Fix dsymutil to handle universal files that exceed 4GB.

[clayborg]

Summary

This fixes a bug where if a unviversal mach-o file exceeded 4GB, dsymutil would return an error even if each slice was under 4GB in size, but the total universal file size exceeded 4GB.

[wallace]

Lgtm

llvm/tools/dsymutil/dsymutil.cpp

747

You can merge this if and the next one to reduce the indentation

[clayborg]

We are not sure if this is the way we want to fix this, the alternate fix is in https://reviews.llvm.org/D121398

[clayborg]

Jonas, let me know if you want to me check this in by accepting it or not vs the other patch. If we want this code then great, else we could remove this code as part of https://reviews.llvm.org/D121398

[JDevlieghere]

I prefer the way the other patch deals with non-fat Mach-O files. For fat binaries, we should iterate over the temp files and calculate the sum of the size and error out unless the final slice has an offset < UINT32_MAX. For example, having 3 architectures that are 1.5GB each is fine because the last slice starts at 3GB even though the final binary will be 4.5GB, but having 4 slices won't work.

[clayborg]

In D121396#3373462, @JDevlieghere wrote:

I prefer the way the other patch deals with non-fat Mach-O files. For fat binaries, we should iterate over the temp files and calculate the sum of the size and error out unless the final slice has an offset < UINT32_MAX. For example, having 3 architectures that are 1.5GB each is fine because the last slice starts at 3GB even though the final binary will be 4.5GB, but having 4 slices won't work.

So this code needs to be removed then right as part of the other patch?

[clayborg]

Abandoning in favor of https://reviews.llvm.org/D121398

llvm/tools/dsymutil/dsymutil.cpp

for (auto &InputFile : Options.InputFiles) {
     if (!AllOK)
       return EXIT_FAILURE;
 
     if (NeedsTempFiles) {
       if (!MachOUtils::generateUniversalBinary(TempFiles,
                                                OutputLocationOrErr->DWARFFile,
                                                Options.LinkOpts, SDKPath))
         return EXIT_FAILURE;
-    }
+    } else {
+      // Only check the size of a skinny mach-o file. If we use temp files then
+      // we have multiple architectures and the "lipo" command will fail to
+      // produce a valid universal file if any file is over 4GB in size.
 
-    // The Mach-O object file format is limited to 4GB. Make sure that we print
-    // an error when we emit an invalid Mach-O companion file. Leave the
+      // The Mach-O object file format is limited to 4GB. Make sure that we
+      // print an error when we emit an invalid Mach-O companion file. Leave the
       // invalid object file around on disk for inspection.
       ErrorOr<vfs::Status> stat =
           Options.LinkOpts.VFS->status(OutputLocationOrErr->DWARFFile);
       if (stat) {
         if (stat->getSize() > std::numeric_limits<uint32_t>::max()) {
           WithColor::error() << "the linked debug info exceeds the 4GB Mach-O "
                                 "object file format.";
           return EXIT_FAILURE;
         }
       }
     }
+  }
 
   return EXIT_SUCCESS;
 }