[PATCH] D69173: [clang][ThinLTO][Legacy] Don't add -fsplit-lto-unit for legacy thin LTO builds

[Eugene Leviant via Phabricator via llvm-commits]

evgeny777 updated this revision to Diff 226049.
evgeny777 added a comment.

Addressed


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D69173/new/

https://reviews.llvm.org/D69173

Files:
  include/clang/Driver/ToolChain.h
  lib/Driver/ToolChains/Clang.cpp
  lib/Driver/ToolChains/Darwin.h
  lib/Driver/ToolChains/PS4CPU.h
  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
@@ -3,6 +3,10 @@
 // RUN: %clang -target x86_64-unknown-linux -### %s -flto=thin -fno-split-lto-unit 2>&1 | FileCheck --check-prefix=NOUNIT %s
 // RUN: %clang -target x86_64-unknown-linux -### %s -flto=thin -fno-split-lto-unit -fwhole-program-vtables 2>&1 | FileCheck --check-prefix=ERROR1 %s
 // RUN: %clang -target x86_64-unknown-linux -### %s -flto=thin -fno-split-lto-unit -fsanitize=cfi 2>&1 | FileCheck --check-prefix=ERROR2 %s
+// RUN: %clang -target x86_64-apple-darwin13.3.0 -### %s -fwhole-program-vtables -flto=full 2>&1 | FileCheck --check-prefix=UNIT %s
+// RUN: %clang -target x86_64-apple-darwin13.3.0 -### %s -fwhole-program-vtables -flto=thin 2>&1 | FileCheck --check-prefix=NOUNIT %s
+// RUN: %clang -target x86_64-scei-ps4 -### %s -fwhole-program-vtables -flto=full 2>&1 | FileCheck --check-prefix=UNIT %s
+// RUN: %clang -target x86_64-scei-ps4 -### %s -fwhole-program-vtables -flto=thin 2>&1 | FileCheck --check-prefix=NOUNIT %s
 
 // UNIT: "-fsplit-lto-unit"
 // NOUNIT-NOT: "-fsplit-lto-unit"
Index: lib/Driver/ToolChains/PS4CPU.h
===================================================================
--- lib/Driver/ToolChains/PS4CPU.h
+++ lib/Driver/ToolChains/PS4CPU.h
@@ -84,6 +84,10 @@
 
   SanitizerMask getSupportedSanitizers() const override;
 
+  // PS4 toolchain uses legacy thin LTO API, which is not
+  // capable of unit splitting.
+  bool canSplitThinLTOUnit() const override { return false; }
+
 protected:
   Tool *buildAssembler() const override;
   Tool *buildLinker() const override;
Index: lib/Driver/ToolChains/Darwin.h
===================================================================
--- lib/Driver/ToolChains/Darwin.h
+++ lib/Driver/ToolChains/Darwin.h
@@ -258,6 +258,9 @@
     return "";
   }
 
+  // Darwin toolchain uses legacy thin LTO API, which is not
+  // capable of unit splitting.
+  bool canSplitThinLTOUnit() const override { return false; }
   /// }
 };
 
Index: lib/Driver/ToolChains/Clang.cpp
===================================================================
--- lib/Driver/ToolChains/Clang.cpp
+++ lib/Driver/ToolChains/Clang.cpp
@@ -5395,7 +5395,9 @@
     CmdArgs.push_back("-fwhole-program-vtables");
   }
 
-  bool DefaultsSplitLTOUnit = WholeProgramVTables || Sanitize.needsLTO();
+  bool DefaultsSplitLTOUnit =
+      (WholeProgramVTables || Sanitize.needsLTO()) &&
+      (D.getLTOMode() == LTOK_Full || TC.canSplitThinLTOUnit());
   bool SplitLTOUnit =
       Args.hasFlag(options::OPT_fsplit_lto_unit,
                    options::OPT_fno_split_lto_unit, DefaultsSplitLTOUnit);
Index: include/clang/Driver/ToolChain.h
===================================================================
--- include/clang/Driver/ToolChain.h
+++ include/clang/Driver/ToolChain.h
@@ -600,6 +600,10 @@
   virtual SanitizerMask getDefaultSanitizers() const {
     return SanitizerMask();
   }
+
+  /// Returns true when it's possible to split LTO unit to use whole
+  /// program devirtualization and CFI santiizers.
+  virtual bool canSplitThinLTOUnit() const { return true; }
 };
 
 /// Set a ToolChain's effective triple. Reset it when the registration object


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