[clang] [FatLTO] Allow -fno-fat-lto-objects to override -ffat-lto-objects (PR #128157)

[Vincent Lee via cfe-commits]

https://github.com/thevinster updated https://github.com/llvm/llvm-project/pull/128157

>From 4d44ed82dc822e486aee3620707b463214fb18cb Mon Sep 17 00:00:00 2001
From: Vincent Lee <leevince at fb.com>
Date: Fri, 21 Feb 2025 02:04:53 -0800
Subject: [PATCH 1/2] [FatLTO] Allow -fno-fat-lto-objects to override
 -ffat-lto-objects

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 2 +-
 clang/test/Driver/fat-lto-objects.c        | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 1a2299a92c54e..50db1e2f7d509 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -860,7 +860,7 @@ void tools::addLTOOptions(const ToolChain &ToolChain, const ArgList &Args,
   const bool IsAMDGCN = Triple.isAMDGCN();
   const char *Linker = Args.MakeArgString(ToolChain.GetLinkerPath());
   const Driver &D = ToolChain.getDriver();
-  const bool IsFatLTO = Args.hasArg(options::OPT_ffat_lto_objects);
+  const bool IsFatLTO = Args.hasFlag(options::OPT_ffat_lto_objects, options::OPT_fno_fat_lto_objects, false);
   const bool IsUnifiedLTO = Args.hasArg(options::OPT_funified_lto);
   if (llvm::sys::path::filename(Linker) != "ld.lld" &&
       llvm::sys::path::stem(Linker) != "ld.lld" && !Triple.isOSOpenBSD()) {
diff --git a/clang/test/Driver/fat-lto-objects.c b/clang/test/Driver/fat-lto-objects.c
index d9a5ba88ea6d6..691fcbfc72140 100644
--- a/clang/test/Driver/fat-lto-objects.c
+++ b/clang/test/Driver/fat-lto-objects.c
@@ -41,6 +41,9 @@
 // CHECK-CC-NOLTO-SAME: -emit-obj
 // CHECK-CC-NOLTO-NOT: -ffat-lto-objects
 
+/// Disable fat LTO when it is overridden by -fno-fat-lto-objects
+// RUN: %clang --target=x86_64-unknown-linux-gnu -flto -ffat-lto-objects -fno-fat-lto-objects -### %s -c 2>&1 | FileCheck %s -check-prefix=CHECK-CC-NOLTO
+
 /// We need to pass an additional flag (--fat-lto-objects) to lld when linking w/ -flto -ffat-lto-objects
 /// But it should not be there when LTO is disabled w/ -fno-lto
 // RUN: %clang --target=x86_64-unknown-linux-gnu --sysroot=%S/Inputs/basic_cross_linux_tree %s \

>From 6336c91ed91c5605e012aa1fdf669dcf3d0f01ad Mon Sep 17 00:00:00 2001
From: Vincent Lee <leevince at fb.com>
Date: Fri, 21 Feb 2025 02:17:55 -0800
Subject: [PATCH 2/2] format

---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 50db1e2f7d509..7c931649de3c4 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -860,7 +860,8 @@ void tools::addLTOOptions(const ToolChain &ToolChain, const ArgList &Args,
   const bool IsAMDGCN = Triple.isAMDGCN();
   const char *Linker = Args.MakeArgString(ToolChain.GetLinkerPath());
   const Driver &D = ToolChain.getDriver();
-  const bool IsFatLTO = Args.hasFlag(options::OPT_ffat_lto_objects, options::OPT_fno_fat_lto_objects, false);
+  const bool IsFatLTO = Args.hasFlag(options::OPT_ffat_lto_objects,
+                                     options::OPT_fno_fat_lto_objects, false);
   const bool IsUnifiedLTO = Args.hasArg(options::OPT_funified_lto);
   if (llvm::sys::path::filename(Linker) != "ld.lld" &&
       llvm::sys::path::stem(Linker) != "ld.lld" && !Triple.isOSOpenBSD()) {