[gold] Add support for optimization remarks

Summary:
Adds support for LTO opt remarks (optionally with hotness) to
gold-plugin.

Reviewers: anemet

Subscribers: fhahn, mehdi_amini, llvm-commits

Differential Revision: https://reviews.llvm.org/D45752

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@330252 91177308-0d34-0410-b5e6-96231b3b80d8

test/tools/gold/X86/opt-remarks.ll

@@ -0,0 +1,76 @@
+; Test plugin options for opt-remarks.
+; RUN: llvm-as %s -o %t.o
+; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold%shlibext -shared \
+; RUN:	  -plugin-opt=save-temps \
+; RUN:    -plugin-opt=opt-remarks-filename=%t.yaml %t.o -o %t2.o 2>&1
+; RUN: llvm-dis %t2.o.0.4.opt.bc -o - | FileCheck %s
+; RUN: %gold -m elf_x86_64 -plugin %llvmshlibdir/LLVMgold%shlibext -shared \
+; RUN:    -plugin-opt=opt-remarks-with-hotness \
+; RUN:	  -plugin-opt=opt-remarks-filename=%t.hot.yaml %t.o -o %t2.o 2>&1
+; RUN: cat %t.yaml | FileCheck %s -check-prefix=YAML
+; RUN: cat %t.hot.yaml | FileCheck %s -check-prefix=YAML-HOT
+
+; Check that @f is inlined after optimizations.
+; CHECK-LABEL: define i32 @_start
+; CHECK-NEXT:  %a.i = call i32 @bar()
+; CHECK-NEXT:  ret i32 %a.i
+; CHECK-NEXT: }
+
+; YAML: --- !Missed
+; YAML-NEXT: Pass:            inline
+; YAML-NEXT: Name:            NoDefinition
+; YAML-NEXT: Function:        f
+; YAML-NEXT: Args:
+; YAML-NEXT:   - Callee:          bar
+; YAML-NEXT:   - String:          ' will not be inlined into '
+; YAML-NEXT:   - Caller:          f
+; YAML-NEXT:   - String:          ' because its definition is unavailable'
+; YAML-NEXT: ...
+; YAML-NEXT: --- !Passed
+; YAML-NEXT: Pass:            inline
+; YAML-NEXT: Name:            Inlined
+; YAML-NEXT: Function:        _start
+; YAML-NEXT: Args:
+; YAML-NEXT:   - Callee:          f
+; YAML-NEXT:   - String:          ' inlined into '
+; YAML-NEXT:   - Caller:          _start
+; YAML-NEXT:   - String:          ' with cost='
+; YAML-NEXT:   - Cost:            '0'
+; YAML-NEXT:   - String:          ' (threshold='
+; YAML-NEXT:   - Threshold:       '337'
+; YAML-NEXT:   - String:          ')'
+; YAML-NEXT: ...
+
+; YAML-HOT: ...
+; YAML-HOT: --- !Passed
+; YAML-HOT: Pass:            inline
+; YAML-HOT-NEXT: Name:            Inlined
+; YAML-HOT-NEXT: Function:        _start
+; YAML-HOT-NEXT: Hotness:         300
+; YAML-HOT-NEXT: Args:
+; YAML-HOT-NEXT:   - Callee:          f
+; YAML-HOT-NEXT:   - String:          ' inlined into '
+; YAML-HOT-NEXT:   - Caller:          _start
+; YAML-HOT-NEXT:   - String:          ' with cost='
+; YAML-HOT-NEXT:   - Cost:            '0'
+; YAML-HOT-NEXT:   - String:          ' (threshold='
+; YAML-HOT-NEXT:   - Threshold:       '337'
+; YAML-HOT-NEXT:   - String:          ')'
+; YAML-HOT-NEXT: ...
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+declare i32 @bar()
+
+define i32 @f() {
+  %a = call i32 @bar()
+  ret i32 %a
+}
+
+define i32 @_start() !prof !0 {
+  %call = call i32 @f()
+  ret i32 %call
+}
+
+!0 = !{!"function_entry_count", i64 300}

tools/gold/gold-plugin.cpp

@@ -204,6 +204,10 @@ namespace options {
   // Directory to store the .dwo files.
   static std::string dwo_dir;
 
+  // Optimization remarks filename and hotness options
+  static std::string OptRemarksFilename;
+  static bool OptRemarksWithHotness = false;
+
   static void process_plugin_option(const char *opt_)
   {
     if (opt_ == nullptr)
@@ -270,6 +274,10 @@ namespace options {
       objcopy = opt.substr(strlen("objcopy="));
     } else if (opt.startswith("dwo_dir=")) {
       dwo_dir = opt.substr(strlen("dwo_dir="));
+    } else if (opt.startswith("opt-remarks-filename=")) {
+      OptRemarksFilename = opt.substr(strlen("opt-remarks-filename="));
+    } else if (opt == "opt-remarks-with-hotness") {
+      OptRemarksWithHotness = true;
     } else {
       // Save this option to pass to the code generator.
       // ParseCommandLineOptions() expects argv[0] to be program name. Lazily
@@ -882,6 +890,10 @@ static std::unique_ptr<LTO> createLTO(IndexWriteCallback OnIndexWrite,
 
   Conf.Objcopy = options::objcopy;
 
+  // Set up optimization remarks handling.
+  Conf.RemarksFilename = options::OptRemarksFilename;
+  Conf.RemarksWithHotness = options::OptRemarksWithHotness;
+
   // Use new pass manager if set in driver
   Conf.UseNewPM = options::new_pass_manager;
   // Debug new pass manager if requested