From: Reid Kleckner <rnk@google.com>
Date: Fri, 16 Nov 2018 18:47:41 +0000 (+0000)
Subject: [codeview] Expose -gcodeview-ghash for global type hashing
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=9bb670a6fd5843d7cb9ba98460671c4d5f15f4ea;p=clang

[codeview] Expose -gcodeview-ghash for global type hashing

Summary:
Experience has shown that the functionality is useful. It makes linking
optimized clang with debug info for me a lot faster, 20s to 13s. The
type merging phase of PDB writing goes from 10s to 3s.

This removes the LLVM cl::opt and replaces it with a metadata flag.

After this change, users can do the following to use ghash:
- add -gcodeview-ghash to compiler flags
- replace /DEBUG with /DEBUG:GHASH in linker flags

Reviewers: zturner, hans, thakis, takuto.ikuta

Subscribers: aprantl, hiraditya, JDevlieghere, llvm-commits

Differential Revision: https://reviews.llvm.org/D54370

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@347072 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/clang/Driver/Options.td b/include/clang/Driver/Options.td
index 70cfec0d3e..48644617bc 100644
--- a/include/clang/Driver/Options.td
+++ b/include/clang/Driver/Options.td
@@ -1818,9 +1818,15 @@ def gdwarf_4 : Flag<["-"], "gdwarf-4">, Group<g_Group>,
   HelpText<"Generate source-level debug information with dwarf version 4">;
 def gdwarf_5 : Flag<["-"], "gdwarf-5">, Group<g_Group>,
   HelpText<"Generate source-level debug information with dwarf version 5">;
+
 def gcodeview : Flag<["-"], "gcodeview">,
   HelpText<"Generate CodeView debug information">,
   Flags<[CC1Option, CC1AsOption, CoreOption]>;
+def gcodeview_ghash : Flag<["-"], "gcodeview-ghash">,
+  HelpText<"Emit type record hashes in a .debug$H section">,
+  Flags<[CC1Option, CoreOption]>;
+def gno_codeview_ghash : Flag<["-"], "gno-codeview-ghash">, Flags<[CoreOption]>;
+
 // Equivalent to our default dwarf version. Forces usual dwarf emission when
 // CodeView is enabled.
 def gdwarf : Flag<["-"], "gdwarf">, Alias<gdwarf_4>, Flags<[CoreOption]>;
diff --git a/include/clang/Frontend/CodeGenOptions.def b/include/clang/Frontend/CodeGenOptions.def
index fd87f3b713..a2fb1507ce 100644
--- a/include/clang/Frontend/CodeGenOptions.def
+++ b/include/clang/Frontend/CodeGenOptions.def
@@ -297,6 +297,9 @@ VALUE_CODEGENOPT(DwarfVersion, 3, 0)
 /// CodeView and DWARF into the same object.
 CODEGENOPT(EmitCodeView, 1, 0)
 
+/// Whether to emit the .debug$H section containing hashes of CodeView types.
+CODEGENOPT(CodeViewGHash, 1, 0)
+
 /// The kind of inlining to perform.
 ENUM_CODEGENOPT(Inlining, InliningMethod, 2, NormalInlining)
 
diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index 7b9af628de..f03da97940 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -458,6 +458,9 @@ void CodeGenModule::Release() {
     // Indicate that we want CodeView in the metadata.
     getModule().addModuleFlag(llvm::Module::Warning, "CodeView", 1);
   }
+  if (CodeGenOpts.CodeViewGHash) {
+    getModule().addModuleFlag(llvm::Module::Warning, "CodeViewGHash", 1);
+  }
   if (CodeGenOpts.ControlFlowGuard) {
     // We want function ID tables for Control Flow Guard.
     getModule().addModuleFlag(llvm::Module::Warning, "cfguardtable", 1);
diff --git a/lib/Driver/ToolChains/Clang.cpp b/lib/Driver/ToolChains/Clang.cpp
index b2d0ae7f1d..dd79e8ee86 100644
--- a/lib/Driver/ToolChains/Clang.cpp
+++ b/lib/Driver/ToolChains/Clang.cpp
@@ -3198,9 +3198,16 @@ static void RenderDebugOptions(const ToolChain &TC, const Driver &D,
       CmdArgs.push_back("-gembed-source");
   }
 
-  if (EmitCodeView)
+  if (EmitCodeView) {
     CmdArgs.push_back("-gcodeview");
 
+    // Emit codeview type hashes if requested.
+    if (Args.hasFlag(options::OPT_gcodeview_ghash,
+                     options::OPT_gno_codeview_ghash, false)) {
+      CmdArgs.push_back("-gcodeview-ghash");
+    }
+  }
+
   RenderDebugEnablingArgs(Args, CmdArgs, DebugInfoKind, DWARFVersion,
                           DebuggerTuning);
 
diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index 1ea3df4303..7df65e78f8 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -593,6 +593,7 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
   Opts.DwarfVersion = getLastArgIntValue(Args, OPT_dwarf_version_EQ, 0, Diags);
   Opts.DebugColumnInfo = Args.hasArg(OPT_dwarf_column_info);
   Opts.EmitCodeView = Args.hasArg(OPT_gcodeview);
+  Opts.CodeViewGHash = Args.hasArg(OPT_gcodeview_ghash);
   Opts.MacroDebugInfo = Args.hasArg(OPT_debug_info_macro);
   Opts.WholeProgramVTables = Args.hasArg(OPT_fwhole_program_vtables);
   Opts.LTOVisibilityPublicStd = Args.hasArg(OPT_flto_visibility_public_std);
diff --git a/test/CodeGenCXX/debug-info-ms-abi.cpp b/test/CodeGenCXX/debug-info-ms-abi.cpp
index e83d7e9423..dfcd06c636 100644
--- a/test/CodeGenCXX/debug-info-ms-abi.cpp
+++ b/test/CodeGenCXX/debug-info-ms-abi.cpp
@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 %s -triple=i686-pc-windows-msvc -debug-info-kind=limited -gcodeview -emit-llvm -o - | FileCheck %s
+// RUN: %clang_cc1 %s -triple=i686-pc-windows-msvc -debug-info-kind=limited -gcodeview -gcodeview-ghash -emit-llvm -o - | FileCheck %s --check-prefixes=CHECK,GHASH
 
 // Tests that certain miscellaneous features work in the MS ABI.
 
@@ -45,3 +46,6 @@ Foo::Nested n;
 // CHECK-NEXT: ![[dummy:[0-9]+]] = !DISubroutineType(types: ![[Signature:[0-9]+]])
 // CHECK: ![[Signature]] = !{null, ![[BasicInt:[0-9]+]], ![[BasicInt]]}
 // CHECK: ![[BasicInt]] = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+
+// CHECK: !{{[0-9]+}} = !{i32 2, !"CodeView", i32 1}
+// GHASH: !{{[0-9]+}} = !{i32 2, !"CodeViewGHash", i32 1}