[PATCH] D60452: Add argument name mangling to llvm-mc-assemble-fuzzer

[Brandon Jones via Phabricator via llvm-commits]

BrandonTJones created this revision.
BrandonTJones added reviewers: andreadb, grosbach.
Herald added a subscriber: mgorny.
Herald added a project: LLVM.

This is one of the only fuzzers that has an untraditional command line in context of argument parsing. A part of this is the number of different arguments llvm-mc itself can take. To help make this binary OSS-Fuzz compatible I have added -mtarget name mangling to this binary.


Repository:
  rL LLVM

https://reviews.llvm.org/D60452

Files:
  llvm/tools/llvm-mc-assemble-fuzzer/CMakeLists.txt
  llvm/tools/llvm-mc-assemble-fuzzer/llvm-mc-assemble-fuzzer.cpp


Index: llvm/tools/llvm-mc-assemble-fuzzer/llvm-mc-assemble-fuzzer.cpp
===================================================================
--- llvm/tools/llvm-mc-assemble-fuzzer/llvm-mc-assemble-fuzzer.cpp
+++ llvm/tools/llvm-mc-assemble-fuzzer/llvm-mc-assemble-fuzzer.cpp
@@ -8,6 +8,8 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/FuzzMutate/FuzzerCLI.h"
+#include "llvm/FuzzMutate/IRMutator.h"
 #include "llvm-c/Target.h"
 #include "llvm/MC/SubtargetFeature.h"
 #include "llvm/MC/MCAsmBackend.h"
@@ -36,6 +38,10 @@
 
 using namespace llvm;
 
+// This is used for overriding target triple through name mangling in the binary name.
+static cl::opt<std::string>
+    TargetTripleStr("mtriple", cl::desc("Override target triple for module"));
+
 static cl::opt<std::string>
     TripleName("triple", cl::desc("Target triple to assemble for, "
                                   "see -version for available targets"));
@@ -55,6 +61,7 @@
     MAttrs("mattr", cl::CommaSeparated,
            cl::desc("Target specific attributes (-mattr=help for details)"),
            cl::value_desc("a1,+a2,-a3,..."));
+
 // The feature string derived from -mattr's values.
 std::string FeaturesStr;
 
@@ -62,6 +69,7 @@
     FuzzerArgs("fuzzer-args", cl::Positional,
                cl::desc("Options to pass to the fuzzer"), cl::ZeroOrMore,
                cl::PositionalEatsArgs);
+
 static std::vector<char *> ModifiedArgv;
 
 enum OutputFileType {
@@ -250,9 +258,12 @@
 extern "C" LLVM_ATTRIBUTE_USED int LLVMFuzzerInitialize(int *argc,
                                                         char ***argv) {
   // The command line is unusual compared to other fuzzers due to the need to
-  // specify the target. Options like -triple, -mcpu, and -mattr work like
-  // their counterparts in llvm-mc, while -fuzzer-args collects options for the
-  // fuzzer itself.
+  // specify more than just the target. Options like -triple, -mcpu,
+  // and -mattr work like their counterparts in llvm-mc, while -fuzzer-args
+  // collects options for the fuzzer itself.
+  // Like other fuzzers though, you may mangle the target argument into
+  // file name of the binary itself. If you do this it will override the
+  // -triple argument.
   //
   // Examples:
   //
@@ -278,6 +289,10 @@
   LLVMInitializeAllTargetMCs();
   LLVMInitializeAllAsmParsers();
 
+  // Parse any arguments mangled into the file name.
+  llvm::handleExecNameEncodedOptimizerOpts(*argv[0]);
+  parseFuzzerCLOpts(*argc, *argv);
+
   cl::ParseCommandLineOptions(*argc, OriginalArgv);
 
   // Rebuild the argv without the arguments llvm-mc-fuzzer consumed so that
@@ -306,8 +321,14 @@
     FeaturesStr = Features.getString();
   }
 
-  if (TripleName.empty())
+  // If the binary name has a target triple mangled into it, overwride the triple
+  // argument with it.
+  if (!TargetTripleStr.empty()){
+    TripleName.setValue(TargetTripleStr.getValue());
+  }
+  else if (TripleName.empty()){
     TripleName = sys::getDefaultTargetTriple();
+  }
 
   return 0;
 }
Index: llvm/tools/llvm-mc-assemble-fuzzer/CMakeLists.txt
===================================================================
--- llvm/tools/llvm-mc-assemble-fuzzer/CMakeLists.txt
+++ llvm/tools/llvm-mc-assemble-fuzzer/CMakeLists.txt
@@ -6,6 +6,7 @@
     MC
     MCParser
     Support
+    FuzzMutate
 )
 add_llvm_fuzzer(llvm-mc-assemble-fuzzer
   llvm-mc-assemble-fuzzer.cpp


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