[PATCH] D68029: [ThinLTO] Enable index-only WPD from clang

[Teresa Johnson via Phabricator via cfe-commits]

tejohnson created this revision.
tejohnson added a reviewer: pcc.
Herald added subscribers: arphaman, dexonsmith, steven_wu, inglorion, mehdi_amini.
Herald added a project: clang.

To trigger the index-only Whole Program Devirt support added to LLVM, we
need to be able to specify -fno-split-lto-unit in conjunction with
-fwhole-program-vtables. Keep the default for -fwhole-program-vtables as
-fsplit-lto-unit, but don't error on that option combination.


Repository:
  rC Clang

https://reviews.llvm.org/D68029

Files:
  lib/Driver/ToolChains/Clang.cpp
  test/Driver/split-lto-unit.c


Index: test/Driver/split-lto-unit.c
===================================================================
--- test/Driver/split-lto-unit.c
+++ test/Driver/split-lto-unit.c
@@ -6,5 +6,5 @@
 
 // UNIT: "-fsplit-lto-unit"
 // NOUNIT-NOT: "-fsplit-lto-unit"
-// ERROR1: error: invalid argument '-fno-split-lto-unit' not allowed with '-fwhole-program-vtables'
+// ERROR1-NOT: error: invalid argument
 // ERROR2: error: invalid argument '-fno-split-lto-unit' not allowed with '-fsanitize=cfi'
Index: lib/Driver/ToolChains/Clang.cpp
===================================================================
--- lib/Driver/ToolChains/Clang.cpp
+++ lib/Driver/ToolChains/Clang.cpp
@@ -5446,14 +5446,13 @@
     CmdArgs.push_back("-fwhole-program-vtables");
   }
 
-  bool RequiresSplitLTOUnit = WholeProgramVTables || Sanitize.needsLTO();
+  bool DefaultsSplitLTOUnit = WholeProgramVTables || Sanitize.needsLTO();
   bool SplitLTOUnit =
       Args.hasFlag(options::OPT_fsplit_lto_unit,
-                   options::OPT_fno_split_lto_unit, RequiresSplitLTOUnit);
-  if (RequiresSplitLTOUnit && !SplitLTOUnit)
-    D.Diag(diag::err_drv_argument_not_allowed_with)
-        << "-fno-split-lto-unit"
-        << (WholeProgramVTables ? "-fwhole-program-vtables" : "-fsanitize=cfi");
+                   options::OPT_fno_split_lto_unit, DefaultsSplitLTOUnit);
+  if (Sanitize.needsLTO() && !SplitLTOUnit)
+    D.Diag(diag::err_drv_argument_not_allowed_with) << "-fno-split-lto-unit"
+                                                    << "-fsanitize=cfi";
   if (SplitLTOUnit)
     CmdArgs.push_back("-fsplit-lto-unit");
 


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