dsymutil: Only warn about clang module DWO id mismatches in verbose mode.

Until PR27449 (https://llvm.org/bugs/show_bug.cgi?id=27449) is fixed in
clang this warning is pointless, since ASTFileSignatures will change
randomly when a module is rebuilt.

rdar://problem/25610919

llvm-svn: 267427

llvm/test/tools/dsymutil/X86/mismatch.m

@@ -14,7 +14,7 @@
       -fdisable-module-hash mismatch.m -o /dev/null
 */
 
-// RUN: llvm-dsymutil -f -oso-prepend-path=%p/../Inputs/mismatch \
+// RUN: llvm-dsymutil --verbose -f -oso-prepend-path=%p/../Inputs/mismatch \
 // RUN:   -y %p/dummy-debug-map.map -o %t.bin 2>&1 | FileCheck %s
 
 @import mismatch;

llvm/tools/dsymutil/DwarfLinker.cpp

@@ -3340,7 +3340,10 @@ void DwarfLinker::loadClangModule(StringRef Filename, StringRef ModulePath,
                << " 1 compile unit.\n";
         exitDsymutil(1);
       }
-      if (getDwoId(*CUDie, *CU) != DwoId)
+      // FIXME: Until PR27449 (https://llvm.org/bugs/show_bug.cgi?id=27449) is
+      // fixed in clang, only warn about DWO_id mismatches in verbose mode.
+      // ASTFileSignatures will change randomly when a module is rebuilt.
+      if (Options.Verbose && (getDwoId(*CUDie, *CU) != DwoId))
         reportWarning(
             Twine("hash mismatch: this object file was built against a "
                   "different version of the module ") + Filename);