[PATCH] D105320: [CodeView] Skip emitting values bigger than supported by APInt.

[Matheus Izvekov via Phabricator via llvm-commits]

mizvekov created this revision.
Herald added subscribers: pengfei, hiraditya.
mizvekov requested review of this revision.
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This fixes an assert firing when compiling code such as:

  struct f {
    static __int128 g() { return e; }
    static const __int128 e = __int128(1) << 128;
  };
  void h() { f::g(); }

with `clang -cc1 -triple x86_64-w64-windows-gnu -emit-obj -gcodeview -debug-info-kind=limited t.cc`.

Which would trigger following assert:

  Assertion failed: getMinSignedBits() <= 64 && "Too many bits for int64_t", file llvm/include/llvm/ADT/APInt.h, line 1646

To get around this, we just stop emitting the Value attribute when
printing constant symbol records.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D105320

Files:
  llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
  llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h


Index: llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
===================================================================
--- llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
+++ llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
@@ -315,6 +315,8 @@
   void collectDebugInfoForGlobals();
   void emitDebugInfoForGlobals();
   void emitGlobalVariableList(ArrayRef<CVGlobalVariable> Globals);
+  void emitConstantSymbolRecord(const DIType *DTy, APSInt &Value,
+                                const std::string &QualifiedName);
   void emitDebugInfoForGlobal(const CVGlobalVariable &CVGV);
   void emitStaticConstMemberList();
 
Index: llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
===================================================================
--- llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -3157,6 +3157,30 @@
   }
 }
 
+void CodeViewDebug::emitConstantSymbolRecord(const DIType *DTy, APSInt &Value,
+                                             const std::string &QualifiedName) {
+  MCSymbol *SConstantEnd = beginSymbolRecord(SymbolKind::S_CONSTANT);
+  OS.AddComment("Type");
+  OS.emitInt32(getTypeIndex(DTy).getIndex());
+
+  // TODO: Need to support bigger ints like __int128.
+  if (Value.getNumWords() <= 1U) {
+    OS.AddComment("Value");
+
+    // Encoded integers shouldn't need more than 10 bytes.
+    uint8_t Data[10];
+    BinaryStreamWriter Writer(Data, llvm::support::endianness::little);
+    CodeViewRecordIO IO(Writer);
+    cantFail(IO.mapEncodedInteger(Value));
+    StringRef SRef((char *)Data, Writer.getOffset());
+    OS.emitBinaryData(SRef);
+  }
+
+  OS.AddComment("Name");
+  emitNullTerminatedSymbolName(OS, QualifiedName);
+  endSymbolRecord(SConstantEnd);
+}
+
 void CodeViewDebug::emitStaticConstMemberList() {
   for (const DIDerivedType *DTy : StaticConstMembers) {
     const DIScope *Scope = DTy->getScope();
@@ -3172,24 +3196,8 @@
     else
       llvm_unreachable("cannot emit a constant without a value");
 
-    std::string QualifiedName = getFullyQualifiedName(Scope, DTy->getName());
-
-    MCSymbol *SConstantEnd = beginSymbolRecord(SymbolKind::S_CONSTANT);
-    OS.AddComment("Type");
-    OS.emitInt32(getTypeIndex(DTy->getBaseType()).getIndex());
-    OS.AddComment("Value");
-
-    // Encoded integers shouldn't need more than 10 bytes.
-    uint8_t Data[10];
-    BinaryStreamWriter Writer(Data, llvm::support::endianness::little);
-    CodeViewRecordIO IO(Writer);
-    cantFail(IO.mapEncodedInteger(Value));
-    StringRef SRef((char *)Data, Writer.getOffset());
-    OS.emitBinaryData(SRef);
-
-    OS.AddComment("Name");
-    emitNullTerminatedSymbolName(OS, QualifiedName);
-    endSymbolRecord(SConstantEnd);
+    emitConstantSymbolRecord(DTy->getBaseType(), Value,
+                             getFullyQualifiedName(Scope, DTy->getName()));
   }
 }
 
@@ -3253,22 +3261,6 @@
                           ? true
                           : DebugHandlerBase::isUnsignedDIType(DIGV->getType());
     APSInt Value(APInt(/*BitWidth=*/64, DIE->getElement(1)), isUnsigned);
-
-    MCSymbol *SConstantEnd = beginSymbolRecord(SymbolKind::S_CONSTANT);
-    OS.AddComment("Type");
-    OS.emitInt32(getTypeIndex(DIGV->getType()).getIndex());
-    OS.AddComment("Value");
-
-    // Encoded integers shouldn't need more than 10 bytes.
-    uint8_t data[10];
-    BinaryStreamWriter Writer(data, llvm::support::endianness::little);
-    CodeViewRecordIO IO(Writer);
-    cantFail(IO.mapEncodedInteger(Value));
-    StringRef SRef((char *)data, Writer.getOffset());
-    OS.emitBinaryData(SRef);
-
-    OS.AddComment("Name");
-    emitNullTerminatedSymbolName(OS, QualifiedName);
-    endSymbolRecord(SConstantEnd);
+    emitConstantSymbolRecord(DIGV->getType(), Value, QualifiedName);
   }
 }


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