Add a /nopdb flag to disable PDB generation

This will be used in the sanitizer test suite, which wants to use DWARF
line tables.

At some point we should reconsider how LLD handles the long section
names required by DWARF debug sections.

llvm-svn: 298544

lld/COFF/Driver.cpp

@@ -896,6 +896,10 @@ void LinkerDriver::link(ArrayRef<const char *> ArgsArr) {
     sys::path::replace_extension(Config->PDBPath, ".pdb");
   }
 
+  // Disable PDB generation if the user requested it.
+  if (Args.hasArg(OPT_nopdb))
+    Config->PDBPath = "";
+
   // Set default image base if /base is not given.
   if (Config->ImageBase == uint64_t(-1))
     Config->ImageBase = getDefaultImageBase();

lld/COFF/Options.td

@@ -93,6 +93,7 @@ def help : F<"help">;
 def help_q : Flag<["/?", "-?"], "">, Alias<help>;
 
 // LLD extensions
+def nopdb : F<"nopdb">, HelpText<"Disable PDB generation for DWARF users">;
 def nosymtab : F<"nosymtab">;
 def msvclto : F<"msvclto">;
 

lld/test/COFF/nopdb.test

@@ -0,0 +1,14 @@
+# Check that /debug creates %t.pdb.
+# RUN: rm -f %t.pdb
+# RUN: lld-link /debug /entry:main /out:%t.exe %p/Inputs/ret42.obj
+# RUN: ls %t.pdb
+
+# Check that /debug /nopdb does not create %t.pdb.
+# RUN: rm -f %t.pdb
+# RUN: lld-link /debug /nopdb /entry:main /out:%t.exe %p/Inputs/ret42.obj
+# RUN: not ls %t.pdb
+
+# Check that /debug /nopdb /pdb:%t.pdb does not create %t.pdb.
+# RUN: rm -f %t.pdb
+# RUN: lld-link /debug /nopdb /pdb:%t.pdb /entry:main /out:%t.exe %p/Inputs/ret42.obj
+# RUN: not ls %t.pdb