[opt] Remove the ExternalFunctionsPassedConstants pass

[bjope]

Summary

This commit is removing the last pieces of AnalysisWrapper.cpp
(including the ExternalFunctionsPassedConstants pass, aka
print-externalfnconstants).

The pass only existed for the legacy PM, and it was not regression
tested. And since the pass did not force the use of the legacy pass
manager there was no simply way to run the pass nowadays, at least
not by using opt.

[nikic]

LGTM

llvm/docs/Passes.rst

 standard error in a human-readable form.
 
 ``-print-cfg-sccs``: Print SCCs of each function CFG
 ----------------------------------------------------
 
 This pass, only available in ``opt``, printsthe SCCs of each function CFG to
 standard error in a human-readable fom.
 
-``-print-externalfnconstants``: Print external fn callsites passed constants
-----------------------------------------------------------------------------
-
-This pass, only available in ``opt``, prints out call sites to external
-functions that are called with constant arguments.  This can be useful when
-looking for standard library functions we should constant fold or handle in
-alias analyses.
-
 ``-print-function``: Print function to stderr
 ---------------------------------------------
 
 The ``PrintFunctionPass`` class is designed to be pipelined with other
 ``FunctionPasses``, and prints out the functions of the module as they are
 processed.
 
 ``-print-module``: Print module to stderr

llvm/tools/opt/AnalysisWrappers.cpp

-//===- AnalysisWrappers.cpp - Wrappers around non-pass analyses -----------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-//
-// This file defines pass wrappers around LLVM analyses that don't make sense to
-// be passes.  It provides a nice standard pass interface to these classes so
-// that they can be printed out by analyze.
-//
-// These classes are separated out of analyze.cpp so that it is more clear which
-// code is the integral part of the analyze tool, and which part of the code is
-// just making it so more passes are available.
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/Analysis/CallGraph.h"
-#include "llvm/IR/Module.h"
-#include "llvm/Pass.h"
-#include "llvm/Support/raw_ostream.h"
-using namespace llvm;
-
-namespace {
-  /// ExternalFunctionsPassedConstants - This pass prints out call sites to
-  /// external functions that are called with constant arguments.  This can be
-  /// useful when looking for standard library functions we should constant fold
-  /// or handle in alias analyses.
-  struct ExternalFunctionsPassedConstants : public ModulePass {
-    static char ID; // Pass ID, replacement for typeid
-    ExternalFunctionsPassedConstants() : ModulePass(ID) {}
-    bool runOnModule(Module &M) override {
-      for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
-        if (!I->isDeclaration()) continue;
-
-        bool PrintedFn = false;
-        for (User *U : I->users()) {
-          Instruction *UI = dyn_cast<Instruction>(U);
-          if (!UI) continue;
-
-          CallBase *CB = dyn_cast<CallBase>(UI);
-          if (!CB)
-            continue;
-
-          for (auto AI = CB->arg_begin(), E = CB->arg_end(); AI != E; ++AI) {
-            if (!isa<Constant>(*AI)) continue;
-
-            if (!PrintedFn) {
-              errs() << "Function '" << I->getName() << "':\n";
-              PrintedFn = true;
-            }
-            errs() << *UI;
-            break;
-          }
-        }
-      }
-
-      return false;
-    }
-
-    void getAnalysisUsage(AnalysisUsage &AU) const override {
-      AU.setPreservesAll();
-    }
-  };
-}
-
-char ExternalFunctionsPassedConstants::ID = 0;
-static RegisterPass<ExternalFunctionsPassedConstants>
-  P1("print-externalfnconstants",
-     "Print external fn callsites passed constants");

llvm/tools/opt/CMakeLists.txt

set(LLVM_LINK_COMPONENTS
   Target
   TargetParser
   TransformUtils
   Vectorize
   Passes
   )
 
 add_llvm_tool(opt
-  AnalysisWrappers.cpp
   NewPMDriver.cpp
   opt.cpp
 
   DEPENDS
   intrinsics_gen
   SUPPORT_PLUGINS
   )
 export_executable_symbols_for_plugins(opt)

llvm/utils/gn/secondary/llvm/tools/opt/BUILD.gn

deps = [
     "//llvm/lib/Transforms/IPO",
     "//llvm/lib/Transforms/Instrumentation",
     "//llvm/lib/Transforms/ObjCARC",
     "//llvm/lib/Transforms/Scalar",
     "//llvm/lib/Transforms/Utils",
     "//llvm/lib/Transforms/Vectorize",
   ]
   sources = [
-    "AnalysisWrappers.cpp",
     "NewPMDriver.cpp",
     "opt.cpp",
   ]
 
   # Support plugins.
   # FIXME: Disable dead stripping once other binaries are dead-stripped.
   if (host_os != "mac" && host_os != "win") {
     # Corresponds to export_executable_symbols() in cmake.
     ldflags = [ "-rdynamic" ]
   }
 }