[ThinLTO] Pass -save-temps to LTO backend for distributed ThinLTO builds

Summary:
The clang driver option -save-temps was not passed to the LTO config,
so when invoking the ThinLTO backends via clang during distributed
builds there was no way to get LTO to save temp files.

Getting this to work with ThinLTO distributed builds also required
changing the driver to avoid a separate compile step to emit unoptimized
bitcode when the input was already bitcode under -save-temps. Not only is
this unnecessary in general, it is problematic for ThinLTO backends since
the temporary bitcode file to the backend would not match the module path
in the combined index, leading to incorrect ThinLTO backend index-based
optimizations.

Reviewers: pcc

Subscribers: mehdi_amini, inglorion, eraman, cfe-commits

Differential Revision: https://reviews.llvm.org/D45217

llvm-svn: 330194

2 files changed, 19 insertions, 2 deletions

diff --git a/clang/test/CodeGen/thinlto_backend.ll b/clang/test/CodeGen/thinlto_backend.ll
index 40530ec5364..5b1964ac7d5 100644
--- a/clang/test/CodeGen/thinlto_backend.ll
+++ b/clang/test/CodeGen/thinlto_backend.ll
@@ -26,8 +26,16 @@
 ; RUN: %clang -target x86_64-unknown-linux-gnu -O2 -o %t4.o -x ir %t5.o -c -fthinlto-index=%t.thinlto.bc
 ; RUN: llvm-nm %t4.o | count 0
 
-; Ensure f2 was imported
-; RUN: %clang -target x86_64-unknown-linux-gnu -O2 -o %t3.o -x ir %t1.o -c -fthinlto-index=%t.thinlto.bc
+; Ensure f2 was imported. Check for all 3 flavors of -save-temps[=cwd|obj].
+; RUN: %clang -target x86_64-unknown-linux-gnu -O2 -o %t3.o -x ir %t1.o -c -fthinlto-index=%t.thinlto.bc -save-temps=obj
+; RUN: llvm-dis %t1.s.0.3.import.bc -o - | FileCheck --check-prefix=CHECK-IMPORT %s
+; RUN: mkdir -p %T/dir1
+; RUN: (cd %T/dir1 && %clang -target x86_64-unknown-linux-gnu -O2 -o %t3.o -x ir %t1.o -c -fthinlto-index=%t.thinlto.bc -save-temps=cwd)
+; RUN: llvm-dis %T/dir1/*1.s.0.3.import.bc -o - | FileCheck --check-prefix=CHECK-IMPORT %s
+; RUN: mkdir -p %T/dir2
+; RUN: (cd %T/dir2 && %clang -target x86_64-unknown-linux-gnu -O2 -o %t3.o -x ir %t1.o -c -fthinlto-index=%t.thinlto.bc -save-temps)
+; RUN: llvm-dis %T/dir2/*1.s.0.3.import.bc -o - | FileCheck --check-prefix=CHECK-IMPORT %s
+; CHECK-IMPORT: define available_externally void @f2()
 ; RUN: llvm-nm %t3.o | FileCheck --check-prefix=CHECK-OBJ %s
 ; CHECK-OBJ: T f1
 ; CHECK-OBJ-NOT: U f2
diff --git a/clang/test/Driver/thinlto_backend.c b/clang/test/Driver/thinlto_backend.c
index 6def5821b6a..b2b45f57088 100644
--- a/clang/test/Driver/thinlto_backend.c
+++ b/clang/test/Driver/thinlto_backend.c
@@ -5,6 +5,15 @@
 // RUN: %clang -O2 -o %t1.o -x ir %t.o -c -fthinlto-index=%t.thinlto.bc -### 2>&1 | FileCheck %s -check-prefix=CHECK-THINLTOBE-ACTION
 // CHECK-THINLTOBE-ACTION: -fthinlto-index=
 
+// -save-temps should be passed to cc1
+// RUN: %clang -O2 -o %t1.o -x ir %t.o -c -fthinlto-index=%t.thinlto.bc -save-temps -### 2>&1 | FileCheck %s -check-prefix=CHECK-SAVE-TEMPS -check-prefix=CHECK-SAVE-TEMPS-CWD
+// RUN: %clang -O2 -o %t1.o -x ir %t.o -c -fthinlto-index=%t.thinlto.bc -save-temps=cwd -### 2>&1 | FileCheck %s -check-prefix=CHECK-SAVE-TEMPS -check-prefix=CHECK-SAVE-TEMPS-CWD
+// RUN: %clang -O2 -o %t1.o -x ir %t.o -c -fthinlto-index=%t.thinlto.bc -save-temps=obj -### 2>&1 | FileCheck %s -check-prefix=CHECK-SAVE-TEMPS -check-prefix=CHECK-SAVE-TEMPS-OBJ
+// CHECK-SAVE-TEMPS-NOT: -emit-llvm-bc
+// CHECK-SAVE-TEMPS-CWD: -save-temps=cwd
+// CHECK-SAVE-TEMPS-OBJ: -save-temps=obj
+// CHECK-SAVE-TEMPS-NOT: -emit-llvm-bc
+
 // Ensure clang driver gives the expected error for incorrect input type
 // RUN: not %clang -O2 -o %t1.o %s -c -fthinlto-index=%t.thinlto.bc 2>&1 | FileCheck %s -check-prefix=CHECK-WARNING
 // CHECK-WARNING: error: invalid argument '-fthinlto-index={{.*}}' only allowed with '-x ir'