Debugger: Implement new expression operands.

DWARF4 adds two new expression operands for values that are known, but
not located anywhere in memory (e.g. a known constant or a value computed
from a composite of other values/locations in the program). These are
DW_OP_implicit_value, which supplies the value directly as an LEB128 +
data block, and DW_OP_stack_value, which indicates the top of the
expression stack is the value.

Implements corresponding support in DwarfExpressionEvaluator,
ValueLocation and ValueLoader.

src/apps/debugger/dwarf/Dwarf.h

@@ -306,6 +306,8 @@ enum {
 	DW_OP_form_tls_address		= 0x9b,
 	DW_OP_call_frame_cfa		= 0x9c,
 	DW_OP_bit_piece				= 0x9d,
+	DW_OP_implicit_value		= 0x9e,
+	DW_OP_stack_value			= 0x9f,
 	DW_OP_lo_user				= 0xe0,
 	DW_OP_hi_user				= 0xff
 };

src/apps/debugger/dwarf/DwarfExpressionEvaluator.cpp

@@ -1,5 +1,6 @@
 /*
  * Copyright 2009-2012, Ingo Weinhold, [email protected].
+ * Copyright 2013, Rene Gollent, [email protected].
  * Distributed under the terms of the MIT License.
  */
 
@@ -631,6 +632,36 @@ DwarfExpressionEvaluator::_Evaluate(ValuePieceLocation* _piece)
 				TRACE_EXPR("  DW_OP_nop\n");
 				break;
 
+			case DW_OP_implicit_value:
+			{
+				TRACE_EXPR("  DW_OP_implicit_value\n");
+				if (_piece == NULL) {
+					throw EvaluationException(
+						"DW_OP_implicit_value in non-location expression");
+				}
+				uint32 length = fDataReader.ReadUnsignedLEB128(0);
+				if (length == 0)
+					return B_BAD_DATA;
+
+				if (fDataReader.BytesRemaining() < length)
+					return B_BAD_DATA;
+
+				_piece->SetToValue(fDataReader.Data(), length);
+				return B_OK;
+			}
+			case DW_OP_stack_value:
+			{
+				TRACE_EXPR("  DW_OP_stack_value\n");
+				if (_piece == NULL) {
+					throw EvaluationException(
+						"DW_OP_stack_value in non-location expression");
+				}
+				if (fStackSize == 0)
+					return B_BAD_DATA;
+				target_addr_t value = _Pop();
+				_piece->SetToValue(&value, sizeof(target_addr_t));
+				return B_OK;
+			}
 			default:
 				if (opcode >= DW_OP_lit0 && opcode <= DW_OP_lit31) {
 					TRACE_EXPR("  DW_OP_lit%u\n", opcode - DW_OP_lit0);

src/apps/debugger/types/ValueLocation.cpp

@@ -1,5 +1,6 @@
 /*
  * Copyright 2009-2012, Ingo Weinhold, ingo_weinhold@gmx.de.
+ * Copyright 2013, Rene Gollent, rene@gollent.com.
  * Distributed under the terms of the MIT License.
  */
 
@@ -258,6 +259,11 @@ ValueLocation::Dump() const
 			case VALUE_PIECE_LOCATION_REGISTER:
 				printf("  register %" B_PRIu32, piece.reg);
 				break;
+			case VALUE_PIECE_LOCATION_IMPLICIT:
+				printf("  implicit value: ");
+				for (uint32 j = 0; j < piece.size; j++)
+					printf("%x ", ((char *)piece.value)[j]);
+				break;
 		}
 
 		printf(" size: %" B_PRIu64 " (%" B_PRIu64 " bits), offset: %" B_PRIu64

src/apps/debugger/types/ValueLocation.h

@@ -1,5 +1,6 @@
 /*
  * Copyright 2009-2012, Ingo Weinhold, ingo_weinhold@gmx.de.
+ * Copyright 2013, Rene Gollent, rene@gollent.com.
  * Distributed under the terms of the MIT License.
  */
 #ifndef VALUE_LOCATION_H
@@ -16,7 +17,8 @@ enum value_piece_location_type {
 	VALUE_PIECE_LOCATION_INVALID,	// structure is invalid
 	VALUE_PIECE_LOCATION_UNKNOWN,	// location unknown, but size is valid
 	VALUE_PIECE_LOCATION_MEMORY,	// piece is in memory
-	VALUE_PIECE_LOCATION_REGISTER	// piece is in a register
+	VALUE_PIECE_LOCATION_REGISTER,	// piece is in a register
+	VALUE_PIECE_LOCATION_IMPLICIT	// value isn't stored anywhere in memory but is known
 };
 
