Add -f[no-]loop-versioning option

[Leporacanthicus]

Summary

Add flags for loop-versioning pass enable/disable

[Leporacanthicus]

Rebase

[Leporacanthicus]

Rebased and updated help-message

Also using different type of template for the option

[Leporacanthicus]

Update for rebase.

[tblah]

Please could you add tests for the flag forwarding logic in flang/tests/Driver/frontend-forwarding.f90. For example see https://reviews.llvm.org/rGd0d4b635786d510cd919cadbeb7e5e19983242cf

clang/lib/Driver/ToolChains/Flang.cpp

95

Does GFortran only enable this with -Ofast? I would have thought this would be an -On thing because it doesn't impact precision.

flang/include/flang/Frontend/CodeGenOptions.def

27

nit: comment

[Leporacanthicus]

Updates based on review comments:

• Add tests.
• Enable on -O3

Also changed the name to match gfortran.

[Leporacanthicus]

clang/lib/Driver/ToolChains/Flang.cpp

95

No, good point.

flang/include/flang/Frontend/CodeGenOptions.def

27

Darn, missed fixing this.

[Leporacanthicus]

Fix copied comment to reflect the new content.

[tblah]

Looks good to me

[Leporacanthicus]

Rebase and fix conflicts

[Leporacanthicus]

Rebase.

[Leporacanthicus]

Rebase only

[awarzynski]

Mats, thanks for working on this! Just a few minor suggestions from me.

clang/lib/Driver/ToolChains/Flang.cpp

54

Could you add a short Docstring, pls? In particular, is the logic implemented by this method consistent with GFortran? Are there any external docs that could be referred to here?

55

Please rewrite this to use early exit, e.g.:

Arg *LoopVersionOption = Args.getLastArg(options::OPT_Ofast, options::OPT_O,
                             options::OPT_O4, options::OPT_floop_versioning,
                             options::OPT_fno_loop_versioning)
if !(LoopVersionOption)
  return false;

// The remaining logic HERE

94–95

Would you classify this as a code-gen option? Alongside -fstack-arrays and -flang-experimental-hlfir? It sound like we could introduce another hook here, adddCodeGenOptions?

flang/test/Driver/version-loops.f90

3

6

[nit] If you are using -###, then you can just skip -fsyntax-only (it doesn't really matter what "action" is requested from the frontend driver).

34–35

Similar suggestion for other CHECK lines - this will make the test a bit more explicit about the expected output.

[Leporacanthicus]

Rebase only.

[Leporacanthicus]

• Add new function to help clarify the purpose of the options being used.
• Add descriptive comment to make function use clearer.
• Update tests to make them a more explicit.

[awarzynski]

LGTM, thanks!

[Leporacanthicus]

Remove unnecessary braces in if-statement.

[Leporacanthicus]

Rebase only

[Leporacanthicus]

Rebase only

clang/include/clang/Driver/Options.td

 defm underscoring : OptInFC1FFlag<"underscoring", "Appends one trailing underscore to external names">;
 
 def fno_automatic : Flag<["-"], "fno-automatic">, Group<f_Group>,
   HelpText<"Implies the SAVE attribute for non-automatic local objects in subprograms unless RECURSIVE">;
 
 defm stack_arrays : BoolOptionWithoutMarshalling<"f", "stack-arrays",
   PosFlag<SetTrue, [], "Attempt to allocate array temporaries on the stack, no matter their size">,
   NegFlag<SetFalse, [], "Allocate array temporaries on the heap (default)">>;
-
+defm loop_versioning : BoolOptionWithoutMarshalling<"f", "version-loops-for-stride",
+  PosFlag<SetTrue, [], "Create unit-strided versions of loops">,
+   NegFlag<SetFalse, [], "Do not create unit-strided loops (default)">>;
 } // let Flags = [FC1Option, FlangOption, FlangOnlyOption]
 
 def J : JoinedOrSeparate<["-"], "J">,
   Flags<[RenderJoined, FlangOption, FC1Option, FlangOnlyOption]>,
   Group<gfortran_Group>,
   Alias<module_dir>;
 
 //===----------------------------------------------------------------------===//

clang/lib/Driver/ToolChains/Flang.cpp

 
 void Flang::addPreprocessingOptions(const ArgList &Args,
                                     ArgStringList &CmdArgs) const {
   Args.AddAllArgs(CmdArgs,
                   {options::OPT_P, options::OPT_D, options::OPT_U,
                    options::OPT_I, options::OPT_cpp, options::OPT_nocpp});
 }
 
