bugpoint: add flag -verbose-errors

The default behavior of bugpoint is to print "<crash>" when it finds a reduced
test that crashes compilation.  With this flag we now can see the output of the
crashing program.  This is useful to make sure it is the same error being
tracked down and not a different error that happens to crash the compiler as
well.

Differential Revision: https://reviews.llvm.org/D22411

llvm-svn: 275646

2 files changed, 15 insertions, 1 deletions

diff --git a/llvm/docs/CommandGuide/bugpoint.rst b/llvm/docs/CommandGuide/bugpoint.rst
index 2e6341de719..8c2a0d12498 100644
--- a/llvm/docs/CommandGuide/bugpoint.rst
+++ b/llvm/docs/CommandGuide/bugpoint.rst
@@ -176,6 +176,14 @@ OPTIONS
  **--safe-{int,jit,llc,custom}**
  option.
 
+**--verbose-errors**\ =\ *{true,false}*
+
+ The default behavior of bugpoint is to print "<crash>" when it finds a reduced
+ test that crashes compilation. This flag prints the output of the crashing
+ program to stderr. This is useful to make sure it is the same error being
+ tracked down and not a different error that happens to crash the compiler as
+ well. Defaults to false.
+
 EXIT STATUS
 -----------
 
diff --git a/llvm/tools/bugpoint/CrashDebugger.cpp b/llvm/tools/bugpoint/CrashDebugger.cpp
index 07fe0d7acbd..b25e6ecec19 100644
--- a/llvm/tools/bugpoint/CrashDebugger.cpp
+++ b/llvm/tools/bugpoint/CrashDebugger.cpp
@@ -54,6 +54,9 @@ namespace {
   cl::opt<bool> NoNamedMDRM("disable-namedmd-remove",
                             cl::desc("Do not remove global named metadata"),
                             cl::init(false));
+  cl::opt<bool> VerboseErrors("verbose-errors",
+                            cl::desc("Print the output of crashing program"),
+                            cl::init(false));
 }
 
 namespace llvm {
@@ -905,7 +908,10 @@ static bool TestForCodeGenCrash(const BugDriver &BD, Module *M) {
   std::string Error;
   BD.compileProgram(M, &Error);
   if (!Error.empty()) {
-    errs() << "<crash>\n";
+    if (VerboseErrors)
+      errs() << Error << "\n";
+    else
+      errs() << "<crash>\n";
     return true;  // Tool is still crashing.
   }
   errs() << '\n';