[DWARF] Fix undefined behaviour in dwarf type printer

[momo5502]

Summary

The value to be formatted here, Val, is an int64_t which can not be formatted using %x.
This commit adjusts all misuses I was able to find in the llvm-dwarfdump project.

Failing tests in https://reviews.llvm.org/D153800 lead to the discovery and analysis of this issue.

[efriedma]

LGTM

Longer term, we should consider what we can do to mitigate this sort of issue showing up again (adding a "format" attribute to llvm::format and/or switching more code over to other formatting functions like llvm::formatv).

llvm/lib/DebugInfo/DWARF/DWARFTypePrinter.cpp

431

Not really related to this change, but while you're here, can you drop the to_string calls? OS << llvm::format() should just work.

[momo5502]

Thank you for reviewing, and yes, I totally aggree. Preventing such issues from happening in the first place is would be better.
Will update this change tomorrow to drop the to_string calls.

Btw, before I forget it, for future commits of mine, can you please use the following details from now on: Maurice Heumann <[e-mail]>.

[momo5502]

Remove to_string usages

[dblaikie]

Thanks for the catch!

llvm/lib/DebugInfo/DWARF/DWARFTypePrinter.cpp

if (C.getTag() == dwarf::DW_TAG_template_value_parameter) {
         default:
           if ((Val & ~0xFFu) == ~0xFFu)
             Val &= 0xFFu;
           if (Val < 127 && Val >= 32) {
             OS << "'";
             OS << (char)Val;
             OS << "'";
           } else if (Val < 256)
-            OS << to_string(llvm::format("'\\x%02x'", Val));
+            OS << llvm::format("'\\x%02" PRIx64 "'", Val);
           else if (Val <= 0xFFFF)
-            OS << to_string(llvm::format("'\\u%04x'", Val));
+            OS << llvm::format("'\\u%04" PRIx64 "'", Val);
           else
-            OS << to_string(llvm::format("'\\U%08x'", Val));
+            OS << llvm::format("'\\U%08" PRIx64 "'", Val);
         }
       }
       continue;
     }
     if (C.getTag() == dwarf::DW_TAG_GNU_template_template_param) {
       const char *RawName =
           dwarf::toString(C.find(DW_AT_GNU_template_name), nullptr);
       assert(RawName);