Make llvm-as --help great again

[serge-sans-paille]

Summary

This is a follow-up to https://reviews.llvm.org/D60411, but for llvm-as.

New output:

OVERVIEW: llvm .ll -> .bc assembler

USAGE: llvm-as [options] <input .llvm file>

OPTIONS:

Generic Options:

  -help                        - Display available options (-help-hidden for more)
  -help-list                   - Display list of available options (-help-list-hidden for more)
  -version                     - Display the version of this program

llvm-as Options:

  -data-layout=<layout-string> - data layout string to use
  -disable-output              - Disable output
  -f                           - Enable binary output on terminals
  -module-hash                 - Emit module hash
  -o=<filename>                - Override output filename

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Without category filtered:

OVERVIEW: llvm .ll -> .bc assembler

USAGE: llvm-as [options] <input .llvm file>

OPTIONS:

Color Options:

  -color                            - Use colors in output (default=autodetect)

General options:

  -cost-kind=<value>                - Target cost kind
    =throughput                     -   Reciprocal throughput
    =latency                        -   Instruction latency
    =code-size                      -   Code size
  -safepoint-ir-verifier-print-only - 
  -verify-region-info               - Verify region info (time consuming)

Generic Options:

  -help                             - Display available options (-help-hidden for more)
  -help-list                        - Display list of available options (-help-list-hidden for more)
  -version                          - Display the version of this program

llvm-as Options:

  -data-layout=<layout-string>      - data layout string to use
  -disable-output                   - Disable output
  -f                                - Enable binary output on terminals
  -module-hash                      - Emit module hash
  -o=<filename>                     - Override output filename

[serge-sans-paille]

Including test case

[jhenderson]

I don't really know much about llvm-as. Are all the filtered-out options irrelevant? In particular -color seems like it might be relevant.

[serge-sans-paille]

@jhenderson I've added a few potential reviewers based on the file history.

[serge-sans-paille]

Up!

[serge-sans-paille]

@jhenderson , @ddunbar : I've checked the callgraph of llvm-as, and none of theses flags are actually reachable:

Color Options:

  -color                            - Use colors in output (default=autodetect)

General options:

  -cost-kind=<value>                - Target cost kind
    =throughput                     -   Reciprocal throughput
    =latency                        -   Instruction latency
    =code-size                      -   Code size
  -safepoint-ir-verifier-print-only - 
  -verify-region-info               - Verify region info (time consuming)

[jhenderson]

Great! LGTM.

llvm/trunk/test/tools/llvm-as/help.test

+RUN: llvm-as --help 2>&1 | FileCheck --implicit-check-not="General Options:" %s
+CHECK: Generic Options:
+CHECK: llvm-as Options:

llvm/trunk/test/tools/llvm-as/lit.local.cfg

+if not 'X86' in config.root.targets:
+    config.unsupported = True
+
+config.suffixes = ['.ll', '.s', '.test', '.yaml']

llvm/trunk/tools/llvm-as/llvm-as.cpp

 #include "llvm/Support/InitLLVM.h"
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/SystemUtils.h"
 #include "llvm/Support/ToolOutputFile.h"
 #include <memory>
 using namespace llvm;
 
+cl::OptionCategory AsCat("llvm-as Options");
+
 static cl::opt<std::string> InputFilename(cl::Positional,
                                           cl::desc("<input .llvm file>"),
                                           cl::init("-"));
 
 static cl::opt<std::string> OutputFilename("o",
                                            cl::desc("Override output filename"),
-                                           cl::value_desc("filename"));
+                                           cl::value_desc("filename"),
+                                           cl::cat(AsCat));
 
-static cl::opt<bool> Force("f", cl::desc("Enable binary output on terminals"));
+static cl::opt<bool> Force("f", cl::desc("Enable binary output on terminals"),
+                           cl::cat(AsCat));
 
 static cl::opt<bool> DisableOutput("disable-output", cl::desc("Disable output"),
-                                   cl::init(false));
+                                   cl::init(false), cl::cat(AsCat));
 
 static cl::opt<bool> EmitModuleHash("module-hash", cl::desc("Emit module hash"),
-                                    cl::init(false));
+                                    cl::init(false), cl::cat(AsCat));
 
 static cl::opt<bool> DumpAsm("d", cl::desc("Print assembly as parsed"),
-                             cl::Hidden);
+                             cl::Hidden, cl::cat(AsCat));
 
 static cl::opt<bool>
     DisableVerify("disable-verify", cl::Hidden,
-                  cl::desc("Do not run verifier on input LLVM (dangerous!)"));
+                  cl::desc("Do not run verifier on input LLVM (dangerous!)"),
+                  cl::cat(AsCat));
 
 static cl::opt<bool> PreserveBitcodeUseListOrder(
     "preserve-bc-uselistorder",
     cl::desc("Preserve use-list order when writing LLVM bitcode."),
-    cl::init(true), cl::Hidden);
+    cl::init(true), cl::Hidden, cl::cat(AsCat));
 
 static cl::opt<std::string> ClDataLayout("data-layout",
                                          cl::desc("data layout string to use"),
                                          cl::value_desc("layout-string"),
-                                         cl::init(""));
+                                         cl::init(""), cl::cat(AsCat));
 
 static void WriteOutputFile(const Module *M, const ModuleSummaryIndex *Index) {
   // Infer the output filename if needed.
   if (OutputFilename.empty()) {
     if (InputFilename == "-") {
       OutputFilename = "-";
     } else {
       StringRef IFN = InputFilename;
static void WriteOutputFile(const Module *M, const ModuleSummaryIndex *Index) {
 
   // Declare success.
   Out->keep();
 }
 
 int main(int argc, char **argv) {
   InitLLVM X(argc, argv);
   LLVMContext Context;
+  cl::HideUnrelatedOptions(AsCat);
   cl::ParseCommandLineOptions(argc, argv, "llvm .ll -> .bc assembler\n");
 
   // Parse the file now...
   SMDiagnostic Err;
   auto ModuleAndIndex = parseAssemblyFileWithIndex(
       InputFilename, Err, Context, nullptr, !DisableVerify, ClDataLayout);
   std::unique_ptr<Module> M = std::move(ModuleAndIndex.Mod);
   if (!M.get()) {