Add an option to the LTO code generator to disable vectorization during LTO

We used to always vectorize (slp and loop vectorize) in the LTO pass pipeline.

r220345 changed it so that we used the PassManager's fields 'LoopVectorize' and
'SLPVectorize' out of the desire to be able to disable vectorization using the
cl::opt flags 'vectorize-loops'/'slp-vectorize' which the before mentioned
fields default to.
Unfortunately, this turns off vectorization because those fields
default to false.
This commit adds flags to the LTO library to disable lto vectorization which
reconciles the desire to optionally disable vectorization during LTO and
the desired behavior of defaulting to enabled vectorization.

We really want tools to set PassManager flags directly to enable/disable
vectorization and not go the route via cl::opt flags *in*
PassManagerBuilder.cpp.

llvm-svn: 220652

include/llvm/LTO/LTOCodeGenerator.h

@@ -101,6 +101,7 @@ struct LTOCodeGenerator {
                        bool disableOpt,
                        bool disableInline,
                        bool disableGVNLoadPRE,
+                       bool disableVectorization,
                        std::string &errMsg);
 
   // As with compile_to_file(), this function compiles the merged module into
@@ -112,6 +113,7 @@ struct LTOCodeGenerator {
                       bool disableOpt,
                       bool disableInline,
                       bool disableGVNLoadPRE,
+                      bool disableVectorization,
                       std::string &errMsg);
 
   void setDiagnosticHandler(lto_diagnostic_handler_t, void *);
@@ -120,7 +122,8 @@ private:
   void initializeLTOPasses();
 
   bool generateObjectFile(raw_ostream &out, bool disableOpt, bool disableInline,
-                          bool disableGVNLoadPRE, std::string &errMsg);
+                          bool disableGVNLoadPRE, bool disableVectorization,
+                          std::string &errMsg);
   void applyScopeRestrictions();
   void applyRestriction(GlobalValue &GV, ArrayRef<StringRef> Libcalls,
                         std::vector<const char *> &MustPreserveList,

lib/LTO/LTOCodeGenerator.cpp

@@ -188,6 +188,7 @@ bool LTOCodeGenerator::compile_to_file(const char** name,
                                        bool disableOpt,
                                        bool disableInline,
                                        bool disableGVNLoadPRE,
+                                       bool disableVectorization,
                                        std::string& errMsg) {
   // make unique temp .o file to put generated object file
   SmallString<128> Filename;
@@ -202,8 +203,9 @@ bool LTOCodeGenerator::compile_to_file(const char** name,
   // generate object file
   tool_output_file objFile(Filename.c_str(), FD);
 
-  bool genResult = generateObjectFile(objFile.os(), disableOpt, disableInline,
-                                      disableGVNLoadPRE, errMsg);
+  bool genResult =
+      generateObjectFile(objFile.os(), disableOpt, disableInline,
+                         disableGVNLoadPRE, disableVectorization, errMsg);
   objFile.os().close();
   if (objFile.os().has_error()) {
     objFile.os().clear_error();
@@ -226,10 +228,11 @@ const void* LTOCodeGenerator::compile(size_t* length,
                                       bool disableOpt,
                                       bool disableInline,
                                       bool disableGVNLoadPRE,
+                                      bool disableVectorization,
                                       std::string& errMsg) {
   const char *name;
   if (!compile_to_file(&name, disableOpt, disableInline, disableGVNLoadPRE,
-                       errMsg))
+                       disableVectorization, errMsg))
     return nullptr;
 
   // read .o file into memory buffer
@@ -441,6 +444,7 @@ bool LTOCodeGenerator::generateObjectFile(raw_ostream &out,
                                           bool DisableOpt,
                                           bool DisableInline,
                                           bool DisableGVNLoadPRE,
+                                          bool DisableVectorization,
                                           std::string &errMsg) {
   if (!this->determineTarget(errMsg))
     return false;
@@ -459,6 +463,8 @@ bool LTOCodeGenerator::generateObjectFile(raw_ostream &out,
   Triple TargetTriple(TargetMach->getTargetTriple());
   PassManagerBuilder PMB;
   PMB.DisableGVNLoadPRE = DisableGVNLoadPRE;
+  PMB.LoopVectorize = !DisableVectorization;
+  PMB.SLPVectorize = !DisableVectorization;
   if (!DisableInline)
     PMB.Inliner = createFunctionInliningPass();
   PMB.LibraryInfo = new TargetLibraryInfo(TargetTriple);