+static bool shouldLoopVersion(const ArgList &Args) {
+  if (Arg *A = Args.getLastArg(options::OPT_Ofast, options::OPT_O,
+                               options::OPT_O4, options::OPT_floop_versioning,
+                               options::OPT_fno_loop_versioning)) {
+    if (A->getOption().matches(options::OPT_fno_loop_versioning))
+      return false;
+
+    if (A->getOption().matches(options::OPT_floop_versioning))
+      return true;
+
+    if (A->getOption().matches(options::OPT_Ofast) ||
+        A->getOption().matches(options::OPT_O4))
+      return true;
+
+    if (A->getOption().matches(options::OPT_O)) {
+      StringRef S(A->getValue());
+      unsigned OptLevel = 0;
+      if (S.getAsInteger(10, OptLevel))
+        return false;
+
+      return OptLevel > 2;
+    }
+  }
+  return false;
+}
+
 void Flang::addOtherOptions(const ArgList &Args, ArgStringList &CmdArgs) const {
   Args.AddAllArgs(CmdArgs,
                   {options::OPT_module_dir, options::OPT_fdebug_module_writer,
                    options::OPT_fintrinsic_modules_path, options::OPT_pedantic,
                    options::OPT_std_EQ, options::OPT_W_Joined,
                    options::OPT_fconvert_EQ, options::OPT_fpass_plugin_EQ,
                    options::OPT_funderscoring, options::OPT_fno_underscoring});
 
   Arg *stackArrays =
       Args.getLastArg(options::OPT_Ofast, options::OPT_fstack_arrays,
                       options::OPT_fno_stack_arrays);
   if (stackArrays &&
       !stackArrays->getOption().matches(options::OPT_fno_stack_arrays))
     CmdArgs.push_back("-fstack-arrays");
+  if (shouldLoopVersion(Args))
+    CmdArgs.push_back("-fversion-loops-for-stride");
 }
 
 void Flang::addPicOptions(const ArgList &Args, ArgStringList &CmdArgs) const {
   // ParsePICArgs parses -fPIC/-fPIE and their variants and returns a tuple of
   // (RelocationModel, PICLevel, IsPIE).
   llvm::Reloc::Model RelocationModel;
   unsigned PICLevel;
   bool IsPIE;

flang/include/flang/Frontend/CodeGenOptions.def

 CODEGENOPT(Name, Bits, Default)
 #endif
 
 CODEGENOPT(OptimizationLevel, 2, 0) ///< The -O[0-3] option specified.
 
 CODEGENOPT(DebugPassManager, 1, 0) ///< Prints debug information for the new
                                    ///< pass manager.
 
+CODEGENOPT(LoopVersioning, 1, 0) ///< PIC level of the LLVM module.
 CODEGENOPT(PICLevel, 2, 0) ///< PIC level of the LLVM module.
 CODEGENOPT(IsPIE, 1, 0) ///< PIE level is the same as PIC Level.
 CODEGENOPT(StackArrays, 1, 0) ///< -fstack-arrays (enable the stack-arrays pass)
 
 CODEGENOPT(Underscoring, 1, 1)
 ENUM_CODEGENOPT(RelocationModel, llvm::Reloc::Model, 3, llvm::Reloc::PIC_) ///< Name of the relocation model to use.
 
 #undef CODEGENOPT
 #undef ENUM_CODEGENOPT

flang/include/flang/Tools/CLOptions.inc

 DisableOption(TargetRewrite, "target-rewrite", "rewrite FIR for target");
 DisableOption(DebugFoundation, "debug-foundation", "Add debug foundation");
 DisableOption(FirToLlvmIr, "fir-to-llvmir", "FIR to LLVM-IR dialect");
 DisableOption(LlvmIrToLlvm, "llvm", "conversion to LLVM");
 DisableOption(BoxedProcedureRewrite, "boxed-procedure-rewrite",
     "rewrite boxed procedures");
 #endif
 
-DisableOption(ExternalNameConversion, "external-name-interop", "convert names with external convention");
+DisableOption(ExternalNameConversion, "external-name-interop",
+    "convert names with external convention");
 
