[clang][PS4] Enable SplitLTOUnits by default

[ormris]

Summary

This patch contains the parts of the unified LTO pipeline specific to PS4/5. See this conversation: https://discourse.llvm.org/t/rfc-a-unified-lto-bitcode-frontend/61774/15

[MaskRay]

If a vendor wants to change some driver default, that's fine, especially when on/off already has a condition. But please include full context per https://llvm.org/docs/Phabricator.html#requesting-a-review-via-the-web-interface and add a clang/test/Driver/ test.
Also, "SIE" isn't a clear abbreviation. PS4 seems more understandable by other contributors.

[ormris]

Add context.

[ormris]

Changelog:

• Rebased
• Add tests

[ormris]

Attempt to fix pre-merge checks

[ormris]

clang-format

[probinson]

clang/test/Driver/split-lto-unit.c

2

This all shows that -funified-lto has the desired effect, but not what the defaults are (yes for PS4, no for e.g. linux).

[ormris]

• Unified LTO default for all PlayStation targets
• Add default case to tests
• SplitLTOUnit not default for PS4

clang/test/Driver/split-lto-unit.c

2

Should be fixed.

[probinson]

LGTM

[ormris]

Thanks!

clang/lib/Driver/ToolChains/Clang.cpp

void Clang::ConstructJob(Compilation &C, const JobAction &JA,
 
   // FIXME: Subclass ToolChain for SPIR and move this to addClangWarningOptions.
   if (Triple.isSPIR() || Triple.isSPIRV())
     CmdArgs.push_back("-Wspir-compat");
 
   // Select the appropriate action.
   RewriteKind rewriteKind = RK_None;
 
-  bool UnifiedLTO = false;
+  bool UnifiedLTO =  Triple.isPS();;
   if (IsUsingLTO) {
     UnifiedLTO = Args.hasFlag(options::OPT_funified_lto,
                               options::OPT_fno_unified_lto, false);
     if (UnifiedLTO)
       CmdArgs.push_back("-funified-lto");
   }
 
   // If CollectArgsForIntegratedAssembler() isn't called below, claim the args
if (WholeProgramVTables) {
 
     // Propagate -fwhole-program-vtables if this is an LTO compile.
     if (IsUsingLTO)
       CmdArgs.push_back("-fwhole-program-vtables");
   }
 
   bool DefaultsSplitLTOUnit =
       (WholeProgramVTables || SanitizeArgs.needsLTO()) &&
-      (LTOMode == LTOK_Full || TC.canSplitThinLTOUnit());
+          (LTOMode == LTOK_Full || TC.canSplitThinLTOUnit()) ||
+      (!Triple.isPS4() && UnifiedLTO);
   bool SplitLTOUnit =
       Args.hasFlag(options::OPT_fsplit_lto_unit,
                    options::OPT_fno_split_lto_unit, DefaultsSplitLTOUnit);
   if (SanitizeArgs.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");

clang/test/CodeGen/split-lto-unit.c

 // ; Check that -flto=thin without -fsplit-lto-unit has EnableSplitLTOUnit = 0
 // RUN: %clang_cc1 -flto=thin -emit-llvm-bc < %s | llvm-dis -o - | FileCheck %s
 // RUN: %clang_cc1 -flto=thin -emit-llvm < %s | FileCheck %s
+// RUN: %clang_cc1 -flto=thin -funified-lto -triple=x86_64-scei-ps4 -emit-llvm-bc < %s | llvm-dis -o - | FileCheck %s
 // CHECK: !{i32 1, !"EnableSplitLTOUnit", i32 0}
 //
 // ; Check that -flto=thin with -fsplit-lto-unit has EnableSplitLTOUnit = 1
 // RUN: %clang_cc1 -flto=thin -fsplit-lto-unit -emit-llvm-bc < %s | llvm-dis -o - | FileCheck %s --check-prefix=SPLIT
 // RUN: %clang_cc1 -flto=thin -fsplit-lto-unit -emit-llvm < %s | FileCheck %s --check-prefix=SPLIT
 // SPLIT: !{i32 1, !"EnableSplitLTOUnit", i32 1}
 //
 // ; Check that regular LTO has EnableSplitLTOUnit = 1
 // RUN: %clang_cc1 -flto -triple x86_64-pc-linux-gnu -emit-llvm-bc < %s | llvm-dis -o - | FileCheck %s --implicit-check-not="EnableSplitLTOUnit" --check-prefix=SPLIT
 // RUN: %clang_cc1 -flto -triple x86_64-pc-linux-gnu -emit-llvm < %s | FileCheck %s --implicit-check-not="EnableSplitLTOUnit" --check-prefix=SPLIT
 
