644
+--- a/platform.in
++++ b/platform.in
+@@ -59,9 +59,6 @@
+ 
+ %_smp_mflags -j%{_smp_build_ncpus}
+ 
+-# Enable LTO optimization with a maximal parallelism
+-%_lto_cflags -flto=%{_smp_build_ncpus}
+-
+ #==============================================================================
+ # ---- Build policy macros.
+ #
+-- 
+2.21.0
+

0001-Fix-build-code-thread-cap-logic-for-unlimited-CPUs.patch

@@ -0,0 +1,32 @@
+From 3ba0136000c986c692baab7b112aba163173d2d3 Mon Sep 17 00:00:00 2001
+Message-Id: <3ba0136000c986c692baab7b112aba163173d2d3.1566556488.git.pmatilai@redhat.com>
+From: Panu Matilainen <pmatilai@redhat.com>
+Date: Fri, 23 Aug 2019 11:09:40 +0300
+Subject: [PATCH 1/2] Fix build code thread cap logic for unlimited CPUs
+
+If there's no clear cap set from rpm configuration, just let OMP do
+its own thing (ie use all available CPUs)  instead of artificially
+limiting to 1.
+---
+ build/parseSpec.c | 5 ++---
+ 1 file changed, 2 insertions(+), 3 deletions(-)
+
+diff --git a/build/parseSpec.c b/build/parseSpec.c
+index 055bdf012..61858aabd 100644
+--- a/build/parseSpec.c
++++ b/build/parseSpec.c
+@@ -1036,9 +1036,8 @@ static rpmSpec parseSpec(const char *specFile, rpmSpecFlags flags,
+ #ifdef ENABLE_OPENMP
+     /* Set number of OMP threads centrally */
+     int ncpus = rpmExpandNumeric("%{?_smp_build_ncpus}");
+-    if (ncpus <= 0)
+-	ncpus = 1;
+-    omp_set_num_threads(ncpus);
++    if (ncpus > 0) {
++	omp_set_num_threads(ncpus);
+ #endif
+ 
+     if (spec->clean == NULL) {
+-- 
+2.21.0
+

0002-Cap-number-of-threads-on-32bit-platforms-add-a-tunab.patch

@@ -0,0 +1,62 @@
+From bcaa30872087a1002648653358ab9514f829de9a Mon Sep 17 00:00:00 2001
+Message-Id: <bcaa30872087a1002648653358ab9514f829de9a.1566556488.git.pmatilai@redhat.com>
+In-Reply-To: <3ba0136000c986c692baab7b112aba163173d2d3.1566556488.git.pmatilai@redhat.com>
+References: <3ba0136000c986c692baab7b112aba163173d2d3.1566556488.git.pmatilai@redhat.com>
+From: Panu Matilainen <pmatilai@redhat.com>
+Date: Fri, 23 Aug 2019 11:17:21 +0300
+Subject: [PATCH 2/2] Cap number of threads on 32bit platforms, add a tunable
+ (RhBug:1729382)
+
+On 32bit plaforms, address space is easily exhausted with multiple
+threads, causing arbitrary builds failure regressions (RhBug:1729382).
+Simply cap the number of threads to maximum of four on any 32bit
+platform to play it safe. It's still three more than we were able to
+use on older releases...
+
+In addition, introduce a separate tunable for tweaking the maximum
+number of threads just in case, defaulting to max CPUs available.
+---
+ build/parseSpec.c | 10 +++++++++-
+ platform.in       |  3 +++
+ 2 files changed, 12 insertions(+), 1 deletion(-)
+
+diff --git a/build/parseSpec.c b/build/parseSpec.c
+index 61858aabd..d987bdc7b 100644
+--- a/build/parseSpec.c
++++ b/build/parseSpec.c
+@@ -1035,9 +1035,17 @@ static rpmSpec parseSpec(const char *specFile, rpmSpecFlags flags,
+ 
+ #ifdef ENABLE_OPENMP
+     /* Set number of OMP threads centrally */
+-    int ncpus = rpmExpandNumeric("%{?_smp_build_ncpus}");
++    int ncpus = rpmExpandNumeric("%{?_smp_nthreads_max}");
++#if __WORDSIZE == 32
++    /* On 32bit platforms, address space shortage is an issue. Play safe. */
++    if (ncpus <= 0 || ncpus > 4) {
++	ncpus = 4;
++	rpmlog(RPMLOG_DEBUG,
++		"limiting number of threads to %d due to platform\n", ncpus);
++    }
+     if (ncpus > 0) {
+ 	omp_set_num_threads(ncpus);
++#endif
+ #endif
+ 
+     if (spec->clean == NULL) {
+diff --git a/platform.in b/platform.in
+index db6d2382f..c70f44193 100644
+--- a/platform.in
++++ b/platform.in
+@@ -59,6 +59,9 @@
+ 
+ %_smp_mflags -j%{_smp_build_ncpus}
+ 
++# Maximum number of CPU's to use for threads
++%_smp_nthreads_max %{_smp_build_ncpus}
++
+ #==============================================================================
+ # ---- Build policy macros.
+ #
+-- 
+2.21.0
+

rpm.spec

@@ -21,7 +21,7 @@
 
 %global rpmver 4.15.0
 %global snapver beta
-%global rel 3
+%global rel 4
 
 %global srcver %{version}%{?snapver:-%{snapver}}
 %global srcdir %{?snapver:testing}%{!?snapver:%{name}-%(echo %{version} | cut -d'.' -f1-2).x}
@@ -57,8 +57,12 @@ Patch101: 0001-Do-not-set-RPMTAG_BUILDTIME-to-SOURCE_DATE_EPOCH-whe.patch
 Patch110: 0001-Support-running-rpmfcExec-without-any-piped-input-ou.patch
 Patch111: 0002-Restore-strict-order-of-build-scriptlet-stdout-stder.patch
 Patch112: 0003-Drop-the-no-longer-needed-rpmfcExec-output-duplicati.patch
+Patch113: 0001-Drop-_lto_cflags-macro-afterall.patch
 
 # These are not yet upstream
+Patch200: 0001-Fix-build-code-thread-cap-logic-for-unlimited-CPUs.patch
+Patch201: 0002-Cap-number-of-threads-on-32bit-platforms-add-a-tunab.patch
+
 Patch906: rpm-4.7.1-geode-i686.patch
 # Probably to be upstreamed in slightly different form
 Patch907: rpm-4.15.x-ldflags.patch
@@ -543,6 +547,10 @@ make check || (cat tests/rpmtests.log; exit 0)
 %doc doc/librpm/html/*
 
 %changelog
+* Fri Aug 23 2019 Panu Matilainen <pmatilai@redhat.com> - 4.15.0-0.beta.4
+- Cap number of threads on 32bit platforms (#1729382)
+- Drop %%_lto_cflags macro (reverted upstream)
+
 * Fri Aug 23 2019 Panu Matilainen <pmatilai@redhat.com> - 4.15.0-0.beta.3
 - Restore strict order of build scriptlet stdout/stderr output