[Bugpoint][NewPM] Pin bugpoint to legacy PM

Bugpoint has lots of assumptions and hacks around the legacy PM, put off migrating it to NPM until later.
Fixes tests under BugPoint under NPM.

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D87655

Author: aeubanks

llvm/test/BugPoint/unsymbolized.ll

@@ -3,7 +3,7 @@
 ; RUN: echo "print('args = ' + str(sys.argv))" >> %t.py
 ; RUN: echo "exit(1)" >> %t.py
 ; RUN: not bugpoint -load %llvmshlibdir/BugpointPasses%shlibext %s -output-prefix %t -bugpoint-crashcalls -opt-command=%python -opt-args %t.py | FileCheck %s
-; RUN: not --crash opt -load %llvmshlibdir/BugpointPasses%shlibext %s -bugpoint-crashcalls -disable-symbolication 2>&1 | FileCheck --check-prefix=CRASH %s
+; RUN: not --crash opt -enable-new-pm=0 -load %llvmshlibdir/BugpointPasses%shlibext %s -bugpoint-crashcalls -disable-symbolication 2>&1 | FileCheck --check-prefix=CRASH %s
 ; RUN: not bugpoint -load %llvmshlibdir/BugpointPasses%shlibext %s -output-prefix %t -bugpoint-crashcalls -opt-command=%t.non.existent.opt.binary -opt-args %t.py 2>&1 | FileCheck %s --check-prefix=BAD-OPT
 
 ; Test that bugpoint disables symbolication on the opt tool to reduce runtime overhead when opt crashes

llvm/tools/bugpoint/OptimizerDriver.cpp

@@ -205,6 +205,9 @@ bool BugDriver::runPasses(Module &Program,
 
   for (unsigned i = 0, e = OptArgs.size(); i != e; ++i)
     Args.push_back(OptArgs[i]);
+  // Pin to legacy PM since bugpoint has lots of infra and hacks revolving
+  // around the legacy PM.
+  Args.push_back("-enable-new-pm=0");
   Args.push_back("-disable-symbolication");
   Args.push_back("-o");
   Args.push_back(OutputFilename);