+// ; Check that regular LTO has EnableSplitLTOUnit = 1, if using distinct pipelines. For unified pipelines, use EnableSplitLTOUnit = 0.
+// RUN: %clang_cc1 -flto -triple x86_64-pc-linux-gnu -emit-llvm-bc < %s | llvm-dis -o - | FileCheck %s --implicit-check-not="EnableSplitLTOUnit" --check-prefix=SPLIT
+// RUN: %clang_cc1 -flto -funified-lto -triple x86_64-scei-ps4 -emit-llvm-bc < %s | llvm-dis -o - | FileCheck %s
+// RUN: %clang_cc1 -flto=thin -funified-lto -fsplit-lto-unit -triple x86_64-pc-linux-gnu -emit-llvm-bc < %s | llvm-dis -o - | FileCheck %s --implicit-check-not="EnableSplitLTOUnit" --check-prefix=SPLIT
+
 int main(void) {}

clang/test/CodeGenCXX/unified-cfi-lto.cpp

 // Ensure that the frontend adds the proper metadata when CFI is
 // enabled.
-// RUN: %clang --target=x86_64-scei-ps4 -funified-lto -flto -fsanitize=cfi -fvisibility=hidden -c %s -o %t.o
+// RUN: %clang --target=x86_64-scei-ps4 -funified-lto -flto -fsanitize=cfi -fvisibility=hidden -fno-sanitize-ignorelist -c %s -o %t.o
 // RUN: llvm-dis %t.o -o %t1
 // RUN: FileCheck <%t1.0 %s
 
 typedef int (*FuncPtr)();
 
 int a() { return 1; }
 int b() { return 2; }
 int c() { return 3; }

clang/test/Driver/lto-unit.c

 // RUN: %clang --target=x86_64-unknown-linux -### %s -flto=full 2>&1 | FileCheck --check-prefix=UNIT %s
 // RUN: %clang --target=x86_64-unknown-linux -### %s -flto=thin 2>&1 | FileCheck --check-prefix=UNIT %s
 // RUN: %clang --target=x86_64-apple-darwin13.3.0 -### %s -flto=full 2>&1 | FileCheck --check-prefix=UNIT %s
 // RUN: %clang --target=x86_64-apple-darwin13.3.0 -### %s -flto=thin 2>&1 | FileCheck --check-prefix=UNIT %s
 // RUN: %clang --target=x86_64-scei-ps4 -### %s -flto=full 2>&1 | FileCheck --check-prefix=UNIT %s
 // RUN: %clang --target=x86_64-scei-ps4 -### %s -flto=thin 2>&1 | FileCheck --check-prefix=UNIT %s
+// RUN: %clang --target=x86_64-scei-ps4 -### %s -flto=full -funified-lto 2>&1 | FileCheck --check-prefix=UNIT %s
+// RUN: %clang --target=x86_64-scei-ps4 -### %s -flto=thin -funified-lto 2>&1 | FileCheck --check-prefix=NOUNIT %s
+// RUN: %clang --target=x86_64-unknown-linux -### %s -flto=full -funified-lto 2>&1 | FileCheck --check-prefix=UNIT %s
+// RUN: %clang --target=x86_64-unknown-linux -### %s -flto=thin -funified-lto 2>&1 | FileCheck --check-prefix=UNIT %s
 
 // UNIT: "-flto-unit"
+// NOUNIT-NOT: "-flto-unit"

clang/test/Driver/split-lto-unit.c

 // RUN: %clang --target=x86_64-unknown-linux -### %s -flto=thin 2>&1 | FileCheck --check-prefix=NOUNIT %s
 // RUN: %clang --target=x86_64-unknown-linux -### %s -flto=thin -fsplit-lto-unit 2>&1 | FileCheck --check-prefix=UNIT %s
 // 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
+// RUN: %clang --target=x86_64-sie-ps5 -### %s -fwhole-program-vtables -flto=full 2>&1 | FileCheck --check-prefix=UNIT %s
+// RUN: %clang --target=x86_64-sie-ps5 -### %s -fwhole-program-vtables -flto=thin 2>&1 | FileCheck --check-prefix=UNIT %s
+// RUN: %clang --target=x86_64-unknown-linux -### %s -fwhole-program-vtables -flto=full -funified-lto 2>&1 | FileCheck --check-prefix=UNIT %s
+// RUN: %clang --target=x86_64-unknown-linux -### %s -fwhole-program-vtables -flto=thin -funified-lto 2>&1 | FileCheck --check-prefix=UNIT %s
 
 // UNIT: "-fsplit-lto-unit"
 // NOUNIT-NOT: "-fsplit-lto-unit"
 // ERROR1-NOT: error: invalid argument
 // ERROR2: error: invalid argument '-fno-split-lto-unit' not allowed with '-fsanitize=cfi'