From dad1d14ef833bf4b39fd65bc026a3e346fd0a48a Mon Sep 17 00:00:00 2001
From: Brian Carroll <brian.carroll.ireland@gmail.com>
Date: Thu, 26 May 2022 08:04:54 +0100
Subject: [PATCH] wasm: make host file relocatable

---
 compiler/build/src/link.rs |  4 ++--
 compiler/test_gen/build.rs | 18 +++++++++++++-----
 repl_wasm/build.rs         |  1 +
 3 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/compiler/build/src/link.rs b/compiler/build/src/link.rs
index cd011243da..5b3c31b019 100644
--- a/compiler/build/src/link.rs
+++ b/compiler/build/src/link.rs
@@ -1155,7 +1155,7 @@ pub fn preprocess_host_wasm32(host_input_path: &Path, preprocessed_host_path: &P
     Notes:
         zig build-obj just gives you back the first input file, doesn't combine them!
         zig build-lib works but doesn't emit relocations, even with --emit-relocs (bug?)
-            (gen_wasm needs relocs to adjust stack size by changing the __heap_base constant)
+            (gen_wasm needs relocs for host-to-app calls and stack size adjustment)
         zig wasm-ld is a wrapper around wasm-ld and gives us maximum flexiblity
             (but seems to be an unofficial API)
     */
@@ -1172,7 +1172,7 @@ pub fn preprocess_host_wasm32(host_input_path: &Path, preprocessed_host_path: &P
         "--export-all",
         "--no-entry",
         "--import-undefined",
-        // "--relocatable", // enable this when gen_wasm can handle Custom sections in any order
+        "--relocatable",
     ];
 
     command.args(args);
diff --git a/compiler/test_gen/build.rs b/compiler/test_gen/build.rs
index 1f9e9f8f38..480b57b110 100644
--- a/compiler/test_gen/build.rs
+++ b/compiler/test_gen/build.rs
@@ -45,7 +45,7 @@ fn build_wasm() {
         &format!("{}/{}.o", out_dir, PLATFORM_FILENAME),
         "--export-all",
         "--no-entry",
-        // "--emit-relocs", // TODO: resize stack by relocating __heap_base (issue #2480) here and in repl_test build
+        "--relocatable",
     ];
 
     let zig = zig_executable();
@@ -98,10 +98,18 @@ fn build_wasm_libc_compilerrt(out_dir: &str, source_path: &str) -> (String, Stri
         ],
     );
 
-    (
-        run_command("find", &[&zig_cache_dir, "-name", "libc.a"]),
-        run_command("find", &[&zig_cache_dir, "-name", "compiler_rt.o"]),
-    )
+    let libc_path = run_command("find", &[&zig_cache_dir, "-name", "libc.a"])
+        .split('\n')
+        .next()
+        .unwrap()
+        .into();
+    let compiler_rt_path = run_command("find", &[&zig_cache_dir, "-name", "compiler_rt.o"])
+        .split('\n')
+        .next()
+        .unwrap()
+        .into();
+
+    (libc_path, compiler_rt_path)
 }
 
 fn feature_is_enabled(feature_name: &str) -> bool {
diff --git a/repl_wasm/build.rs b/repl_wasm/build.rs
index 832a1b7c56..492f6e15a1 100644
--- a/repl_wasm/build.rs
+++ b/repl_wasm/build.rs
@@ -40,6 +40,7 @@ fn main() {
         PRE_LINKED_BINARY,
         "--export-all",
         "--no-entry",
+        "--relocatable",
     ];
 
     let zig = zig_executable();