Support missing DWARF opcodes (#679)

Experimental support of extra DWARF operations

As this functionality is not documented by any formal SPIR-V extension or SPIR-V
extended instruction set specification, it is disabled by default and in order
to enable generation of extra debug information, user needs to pass
`spirv-allow-extra-diexpressions` command line option to the
translator.

Signed-off-by: Andrew Savonichev <andrew.savonichev@intel.com>

Author: Andrew Savonichev

llvm-spirv/include/LLVMSPIRVOpts.h

@@ -148,6 +148,14 @@ class TranslatorOpts {
     SPIRVAllowUnknownIntrinsics = AllowUnknownIntrinsics;
   }
 
+  bool allowExtraDIExpressions() const noexcept {
+    return AllowExtraDIExpressions;
+  }
+
+  void setAllowExtraDIExpressionsEnabled(bool Allow) noexcept {
+    AllowExtraDIExpressions = Allow;
+  }
+
   DebugInfoEIS getDebugInfoEIS() const { return DebugInfoVersion; }
 
   void setDebugInfoEIS(DebugInfoEIS EIS) { DebugInfoVersion = EIS; }
@@ -179,6 +187,10 @@ class TranslatorOpts {
   // SPIR-V
   bool SPIRVAllowUnknownIntrinsics = false;
 
+  // Enable support for extra DIExpression opcodes not listed in the SPIR-V
+  // DebugInfo specification.
+  bool AllowExtraDIExpressions = false;
+
   DebugInfoEIS DebugInfoVersion = DebugInfoEIS::OpenCL_DebugInfo_100;
 };
 

llvm-spirv/lib/SPIRV/LLVMToSPIRVDbgTran.cpp

@@ -959,10 +959,14 @@ SPIRVEntry *LLVMToSPIRVDbgTran::transDbgExpression(const DIExpression *Expr) {
   for (unsigned I = 0, N = Expr->getNumElements(); I < N; ++I) {
     using namespace SPIRVDebug::Operand::Operation;
     auto DWARFOpCode = static_cast<dwarf::LocationAtom>(Expr->getElement(I));
+
     SPIRVDebug::ExpressionOpCode OC =
         SPIRV::DbgExpressionOpCodeMap::map(DWARFOpCode);
-    assert(OpCountMap.find(OC) != OpCountMap.end() &&
-           "unhandled opcode found in DIExpression");
+    if (OpCountMap.find(OC) == OpCountMap.end())
+      report_fatal_error("unknown opcode found in DIExpression");
+    if (OC > SPIRVDebug::Fragment && !BM->allowExtraDIExpressions())
+      report_fatal_error("unsupported opcode found in DIExpression");
+
     unsigned OpCount = OpCountMap[OC];
     SPIRVWordVec Op(OpCount);
     Op[OpCodeIdx] = OC;