[clang] -falign-loops=

Author: MaskRay

clang/include/clang/Basic/CodeGenOptions.def

@@ -293,6 +293,8 @@ CODEGENOPT(StackRealignment  , 1, 0) ///< Control whether to force stack
                                      ///< realignment.
 CODEGENOPT(UseInitArray      , 1, 0) ///< Control whether to use .init_array or
                                      ///< .ctors.
+VALUE_CODEGENOPT(LoopAlignment     , 32, 0) ///< Overrides default loop
+                                            ///< alignment, if not 0.
 VALUE_CODEGENOPT(StackAlignment    , 32, 0) ///< Overrides default stack
                                             ///< alignment, if not 0.
 VALUE_CODEGENOPT(StackProbeSize    , 32, 4096) ///< Overrides default stack

clang/include/clang/Basic/LangOptions.def

@@ -396,6 +396,7 @@ ENUM_LANGOPT(ClangABICompat, ClangABI, 4, ClangABI::Latest,
              "with")
 
 COMPATIBLE_VALUE_LANGOPT(FunctionAlignment, 5, 0, "Default alignment for functions")
+COMPATIBLE_VALUE_LANGOPT(LoopAlignment, 4, 0, "Default alignment for loops")
 
 LANGOPT(FixedPoint, 1, 0, "fixed point types")
 LANGOPT(PaddingOnUnsignedFixedPoint, 1, 0,

clang/include/clang/Driver/Options.td

@@ -1064,6 +1064,8 @@ defm access_control : BoolFOption<"access-control",
   PosFlag<SetTrue>>;
 def falign_functions : Flag<["-"], "falign-functions">, Group<f_Group>;
 def falign_functions_EQ : Joined<["-"], "falign-functions=">, Group<f_Group>;
+def falign_loops_EQ : Joined<["-"], "falign-loops=">, Group<f_Group>,
+  MarshallingInfoInt<CodeGenOpts<"LoopAlignment">>;
 def fno_align_functions: Flag<["-"], "fno-align-functions">, Group<f_Group>;
 defm allow_editor_placeholders : BoolFOption<"allow-editor-placeholders",
   LangOpts<"AllowEditorPlaceholders">, DefaultFalse,
@@ -4293,7 +4295,6 @@ def ld_path_EQ : Joined<["--"], "ld-path=">, Group<Link_Group>;
 defm align_labels : BooleanFFlag<"align-labels">, Group<clang_ignored_gcc_optimization_f_Group>;
 def falign_labels_EQ : Joined<["-"], "falign-labels=">, Group<clang_ignored_gcc_optimization_f_Group>;
 defm align_loops : BooleanFFlag<"align-loops">, Group<clang_ignored_gcc_optimization_f_Group>;
-def falign_loops_EQ : Joined<["-"], "falign-loops=">, Group<clang_ignored_gcc_optimization_f_Group>;
 defm align_jumps : BooleanFFlag<"align-jumps">, Group<clang_ignored_gcc_optimization_f_Group>;
 def falign_jumps_EQ : Joined<["-"], "falign-jumps=">, Group<clang_ignored_gcc_optimization_f_Group>;
 

clang/lib/CodeGen/BackendUtil.cpp

@@ -581,6 +581,8 @@ static bool initTargetOptions(DiagnosticsEngine &Diags,
       CodeGenOpts.ValueTrackingVariableLocations;
   Options.XRayOmitFunctionIndex = CodeGenOpts.XRayOmitFunctionIndex;
 
+  Options.LoopAlignment = CodeGenOpts.LoopAlignment;
+
   Options.MCOptions.SplitDwarfFile = CodeGenOpts.SplitDwarfFile;
   Options.MCOptions.MCRelaxAll = CodeGenOpts.RelaxAll;
   Options.MCOptions.MCSaveTempLabels = CodeGenOpts.SaveTempLabels;

clang/lib/Driver/ToolChains/Clang.cpp

@@ -4720,6 +4720,15 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     CmdArgs.push_back(Args.MakeArgString(std::to_string(FunctionAlignment)));
   }
 
+  if (const Arg *A = Args.getLastArg(options::OPT_falign_loops_EQ)) {
+    unsigned Value = 0;
+    if (StringRef(A->getValue()).getAsInteger(10, Value) || Value > 65536)
+      TC.getDriver().Diag(diag::err_drv_invalid_int_value)
+          << A->getAsString(Args) << A->getValue();
+    Value = Value ? 1u << llvm::Log2_32_Ceil(std::min(Value, 65536u)) : 0;
+    CmdArgs.push_back(Args.MakeArgString("-falign-loops=" + Twine(Value)));
+  }
+
   llvm::Reloc::Model RelocationModel;
   unsigned PICLevel;
   bool IsPIE;

llvm/include/llvm/Target/TargetOptions.h

@@ -328,6 +328,8 @@ namespace llvm {
     /// passed on the command line.
     std::string StackUsageOutput;
 
+    unsigned LoopAlignment = 0;
+
     /// FloatABIType - This setting is set by -float-abi=xxx option is specfied
     /// on the command line. This setting may either be Default, Soft, or Hard.
     /// Default selects the target's default behavior. Soft selects the ABI for