[clang][driver] Enable '-flto' on AVR

[benshi001]

Summary

Closes https://github.com/llvm/llvm-project/issues/55940

[benshi001]

ping ...

[benshi001]

ping ...

[MaskRay]

"Close" seems more appropriate to me as this isn't a bug (previously not an intended use case).

clang/test/Driver/avr-ld.c

59

[gulfem]

We started seeing a test failure in avr-ld.c.

/b/s/w/ir/x/w/llvm-llvm-project/clang/test/Driver/avr-ld.c:48:11: error: 
// LINKP: {{".*ld.*"}} {{.*}} "--defsym=__DATA_REGION_ORIGIN__=0x800100" "-plugin" {{.*}} "-plugin-opt=mcpu=atmega328"
          ^
<stdin>:1:1: note: scanning from here
Fuchsia clang version 17.0.0 (https://llvm.googlesource.com/llvm-project 0d37efdbc599e61ce2a0418723a66d6b45aea8d7)
^
<stdin>:6:239: note: possible intended match here

https://luci-milo.appspot.com/ui/p/fuchsia/builders/toolchain.ci/clang-linux-x64/b8785950851645447937/overview

[MaskRay]

In D145646#4213547, @gulfem wrote:

We started seeing a test failure in avr-ld.c.

/b/s/w/ir/x/w/llvm-llvm-project/clang/test/Driver/avr-ld.c:48:11: error: 
// LINKP: {{".*ld.*"}} {{.*}} "--defsym=__DATA_REGION_ORIGIN__=0x800100" "-plugin" {{.*}} "-plugin-opt=mcpu=atmega328"
          ^
<stdin>:1:1: note: scanning from here
Fuchsia clang version 17.0.0 (https://llvm.googlesource.com/llvm-project 0d37efdbc599e61ce2a0418723a66d6b45aea8d7)
^
<stdin>:6:239: note: possible intended match here

https://luci-milo.appspot.com/ui/p/fuchsia/builders/toolchain.ci/clang-linux-x64/b8785950851645447937/overview

I am testing a change and will fix it in one minute.

[gulfem]

In D145646#4213975, @MaskRay wrote:

In D145646#4213547, @gulfem wrote:

We started seeing a test failure in avr-ld.c.

/b/s/w/ir/x/w/llvm-llvm-project/clang/test/Driver/avr-ld.c:48:11: error: 
// LINKP: {{".*ld.*"}} {{.*}} "--defsym=__DATA_REGION_ORIGIN__=0x800100" "-plugin" {{.*}} "-plugin-opt=mcpu=atmega328"
          ^
<stdin>:1:1: note: scanning from here
Fuchsia clang version 17.0.0 (https://llvm.googlesource.com/llvm-project 0d37efdbc599e61ce2a0418723a66d6b45aea8d7)
^
<stdin>:6:239: note: possible intended match here

https://luci-milo.appspot.com/ui/p/fuchsia/builders/toolchain.ci/clang-linux-x64/b8785950851645447937/overview

I am testing a change and will fix it in one minute.

Thanks, and it fixed the test failure that we have been seeing.

[benshi001]

In D145646#4213975, @MaskRay wrote:

In D145646#4213547, @gulfem wrote:

We started seeing a test failure in avr-ld.c.

/b/s/w/ir/x/w/llvm-llvm-project/clang/test/Driver/avr-ld.c:48:11: error: 
// LINKP: {{".*ld.*"}} {{.*}} "--defsym=__DATA_REGION_ORIGIN__=0x800100" "-plugin" {{.*}} "-plugin-opt=mcpu=atmega328"
          ^
<stdin>:1:1: note: scanning from here
Fuchsia clang version 17.0.0 (https://llvm.googlesource.com/llvm-project 0d37efdbc599e61ce2a0418723a66d6b45aea8d7)
^
<stdin>:6:239: note: possible intended match here

https://luci-milo.appspot.com/ui/p/fuchsia/builders/toolchain.ci/clang-linux-x64/b8785950851645447937/overview

I am testing a change and will fix it in one minute.

