[ThinLTO] Pass CodeGenOpts like UnrollLoops/VectorizeLoop/VectorizeSLP

down to pass builder in ltobackend.

Currently CodeGenOpts like UnrollLoops/VectorizeLoop/VectorizeSLP in clang
are not passed down to pass builder in ltobackend when new pass manager is
used. This is inconsistent with the behavior when new pass manager is used
and thinlto is not used. Such inconsistency causes slp vectorization pass
not being enabled in ltobackend for O3 + thinlto right now. This patch
fixes that.

Differential Revision: https://reviews.llvm.org/D72386

2 files changed, 56 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index ed881f2ddf6..d58bcf5a790 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -1437,6 +1437,12 @@ static void runThinLTOBackend(ModuleSummaryIndex *CombinedIndex, Module *M,
   Conf.OptLevel = CGOpts.OptimizationLevel;
   initTargetOptions(Conf.Options, CGOpts, TOpts, LOpts, HeaderOpts);
   Conf.SampleProfile = std::move(SampleProfile);
+  Conf.PTO.LoopUnrolling = CGOpts.UnrollLoops;
+  // For historical reasons, loop interleaving is set to mirror setting for loop
+  // unrolling.
+  Conf.PTO.LoopInterleaving = CGOpts.UnrollLoops;
+  Conf.PTO.LoopVectorization = CGOpts.VectorizeLoop;
+  Conf.PTO.SLPVectorization = CGOpts.VectorizeSLP;
 
   // Context sensitive profile.
   if (CGOpts.hasProfileCSIRInstr()) {
diff --git a/clang/test/CodeGen/thinlto-slp-vectorize-pm.c b/clang/test/CodeGen/thinlto-slp-vectorize-pm.c
new file mode 100644
index 00000000000..4700da6ed0e
--- /dev/null
+++ b/clang/test/CodeGen/thinlto-slp-vectorize-pm.c
@@ -0,0 +1,50 @@
+// REQUIRES: x86-registered-target
+// RUN: %clang_cc1 -o %t.o -flto=thin -fexperimental-new-pass-manager -triple x86_64-unknown-linux-gnu -emit-llvm-bc %s
+// RUN: llvm-lto -thinlto -o %t %t.o
+
+// Test to ensure the slp vectorize codegen option is passed down to the
+// ThinLTO backend. -vectorize-slp is a cc1 option and will be added
+// automatically when O2/O3/Os/Oz is available for clang. Once -vectorize-slp
+// is enabled, "-mllvm -vectorize-slp=false" won't disable slp vectorization
+// currently. "-mllvm -vectorize-slp=false" is added here in the test to
+// ensure the slp vectorization is executed because the -vectorize-slp cc1
+// flag is passed down, not because "-mllvm -vectorize-slp" is enabled
+// by default.
+//
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-obj -O2 -vectorize-slp -mllvm -vectorize-slp=false -o %t2.o -x ir %t.o -fthinlto-index=%t.thinlto.bc -fdebug-pass-manager -fexperimental-new-pass-manager 2>&1 | FileCheck %s --check-prefix=O2-SLP
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-obj -O0 -vectorize-slp -mllvm -vectorize-slp=false -o %t2.o -x ir %t.o -fthinlto-index=%t.thinlto.bc -fdebug-pass-manager -fexperimental-new-pass-manager 2>&1 | FileCheck %s --check-prefix=O0-SLP
+// O2-SLP: Running pass: SLPVectorizerPass
+// O0-SLP-NOT: Running pass: SLPVectorizerPass
+
+// Test to ensure the loop vectorize codegen option is passed down to the
+// ThinLTO backend. -vectorize-loops is a cc1 option and will be added
+// automatically when O2/O3/Os is available for clang. Once -vectorize-loops is
+// enabled, "-mllvm -vectorize-loops=false" won't disable loop vectorization
+// currently. "-mllvm -vectorize-loops=false" is added here in the test to
+// ensure the loop vectorization is executed because the -vectorize-loops cc1
+// flag is passed down, not because "-mllvm -vectorize-loops" is enabled
+// by default.
+//
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-obj -O2 -vectorize-loops -mllvm -vectorize-loops=false -mllvm -force-vector-width=2 -mllvm -force-vector-interleave=1 -emit-llvm -o - -x ir %t.o -fthinlto-index=%t.thinlto.bc -fexperimental-new-pass-manager 2>&1 | FileCheck %s --check-prefix=O2-LPV
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-obj -O0 -vectorize-loops -mllvm -vectorize-loops=false -mllvm -force-vector-width=2 -mllvm -force-vector-interleave=1 -emit-llvm -o - -x ir %t.o -fthinlto-index=%t.thinlto.bc -fexperimental-new-pass-manager 2>&1 | FileCheck %s --check-prefix=O0-LPV
+// O2-LPV: = !{!"llvm.loop.isvectorized", i32 1}
+// O0-LPV-NOT: = !{!"llvm.loop.isvectorized", i32 1}
+
+// Test to ensure the loop interleave codegen option is passed down to the
+// ThinLTO backend. The internal loop interleave codegen option will be
+// enabled automatically when O2/O3 is available for clang. Once the loop
+// interleave option is enabled, "-mllvm -interleave-loops=false" won't disable
+// the interleave. currently. "-mllvm -interleave-loops=false" is added here
+// in the test to ensure the loop interleave is executed because the interleave
+// codegen flag is passed down, not because "-mllvm -interleave-loops" is
+// enabled by default.
+//
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-obj -O2 -vectorize-loops -mllvm -interleave-loops=false -mllvm -force-vector-width=1 -mllvm -force-vector-interleave=2 -emit-llvm -o - -x ir %t.o -fthinlto-index=%t.thinlto.bc -fexperimental-new-pass-manager 2>&1 | FileCheck %s --check-prefix=O2-InterLeave
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-obj -O0 -vectorize-loops -mllvm -interleave-loops=false -mllvm -force-vector-width=1 -mllvm -force-vector-interleave=2 -emit-llvm -o - -x ir %t.o -fthinlto-index=%t.thinlto.bc -fexperimental-new-pass-manager 2>&1 | FileCheck %s --check-prefix=O0-InterLeave
+// O2-InterLeave: = !{!"llvm.loop.isvectorized", i32 1}
+// O0-InterLeave-NOT: = !{!"llvm.loop.isvectorized", i32 1}
+
+void foo(double *a) {
+  for (int i = 0; i < 1000; i++)
+    a[i] = 10;
+}