[clang] 1ae8e8d - Don't add -fsplit-lto-unit for thin LTO builds with PS4 and Darwin toolchains

[via cfe-commits]

Author: evgeny
Date: 2019-10-24T14:10:03+03:00
New Revision: 1ae8e8d25fd87048d3d8d7429308e52b236c79a1

URL: https://github.com/llvm/llvm-project/commit/1ae8e8d25fd87048d3d8d7429308e52b236c79a1
DIFF: https://github.com/llvm/llvm-project/commit/1ae8e8d25fd87048d3d8d7429308e52b236c79a1.diff

LOG: Don't add -fsplit-lto-unit for thin LTO builds with PS4 and Darwin toolchains

These toolchains use legacy thin LTO API, which is not capable of unit splitting
Differential revision: https://reviews.llvm.org/D69173

Added: 
    

Modified: 
    clang/include/clang/Driver/ToolChain.h
    clang/lib/Driver/ToolChains/Clang.cpp
    clang/lib/Driver/ToolChains/Darwin.h
    clang/lib/Driver/ToolChains/PS4CPU.h
    clang/test/Driver/split-lto-unit.c

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/Driver/ToolChain.h b/clang/include/clang/Driver/ToolChain.h
index f0676eee2d6c..c40af1e6e01f 100644
--- a/clang/include/clang/Driver/ToolChain.h
+++ b/clang/include/clang/Driver/ToolChain.h
@@ -600,6 +600,10 @@ class ToolChain {
   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

diff  --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 55d631733add..198b0b5b228f 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -5395,7 +5395,9 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     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);

diff  --git a/clang/lib/Driver/ToolChains/Darwin.h b/clang/lib/Driver/ToolChains/Darwin.h
index 2dc7c85880f7..1b1c358c40a4 100644
--- a/clang/lib/Driver/ToolChains/Darwin.h
+++ b/clang/lib/Driver/ToolChains/Darwin.h
@@ -258,6 +258,9 @@ class LLVM_LIBRARY_VISIBILITY MachO : public ToolChain {
     return "";
   }
 
+  // Darwin toolchain uses legacy thin LTO API, which is not
+  // capable of unit splitting.
+  bool canSplitThinLTOUnit() const override { return false; }
   /// }
 };
 

diff  --git a/clang/lib/Driver/ToolChains/PS4CPU.h b/clang/lib/Driver/ToolChains/PS4CPU.h
index e9f0891c1194..18852b2808cb 100644
--- a/clang/lib/Driver/ToolChains/PS4CPU.h
+++ b/clang/lib/Driver/ToolChains/PS4CPU.h
@@ -84,6 +84,10 @@ class LLVM_LIBRARY_VISIBILITY PS4CPU : public Generic_ELF {
 
   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;

diff  --git a/clang/test/Driver/split-lto-unit.c b/clang/test/Driver/split-lto-unit.c
index d2ed253ca201..66314161c942 100644
--- a/clang/test/Driver/split-lto-unit.c
+++ b/clang/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"