[3.13] reinstate _OPTIMIZED & LTO_CFLAGS for correct flag handling in install_base.sh

recipe/install_base.sh

@@ -13,9 +13,12 @@ VER=${PKG_VERSION%.*}
 _buildd_static=build-static
 _buildd_shared=build-shared
 
+# For debugging builds, set this to no to disable profile-guided optimization
 if [[ ${PY_INTERP_DEBUG} == yes ]]; then
+  _OPTIMIZED=no
   DBG=d
 else
+  _OPTIMIZED=yes
   DBG=
 fi
 
@@ -35,6 +38,24 @@ VERABI_NO_DBG=${VER}${THREAD}
 unset _PYTHON_SYSCONFIGDATA_NAME
 unset _CONDA_PYTHON_SYSCONFIGDATA_NAME
 
+declare -a LTO_CFLAGS=()
+if [[ ${_OPTIMIZED} == yes ]]; then
+  if [[ ${CC} =~ .*gcc.* ]]; then
+    LTO_CFLAGS+=(-fuse-linker-plugin)
+    LTO_CFLAGS+=(-ffat-lto-objects)
+    # -flto must come after -flto-partition due to the replacement code
+    # TODO :: Replace the replacement code using conda-build's in-build regex replacement.
+    LTO_CFLAGS+=(-flto-partition=none)
+    LTO_CFLAGS+=(-flto)
+  else
+    # TODO :: Check if -flto=thin gives better results. It is about faster
+    #         compilation rather than faster execution so probably not:
+    # http://clang.llvm.org/docs/ThinLTO.html
+    # http://blog.llvm.org/2016/06/thinlto-scalable-and-incremental-lto.html
+    LTO_CFLAGS+=(-flto)
+  fi
+fi
+
 make -C ${_buildd_static} install
 
 declare -a _FLAGS_REPLACE=()

recipe/meta.yaml

@@ -4,7 +4,7 @@
 {% set ver2 = '.'.join(version.split('.')[0:2]) %}
 {% set ver2nd = ''.join(version.split('.')[0:2]) %}
 {% set ver3nd = ''.join(version.split('.')[0:3]) %}
-{% set build_number = 1 %}
+{% set build_number = 2 %}
 
 # this makes the linter happy
 {% set channel_targets = channel_targets or 'conda-forge main' %}