Wasm: pre-link app-independent code before running tests (builtins, plaform & libc)

compiler/test_gen/Cargo.toml

@@ -9,6 +9,9 @@ edition = "2018"
 name = "test_gen"
 path = "src/tests.rs"
 
+[build-dependencies]
+roc_builtins = { path = "../builtins" }
+
 [dev-dependencies]
 roc_gen_llvm = { path = "../gen_llvm" }
 roc_gen_dev = { path = "../gen_dev" }

compiler/test_gen/build.rs

@@ -1,3 +1,4 @@
+use roc_builtins::bitcode;
 use std::env;
 use std::ffi::OsStr;
 use std::path::Path;
@@ -5,8 +6,6 @@ use std::process::Command;
 
 const PLATFORM_FILENAME: &str = "wasm_test_platform";
 const OUT_DIR_VAR: &str = "TEST_GEN_OUT";
-const LIBC_PATH_VAR: &str = "TEST_GEN_WASM_LIBC_PATH";
-const COMPILER_RT_PATH_VAR: &str = "TEST_GEN_WASM_COMPILER_RT_PATH";
 
 fn main() {
     println!("cargo:rerun-if-changed=build.rs");
@@ -20,8 +19,7 @@ fn build_wasm() {
 
     println!("cargo:rustc-env={}={}", OUT_DIR_VAR, out_dir);
 
-    build_wasm_test_platform(&out_dir);
-    build_wasm_libc(&out_dir);
+    build_wasm_platform_and_builtins(&out_dir);
 }
 
 fn zig_executable() -> String {
@@ -31,52 +29,25 @@ fn zig_executable() -> String {
     }
 }
 
-fn build_wasm_test_platform(out_dir: &str) {
+/// Create an all-in-one object file: platform + builtins + libc
+fn build_wasm_platform_and_builtins(out_dir: &str) {
     println!("cargo:rerun-if-changed=src/helpers/{}.c", PLATFORM_FILENAME);
 
-    run_command(
-        Path::new("."),
-        &zig_executable(),
-        [
-            "build-obj",
-            "-target",
-            "wasm32-wasi",
-            "-lc",
-            &format!("src/helpers/{}.c", PLATFORM_FILENAME),
-            &format!("-femit-bin={}/{}.o", out_dir, PLATFORM_FILENAME),
-        ],
-    );
-}
+    // See discussion with Luuk de Gram (Zig contributor)
+    // https://github.com/rtfeldman/roc/pull/2181#pullrequestreview-839608063
+    // This builds a library file that exports everything. It has no linker data but we don't need that.
+    let args = [
+        "build-lib",
+        "-target",
+        "wasm32-wasi",
+        "-lc",
+        "-dynamic", // -dynamic ensures libc code goes into the binary
+        bitcode::BUILTINS_WASM32_OBJ_PATH,
+        &format!("src/helpers/{}.c", PLATFORM_FILENAME),
+        &format!("-femit-bin={}/{}.o", out_dir, PLATFORM_FILENAME),
+    ];
 
-fn build_wasm_libc(out_dir: &str) {
-    let source_path = "src/helpers/dummy_libc_program.c";
-    println!("cargo:rerun-if-changed={}", source_path);
-    let cwd = Path::new(".");
-    let zig_cache_dir = format!("{}/zig-cache-wasm32", out_dir);
-
-    run_command(
-        cwd,
-        &zig_executable(),
-        [
-            "build-exe", // must be an executable or it won't compile libc
-            "-target",
-            "wasm32-wasi",
-            "-lc",
-            source_path,
-            "-femit-bin=/dev/null",
-            "--global-cache-dir",
-            &zig_cache_dir,
-        ],
-    );
-
-    let libc_path = run_command(cwd, "find", [&zig_cache_dir, "-name", "libc.a"]);
-    let compiler_rt_path = run_command(cwd, "find", [&zig_cache_dir, "-name", "compiler_rt.o"]);
-
-    println!("cargo:rustc-env={}={}", LIBC_PATH_VAR, libc_path);
-    println!(
-        "cargo:rustc-env={}={}",
-        COMPILER_RT_PATH_VAR, compiler_rt_path
-    );
+    run_command(Path::new("."), &zig_executable(), args);
 }
 
 fn feature_is_enabled(feature_name: &str) -> bool {

compiler/test_gen/src/helpers/wasm.rs

@@ -8,7 +8,6 @@ use wasmer::{Memory, WasmPtr};
 
 use crate::helpers::from_wasm32_memory::FromWasm32Memory;
 use crate::helpers::wasm32_test_result::Wasm32TestResult;
-use roc_builtins::bitcode;
 use roc_can::builtins::builtin_defs_map;
 use roc_collections::all::{MutMap, MutSet};
 use roc_gen_wasm::{DEBUG_LOG_SETTINGS, MEMORY_NAME};
@@ -16,8 +15,6 @@ use roc_gen_wasm::{DEBUG_LOG_SETTINGS, MEMORY_NAME};
 // Should manually match build.rs
 const PLATFORM_FILENAME: &str = "wasm_test_platform";
 const OUT_DIR_VAR: &str = "TEST_GEN_OUT";
-const LIBC_PATH_VAR: &str = "TEST_GEN_WASM_LIBC_PATH";
-const COMPILER_RT_PATH_VAR: &str = "TEST_GEN_WASM_COMPILER_RT_PATH";
 
 #[allow(unused_imports)]
 use roc_mono::ir::PRETTY_PRINT_IR_SYMBOLS;
@@ -175,8 +172,6 @@ fn run_linker(
     let app_o_file = wasm_build_dir.join("app.o");
     let test_out_dir = std::env::var(OUT_DIR_VAR).unwrap();
     let test_platform_o = format!("{}/{}.o", test_out_dir, PLATFORM_FILENAME);
-    let libc_a_file = std::env::var(LIBC_PATH_VAR).unwrap();
-    let compiler_rt_o_file = std::env::var(COMPILER_RT_PATH_VAR).unwrap();
 
     // write the module to a file so the linker can access it
     std::fs::write(&app_o_file, &app_module_bytes).unwrap();
@@ -185,10 +180,7 @@ fn run_linker(
         "wasm-ld",
         // input files
         app_o_file.to_str().unwrap(),
-        bitcode::BUILTINS_WASM32_OBJ_PATH,
         &test_platform_o,
-        &libc_a_file,
-        &compiler_rt_o_file,
         // output
         "-o",
         final_wasm_file.to_str().unwrap(),