profiler_builtins support wasi maybe?

patch.diff

diff --git a/library/profiler_builtins/build.rs b/library/profiler_builtins/build.rs
index 7d5c601df53..fdd41522852 100644
--- a/library/profiler_builtins/build.rs
+++ b/library/profiler_builtins/build.rs
@@ -72,6 +72,15 @@ fn main() {
         cfg.define("COMPILER_RT_HAS_ATOMICS", Some("1"));
     }
 
+    if let Ok(sysroot) = env::var("CARGO_CFG_WASI_SYSROOT") {
+        cfg.flag(&format!("--sysroot={}", sysroot))
+            .define("_WASI_EMULATED_MMAN", None)
+            .flag("-lwasi-emulated-mman");
+    } else {
+        // FIXME this is almost certianly broken for windows
+        cfg.define("COMPILER_RT_HAS_FORK", None);
+    }
+
     // Note that this should exist if we're going to run (otherwise we just
     // don't build profiler builtins at all).
     let root = Path::new("../../src/llvm-project/compiler-rt");
diff --git a/src/bootstrap/compile.rs b/src/bootstrap/compile.rs
index 34002019a6f..25a8b051678 100644
--- a/src/bootstrap/compile.rs
+++ b/src/bootstrap/compile.rs
@@ -274,8 +274,12 @@ pub fn std_cargo(builder: &Builder<'_>, target: TargetSelection, stage: u32, car
 
         if target.ends_with("-wasi") {
             if let Some(p) = builder.wasi_root(target) {
-                let root = format!("native={}/lib/wasm32-wasi", p.to_str().unwrap());
-                cargo.rustflag("-L").rustflag(&root);
+                let path = p.to_str().unwrap();
+                let root = format!("native={}/lib/wasm32-wasi", path);
+                cargo
+                    .rustflag("-L")
+                    .rustflag(&root)
+                    .env("CARGO_CFG_WASI_SYSROOT", path);
             }
         }
     }
Submodule src/llvm-project contains modified content
diff --git a/src/llvm-project/compiler-rt/lib/profile/CMakeLists.txt b/src/llvm-project/compiler-rt/lib/profile/CMakeLists.txt
index 29c6c02f2d03..784f72324010 100644
--- a/src/llvm-project/compiler-rt/lib/profile/CMakeLists.txt
+++ b/src/llvm-project/compiler-rt/lib/profile/CMakeLists.txt
@@ -38,6 +38,15 @@ int main() {
 
 " COMPILER_RT_TARGET_HAS_FCNTL_LCK)
 
+CHECK_CXX_SOURCE_COMPILES("
+#include <unistd.h>
+int main() {
+ pid_t pid = fork();
+ return 0;
+}
+
+" COMPILER_RT_TARGET_HAS_FORK)
+
 CHECK_CXX_SOURCE_COMPILES("
 #include <sys/utsname.h>
 int main() {
@@ -96,7 +105,7 @@ if(COMPILER_RT_TARGET_HAS_ATOMICS)
  set(EXTRA_FLAGS
      ${EXTRA_FLAGS}
      -DCOMPILER_RT_HAS_ATOMICS=1)
-endif() 
+endif()
 
 if(COMPILER_RT_TARGET_HAS_FCNTL_LCK)
  set(EXTRA_FLAGS
@@ -104,6 +113,12 @@ if(COMPILER_RT_TARGET_HAS_FCNTL_LCK)
      -DCOMPILER_RT_HAS_FCNTL_LCK=1)
 endif()
 
+if(COMPILER_RT_TARGET_HAS_FORK)
+ set(EXTRA_FLAGS
+     ${EXTRA_FLAGS}
+     -DCOMPILER_RT_HAS_FORK=1)
+endif()
+
 if(COMPILER_RT_TARGET_HAS_UNAME)
  set(EXTRA_FLAGS
      ${EXTRA_FLAGS}
diff --git a/src/llvm-project/compiler-rt/lib/profile/GCDAProfiling.c b/src/llvm-project/compiler-rt/lib/profile/GCDAProfiling.c
index 82369357e986..b68bce5b6517 100644
--- a/src/llvm-project/compiler-rt/lib/profile/GCDAProfiling.c
+++ b/src/llvm-project/compiler-rt/lib/profile/GCDAProfiling.c
@@ -665,6 +665,7 @@ void llvm_reset_counters(void) {
   }
 }
 
+#ifdef COMPILER_RT_HAS_FORK
 #if !defined(_WIN32)
 COMPILER_RT_VISIBILITY
 pid_t __gcov_fork() {
@@ -683,6 +684,7 @@ pid_t __gcov_fork() {
   return pid;
 }
 #endif
+#endif
 
 COMPILER_RT_VISIBILITY
 void llvm_gcov_init(fn_ptr wfn, fn_ptr ffn, fn_ptr rfn) {