DWARF:

- fix code only executed in debug builds
- fix evaluation of DW_OP_const1u/DW_OP_const1s not advancing pointer
- add support for local variables with location list via DW_FORM_sec_offset

3 files changed, 44 insertions, 35 deletions

diff --git a/src/dwarf2pdb.cpp b/src/dwarf2pdb.cpp
index 58cd936..0c8aa33 100644
--- a/src/dwarf2pdb.cpp
+++ b/src/dwarf2pdb.cpp
@@ -334,8 +334,9 @@ public:
 class CFACursor

 {

 public:

-	CFACursor(const CFIEntry& cfientry, unsigned long location)

-	: entry (cfientry)

+	CFACursor(const PEImage& image, const CFIEntry& cfientry, unsigned long location)

+	: img (image)

+	, entry (cfientry)

 	{

 		loc = location;

 		cfa = { Location::RegRel, DW_REG_CFA, 0 };

@@ -418,7 +419,7 @@ public:
 				attr.type = ExprLoc;

 				attr.expr.len = LEB128(ptr);

 				attr.expr.ptr = ptr;

-				cfa = decodeLocation(attr);

+				cfa = decodeLocation(img, attr);

 				ptr += attr.expr.len;

 				break;

 			}

@@ -457,7 +458,7 @@ public:
 				attr.type = Block;

 				attr.block.len = LEB128(ptr);

 				attr.block.ptr = ptr;

-				cfa = decodeLocation(attr); // TODO: push cfa on stack

+				cfa = decodeLocation(img, attr); // TODO: push cfa on stack

 				ptr += attr.expr.len;

 				break;

 			}

@@ -474,6 +475,7 @@ public:
 		return true;

 	}

 

+	const PEImage& img;

 	const CFIEntry& entry;

 	byte* beg;

 	byte* end;

@@ -498,12 +500,15 @@ Location findBestCFA(const PEImage& img, const CFIIndex* index, unsigned int pcl
 	CFICursor cursor(img);

 	cursor.ptr = fde_ptr;

 

-	assert(cursor.readNext(entry));

-	CFACursor cfa(entry, pclo);

-	while(cfa.processNext()) {}

-	cfa.setInstructions(entry.instructions, entry.instructions_length);

-	while(!cfa.beforeRestore() && cfa.processNext()) {}

-	return cfa.cfa;

+	if (cursor.readNext(entry))

+	{

+		CFACursor cfa(img, entry, pclo);

+		while (cfa.processNext()) {}

+		cfa.setInstructions(entry.instructions, entry.instructions_length);

+		while (!cfa.beforeRestore() && cfa.processNext()) {}

+		return cfa.cfa;

+	}

+	return ebp;

 }

 

 // Location list entry

@@ -522,15 +527,15 @@ public:
 class LOCCursor

 {

 public:

-	LOCCursor(const PEImage& img, DWARF_CompilationUnit* cu, unsigned long off)

-	: beg((byte*)img.debug_loc)

+	LOCCursor(const PEImage& image, unsigned long off)

+	: img (image)

 	, end((byte*)img.debug_loc + img.debug_loc_length)

-	, ptr(beg + off)

+	, ptr((byte*)img.debug_loc + off)

 	{

 		default_address_size = img.isX64() ? 8 : 4;

 	}

 

-	byte* beg;

+	const PEImage& img;

 	byte* end;

 	byte* ptr;

 	byte default_address_size;

@@ -548,16 +553,16 @@ public:
 		attr.type = Block;

 		attr.block.len = RD2(ptr);

 		attr.block.ptr = ptr;

-		entry.loc = decodeLocation(attr);

+		entry.loc = decodeLocation(img, attr);

 		ptr += attr.expr.len;

 		return true;

 	}

 };

 

-Location findBestFBLoc(const PEImage& img, DWARF_CompilationUnit* cu, unsigned long fblocoff)

+Location findBestFBLoc(const PEImage& img, unsigned long fblocoff)

 {

 	int regebp = img.isX64() ? 6 : 5;

-	LOCCursor cursor(img, cu, fblocoff);

+	LOCCursor cursor(img, fblocoff);