 /// Generic for adding a pass to the pass manager if it is not disabled.
 template <typename F>
 void addPassConditionally(
     mlir::PassManager &pm, llvm::cl::opt<bool> &disabled, F ctor) {
   if (!disabled)
     pm.addPass(ctor());
 }

 }
 
 /// Create a pass pipeline for running default optimization passes for
 /// incremental conversion of FIR.
 ///
 /// \param pm - MLIR pass manager that will hold the pipeline definition
 inline void createDefaultFIROptimizerPassPipeline(mlir::PassManager &pm,
     llvm::OptimizationLevel optLevel = defaultOptLevel,
-    bool stackArrays = false) {
+    bool stackArrays = false, bool loopVersioning = false) {
   // simplify the IR
   mlir::GreedyRewriteConfig config;
   config.enableRegionSimplification = false;
   pm.addPass(mlir::createCSEPass());
   fir::addAVC(pm, optLevel);
   pm.addNestedPass<mlir::func::FuncOp>(fir::createCharacterConversionPass());
   pm.addPass(mlir::createCanonicalizerPass(config));
   pm.addPass(fir::createSimplifyRegionLitePass());

 
 #if !defined(FLANG_EXCLUDE_CODEGEN)
 inline void createDefaultFIRCodeGenPassPipeline(mlir::PassManager &pm,
     llvm::OptimizationLevel optLevel = defaultOptLevel,
     bool underscoring = true) {
   fir::addBoxedProcedurePass(pm);
   pm.addNestedPass<mlir::func::FuncOp>(
       fir::createAbstractResultOnFuncOptPass());
-  pm.addNestedPass<fir::GlobalOp>(
-      fir::createAbstractResultOnGlobalOptPass());
+  pm.addNestedPass<fir::GlobalOp>(fir::createAbstractResultOnGlobalOptPass());
   fir::addCodeGenRewritePass(pm);
   fir::addTargetRewritePass(pm);
   fir::addExternalNameConversionPass(pm, underscoring);
   fir::addFIRToLLVMPass(pm, optLevel);
 }
 
 /// Create a pass pipeline for lowering from MLIR to LLVM IR
 ///
 /// \param pm - MLIR pass manager that will hold the pipeline definition
 /// \param optLevel - optimization level used for creating FIR optimization
 ///   passes pipeline
 inline void createMLIRToLLVMPassPipeline(mlir::PassManager &pm,
     llvm::OptimizationLevel optLevel = defaultOptLevel,
-    bool stackArrays = false, bool underscoring = true) {
+    bool stackArrays = false, bool underscoring = true, bool loopVersioning = false) {
   // Add default optimizer pass pipeline.
-  fir::createDefaultFIROptimizerPassPipeline(pm, optLevel, stackArrays);
+  fir::createDefaultFIROptimizerPassPipeline(
+      pm, optLevel, stackArrays, loopVersioning);
 
   // Add codegen pass pipeline.
   fir::createDefaultFIRCodeGenPassPipeline(pm, optLevel, underscoring);
 }
 #undef FLANG_EXCLUDE_CODEGEN
 #endif
 
 } // namespace fir

flang/lib/Frontend/CompilerInvocation.cpp

static void parseCodeGenArgs(Fortran::frontend::CodeGenOptions &opts,
   if (args.hasFlag(clang::driver::options::OPT_fdebug_pass_manager,
                    clang::driver::options::OPT_fno_debug_pass_manager, false))
     opts.DebugPassManager = 1;
 
   if (args.hasFlag(clang::driver::options::OPT_fstack_arrays,
                    clang::driver::options::OPT_fno_stack_arrays, false)) {
     opts.StackArrays = 1;
   }
+  if (args.hasFlag(clang::driver::options::OPT_floop_versioning,
+                   clang::driver::options::OPT_fno_loop_versioning, false)) {
+    opts.LoopVersioning = 1;
+  }
 
   for (auto *a : args.filtered(clang::driver::options::OPT_fpass_plugin_EQ))
     opts.LLVMPassPlugins.push_back(a->getValue());
 
   // -fembed-offload-object option
   for (auto *a :
        args.filtered(clang::driver::options::OPT_fembed_offload_object_EQ))
     opts.OffloadObjects.push_back(a->getValue());

flang/lib/Frontend/FrontendActions.cpp

void CodeGenAction::generateLLVMIR() {
   mlir::PassManager pm((*mlirModule)->getName(),
                        mlir::OpPassManager::Nesting::Implicit);
 
   pm.addPass(std::make_unique<Fortran::lower::VerifierPass>());
   pm.enableVerifier(/*verifyPasses=*/true);
 
   // Create the pass pipeline
   fir::createMLIRToLLVMPassPipeline(pm, level, opts.StackArrays,
-                                    opts.Underscoring);
+                                    opts.Underscoring, opts.LoopVersioning);
   mlir::applyPassManagerCLOptions(pm);
 
   // run the pass manager
   if (!mlir::succeeded(pm.run(*mlirModule))) {
     unsigned diagID = ci.getDiagnostics().getCustomDiagID(
         clang::DiagnosticsEngine::Error, "Lowering to LLVM IR failed");
     ci.getDiagnostics().Report(diagID);
   }

flang/test/Driver/driver-help-hidden.f90

 ! CHECK-NEXT:                        Enable support for generating executables (experimental)
 ! CHECK-NEXT: -flarge-sizes          Use INTEGER(KIND=8) for the result type in size-related intrinsics
 ! CHECK-NEXT: -flogical-abbreviations Enable logical abbreviations
 ! CHECK-NEXT: -fno-automatic         Implies the SAVE attribute for non-automatic local objects in subprograms unless RECURSIVE
 ! CHECK-NEXT: -fno-color-diagnostics  Disable colors in diagnostics
 ! CHECK-NEXT: -fno-integrated-as     Disable the integrated assembler
 ! CHECK-NEXT: -fno-signed-zeros      Allow optimizations that ignore the sign of floating point zeros
 ! CHECK-NEXT: -fno-stack-arrays      Allocate array temporaries on the heap (default)
+! CHECK-NEXT: -fno-version-loops-for-stride
+! CHECK-NEXT:                        Do not create unit-strided loops (default)
 ! CHECK-NEXT: -fopenacc              Enable OpenACC
 ! CHECK-NEXT: -fopenmp               Parse OpenMP pragmas and generate parallel code.
 ! CHECK-NEXT: -fpass-plugin=<dsopath> Load pass plugin from a dynamic shared object file (only with new pass manager).
 ! CHECK-NEXT: -freciprocal-math      Allow division operations to be reassociated
 ! CHECK-NEXT: -fstack-arrays         Attempt to allocate array temporaries on the stack, no matter their size
 ! CHECK-NEXT: -fsyntax-only          Run the preprocessor, parser and semantic analysis stages
 ! CHECK-NEXT: -funderscoring         Appends one trailing underscore to external names
+! CHECK-NEXT: -fversion-loops-for-stride
+! CHECK-NEXT:                        Create unit-strided versions of loops
 ! CHECK-NEXT: -fxor-operator         Enable .XOR. as a synonym of .NEQV.
 ! CHECK-NEXT: -help     Display available options
 ! CHECK-NEXT: -I <dir>               Add directory to the end of the list of include search paths
 ! CHECK-NEXT: -mllvm=<arg>           Alias for -mllvm
 ! CHECK-NEXT: -mllvm <value>         Additional arguments to forward to LLVM's option processing
 ! CHECK-NEXT: -mmlir <value>         Additional arguments to forward to MLIR's option processing
 ! CHECK-NEXT: -module-dir <dir>      Put MODULE files in <dir>
 ! CHECK-NEXT: -nocpp                 Disable predefined and command line preprocessor macros

flang/test/Driver/driver-help.f90

 ! HELP-NEXT:                        Specify where to find the compiled intrinsic modules
 ! HELP-NEXT: -flarge-sizes          Use INTEGER(KIND=8) for the result type in size-related intrinsics
 ! HELP-NEXT: -flogical-abbreviations Enable logical abbreviations
 ! HELP-NEXT: -fno-automatic         Implies the SAVE attribute for non-automatic local objects in subprograms unless RECURSIVE
 ! HELP-NEXT: -fno-color-diagnostics  Disable colors in diagnostics
 ! HELP-NEXT: -fno-integrated-as      Disable the integrated assembler
 ! HELP-NEXT: -fno-signed-zeros      Allow optimizations that ignore the sign of floating point zeros
 ! HELP-NEXT: -fno-stack-arrays      Allocate array temporaries on the heap (default)
+! HELP-NEXT: -fno-version-loops-for-stride
+! HELP-NEXT:                        Do not create unit-strided loops (default)
 ! HELP-NEXT: -fopenacc              Enable OpenACC
 ! HELP-NEXT: -fopenmp               Parse OpenMP pragmas and generate parallel code.
 ! HELP-NEXT: -fpass-plugin=<dsopath> Load pass plugin from a dynamic shared object file (only with new pass manager).
 ! HELP-NEXT: -freciprocal-math      Allow division operations to be reassociated
 ! HELP-NEXT: -fstack-arrays         Attempt to allocate array temporaries on the stack, no matter their size
 ! HELP-NEXT: -fsyntax-only          Run the preprocessor, parser and semantic analysis stages
 ! HELP-NEXT: -funderscoring         Appends one trailing underscore to external names
+! HELP-NEXT: -fversion-loops-for-stride
+! HELP-NEXT:                        Create unit-strided versions of loops
 ! HELP-NEXT: -fxor-operator         Enable .XOR. as a synonym of .NEQV.
 ! HELP-NEXT: -help                  Display available options
 ! HELP-NEXT: -I <dir>               Add directory to the end of the list of include search paths
 ! HELP-NEXT: -mllvm=<arg>           Alias for -mllvm
 ! HELP-NEXT: -mllvm <value>         Additional arguments to forward to LLVM's option processing
 ! HELP-NEXT: -mmlir <value>         Additional arguments to forward to MLIR's option processing
 ! HELP-NEXT: -module-dir <dir>      Put MODULE files in <dir>
 ! HELP-NEXT: -nocpp                 Disable predefined and command line preprocessor macros

 ! HELP-FC1-NEXT: -flogical-abbreviations Enable logical abbreviations
 ! HELP-FC1-NEXT: -fno-analyzed-objects-for-unparse
 ! HELP-FC1-NEXT:                        Do not use the analyzed objects when unparsing
 ! HELP-FC1-NEXT: -fno-automatic         Implies the SAVE attribute for non-automatic local objects in subprograms unless RECURSIVE
 ! HELP-FC1-NEXT: -fno-debug-pass-manager Disables debug printing for the new pass manager
 ! HELP-FC1-NEXT: -fno-reformat          Dump the cooked character stream in -E mode
 ! HELP-FC1-NEXT: -fno-signed-zeros      Allow optimizations that ignore the sign of floating point zeros
 ! HELP-FC1-NEXT: -fno-stack-arrays      Allocate array temporaries on the heap (default)
+! HELP-FC1-NEXT: -fno-version-loops-for-stride
+! HELP-FC1-NEXT:                        Do not create unit-strided loops (default)
 ! HELP-FC1-NEXT: -fopenacc              Enable OpenACC
 ! HELP-FC1-NEXT: -fopenmp-is-device     Generate code only for an OpenMP target device.
 ! HELP-FC1-NEXT: -fopenmp               Parse OpenMP pragmas and generate parallel code.
 ! HELP-FC1-NEXT: -fpass-plugin=<dsopath> Load pass plugin from a dynamic shared object file (only with new pass manager).
 ! HELP-FC1-NEXT: -freciprocal-math      Allow division operations to be reassociated
 ! HELP-FC1-NEXT: -fstack-arrays         Attempt to allocate array temporaries on the stack, no matter their size
 ! HELP-FC1-NEXT: -fsyntax-only          Run the preprocessor, parser and semantic analysis stages
 ! HELP-FC1-NEXT: -funderscoring         Appends one trailing underscore to external names
+! HELP-FC1-NEXT: -fversion-loops-for-stride
+! HELP-FC1-NEXT:                        Create unit-strided versions of loops
 ! HELP-FC1-NEXT: -fxor-operator         Enable .XOR. as a synonym of .NEQV.
 ! HELP-FC1-NEXT: -help                  Display available options
 ! HELP-FC1-NEXT: -init-only             Only execute frontend initialization
 ! HELP-FC1-NEXT: -I <dir>               Add directory to the end of the list of include search paths
 ! HELP-FC1-NEXT: -load <dsopath>        Load the named plugin (dynamic shared object)
 ! HELP-FC1-NEXT: -menable-no-infs       Allow optimization to assume there are no infinities.
 ! HELP-FC1-NEXT: -menable-no-nans       Allow optimization to assume there are no NaNs.
 ! HELP-FC1-NEXT: -mllvm <value>         Additional arguments to forward to LLVM's option processing

