[PATCH] D56114: [LTO] emit assembly listing from LTO stage

[Denis Bakhvalov via Phabricator via llvm-commits]

dendibakh created this revision.
dendibakh added reviewers: mehdi_amini, tejohnson.
Herald added subscribers: llvm-commits, dexonsmith, inglorion.

Sometimes it's useful to emit assembly after LTO stage to modify it manually. Emitting precodegen bitcode file (via save-temps plugin option) and then feeding it to llc doesn't always give the same binary as original.
This patch is simpler alternative to https://reviews.llvm.org/D24020.


Repository:
  rL LLVM

https://reviews.llvm.org/D56114

Files:
  tools/gold/gold-plugin.cpp


Index: tools/gold/gold-plugin.cpp
===================================================================
--- tools/gold/gold-plugin.cpp
+++ tools/gold/gold-plugin.cpp
@@ -128,6 +128,7 @@
     OT_NORMAL,
     OT_DISABLE,
     OT_BC_ONLY,
+    OT_ASM_ONLY,
     OT_SAVE_TEMPS
   };
   static OutputType TheOutputType = OT_NORMAL;
@@ -229,6 +230,8 @@
       TheOutputType = OT_SAVE_TEMPS;
     } else if (opt == "disable-output") {
       TheOutputType = OT_DISABLE;
+    } else if (opt == "emit-asm") {
+      TheOutputType = OT_ASM_ONLY;
     } else if (opt == "thinlto") {
       thinlto = true;
     } else if (opt == "thinlto-index-only") {
@@ -882,6 +885,9 @@
     check(Conf.addSaveTemps(output_name + ".",
                             /* UseInputModulePath */ true));
     break;
+  case options::OT_ASM_ONLY:
+    Conf.CGFileType = TargetMachine::CGFT_AssemblyFile;
+    break;
   }
 
   if (!options::sample_profile.empty())
@@ -1060,6 +1066,23 @@
       options::TheOutputType == options::OT_BC_ONLY)
     return LDPS_OK;
 
+  if (options::TheOutputType == options::OT_ASM_ONLY) {
+    auto CopyFile = [](const std::string &from, const std::string &to) {
+      std::error_code EC = sys::fs::copy_file(from, to);
+      if (EC)
+        message(LDPL_ERROR, "Failed to copy assembly to '%s': %s", to.c_str(),
+                EC.message().c_str());
+    };
+
+    if (Files.size() == 1)
+      CopyFile(Files.front().first.str(), output_name);
+    else
+      for (unsigned i = 0; i < Files.size(); ++i)
+        CopyFile(Files[i].first.str(), output_name + '.' + std::to_string(i));
+
+    return LDPS_OK;
+  }
+
   if (options::thinlto_index_only) {
     llvm_shutdown();
     cleanup_hook();
@@ -1082,6 +1105,7 @@
   llvm_shutdown();
 
   if (options::TheOutputType == options::OT_BC_ONLY ||
+      options::TheOutputType == options::OT_ASM_ONLY ||
       options::TheOutputType == options::OT_DISABLE) {
     if (options::TheOutputType == options::OT_DISABLE) {
       // Remove the output file here since ld.bfd creates the output file


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