Support soft failure on DWP section overflow, producing a truncated but valid DWP(#71902)

When 'ContinueOnCuIndexOverflow' enables without this modification, the
forcibly generated '.dwp' won't be recognized by Debugger(gdb 10.1)
correctly.
<img width="657" alt="image"
src="https://github.com/llvm/llvm-project/assets/150100070/31732775-2548-453a-a47a-fa04c6d05fe9">
it looks like there's a problem with processing the dwarf header, which
makes debugging completely impossible. (unless the consumer walks the debug_info section to rebuild that column (if that's the only section that overflowed - if it's another section, there's no recovery))

**About patch:**
When llvm-dwp enables option '--continue-on-cu-index-overflow=soft-stop'
and recognizes the overflow problem , it will stop packing and generate
the '.dwp' file at once, discarding any DWO files that would not fit
within the 32 bit/4GB limits of the format.
<img width="625" alt="image"
src="https://github.com/llvm/llvm-project/assets/150100070/77d6be24-262b-4f4c-afc0-9a6c49e133c7">

1 files changed, 12 insertions, 3 deletions

diff --git a/llvm/tools/llvm-dwp/llvm-dwp.cpp b/llvm/tools/llvm-dwp/llvm-dwp.cpp
index f976298..5cd4c00 100644
--- a/llvm/tools/llvm-dwp/llvm-dwp.cpp
+++ b/llvm/tools/llvm-dwp/llvm-dwp.cpp
@@ -71,7 +71,7 @@ public:
 // Options
 static std::vector<std::string> ExecFilenames;
 static std::string OutputFilename;
-static bool ContinueOnCuIndexOverflow;
+static std::string ContinueOption;
 
 static Expected<SmallVector<std::string, 16>>
 getDWOFilenames(StringRef ExecFilename) {
@@ -125,6 +125,7 @@ int llvm_dwp_main(int argc, char **argv, const llvm::ToolContext &) {
   DwpOptTable Tbl;
   llvm::BumpPtrAllocator A;
   llvm::StringSaver Saver{A};
+  OnCuIndexOverflow OverflowOptValue = OnCuIndexOverflow::HardStop;
   opt::InputArgList Args =
       Tbl.parseArgs(argc, argv, OPT_UNKNOWN, Saver, [&](StringRef Msg) {
         llvm::errs() << Msg << '\n';
@@ -143,7 +144,15 @@ int llvm_dwp_main(int argc, char **argv, const llvm::ToolContext &) {
   }
 
   OutputFilename = Args.getLastArgValue(OPT_outputFileName, "");
-  ContinueOnCuIndexOverflow = Args.hasArg(OPT_continueOnCuIndexOverflow);
+  if (Args.hasArg(OPT_continueOnCuIndexOverflow)) {
+    ContinueOption =
+        Args.getLastArgValue(OPT_continueOnCuIndexOverflow, "continue");
+    if (ContinueOption == "soft-stop") {
+      OverflowOptValue = OnCuIndexOverflow::SoftStop;
+    } else {
+      OverflowOptValue = OnCuIndexOverflow::Continue;
+    }
+  }
 
   for (const llvm::opt::Arg *A : Args.filtered(OPT_execFileNames))
     ExecFilenames.emplace_back(A->getValue());
@@ -255,7 +264,7 @@ int llvm_dwp_main(int argc, char **argv, const llvm::ToolContext &) {
   if (!MS)
     return error("no object streamer for target " + TripleName, Context);
 
-  if (auto Err = write(*MS, DWOFilenames, ContinueOnCuIndexOverflow)) {
+  if (auto Err = write(*MS, DWOFilenames, OverflowOptValue)) {
     logAllUnhandledErrors(std::move(Err), WithColor::error());
     return 1;
   }