lib/Transforms/IPO/PassManagerBuilder.cpp

@@ -444,7 +444,7 @@ void PassManagerBuilder::addLTOOptimizationPasses(PassManagerBase &PM) {
   // More loops are countable; try to optimize them.
   PM.add(createIndVarSimplifyPass());
   PM.add(createLoopDeletionPass());
-  PM.add(createLoopVectorizePass(DisableUnrollLoops, LoopVectorize));
+  PM.add(createLoopVectorizePass(true, LoopVectorize));
 
   // More scalar chains could be vectorized due to more alias information
   if (RunSLPAfterLoopVectorization)

tools/llvm-lto/llvm-lto.cpp

@@ -38,6 +38,10 @@ static cl::opt<bool>
 DisableGVNLoadPRE("disable-gvn-loadpre", cl::init(false),
   cl::desc("Do not run the GVN load PRE pass"));
 
+static cl::opt<bool>
+DisableLTOVectorization("disable-lto-vectorization", cl::init(false),
+  cl::desc("Do not run loop or slp vectorization during LTO"));
+
 static cl::opt<bool>
 UseDiagnosticHandler("use-diagnostic-handler", cl::init(false),
   cl::desc("Use a diagnostic handler to test the handler interface"));
@@ -179,8 +183,9 @@ int main(int argc, char **argv) {
   if (!OutputFilename.empty()) {
     size_t len = 0;
     std::string ErrorInfo;
-    const void *Code = CodeGen.compile(&len, DisableOpt, DisableInline,
-                                       DisableGVNLoadPRE, ErrorInfo);
+    const void *Code =
+        CodeGen.compile(&len, DisableOpt, DisableInline, DisableGVNLoadPRE,
+                        DisableLTOVectorization, ErrorInfo);
     if (!Code) {
       errs() << argv[0]
              << ": error compiling the code: " << ErrorInfo << "\n";
@@ -200,7 +205,8 @@ int main(int argc, char **argv) {
     std::string ErrorInfo;
     const char *OutputName = nullptr;
     if (!CodeGen.compile_to_file(&OutputName, DisableOpt, DisableInline,
-                                 DisableGVNLoadPRE, ErrorInfo)) {
+                                 DisableGVNLoadPRE, DisableLTOVectorization,
+                                 ErrorInfo)) {
       errs() << argv[0]
              << ": error compiling the code: " << ErrorInfo
              << "\n";

tools/lto/lto.cpp

@@ -32,6 +32,10 @@ static cl::opt<bool>
 DisableGVNLoadPRE("disable-gvn-loadpre", cl::init(false),
   cl::desc("Do not run the GVN load PRE pass"));
 
+static cl::opt<bool>
+DisableLTOVectorization("disable-lto-vectorization", cl::init(false),
+  cl::desc("Do not run loop or slp vectorization during LTO"));
+
 // Holds most recent error string.
 // *** Not thread safe ***
 static std::string sLastErrorString;
@@ -252,7 +256,8 @@ const void *lto_codegen_compile(lto_code_gen_t cg, size_t *length) {
     parsedOptions = true;
   }
   return unwrap(cg)->compile(length, DisableOpt, DisableInline,
-                             DisableGVNLoadPRE, sLastErrorString);
+                             DisableGVNLoadPRE, DisableLTOVectorization,
+                             sLastErrorString);
 }
 
 bool lto_codegen_compile_to_file(lto_code_gen_t cg, const char **name) {
@@ -261,8 +266,9 @@ bool lto_codegen_compile_to_file(lto_code_gen_t cg, const char **name) {
     lto_add_attrs(cg);
     parsedOptions = true;
   }
-  return !unwrap(cg)->compile_to_file(name, DisableOpt, DisableInline,
-                                      DisableGVNLoadPRE, sLastErrorString);
+  return !unwrap(cg)->compile_to_file(
+      name, DisableOpt, DisableInline, DisableGVNLoadPRE,
+      DisableLTOVectorization, sLastErrorString);
 }
 
 void lto_codegen_debug_options(lto_code_gen_t cg, const char *opt) {