llvm: Add llvm-config wrapper to improve flags handling

Add a wrapper for llvm-config which provides flags from the current envrionment
instead of the values hardcoded into llvm-native at compile time. Inspiration
taken from the wrapper in meta-clang but I had to totally rewrite it as:

* the TARGET_* prefixes weren't in our environment
* meson uses --libs --ldflags XXX which didn't work

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 52 insertions, 0 deletions

diff --git a/meta/recipes-devtools/llvm/llvm/llvm-config b/meta/recipes-devtools/llvm/llvm/llvm-config
new file mode 100644
index 0000000000..a45f38c650
--- /dev/null
+++ b/meta/recipes-devtools/llvm/llvm/llvm-config
@@ -0,0 +1,42 @@
+#!/bin/bash
+#
+# Copyright OpenEmbedded Contributors
+#
+# SPDX-License-Identifier: MIT
+#
+# Wrap llvm-config since the native llvm-config will remap some values correctly
+# if placed in the target sysroot but for flags, it would provide the native ones.
+# Provide ours from the environment instead.
+
+NEXT_LLVM_CONFIG="$(which -a llvm-config | sed -n 2p)"
+if [[ $# == 0 ]]; then
+  exec "$NEXT_LLVM_CONFIG"
+fi
+
+remain=""
+output=""
+for arg in "$@"; do
+  case "$arg" in
+    --cppflags)
+      output="${output} ${CPPFLAGS}"
+      ;;
+    --cflags)
+      output="${output} ${CFLAGS}"
+      ;;
+    --cxxflags)
+      output="${output} ${CXXFLAGS}"
+      ;;
+    --ldflags)
+      output="${output} ${LDFLAGS}"
+      ;;
+    *)
+      remain="${remain} ${arg}"
+      ;;
+  esac
+done
+
+if [ "${remain}" != "" ]; then
+      output="${output} "$("$NEXT_LLVM_CONFIG" ${remain})
+fi
+
+echo "${output}"
diff --git a/meta/recipes-devtools/llvm/llvm_git.bb b/meta/recipes-devtools/llvm/llvm_git.bb
index bdea95db96..4c7fadb667 100644
--- a/meta/recipes-devtools/llvm/llvm_git.bb
+++ b/meta/recipes-devtools/llvm/llvm_git.bb
@@ -31,6 +31,7 @@ SRC_URI = "git://github.com/llvm/llvm-project.git;branch=${BRANCH};protocol=http
            file://0006-llvm-TargetLibraryInfo-Undefine-libc-functions-if-th.patch;striplevel=2 \
            file://0007-llvm-allow-env-override-of-exe-path.patch;striplevel=2 \
            file://0001-AsmMatcherEmitter-sort-ClassInfo-lists-by-name-as-we.patch;striplevel=2 \
+           file://llvm-config \
            "
 
 UPSTREAM_CHECK_GITTAGREGEX = "llvmorg-(?P<pver>\d+(\.\d+)+)"
@@ -124,6 +125,15 @@ do_install() {
 do_install:class-native() {
 	install -D -m 0755 ${B}/bin/llvm-tblgen ${D}${bindir}/llvm-tblgen${PV}
 	install -D -m 0755 ${B}/bin/llvm-config ${D}${bindir}/llvm-config${PV}
+	ln -sf llvm-config${PV} ${D}${bindir}/llvm-config
+}
+
+SYSROOT_PREPROCESS_FUNCS:append:class-target = " llvm_sysroot_preprocess"
+
+llvm_sysroot_preprocess() {
+	install -d ${SYSROOT_DESTDIR}${bindir_crossscripts}/
+	install -m 0755 ${WORKDIR}/llvm-config ${SYSROOT_DESTDIR}${bindir_crossscripts}/
+	ln -sf llvm-config ${SYSROOT_DESTDIR}${bindir_crossscripts}/llvm-config${PV}
 }
 
 PACKAGES =+ "${PN}-bugpointpasses ${PN}-llvmhello ${PN}-libllvm ${PN}-liboptremarks ${PN}-liblto"