Add llvm-lto-elf-check script

The brp-llvm-compile-lto-elf script uses PCRE in grep to match
for the -flto flag in bitcode object dumps, using negative
lookahead to exclude the case where -fno-lto is specified after.
When lines in the bitcode dump exceed the length that PCRE can
match against, grep will error out causing brp-llvm-compile-lto-elf
to fail.

This script implements an equivalent regex match in python to avoid
the limit in PCRE grep.

Resolves: rhbz#2017193

brp-llvm-compile-lto-elf

@@ -1,5 +1,10 @@
 #!/usr/bin/bash -eu
 
+# first argument is the path to llvm-lto-elf-check
+MATCH_LTO_SCRIPT=$1
+shift
+
+# remaining args are cflags
 CLANG_FLAGS=$@
 
 if [ -z "$RPM_BUILD_ROOT" ] || [ "$RPM_BUILD_ROOT" = "/" ]; then
@@ -15,7 +20,7 @@ check_convert_bitcode () {
   if [[ "${file_type}" == *"LLVM IR bitcode"*  ]]; then
     # check for an indication that the bitcode was
     # compiled with -flto
-    llvm-bcanalyzer -dump ${file_name} | grep -xP '.*\-flto((?!-fno-lto).)*' 2>&1 > /dev/null
+    llvm-bcanalyzer -dump ${file_name} | ${MATCH_LTO_SCRIPT} 2>&1 > /dev/null
     if [ $? -eq 0 ]; then
       echo "Compiling LLVM bitcode file ${file_name}."
       # create path to file in temp dir

llvm-lto-elf-check

@@ -0,0 +1,39 @@
+#!/usr/bin/python3
+
+# Check an llvm bcanalyzer dump for -flto
+
+# This script implements the following command in python
+# to avoid PCRE backtrace limits in grep.
+# grep -xP '.*\-flto((?!-fno-lto).)*' <input file>
+
+import re
+import sys
+
+def open_input_file():
+  if len(sys.argv) > 1:
+    f = open(sys.argv[1], "r")
+  else:
+    f = sys.stdin
+  if not f:
+    raise Exception("Could not open input file")
+  return f
+
+def match_lto(input_lines):
+  match_found = False
+  for line in input_lines:
+    match = re.match(r"^.*\-flto((?!-fno-lto).)*$", line)
+    if match:
+      match_found = True
+      print(f"{match.group(0)}")
+  return match_found
+
+def main():
+  input_file = open_input_file()
+  input_lines = input_file.readlines()
+  if input_file != sys.stdin:
+    input_file.close()
+  if match_lto(input_lines):
+    sys.exit(0)
+  sys.exit(1)
+
+main()

macros

@@ -257,7 +257,8 @@ print(result)
 # __brp_mangle_shebangs_exclude_from_file - file from which to get files to ignore
 %__brp_mangle_shebangs /usr/lib/rpm/redhat/brp-mangle-shebangs %{?__brp_mangle_shebangs_exclude:--shebangs "%{?__brp_mangle_shebangs_exclude}"} %{?__brp_mangle_shebangs_exclude_file:--shebangs-from "%{__brp_mangle_shebangs_exclude_file}"} %{?__brp_mangle_shebangs_exclude_from:--files "%{?__brp_mangle_shebangs_exclude_from}"} %{?__brp_mangle_shebangs_exclude_from_file:--files-from "%{__brp_mangle_shebangs_exclude_from_file}"}
 
-%__brp_llvm_compile_lto_elf /usr/lib/rpm/redhat/brp-llvm-compile-lto-elf %{build_cflags} %{build_ldflags}
+%__llvm_lto_elf_check /usr/lib/rpm/redhat/llvm-lto-elf-check
+%__brp_llvm_compile_lto_elf /usr/lib/rpm/redhat/brp-llvm-compile-lto-elf %{__llvm_lto_elf_check} %{build_cflags} %{build_ldflags}
 
 # note: %%__os_install_post_python is defined in python-srpm-macros and contains several policies
 # redhat-rpm-config maintainers, don't remove it from %%__os_install_post unless coordinating the change with Python maintainers

redhat-rpm-config.spec

@@ -6,7 +6,7 @@
 
 Summary: Red Hat specific rpm configuration files
 Name: redhat-rpm-config
-Version: 201
+Version: 202
 Release: 1%{?dist}
 # No version specified.
 License: GPL+
@@ -67,6 +67,7 @@ Source401: rpmsort
 Source402: symset-table
 Source403: kmodtool
 Source404: gpgverify
+Source405: llvm-lto-elf-check
 
 # 2016-10-02 snapshots from http://git.savannah.gnu.org/gitweb/?p=config.git
 Source500: config.guess
@@ -173,6 +174,8 @@ mkdir -p %{buildroot}%{_rpmluadir}/fedora/{rpm,srpm}
 install -p -m 644 -t %{buildroot}%{_rpmluadir}/fedora common.lua
 install -p -m 644 -t %{buildroot}%{_rpmluadir}/fedora/srpm forge.lua
 
+install -p -m 755 -t %{buildroot}%{rrcdir} llvm-lto-elf-check
+
 %files
 %dir %{rrcdir}
 %{rrcdir}/macros
@@ -186,6 +189,7 @@ install -p -m 644 -t %{buildroot}%{_rpmluadir}/fedora/srpm forge.lua
 %{rrcdir}/find-provides
 %{rrcdir}/find-requires
 %{rrcdir}/brp-ldconfig
+%{rrcdir}/llvm-lto-elf-check
 %{_fileattrsdir}/*.attr
 %{_rpmconfigdir}/macros.d/macros.*-srpm
 %{_rpmconfigdir}/macros.d/macros.build-constraints
@@ -214,6 +218,10 @@ install -p -m 644 -t %{buildroot}%{_rpmluadir}/fedora/srpm forge.lua
 %{_rpmconfigdir}/macros.d/macros.kmp
 
 %changelog
+* Wed Nov 03 2021 David Benoit <dbenoit@redhat.com> - 202-1
+- Add llvm-lto-elf-check script
+- Resolves: rhbz#2017193
+
 * Mon Nov 01 2021 Jason L Tibbitts III <j@tib.bs> - 201-1
 - Better error handling for %%constrain_build.