Thanks! I should pay attention to Fuchsia next time.

clang/lib/Driver/ToolChains/AVR.h

addClangTargetOptions(const llvm::opt::ArgList &DriverArgs,
                         llvm::opt::ArgStringList &CC1Args,
                         Action::OffloadKind DeviceOffloadKind) const override;
 
   std::optional<std::string> findAVRLibcInstallation() const;
   StringRef getGCCInstallPath() const { return GCCInstallPath; }
   std::string getCompilerRT(const llvm::opt::ArgList &Args, StringRef Component,
                             FileType Type) const override;
 
+  bool HasNativeLLVMSupport() const override { return true; }
+
 protected:
   Tool *buildLinker() const override;
 
 private:
   StringRef GCCInstallPath;
 };
 
 } // end namespace toolchains

clang/lib/Driver/ToolChains/AVR.cpp

if (SectionAddressData) {
     CmdArgs.push_back(
         Args.MakeArgString("--defsym=__DATA_REGION_ORIGIN__=0x" +
                            Twine::utohexstr(*SectionAddressData)));
   } else {
     // We do not have an entry for this CPU in the address mapping table yet.
     D.Diag(diag::warn_drv_avr_linker_section_addresses_not_implemented) << CPU;
   }
 
+  if (D.isUsingLTO()) {
+    assert(!Inputs.empty() && "Must have at least one input.");
+    addLTOOptions(getToolChain(), Args, CmdArgs, Output, Inputs[0],
+                  D.getLTOMode() == LTOK_Thin);
+  }
+
   // If the family name is known, we can link with the device-specific libgcc.
   // Without it, libgcc will simply not be linked. This matches avr-gcc
   // behavior.
   if (LinkStdlib) {
     assert(!CPU.empty() && "CPU name must be known in order to link stdlibs");
 
     CmdArgs.push_back("--start-group");
 

clang/test/Driver/avr-ld.c

 // RUN: %clang -### --target=avr -mmcu=atxmega64b3 --rtlib=libgcc --sysroot %S/Inputs/basic_avr_tree %s 2>&1 | FileCheck -check-prefix LINKM %s
 // LINKM: {{".*ld.*"}} {{.*}} {{"-L.*avrxmega4"}} {{.*}} "--defsym=__DATA_REGION_ORIGIN__=0x802000" "--start-group" {{.*}} "-latxmega64b3" {{.*}} "--end-group" "--relax" "-mavrxmega4"
 
 // RUN: %clang -### --target=avr -mmcu=atxmega128a3u --rtlib=libgcc --sysroot %S/Inputs/basic_avr_tree %s 2>&1 | FileCheck -check-prefix LINKN %s
 // LINKN: {{".*ld.*"}} {{.*}} {{"-L.*avrxmega6"}} {{.*}} "--defsym=__DATA_REGION_ORIGIN__=0x802000" "--start-group" {{.*}} "-latxmega128a3u" {{.*}} "--end-group" "--relax" "-mavrxmega6"
 
 // RUN: %clang -### --target=avr -mmcu=atxmega128a1 --rtlib=libgcc --sysroot %S/Inputs/basic_avr_tree %s 2>&1 | FileCheck -check-prefix LINKO %s
 // LINKO: {{".*ld.*"}} {{.*}} {{"-L.*avrxmega7"}} {{.*}} "--defsym=__DATA_REGION_ORIGIN__=0x802000" "--start-group" {{.*}} "-latxmega128a1" {{.*}} "--end-group" "--relax" "-mavrxmega7"
+
+// RUN: %clang -### --target=avr -mmcu=atmega328 -flto --sysroot %S/Inputs/basic_avr_tree %s 2>&1 | FileCheck -check-prefix LINKP %s
+// LINKP: {{".*ld.*"}} {{.*}} "--defsym=__DATA_REGION_ORIGIN__=0x800100" "-plugin" {{.*}}  "-plugin-opt=mcpu=atmega328"
+
+// RUN: %clang -### --target=avr -flto --sysroot %S/Inputs/basic_avr_tree %s 2>&1 | FileCheck -check-prefix LINKQ %s
+// LINKQ: {{".*ld.*"}} {{.*}} "-plugin"
+// LINKQ-NOT: "-plugin-opt=mcpu"
+
+// RUN: %clang -### --target=avr -mmcu=atmega328 -flto=thin --sysroot %S/Inputs/basic_avr_tree %s 2>&1 | FileCheck -check-prefix LINKR %s
+// LINKR: {{".*ld.*"}} {{.*}} "--defsym=__DATA_REGION_ORIGIN__=0x800100" "-plugin" {{.*}}  "-plugin-opt=mcpu=atmega328" "-plugin-opt=thinlto"
+
+// RUN: %clang -### --target=avr -mmcu=atmega328 -flto --sysroot %S/Inputs/basic_avr_tree %s 2>&1 | FileCheck -check-prefix LINKS %s
+// LINKS: {{".*ld.*"}} {{.*}} "--defsym=__DATA_REGION_ORIGIN__=0x800100" "-plugin" {{.*}}  "-plugin-opt=mcpu=atmega328"
+// LINKS-NOT: "-plugin-opt=thinlto"