[gold] emit assembly listing from gold plugin on LTO stage

Summary:
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.

Patch by Denis Bakhvalov.

Reviewers: mehdi_amini, tejohnson

Reviewed By: tejohnson

Subscribers: MaskRay, inglorion, dexonsmith, llvm-commits

Differential Revision: https://reviews.llvm.org/D56114

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@350276 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/test/tools/gold/X86/emit-asm.ll b/test/tools/gold/X86/emit-asm.ll
new file mode 100644 (file)
index 0000000..40ff71f
--- /dev/null
+++ b/test/tools/gold/X86/emit-asm.ll
@@ -0,0 +1,25 @@
+; RUN: llvm-as %s -o %t.o
+
+; RUN: %gold -plugin %llvmshlibdir/LLVMgold%shlibext \
+; RUN:    -m elf_x86_64 --plugin-opt=emit-asm \
+; RUN:    -shared %t.o -o %t2.s
+; RUN: FileCheck --input-file %t2.s %s
+
+; RUN: %gold -plugin %llvmshlibdir/LLVMgold%shlibext \
+; RUN:    -m elf_x86_64 --plugin-opt=emit-asm --plugin-opt=lto-partitions=2\
+; RUN:    -shared %t.o -o %t2.s
+; RUN: cat %t2.s %t2.s1 > %t3.s
+; RUN: FileCheck --input-file %t3.s %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; CHECK-DAG: f1:
+define void @f1() {
+  ret void
+}
+
+; CHECK-DAG: f2:
+define void @f2() {
+  ret void
+}

diff --git a/tools/gold/gold-plugin.cpp b/tools/gold/gold-plugin.cpp
index 8ffa5877ba665c7dbfe9c9f0bdc7737a3c4b8a84..738cafa6cacf23d7623e96b67e738dd2951ede6d 100644 (file)
--- a/tools/gold/gold-plugin.cpp
+++ b/tools/gold/gold-plugin.cpp
@@ -128,6 +128,7 @@ namespace options {
     OT_NORMAL,
     OT_DISABLE,
     OT_BC_ONLY,
+    OT_ASM_ONLY,
     OT_SAVE_TEMPS
   };
   static OutputType TheOutputType = OT_NORMAL;
@@ -229,6 +230,8 @@ namespace options {
       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 @@ static std::unique_ptr<LTO> createLTO(IndexWriteCallback OnIndexWrite,
     check(Conf.addSaveTemps(output_name + ".",
                             /* UseInputModulePath */ true));
     break;
+  case options::OT_ASM_ONLY:
+    Conf.CGFileType = TargetMachine::CGFT_AssemblyFile;
+    break;
   }
 
   if (!options::sample_profile.empty())
@@ -1009,6 +1015,8 @@ static std::vector<std::pair<SmallString<128>, bool>> runLTO() {
     Filename = options::obj_path;
   else if (options::TheOutputType == options::OT_SAVE_TEMPS)
     Filename = output_name + ".o";
+  else if (options::TheOutputType == options::OT_ASM_ONLY)
+    Filename = output_name;
   bool SaveTemps = !Filename.empty();
 
   size_t MaxTasks = Lto->getMaxTasks();
@@ -1057,7 +1065,8 @@ static ld_plugin_status allSymbolsReadHook() {
   std::vector<std::pair<SmallString<128>, bool>> Files = runLTO();
 
   if (options::TheOutputType == options::OT_DISABLE ||
-      options::TheOutputType == options::OT_BC_ONLY)
+      options::TheOutputType == options::OT_BC_ONLY ||
+      options::TheOutputType == options::OT_ASM_ONLY)
     return LDPS_OK;
 
   if (options::thinlto_index_only) {
@@ -1082,6 +1091,7 @@ static ld_plugin_status all_symbols_read_hook(void) {
   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