Toolchain+Ports: Update LLVM to 14.0.1

Besides a version bump, the following changes have been made to our
toolchain infrastructure:
- LLVM/Clang is now built with -march=native if the host compiler
  supports it. An exception to this is CI, as the toolchain cache is
  shared among many different machines there.
- The LLVM tarball is not re-extracted if the hash of the applied
  patches doesn't differ.
- The patches have been split up into atomic chunks.
- Port-specific patches have been integrated into the main patches,
  which will aid in the work towards self-hosting.
- <sysroot>/usr/local/lib is now appended to the linker's search path by
  default.
- --pack-dyn-relocs=relr is appended to the linker command line by
  default, meaning ports take advantage of RELR relocations without any
  patches or additional compiler flags.

The formatting of LLVM port's package.sh has been bothering me, so I
also indented the arguments to the CMake invocation.

Toolchain/BuildClang.sh

@@ -70,8 +70,8 @@ echo PREFIX is "$PREFIX"
 
 mkdir -p "$DIR/Tarballs"
 
-LLVM_VERSION="13.0.0"
-LLVM_MD5SUM="bfc5191cbe87954952d25c6884596ccb"
+LLVM_VERSION="14.0.1"
+LLVM_MD5SUM="47a50c31659488a6ae562475b41d2c32"
 LLVM_NAME="llvm-project-$LLVM_VERSION.src"
 LLVM_PKG="$LLVM_NAME.tar.xz"
 LLVM_URL="https://github.com/llvm/llvm-project/releases/download/llvmorg-$LLVM_VERSION/$LLVM_PKG"
@@ -142,6 +142,25 @@ else
     buildstep dependencies echo "LLD not found. Using the default linker."
 fi
 
+buildstep setup echo "Determining if LLVM should be built with -march=native..."
+if [ "$ci" = "1" ]; then
+    # The toolchain cache is shared among all runners, which might have different CPUs.
+    buildstep setup echo "On a CI runner. Using the default compiler settings."
+elif [ -z "${CFLAGS+x}" ] && [ -z "${CXXFLAGS+x}" ]; then
+    if ${CXX:-c++} -o /dev/null -march=native -xc - >/dev/null 2>/dev/null << 'PROGRAM'
+int main() {}
+PROGRAM
+    then
+        export CFLAGS="-march=native"
+        export CXXFLAGS="-march=native"
+        buildstep setup echo "Using -march=native for compiling LLVM."
+    else
+        buildstep setup echo "-march=native is not supported by the compiler. Using the default settings."
+    fi
+else
+    buildstep setup echo "Using user-provided CFLAGS/CXXFLAGS."
+fi
+
 # === CHECK CACHE AND REUSE ===
 
 pushd "$DIR"
@@ -195,28 +214,35 @@ pushd "$DIR/Tarballs"
         echo "Skipped downloading LLVM"
     fi
 
-    if [ -d "$LLVM_NAME" ]; then
-        # Drop the previously patched extracted dir
-        rm -rf "${LLVM_NAME}"
-        # Also drop the build dir
-        rm -rf "$DIR/Build/clang"
-    fi
-    echo "Extracting LLVM..."
-    tar -xJf "$LLVM_PKG"
+    patch_md5="$($MD5SUM "$DIR"/Patches/llvm/*.patch)"
 
-    pushd "$LLVM_NAME"
-        if [ "$dev" = "1" ]; then
-            git init > /dev/null
-            git add . > /dev/null
-            git commit -am "BASE" > /dev/null
-            git am "$DIR"/Patches/llvm-backport-objcopy-update-section.patch > /dev/null
-            git apply "$DIR"/Patches/llvm.patch > /dev/null
-        else
-            patch -p1 < "$DIR/Patches/llvm.patch" > /dev/null
-            patch -p1 < "$DIR/Patches/llvm-backport-objcopy-update-section.patch" > /dev/null
+    if [ ! -d "$LLVM_NAME" ] || [ "$(cat $LLVM_NAME/.patch.applied)" != "$patch_md5" ]; then
+        if [ -d "$LLVM_NAME" ]; then
+            # Drop the previously patched extracted dir
+            rm -rf "${LLVM_NAME}"
         fi
-        $MD5SUM "$DIR/Patches/llvm.patch" "$DIR/Patches/llvm-backport-objcopy-update-section.patch" > .patch.applied
-    popd
+
+        rm -rf "$DIR/Build/clang"
+
+        echo "Extracting LLVM..."
+        tar -xJf "$LLVM_PKG"
+
+        pushd "$LLVM_NAME"
+            if [ "$dev" = "1" ]; then
+                git init > /dev/null
+                git add . > /dev/null
+                git commit -am "BASE" > /dev/null
+                git am "$DIR"/Patches/llvm/*.patch > /dev/null
+            else
+                for patch in "$DIR"/Patches/llvm/*.patch; do
+                    patch -p1 < "$patch" > /dev/null
+                done
+            fi
+            echo "$patch_md5" > .patch.applied
+        popd
+    else
+        echo "Using existing LLVM source directory"
+    fi
 popd
 
 # === COPY HEADERS ===
@@ -273,7 +299,7 @@ pushd "$DIR/Build/clang"
             ${ci:+"-DLLVM_CCACHE_MAXSIZE=$LLVM_CCACHE_MAXSIZE"}
 
         buildstep_ninja "llvm/build" ninja -j "$MAKEJOBS"
-        buildstep "llvm/install" ninja install/strip
+        buildstep_ninja "llvm/install" ninja install/strip
     popd
 
     for arch in $ARCHS; do
@@ -288,8 +314,8 @@ pushd "$DIR/Build/clang"
                 -DCMAKE_INSTALL_PREFIX="$PREFIX" \
                 -C "$DIR/CMake/LLVMRuntimesConfig.cmake"
 
-            buildstep "runtimes/$arch/build" ninja -j "$MAKEJOBS"
-            buildstep "runtimes/$arch/install" ninja install
+            buildstep_ninja "runtimes/$arch/build" ninja -j "$MAKEJOBS"
+            buildstep_ninja "runtimes/$arch/install" ninja install
         popd
     done
 popd