perf: lazy OSX frameworks with lzld

.cargo/config.toml

@@ -18,9 +18,10 @@ rustflags = [
 ]
 
 [target.aarch64-apple-darwin]
+linker = "tools/lzld/lzld"
 rustflags = [
   "-C",
-  "link-args=-fuse-ld=lld -weak_framework Metal -weak_framework MetalPerformanceShaders -weak_framework QuartzCore -weak_framework CoreGraphics",
+  "linker-flavor=ld64.lld",
 ]
 
 [target.'cfg(all())']

.github/workflows/ci.generate.ts

@@ -676,6 +676,16 @@ const ci = {
           run:
             "deno run --allow-write --allow-read --allow-run=git ./tests/node_compat/runner/setup.ts --check",
         },
+        // For remote debugging only.
+        // {
+        //   name: "Setup tmate session",
+        //   if: [
+        //     "(matrix.job == 'test' || matrix.job == 'bench') &&",
+        //     "matrix.profile == 'debug' && (matrix.use_sysroot ||",
+        //     "github.repository == 'denoland/deno')",
+        //   ].join("\n"),
+        //   uses: "mxschmitt/action-tmate@v3",
+        // },
         {
           name: "Build debug",
           if: "matrix.job == 'test' && matrix.profile == 'debug'",

tools/lzld/.gitignore

@@ -0,0 +1,3 @@
+/target
+
+*.o

tools/lzld/Makefile

@@ -0,0 +1,12 @@
+ARCH = $(shell uname -m)
+
+liblzld_${ARCH}.a: lzld.m
+	cc -c lzld.m -o lzld.o
+	ar rcs liblzld_${ARCH}.a lzld.o
+
+clean:
+	rm -f liblzld_${ARCH}.a lzld.o
+
+all: liblzld_${ARCH}.a
+
+.PHONY: clean all

tools/lzld/README.md

@@ -0,0 +1,36 @@
+A `ld -lazy_framework` for macOS. Designed to build Deno.
+
+## Usage
+
+```toml
+[target.aarch64-apple-darwin]
+rustflags = [
+  "-C",
+  "linker=/path/to/lzld/lzld",
+  "-C",
+  "link-args=-L/path/to/lzld -llzld",
+]
+```
+
+### Usage without `lzld` wrapper
+
+1. `rustc -Z link-native-libraries=no -L/path/to/lzld -llzld`: Requires nightly
+   but doesn't need a wrapper linker.
+
+2. Manaully source modification: Remove `#[link]` attributes from all
+   dependencies and link to `liblzld.a`.
+
+## Design
+
+It's pretty simple. Drop in `lzld` as the linker. It strips out `-framework`
+arguments and links a static library (`liblzld.a`) that will lazy load the
+framework via `dlopen` when needed.
+
+Rest of the arguments are passed as-is to `lld`.
+
+<!--
+Supported frameworks:
+- QuartzCore
+- CoreFoundation
+- TODO
+-->

tools/lzld/lzld

@@ -0,0 +1,52 @@
+#!/bin/bash
+arch=$(uname -m)
+
+# Find the path to the `lld` binary.
+lld=$(which lld)
+if [ -z "$lld" ]; then
+  lld=$(which ld64.lld)
+fi
+
+if [ ! -x "$lld" ]; then
+  echo "Error: unable to find 'lld' binary" >&2
+  exit 23
+fi
+
+# Filter out `-framework` arguments.
+args=()
+
+while [ $# -gt 0 ]; do
+  case "$1" in
+    -framework)
+      shift 2
+      ;;
+    -Wl)
+      # Process `-Wl`
+      shift
+      IFS=',' read -r -a wl_args <<< "$1"
+      for arg in "${wl_args[@]}"; do
+        args+=("$arg")
+      done
+      shift
+      ;;
+    *)
+      if [[ $1 == -Wl,* ]]; then
+        IFS=',' read -r -a wl_args <<< "${1:4}"
+        for arg in "${wl_args[@]}"; do
+          args+=("$arg")
+        done
+      else
+        args+=("$1")
+      fi
+      shift
+      ;;
+  esac
+done
+
+args+=("-L$(dirname "$(realpath "$0")")")
+args+=("-llzld_${arch}")
+# Needed for fsevents. TODO: add patches for these as well.
+args+=("-framework" "CoreFoundation" "-framework" "CoreServices")
+
+exec "$lld" "${args[@]}"
+

tools/lzld/lzld.m

@@ -0,0 +1,24 @@
+#import <dlfcn.h>
+
+// -- QuartzCore.framework
+
+extern void *kCAGravityTopLeft = 0;
+
+// -- Metal.framework
+
+void *(*MTLCopyAllDevices_)(void) = 0;
+
+void loadMetalFramework() {
+    void *handle = dlopen("/System/Library/Frameworks/Metal.framework/Metal", RTLD_LAZY);
+    if (handle) {
+        MTLCopyAllDevices_ = dlsym(handle, "MTLCopyAllDevices");
+    }
+}
+
+extern void *MTLCopyAllDevices(void) {
+    if (MTLCopyAllDevices_ == 0) {
+        loadMetalFramework();
+    }
+
+    return MTLCopyAllDevices_();
+}