From 0d37efdbc599e61ce2a0418723a66d6b45aea8d7 Mon Sep 17 00:00:00 2001
From: Ben Shi <powerman1st@163.com>
Date: Thu, 9 Mar 2023 12:04:54 +0800
Subject: [PATCH] [clang][driver] Enable '-flto' on AVR

Reviewed By: MaskRay

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

Differential Revision: https://reviews.llvm.org/D145646
---
 clang/lib/Driver/ToolChains/AVR.cpp |  6 ++++++
 clang/lib/Driver/ToolChains/AVR.h   |  2 ++
 clang/test/Driver/avr-ld.c          | 14 ++++++++++++++
 3 files changed, 22 insertions(+)

diff --git a/clang/lib/Driver/ToolChains/AVR.cpp b/clang/lib/Driver/ToolChains/AVR.cpp
index be2749e..0e1f8dd 100644
--- a/clang/lib/Driver/ToolChains/AVR.cpp
+++ b/clang/lib/Driver/ToolChains/AVR.cpp
@@ -506,6 +506,12 @@ void AVR::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     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.
diff --git a/clang/lib/Driver/ToolChains/AVR.h b/clang/lib/Driver/ToolChains/AVR.h
index ea161fe..d432d81 100644
--- a/clang/lib/Driver/ToolChains/AVR.h
+++ b/clang/lib/Driver/ToolChains/AVR.h
@@ -36,6 +36,8 @@ public:
   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;
 
diff --git a/clang/test/Driver/avr-ld.c b/clang/test/Driver/avr-ld.c
index 80bb428..3088bc0 100644
--- a/clang/test/Driver/avr-ld.c
+++ b/clang/test/Driver/avr-ld.c
@@ -43,3 +43,17 @@
 
 // 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"
-- 
2.7.4