Revert "Use callback-based interface to load ThinLTO import data into rustc."

This reverts commit e045a6cd8c0235a26ef11e6cd9a13ebd817f1265.

2 files changed, 44 insertions, 32 deletions

diff --git a/src/librustc_codegen_llvm/back/lto.rs b/src/librustc_codegen_llvm/back/lto.rs
index 55499552f5c..a68f22b2651 100644
--- a/src/librustc_codegen_llvm/back/lto.rs
+++ b/src/librustc_codegen_llvm/back/lto.rs
@@ -805,7 +805,7 @@ pub struct ThinLTOImports {
 
 impl ThinLTOImports {
 
-    pub fn new() -> ThinLTOImports {
+    pub fn new_empty() -> ThinLTOImports {
         ThinLTOImports {
             imports: FxHashMap(),
         }
@@ -813,46 +813,58 @@ impl ThinLTOImports {
 
     /// Load the ThinLTO import map from ThinLTOData.
     unsafe fn from_thin_lto_data(data: *const llvm::ThinLTOData) -> ThinLTOImports {
+        let raw_data: *const llvm::ThinLTOModuleImports =
+            llvm::LLVMRustGetThinLTOModuleImports(data);
 
-        fn module_name_to_str(c_str: &CStr) -> &str {
-            match c_str.to_str() {
-                Ok(s) => s,
-                Err(e) => {
-                    bug!("Encountered non-utf8 LLVM module name `{}`: {}",
-                        c_str.to_string_lossy(),
-                        e)
-                }
+        assert!(!raw_data.is_null());
+
+        let mut imports = FxHashMap();
+        let mut module_ptr = raw_data;
+        let mut module_index = 0;
+
+        loop {
+            let mut entry_ptr: *const llvm::ThinLTOModuleName = *module_ptr;
+
+            if entry_ptr.is_null() {
+                break;
             }
-        }
 
-        unsafe extern "C" fn imported_module_callback(payload: *mut libc::c_void,
-                                                      importing_module_name: *const libc::c_char,
-                                                      imported_module_name: *const libc::c_char) {
-            let map = &mut* (payload as *mut ThinLTOImports);
+            let importing_module_name = CStr::from_ptr(*entry_ptr)
+                .to_str()
+                .expect("Non-utf8 LLVM module name encountered")
+                .to_owned();
+
+            entry_ptr = entry_ptr.offset(1);
 
-            let importing_module_name = CStr::from_ptr(importing_module_name);
-            let importing_module_name = module_name_to_str(&importing_module_name);
-            let imported_module_name = CStr::from_ptr(imported_module_name);
-            let imported_module_name = module_name_to_str(&imported_module_name);
+            let mut imported_modules = vec![];
 
-            if !map.imports.contains_key(importing_module_name) {
-                map.imports.insert(importing_module_name.to_owned(), vec![]);
+            loop {
+                let imported_module_name = *entry_ptr;
+
+                if imported_module_name.is_null() {
+                    break
+                }
+
+                let imported_module_name = CStr::from_ptr(imported_module_name)
+                    .to_str()
+                    .expect("Non-utf8 LLVM module name encountered")
+                    .to_owned();
+
+                imported_modules.push(imported_module_name);
+                entry_ptr = entry_ptr.offset(1);
             }
 
-            map.imports
-               .get_mut(importing_module_name)
-               .unwrap()
-               .push(imported_module_name.to_owned());
+            imports.insert(importing_module_name, imported_modules);
+
+            module_ptr = module_ptr.offset(1);
+            module_index += 1;
         }
 
-        let mut map = ThinLTOImports {
-            imports: FxHashMap(),
-        };
+        assert_eq!(module_index, imports.len());
 
-        llvm::LLVMRustGetThinLTOModuleImports(data,
-                                              imported_module_callback,
-                                              &mut map as *mut _ as *mut libc::c_void);
-        map
+        ThinLTOImports {
+            imports
+        }
     }
 
     pub fn save_to_file(&self, path: &Path) -> io::Result<()> {
diff --git a/src/librustc_codegen_llvm/base.rs b/src/librustc_codegen_llvm/base.rs
index 451e5cf9a60..603ee78585e 100644
--- a/src/librustc_codegen_llvm/base.rs
+++ b/src/librustc_codegen_llvm/base.rs
@@ -1360,7 +1360,7 @@ fn load_thin_lto_imports(sess: &Session) -> lto::ThinLTOImports {
     );
 
     if !path.exists() {
-        return lto::ThinLTOImports::new();
+        return lto::ThinLTOImports::new_empty();
     }
 
     match lto::ThinLTOImports::load_from_file(&path) {