flang/test/Driver/frontend-forwarding.f90

 ! RUN:     -fconvert=little-endian \
 ! RUN:     -ffp-contract=fast \
 ! RUN:     -fno-honor-nans \
 ! RUN:     -fapprox-func \
 ! RUN:     -fno-signed-zeros \
 ! RUN:     -fassociative-math \
 ! RUN:     -freciprocal-math \
 ! RUN:     -fpass-plugin=Bye%pluginext \
+! RUN:     -fversion-loops-for-stride \
 ! RUN:     -mllvm -print-before-all\
 ! RUN:     -P \
 ! RUN:   | FileCheck %s
 
 ! CHECK: "-P"
 ! CHECK: "-finput-charset=utf-8"
 ! CHECK: "-fdefault-double-8"
 ! CHECK: "-fdefault-integer-8"
 ! CHECK: "-fdefault-real-8"
 ! CHECK: "-flarge-sizes"
 ! CHECK: "-ffp-contract=fast"
 ! CHECK: "-menable-no-nans"
 ! CHECK: "-fapprox-func"
 ! CHECK: "-fno-signed-zeros"
 ! CHECK: "-mreassociate"
 ! CHECK: "-freciprocal-math"
 ! CHECK: "-fconvert=little-endian"
 ! CHECK: "-fpass-plugin=Bye
+! CHECK: "-fversion-loops-for-stride"  
 ! CHECK: "-mllvm" "-print-before-all"

flang/test/Driver/version-loops.f90

+! Test that flang-new forwards the -f{no-,}version-loops-for-stride 
+! options corredly to flang-new -fc1 for different variants of optimisation
+! and explicit flags.
+
+! RUN: %flang -fsyntax-only -### %s -o %t 2>&1 \
+! RUN:   -O3 \
+! RUN:   | FileCheck %s
+  
+! RUN: %flang -fsyntax-only -### %s -o %t 2>&1 \
+! RUN:   -O2 \
+! RUN:   | FileCheck %s --check-prefix=CHECK-O2
+
+! RUN: %flang -fsyntax-only -### %s -o %t 2>&1 \
+! RUN:   -O2 -fversion-loops-for-stride \
+! RUN:   | FileCheck %s --check-prefix=CHECK-O2-with
+  
+! RUN: %flang -fsyntax-only -### %s -o %t 2>&1 \
+! RUN:   -O4 \
+! RUN:   | FileCheck %s --check-prefix=CHECK-O4
+  
+! RUN: %flang -fsyntax-only -### %s -o %t 2>&1 \
+! RUN:   -Ofast \
+! RUN:   | FileCheck %s --check-prefix=CHECK-Ofast
+  
+! RUN: %flang -fsyntax-only -### %s -o %t 2>&1 \
+! RUN:   -Ofast -fno-version-loops-for-stride \
+! RUN:   | FileCheck %s --check-prefix=CHECK-Ofast-no
+
+! RUN: %flang -fsyntax-only -### %s -o %t 2>&1 \
+! RUN:   -O3 -fno-version-loops-for-stride \
+! RUN:   | FileCheck %s --check-prefix=CHECK-O3-no
+  
+! CHECK: "-fversion-loops-for-stride"
+! CHECK: "-O3"
+
+! CHECK-O2-NOT: "-fversion-loops-for-stride"
+! CHECK-O2: "-O2"  
+
+! CHECK-O2-with: "-fversion-loops-for-stride"
+! CHECK-O2-with: "-O2"  
+  
+! CHECK-O4: "-fversion-loops-for-stride"
+! CHECK-O4: "-O3"
+
+! CHECK-Ofast: "-ffast-math"
+! CHECK-Ofast: "-fversion-loops-for-stride"
+! CHECK-Ofast: "-O3"
+
+! CHECK-Ofast-no: "-ffast-math"
+! CHECK-Ofast-no-NOT: "-fversion-loops-for-stride"
+! CHECK-Ofast-no: "-O3"
+
+! CHECK-O3-no-NOT: "-fversion-loops-for-stride"
+! CHECK-O3-no: "-O3"