[clang] Enable fat-lto-object support for COFF targets

[thrimbor]

This change allows using clang's -ffat-lto-objects flag with COFF targets such as i386-pc-win32.

Follow-up to 759fb0a from which it was split off. The added tests are adapted from the pre-existing ELF tests.

[llvmbot]

@llvm/pr-subscribers-clang

@llvm/pr-subscribers-clang-driver

Author: Stefan Schmidt (thrimbor)

Changes

This change allows using clang's -ffat-lto-objects flag with COFF targets such as i386-pc-win32.

Follow-up to 759fb0a from which it was split off. The added tests are adapted from the pre-existing ELF tests.

---

Full diff: https://github.com/llvm/llvm-project/pull/172936.diff

3 Files Affected:

• (modified) clang/lib/Driver/ToolChains/Clang.cpp (+1-1)
• (modified) clang/test/CodeGen/fat-lto-objects.c (+14)
• (modified) clang/test/Driver/fat-lto-objects.c (+8)

diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 310f3b58a211e..ab47d4f7e4e03 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -7837,7 +7837,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
                                options::OPT_fno_fat_lto_objects)) {
     if (IsUsingLTO && A->getOption().matches(options::OPT_ffat_lto_objects)) {
       assert(LTOMode == LTOK_Full || LTOMode == LTOK_Thin);
-      if (!Triple.isOSBinFormatELF()) {
+      if (!Triple.isOSBinFormatELF() && !Triple.isOSBinFormatCOFF()) {
         D.Diag(diag::err_drv_unsupported_opt_for_target)
             << A->getAsString(Args) << TC.getTripleString();
       }
diff --git a/clang/test/CodeGen/fat-lto-objects.c b/clang/test/CodeGen/fat-lto-objects.c
index 36a73684e7bfe..bcbcb31e1579a 100644
--- a/clang/test/CodeGen/fat-lto-objects.c
+++ b/clang/test/CodeGen/fat-lto-objects.c
@@ -35,6 +35,9 @@
 // RUN: %clang -cc1 -triple x86_64-unknown-linux-gnu -flto=full -ffat-lto-objects -fsplit-lto-unit -S < %s -o - \
 // RUN: | FileCheck %s --check-prefixes=ASM
 
+// RUN: %clang -cc1 -triple i386-pc-win32 -flto=full -ffat-lto-objects -fsplit-lto-unit -S < %s -o - \
+// RUN: | FileCheck %s --check-prefixes=ASM-COFF
+
 /// Make sure that FatLTO generates .llvm.lto sections that are the same as the output from normal LTO compilations
 // RUN: %clang -O2 --target=x86_64-unknown-linux-gnu -fPIE -flto=full -ffat-lto-objects -c %s -o %t.fatlto.full.o
 // RUN: llvm-objcopy --dump-section=.llvm.lto=%t.fatlto.full.bc %t.fatlto.full.o
@@ -43,6 +46,13 @@
 // RUN: llvm-dis < %t.nofat.full.bc -o %t.nofat.full.ll
 // RUN: diff %t.fatlto.full.ll %t.nofat.full.ll
 
+// RUN: %clang -O2 --target=i386-pc-win32 -flto=full -ffat-lto-objects -c %s -o %t.fatlto.full.coff.o
+// RUN: llvm-objcopy --dump-section=.llvm.lto=%t.fatlto.full.coff.bc %t.fatlto.full.coff.o
+// RUN: llvm-dis < %t.fatlto.full.coff.bc -o %t.fatlto.full.coff.ll
+// RUN: %clang -O2 --target=i386-pc-win32 -flto=full -c %s -o %t.nofat.full.coff.bc
+// RUN: llvm-dis < %t.nofat.full.coff.bc -o %t.nofat.full.coff.ll
+// RUN: diff %t.fatlto.full.coff.ll %t.nofat.full.coff.ll
+
 // RUN: %clang -O2 --target=x86_64-unknown-linux-gnu -fPIE -flto=thin -ffat-lto-objects -c %s -o %t.fatlto.thin.o
 // RUN: llvm-objcopy --dump-section=.llvm.lto=%t.fatlto.thin.bc %t.fatlto.thin.o
 // RUN: llvm-dis < %t.fatlto.thin.bc -o %t.fatlto.thin.ll
@@ -67,6 +77,10 @@
 // ASM-NEXT:        .asciz  "BC
 // ASM-NEXT: .size   .Lllvm.embedded.object
 
+// ASM-COFF:      .section .llvm.lto,"ynD"
+// ASM-COFF-NEXT: L_llvm.embedded.object:
+// ASM-COFF-NEXT:        .asciz  "BC
+
 const char* foo = "foo";
 
 int test(void) {
diff --git a/clang/test/Driver/fat-lto-objects.c b/clang/test/Driver/fat-lto-objects.c
index 7b87e2b468886..84dd945e208b9 100644
--- a/clang/test/Driver/fat-lto-objects.c
+++ b/clang/test/Driver/fat-lto-objects.c
@@ -1,10 +1,12 @@
 // RUN: %clang --target=x86_64-unknown-linux-gnu -flto -ffat-lto-objects -### %s -c 2>&1 | FileCheck %s -check-prefix=CHECK-CC
+// RUN: %clang --target=i386-pc-win32 -flto -ffat-lto-objects -### %s -c 2>&1 | FileCheck %s -check-prefix=CHECK-CC
 // CHECK-CC: -cc1
 // CHECK-CC-SAME: -emit-obj
 // CHECK-CC-SAME: -ffat-lto-objects
 
