From 85df207ecc3a7b8b7150e2b65c67eec3a23b7c81 Mon Sep 17 00:00:00 2001
From: Victor Ding <victording@google.com>
Date: Mon, 2 Dec 2019 20:53:01 +1100
Subject: [PATCH] Use Module::print() instead of a PrintModulePass

llvm::Module has a print() method. It is unnecessary to create a
pass just for the purpose of printing LLVM IR.
---
 src/librustc_codegen_llvm/back/write.rs | 13 +++-----
 src/librustc_codegen_llvm/llvm/ffi.rs   |  3 +-
 src/rustllvm/PassWrapper.cpp            | 43 ++-----------------------
 3 files changed, 9 insertions(+), 50 deletions(-)

diff --git a/src/librustc_codegen_llvm/back/write.rs b/src/librustc_codegen_llvm/back/write.rs
index 07ac76cec99..187063b866a 100644
--- a/src/librustc_codegen_llvm/back/write.rs
+++ b/src/librustc_codegen_llvm/back/write.rs
@@ -587,14 +587,11 @@ pub(crate) unsafe fn codegen(cgcx: &CodegenContext<LlvmCodegenBackend>,
                     cursor.position() as size_t
                 }
 
-                with_codegen(tm, llmod, config.no_builtins, |cpm| {
-                    let result =
-                        llvm::LLVMRustPrintModule(cpm, llmod, out_c.as_ptr(), demangle_callback);
-                    llvm::LLVMDisposePassManager(cpm);
-                    result.into_result().map_err(|()| {
-                        let msg = format!("failed to write LLVM IR to {}", out.display());
-                        llvm_err(diag_handler, &msg)
-                    })
+                let result =
+                    llvm::LLVMRustPrintModule(llmod, out_c.as_ptr(), demangle_callback);
+                result.into_result().map_err(|()| {
+                    let msg = format!("failed to write LLVM IR to {}", out.display());
+                    llvm_err(diag_handler, &msg)
                 })?;
             }
 
diff --git a/src/librustc_codegen_llvm/llvm/ffi.rs b/src/librustc_codegen_llvm/llvm/ffi.rs
index a49e863fa21..762c821de4d 100644
--- a/src/librustc_codegen_llvm/llvm/ffi.rs
+++ b/src/librustc_codegen_llvm/llvm/ffi.rs
@@ -1726,8 +1726,7 @@ extern "C" {
                                    Output: *const c_char,
                                    FileType: FileType)
                                    -> LLVMRustResult;
-    pub fn LLVMRustPrintModule(PM: &PassManager<'a>,
-                               M: &'a Module,
+    pub fn LLVMRustPrintModule(M: &'a Module,
                                Output: *const c_char,
                                Demangle: extern fn(*const c_char,
                                                    size_t,
diff --git a/src/rustllvm/PassWrapper.cpp b/src/rustllvm/PassWrapper.cpp
index a116ed282ac..40823422c27 100644
--- a/src/rustllvm/PassWrapper.cpp
+++ b/src/rustllvm/PassWrapper.cpp
@@ -660,46 +660,11 @@ public:
   }
 };
 
-class RustPrintModulePass : public ModulePass {
-  raw_ostream* OS;
-  DemangleFn Demangle;
-public:
-  static char ID;
-  RustPrintModulePass() : ModulePass(ID), OS(nullptr), Demangle(nullptr) {}
-  RustPrintModulePass(raw_ostream &OS, DemangleFn Demangle)
-      : ModulePass(ID), OS(&OS), Demangle(Demangle) {}
-
-  bool runOnModule(Module &M) override {
-    RustAssemblyAnnotationWriter AW(Demangle);
-
-    M.print(*OS, &AW, false);
-
-    return false;
-  }
-
-  void getAnalysisUsage(AnalysisUsage &AU) const override {
-    AU.setPreservesAll();
-  }
-
-  static StringRef name() { return "RustPrintModulePass"; }
-};
-
 } // namespace
 
-namespace llvm {
-  void initializeRustPrintModulePassPass(PassRegistry&);
-}
-
-char RustPrintModulePass::ID = 0;
-INITIALIZE_PASS(RustPrintModulePass, "print-rust-module",
-                "Print rust module to stderr", false, false)
-
 extern "C" LLVMRustResult
-LLVMRustPrintModule(LLVMPassManagerRef PMR, LLVMModuleRef M,
-                    const char *Path, DemangleFn Demangle) {
-  llvm::legacy::PassManager *PM = unwrap<llvm::legacy::PassManager>(PMR);
+LLVMRustPrintModule(LLVMModuleRef M, const char *Path, DemangleFn Demangle) {
   std::string ErrorInfo;
-
   std::error_code EC;
   raw_fd_ostream OS(Path, EC, sys::fs::F_None);
   if (EC)
@@ -709,11 +674,9 @@ LLVMRustPrintModule(LLVMPassManagerRef PMR, LLVMModuleRef M,
     return LLVMRustResult::Failure;
   }
 
+  RustAssemblyAnnotationWriter AAW(Demangle);
   formatted_raw_ostream FOS(OS);
-
-  PM->add(new RustPrintModulePass(FOS, Demangle));
-
-  PM->run(*unwrap(M));
+  unwrap(M)->print(FOS, &AAW);
 
   return LLVMRustResult::Success;
 }