 
@@ -31,13 +33,22 @@ struct ValuePieceLocation {
 	uint64						bitOffset;	// bit offset (to the most
 											// significant bit)
 	value_piece_location_type	type;
+	void*						value;		// used for storing implicit values
+
 
 	ValuePieceLocation()
 		:
-		type(VALUE_PIECE_LOCATION_INVALID)
+		type(VALUE_PIECE_LOCATION_INVALID),
+		value(NULL)
 	{
 	}
 
+	~ValuePieceLocation()
+	{
+		if (value != NULL)
+			free(value);
+	}
+
 	bool IsValid() const
 	{
 		return type != VALUE_PIECE_LOCATION_INVALID;
@@ -74,6 +85,18 @@ struct ValuePieceLocation {
 		this->bitOffset = bitOffset;
 	}
 
+	bool SetToValue(const void* data, target_size_t size)
+	{
+		char* valueData = (char*)malloc(size);
+		if (valueData == NULL)
+			return false;
+		memcpy(valueData, data, size);
+		SetSize(size);
+		type = VALUE_PIECE_LOCATION_IMPLICIT;
+		value = valueData;
+		return true;
+	}
+
 	ValuePieceLocation& Normalize(bool bigEndian);
 };
 

src/apps/debugger/value/ValueLoader.cpp

@@ -74,6 +74,7 @@ ValueLoader::LoadValue(ValueLocation* location, type_code valueType,
 				return B_ENTRY_NOT_FOUND;
 			case VALUE_PIECE_LOCATION_MEMORY:
 			case VALUE_PIECE_LOCATION_REGISTER:
+			case VALUE_PIECE_LOCATION_IMPLICIT:
 				break;
 		}
 
@@ -133,15 +134,29 @@ ValueLoader::LoadValue(ValueLocation* location, type_code valueType,
 			case VALUE_PIECE_LOCATION_UNKNOWN:
 				return B_ENTRY_NOT_FOUND;
 			case VALUE_PIECE_LOCATION_MEMORY:
+			case VALUE_PIECE_LOCATION_IMPLICIT:
 			{
 				target_addr_t address = piece.address;
 
-				TRACE_LOCALS("  piece %" B_PRId32 ": memory address: %#"
-					B_PRIx64 ", bits: %" B_PRIu32 "\n", i, address, bitSize);
+				if (piece.type == VALUE_PIECE_LOCATION_MEMORY) {
+					TRACE_LOCALS("  piece %" B_PRId32 ": memory address: %#"
+						B_PRIx64 ", bits: %" B_PRIu32 "\n", i, address,
+						bitSize);
+				} else {
+					TRACE_LOCALS("  piece %" B_PRId32 ": implicit value, "
+						"bits: %" B_PRIu32 "\n", i, bitSize);
+				}
 
 				uint8 pieceBuffer[kMaxPieceSize];
-				ssize_t bytesRead = fTeamMemory->ReadMemory(address,
-					pieceBuffer, bytesToRead);
+				ssize_t bytesRead;
+				if (piece.type == VALUE_PIECE_LOCATION_MEMORY) {
+					bytesRead = fTeamMemory->ReadMemory(address,
+						pieceBuffer, bytesToRead);
+				} else {
+					memcpy(pieceBuffer, piece.value, piece.size);
+					bytesRead = piece.size;
+				}
+
 				if (bytesRead < 0)
 					return bytesRead;
 				if ((uint32)bytesRead != bytesToRead)