Error on bad copy propagation flag combo.

Diagnose passing both -enable-copy-propagation and
-disable-copy-propagation.

Author: nate-chandler

lib/Frontend/CompilerInvocation.cpp

@@ -1543,6 +1543,14 @@ static bool ParseSILArgs(SILOptions &Opts, ArgList &Args,
     }
   }
 
+  if (Args.hasArg(OPT_enable_copy_propagation) &&
+      Args.hasArg(OPT_disable_copy_propagation)) {
+    // Error if copy propagation is enabled and copy propagation is disabled.
+    Diags.diagnose(SourceLoc(), diag::error_invalid_arg_combination,
+                   "enable-copy-propagation", "disable-copy-propagation");
+    return true;
+  }
+
   Opts.EnableCopyPropagation |= Args.hasArg(OPT_enable_copy_propagation);
   Opts.DisableCopyPropagation |= Args.hasArg(OPT_disable_copy_propagation);
   Opts.EnableARCOptimizations &= !Args.hasArg(OPT_disable_arc_opts);

tools/sil-opt/SILOpt.cpp

@@ -524,6 +524,13 @@ int main(int argc, char **argv) {
   SILOpts.EnableSpeculativeDevirtualization = EnableSpeculativeDevirtualization;
   SILOpts.IgnoreAlwaysInline = IgnoreAlwaysInline;
   SILOpts.EnableOSSAModules = EnableOSSAModules;
+
+  if (EnableCopyPropagation && DisableCopyPropagation) {
+    fprintf(stderr, "Error! Cannot specify both -enable-copy-propagation "
+                    "and -disable-copy-propagation.");
+    exit(-1);
+  }
+
   SILOpts.EnableCopyPropagation = EnableCopyPropagation;
   SILOpts.DisableCopyPropagation = DisableCopyPropagation;