Revert "Revert r305164/5/7."

Restore the `-gz` option to the driver with some minor tweaks to handle
the additional case for `-Wa,--compress-debug-sections`.

This intends to make the compression of the debug information
controllable from the driver.  The following is the behaviour:

  -gz           enable compression (ambiguous for format, will default to zlib-gnu)
  -gz=none      disable compression
  -gz=zlib-gnu  enable compression (deprecated GNU style zlib compression)
  -gz=zlib      enable compression (zlib based compression)

Although -Wa,-compress-debug-sections works, it should be discouraged
when using the driver to invoke the assembler.  However, we permit the
assembler to accept the GNU as style argument --compress-debug-sections
to maintain compatibility.

Note, -gz/-gz= does *NOT* imply -g.  That is, you need to additionally
specific -g for debug information to be generated.

llvm-svn: 306115

1 files changed, 16 insertions, 3 deletions

diff --git a/clang/tools/driver/cc1as_main.cpp b/clang/tools/driver/cc1as_main.cpp
index 37c14f4a26e..2fc2b508ef2 100644
--- a/clang/tools/driver/cc1as_main.cpp
+++ b/clang/tools/driver/cc1as_main.cpp
@@ -202,9 +202,22 @@ bool AssemblerInvocation::CreateFromArgs(AssemblerInvocation &Opts,
   Opts.SaveTemporaryLabels = Args.hasArg(OPT_msave_temp_labels);
   // Any DebugInfoKind implies GenDwarfForAssembly.
   Opts.GenDwarfForAssembly = Args.hasArg(OPT_debug_info_kind_EQ);
-  // TODO: base this on -gz instead
-  if (Args.hasArg(OPT_compress_debug_sections))
-    Opts.CompressDebugSections = llvm::DebugCompressionType::GNU;
+
+  if (const Arg *A = Args.getLastArg(OPT_compress_debug_sections,
+                                     OPT_compress_debug_sections_EQ)) {
+    if (A->getOption().getID() == OPT_compress_debug_sections) {
+      // TODO: be more clever about the compression type auto-detection
+      Opts.CompressDebugSections = llvm::DebugCompressionType::GNU;
+    } else {
+      Opts.CompressDebugSections =
+          llvm::StringSwitch<llvm::DebugCompressionType>(A->getValue())
+              .Case("none", llvm::DebugCompressionType::None)
+              .Case("zlib", llvm::DebugCompressionType::Z)
+              .Case("zlib-gnu", llvm::DebugCompressionType::GNU)
+              .Default(llvm::DebugCompressionType::None);
+    }
+  }
+
   Opts.RelaxELFRelocations = Args.hasArg(OPT_mrelax_relocations);
   Opts.DwarfVersion = getLastArgIntValue(Args, OPT_dwarf_version_EQ, 2, Diags);
   Opts.DwarfDebugFlags = Args.getLastArgValue(OPT_dwarf_debug_flags);