[llvm-isel-fuzzer] Use "--" as separator rather than '='.

[morehouse]

Summary

OSS-Fuzz doesn't support '=' in filenames.

[morehouse]

I tested this manually and it seems to work, but doing ninja check-llvm doesn't seem to run these test cases for me. Maybe my config uses rpath?

[kcc]

LGTM

llvm/docs/FuzzingLLVM.rst

 the following command would fuzz AArch64 with :doc:`GlobalISel`:
 
 .. code-block:: shell
 
    % bin/llvm-isel-fuzzer <corpus-dir> -ignore_remaining_args=1 -mtriple aarch64 -global-isel -O0
 
 Some flags can also be specified in the binary name itself in order to support
 OSS Fuzz, which has trouble with required arguments. To do this, you can copy
-or move ``llvm-isel-fuzzer`` to ``llvm-isel-fuzzer=x-y-z``, where x, y, and z
+or move ``llvm-isel-fuzzer`` to ``llvm-isel-fuzzer--x-y-z``, where x, y, and z
 are architecture names (``aarch64``, ``x86_64``), optimization levels (``O0``,
 ``O2``), or specific keywords like ``gisel`` for enabling global instruction
 selection.
 
 llvm-mc-assemble-fuzzer
 -----------------------
 
 A |generic fuzzer| that fuzzes the MC layer's assemblers by treating inputs as

llvm/include/llvm/FuzzMutate/FuzzerCLI.h

 /// Parse cl::opts from a fuzz target commandline.
 ///
 /// This handles all arguments after -ignore_remaining_args=1 as cl::opts.
 void parseFuzzerCLOpts(int ArgC, char *ArgV[]);
 
 /// Handle backend options that are encoded in the executable name.
 ///
 /// Parses some common backend options out of a specially crafted executable
-/// name (argv[0]). For example, a name like llvm-foo-fuzzer:aarch64-gisel might
-/// set up an AArch64 triple and the Global ISel selector. This should be called
-/// *before* parseFuzzerCLOpts if calling both.
+/// name (argv[0]). For example, a name like llvm-foo-fuzzer--aarch64-gisel
+/// might set up an AArch64 triple and the Global ISel selector. This should be
+/// called *before* parseFuzzerCLOpts if calling both.
 ///
 /// This is meant to be used for environments like OSS-Fuzz that aren't capable
 /// of passing in command line arguments in the normal way.
 void handleExecNameEncodedBEOpts(StringRef ExecName);
 
 using FuzzerTestFun = int (*)(const uint8_t *Data, size_t Size);
 using FuzzerInitFun = int (*)(int *argc, char ***argv);
 

llvm/lib/FuzzMutate/FuzzerCLI.cpp

while (I < ArgC)
     CLArgs.push_back(ArgV[I++]);
 
   cl::ParseCommandLineOptions(CLArgs.size(), CLArgs.data());
 }
 
 void llvm::handleExecNameEncodedBEOpts(StringRef ExecName) {
   std::vector<std::string> Args{ExecName};
 
-  auto NameAndArgs = ExecName.split('=');
+  auto NameAndArgs = ExecName.split("--");
   if (NameAndArgs.second.empty())
     return;
 
   SmallVector<StringRef, 4> Opts;
   NameAndArgs.second.split(Opts, '-');
   for (StringRef Opt : Opts) {
     if (Opt.equals("gisel")) {
       Args.push_back("-global-isel");

llvm/test/tools/llvm-isel-fuzzer/aarch64-execname-options.ll

 ; If the binary looks up libraries using an rpath, we can't test this
 ; without copying the whole lib dir or polluting the build dir.
 ; UNSUPPORTED: rpath_in_use
 
 ; REQUIRES: aarch64-registered-target
 
 ; RUN: echo > %t.input
 
-; RUN: cp llvm-isel-fuzzer %t.bin=aarch64
-; RUN: %t.bin=aarch64 %t.input 2>&1 | FileCheck -check-prefix=AARCH64 %s
+; RUN: cp llvm-isel-fuzzer %t.bin--aarch64
+; RUN: %t.bin--aarch64 %t.input 2>&1 | FileCheck -check-prefix=AARCH64 %s
 ; AARCH64: Injected args: -mtriple=aarch64
 
-; RUN: cp llvm-isel-fuzzer %t.bin=aarch64-O1
-; RUN: %t.bin=aarch64-O1 %t.input 2>&1 | FileCheck -check-prefix=OPT-AFTER %s
+; RUN: cp llvm-isel-fuzzer %t.bin--aarch64-O1
+; RUN: %t.bin--aarch64-O1 %t.input 2>&1 | FileCheck -check-prefix=OPT-AFTER %s
 ; OPT-AFTER: Injected args: -mtriple=aarch64 -O1
 
-; RUN: cp llvm-isel-fuzzer %t.bin=O3-aarch64
-; RUN: %t.bin=O3-aarch64 %t.input 2>&1 | FileCheck -check-prefix=OPT-BEFORE %s
+; RUN: cp llvm-isel-fuzzer %t.bin--O3-aarch64
+; RUN: %t.bin--O3-aarch64 %t.input 2>&1 | FileCheck -check-prefix=OPT-BEFORE %s
 ; OPT-BEFORE: Injected args: -O3 -mtriple=aarch64

llvm/test/tools/llvm-isel-fuzzer/execname-options.ll

 ; If the binary looks up libraries using an rpath, we can't test this
 ; without copying the whole lib dir or polluting the build dir.
 ; UNSUPPORTED: rpath_in_use
 
 ; RUN: echo > %t.input
 
-; RUN: cp llvm-isel-fuzzer %t.bin=gisel
-; RUN: not %t.bin=gisel %t.input 2>&1 | FileCheck -check-prefix=GISEL %s
+; RUN: cp llvm-isel-fuzzer %t.bin--gisel
+; RUN: not %t.bin--gisel %t.input 2>&1 | FileCheck -check-prefix=GISEL %s
 ; GISEL: Injected args: -global-isel -O0
 ; GISEL: -mtriple must be specified
 
-; RUN: cp llvm-isel-fuzzer %t.bin=gisel-O2
-; RUN: not %t.bin=gisel-O2 %t.input 2>&1 | FileCheck -check-prefix=GISEL-O2 %s
+; RUN: cp llvm-isel-fuzzer %t.bin--gisel-O2
+; RUN: not %t.bin--gisel-O2 %t.input 2>&1 | FileCheck -check-prefix=GISEL-O2 %s
 ; GISEL-O2: Injected args: -global-isel -O0 -O2
 ; GISEL-O2: -mtriple must be specified
 
-; RUN: cp llvm-isel-fuzzer %t.bin=unexist
-; RUN: not %t.bin=unexist %t.input 2>&1 | FileCheck -check-prefix=NO-OPT %s
+; RUN: cp llvm-isel-fuzzer %t.bin--unexist
+; RUN: not %t.bin--unexist %t.input 2>&1 | FileCheck -check-prefix=NO-OPT %s
 ; NO-OPT: Unknown option: