[AArch64] Add Tiny Code Model for AArch64

[dmgreen]

Summary

Adds a tiny code model as a Clang side of D49673.

[peter.smith]

Looks good to me now that LLVM support has been approved in D49673

[dmgreen]

Thanks

include/clang/Driver/CC1Options.td

def relaxed_aliasing : Flag<["-"], "relaxed-aliasing">,
   HelpText<"Turn off Type Based Alias Analysis">;
 def no_struct_path_tbaa : Flag<["-"], "no-struct-path-tbaa">,
   HelpText<"Turn off struct-path aware Type Based Alias Analysis">;
 def new_struct_path_tbaa : Flag<["-"], "new-struct-path-tbaa">,
   HelpText<"Enable enhanced struct-path aware Type Based Alias Analysis">;
 def masm_verbose : Flag<["-"], "masm-verbose">,
   HelpText<"Generate verbose assembly output">;
 def mcode_model : Separate<["-"], "mcode-model">,
-  HelpText<"The code model to use">, Values<"small,kernel,medium,large">;
+  HelpText<"The code model to use">, Values<"tiny,small,kernel,medium,large">;
 def mdebug_pass : Separate<["-"], "mdebug-pass">,
   HelpText<"Enable additional debug output">;
 def mdisable_fp_elim : Flag<["-"], "mdisable-fp-elim">,
   HelpText<"Disable frame pointer elimination optimization">;
 def mdisable_tail_calls : Flag<["-"], "mdisable-tail-calls">,
   HelpText<"Disable tail call optimization, keeping the call stack accurate">;
 def menable_no_infinities : Flag<["-"], "menable-no-infs">,
   HelpText<"Allow optimization to assume there are no infinities.">;

lib/CodeGen/BackendUtil.cpp

static CodeGenOpt::Level getCGOptLevel(const CodeGenOptions &CodeGenOpts) {
   case 3:
     return CodeGenOpt::Aggressive;
   }
 }
 
 static Optional<llvm::CodeModel::Model>
 getCodeModel(const CodeGenOptions &CodeGenOpts) {
   unsigned CodeModel = llvm::StringSwitch<unsigned>(CodeGenOpts.CodeModel)
+                           .Case("tiny", llvm::CodeModel::Tiny)
                            .Case("small", llvm::CodeModel::Small)
                            .Case("kernel", llvm::CodeModel::Kernel)
                            .Case("medium", llvm::CodeModel::Medium)
                            .Case("large", llvm::CodeModel::Large)
                            .Case("default", ~1u)
                            .Default(~0u);
   assert(CodeModel != ~0u && "invalid code model!");
   if (CodeModel == ~1u)

lib/Frontend/CompilerInvocation.cpp

static void ParseCommentArgs(CommentOptions &Opts, ArgList &Args) {
   Opts.BlockCommandNames = Args.getAllArgValues(OPT_fcomment_block_commands);
   Opts.ParseAllComments = Args.hasArg(OPT_fparse_all_comments);
 }
 
 static StringRef getCodeModel(ArgList &Args, DiagnosticsEngine &Diags) {
   if (Arg *A = Args.getLastArg(OPT_mcode_model)) {
     StringRef Value = A->getValue();
     if (Value == "small" || Value == "kernel" || Value == "medium" ||
-        Value == "large")
+        Value == "large" || Value == "tiny")
       return Value;
     Diags.Report(diag::err_drv_invalid_value) << A->getAsString(Args) << Value;
   }
   return "default";
 }
 
 static llvm::Reloc::Model getRelocModel(ArgList &Args,
                                         DiagnosticsEngine &Diags) {

test/Driver/code-model.c

+// RUN: %clang -### -c -mcmodel=tiny %s 2>&1 | FileCheck -check-prefix CHECK-TINY %s
 // RUN: %clang -### -c -mcmodel=small %s 2>&1 | FileCheck -check-prefix CHECK-SMALL %s
 // RUN: %clang -### -S -mcmodel=kernel %s 2>&1 | FileCheck -check-prefix CHECK-KERNEL %s
 // RUN: %clang -### -c -mcmodel=medium %s 2>&1 | FileCheck -check-prefix CHECK-MEDIUM %s
 // RUN: %clang -### -S -mcmodel=large %s 2>&1 | FileCheck -check-prefix CHECK-LARGE %s
 // RUN: not %clang -c -mcmodel=lager %s 2>&1 | FileCheck -check-prefix CHECK-INVALID %s
 
+// CHECK-TINY: "-mcode-model" "tiny"
 // CHECK-SMALL: "-mcode-model" "small"
 // CHECK-KERNEL: "-mcode-model" "kernel"
 // CHECK-MEDIUM: "-mcode-model" "medium"
 // CHECK-LARGE: "-mcode-model" "large"
 
 // CHECK-INVALID: error: invalid value 'lager' in '-mcode-model lager'