 /// Without -flto -S will just emit normal ASM, so we don't expect -emit-{llvm,obj} or -ffat-lto-objects to be passed to cc1.
 // RUN: %clang --target=x86_64-unknown-linux-gnu -ffat-lto-objects -### %s -S 2>&1 | FileCheck %s -check-prefix=CHECK-CC-S
+// RUN: %clang --target=i386-pc-win32 -ffat-lto-objects -### %s -S 2>&1 | FileCheck %s -check-prefix=CHECK-CC-S
 // CHECK-CC-S: -cc1
 // CHECK-CC-S: -S
 // CHECK-CC-S-NOT: -emit-obj
@@ -13,35 +15,41 @@
 
 /// When fat LTO is enabled with -S, we expect asm output and -ffat-lto-objects to be passed to cc1.
 // RUN: %clang --target=x86_64-unknown-linux-gnu -flto -ffat-lto-objects -### %s -S 2>&1 | FileCheck %s -check-prefix=CHECK-CC-S-LTO
+// RUN: %clang --target=i386-pc-win32 -flto -ffat-lto-objects -### %s -S 2>&1 | FileCheck %s -check-prefix=CHECK-CC-S-LTO
 // CHECK-CC-S-LTO: -cc1
 // CHECK-CC-S-NOT: -emit-llvm
 // CHECK-CC-S-LTO-SAME: -ffat-lto-objects
 
 /// When fat LTO is enabled with -S and -emit-llvm, we expect IR output and -ffat-lto-objects to be passed to cc1.
 // RUN: %clang --target=x86_64-unknown-linux-gnu -flto -ffat-lto-objects -### %s -S -emit-llvm 2>&1 | FileCheck %s -check-prefix=CHECK-CC-S-EL-LTO
+// RUN: %clang --target=i386-pc-win32 -flto -ffat-lto-objects -### %s -S -emit-llvm 2>&1 | FileCheck %s -check-prefix=CHECK-CC-S-EL-LTO
 // CHECK-CC-S-EL-LTO: -cc1
 // CHECK-CC-S-EL-LTO-SAME: -emit-llvm
 // CHECK-CC-S-EL-LTO-SAME: -ffat-lto-objects
 
 /// When fat LTO is enabled without -S we expect native object output and -ffat-lto-object to be passed to cc1.
 // RUN: %clang --target=x86_64-unknown-linux-gnu -flto -ffat-lto-objects -### %s -c 2>&1 | FileCheck %s -check-prefix=CHECK-CC-C-LTO
+// RUN: %clang --target=i386-pc-win32 -flto -ffat-lto-objects -### %s -c 2>&1 | FileCheck %s -check-prefix=CHECK-CC-C-LTO
 // CHECK-CC-C-LTO: -cc1
 // CHECK-CC-C-LTO-SAME: -emit-obj
 // CHECK-CC-C-LTO-SAME: -ffat-lto-objects
 
 /// When fat LTO is enabled with -c and -emit-llvm we expect bitcode output and -ffat-lto-object to be passed to cc1.
 // RUN: %clang --target=x86_64-unknown-linux-gnu -flto -ffat-lto-objects -### %s -c -emit-llvm 2>&1 | FileCheck %s -check-prefix=CHECK-CC-C-EL-LTO
+// RUN: %clang --target=i386-pc-win32 -flto -ffat-lto-objects -### %s -c -emit-llvm 2>&1 | FileCheck %s -check-prefix=CHECK-CC-C-EL-LTO
 // CHECK-CC-C-EL-LTO: -cc1
 // CHECK-CC-C-EL-LTO-SAME: -emit-llvm-bc
 // CHECK-CC-C-EL-LTO-SAME: -ffat-lto-objects
 
 /// Make sure we don't have a warning for -ffat-lto-objects being unused
 // RUN: %clang --target=x86_64-unknown-linux-gnu -ffat-lto-objects -fdriver-only -Werror -v %s -c 2>&1 | FileCheck %s -check-prefix=CHECK-CC-NOLTO
+// RUN: %clang --target=i386-pc-win32 -ffat-lto-objects -fdriver-only -Werror -v %s -c 2>&1 | FileCheck %s -check-prefix=CHECK-CC-NOLTO
 // CHECK-CC-NOLTO: -cc1
 // CHECK-CC-NOLTO-SAME: -emit-obj
 // CHECK-CC-NOLTO-NOT: -ffat-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
+// RUN: %clang --target=i386-pc-win32 -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