Add cases for new dxc exeptions (#3691)

These shouldn't ever really get hit, but there is a chance that the
exception is thrown inside a block that returns the hresult and discards
the exception with its message. We'd rather preserve the message, but as
a last resort, these messages are better than nothing

tools/clang/tools/dxclib/dxc.cpp

@@ -1378,30 +1378,50 @@ int dxc::main(int argc, const char **argv_) {
       Unicode::acp_char printBuffer[128]; // printBuffer is safe to treat as
                                           // UTF-8 because we use ASCII only errors
       if (msg == nullptr || *msg == '\0') {
-        if (hlslException.hr == DXC_E_DUPLICATE_PART) {
+        switch (hlslException.hr) {
+        case DXC_E_DUPLICATE_PART:
           sprintf_s(
               printBuffer, _countof(printBuffer),
               "dxc failed : DXIL container already contains the given part.");
-        } else if (hlslException.hr == DXC_E_MISSING_PART) {
+          break;
+        case DXC_E_MISSING_PART:
           sprintf_s(
               printBuffer, _countof(printBuffer),
               "dxc failed : DXIL container does not contain the given part.");
-        } else if (hlslException.hr == DXC_E_CONTAINER_INVALID) {
+          break;
+        case DXC_E_CONTAINER_INVALID:
           sprintf_s(printBuffer, _countof(printBuffer),
                     "dxc failed : Invalid DXIL container.");
-        } else if (hlslException.hr == DXC_E_CONTAINER_MISSING_DXIL) {
+          break;
+        case DXC_E_CONTAINER_MISSING_DXIL:
           sprintf_s(printBuffer, _countof(printBuffer),
                     "dxc failed : DXIL container is missing DXIL part.");
-        } else if (hlslException.hr == DXC_E_CONTAINER_MISSING_DEBUG) {
+          break;
+        case DXC_E_CONTAINER_MISSING_DEBUG:
           sprintf_s(printBuffer, _countof(printBuffer),
                     "dxc failed : DXIL container is missing Debug Info part.");
-        } else if (hlslException.hr == E_OUTOFMEMORY) {
+          break;
+        case DXC_E_LLVM_FATAL_ERROR:
+          sprintf_s(printBuffer, _countof(printBuffer),
+                    "dxc failed : Internal Compiler Error - LLVM Fatal Error!");
+          break;
+        case DXC_E_LLVM_UNREACHABLE:
+          sprintf_s(printBuffer, _countof(printBuffer),
+                    "dxc failed : Internal Compiler Error - UNREACHABLE executed!");
+          break;
+        case DXC_E_LLVM_CAST_ERROR:
+          sprintf_s(printBuffer, _countof(printBuffer),
+                    "dxc failed : Internal Compiler Error - Cast of incompatible type!");
+          break;
+        case E_OUTOFMEMORY:
           sprintf_s(printBuffer, _countof(printBuffer),
                     "dxc failed : Out of Memory.");
-        } else if (hlslException.hr == E_INVALIDARG) {
+          break;
+        case E_INVALIDARG:
           sprintf_s(printBuffer, _countof(printBuffer),
                     "dxc failed : Invalid argument.");
-        } else {
+          break;
+        default:
           sprintf_s(printBuffer, _countof(printBuffer),
             "dxc failed : error code 0x%08x.\n", hlslException.hr);
         }