 	LOCEntry entry;

 	Location longest = { Location::RegRel, DW_REG_CFA, 0 };

 	unsigned long longest_range = 0;

@@ -738,9 +743,9 @@ bool CV2PDB::addDWARFProc(DWARF_InfoData& procid, DWARF_CompilationUnit* cu, DIE
 	addStackVar("local_var", 0x1001, 8);

 #endif

 

-	Location frameBase = decodeLocation(procid.frame_base, 0, DW_AT_frame_base);

+	Location frameBase = decodeLocation(img, procid.frame_base, 0, DW_AT_frame_base);

 	if (frameBase.is_abs()) // pointer into location list in .debug_loc? assume CFA

-		frameBase = findBestFBLoc(img, cu, frameBase.off);

+		frameBase = findBestFBLoc(img, frameBase.off);

 

     Location cfa = findBestCFA(img, cfi_index, procid.pclo, procid.pchi);

 

@@ -753,11 +758,12 @@ bool CV2PDB::addDWARFProc(DWARF_InfoData& procid, DWARF_CompilationUnit* cu, DIE
 		DIECursor prev = cursor;

 		while (cursor.readNext(id, true))

 		{

-			if (id.tag == DW_TAG_formal_parameter)

+			if (id.tag == DW_TAG_formal_parameter && id.name)

 			{

-				if (id.name && (id.location.type == ExprLoc || id.location.type == Block))

+				if (id.location.type == ExprLoc || id.location.type == Block || id.location.type == SecOffset)

 				{

-					Location loc = decodeLocation(id.location, &frameBase);

+					Location loc = id.location.type == SecOffset ? findBestFBLoc(img, id.location.sec_offset)

+					                                             : decodeLocation(img, id.location, &frameBase);

 					if (loc.is_regrel())

 						appendStackVar(id.name, getTypeByDWARFPtr(cu, id.type), loc, cfa);

 				}

@@ -827,7 +833,8 @@ bool CV2PDB::addDWARFProc(DWARF_InfoData& procid, DWARF_CompilationUnit* cu, DIE
 				{

 					if (id.name && (id.location.type == ExprLoc || id.location.type == Block))

 					{

-						Location loc = decodeLocation(id.location, &frameBase);

+						Location loc = id.location.type == SecOffset ? findBestFBLoc(img, id.location.sec_offset)

+						                                             : decodeLocation(img, id.location, &frameBase);

 						if (loc.is_regrel())

 							appendStackVar(id.name, getTypeByDWARFPtr(cu, id.type), loc, cfa);

 					}

@@ -888,7 +895,7 @@ int CV2PDB::addDWARFStructure(DWARF_InfoData& structid, DWARF_CompilationUnit* c
 				int off = 0;

 				if (!isunion)

 				{

-					Location loc = decodeLocation(id.member_location, 0, DW_AT_data_member_location);

+					Location loc = decodeLocation(img, id.member_location, 0, DW_AT_data_member_location);

 					if (loc.is_abs())

 					{

 						off = loc.off;

@@ -907,7 +914,7 @@ int CV2PDB::addDWARFStructure(DWARF_InfoData& structid, DWARF_CompilationUnit* c
 			else if(id.tag == DW_TAG_inheritance)

 			{

 				int off;

-				Location loc = decodeLocation(id.member_location, 0, DW_AT_data_member_location);

+				Location loc = decodeLocation(img, id.member_location, 0, DW_AT_data_member_location);

 				if (loc.is_abs())

 				{

 					cvid = S_CONSTANT_V2;

@@ -1510,7 +1517,7 @@ bool CV2PDB::createTypes()
 					}

 					else

 					{

-						Location loc = decodeLocation(id.location);

+						Location loc = decodeLocation(img, id.location);

 						if (loc.is_abs())

 						{

 							segOff = loc.off;

diff --git a/src/readDwarf.cpp b/src/readDwarf.cpp
index c91776c..6f5d04d 100644
--- a/src/readDwarf.cpp
+++ b/src/readDwarf.cpp
@@ -38,7 +38,7 @@ static Location mkRegRel(int reg, int off)
 	return l;

 }

 

-Location decodeLocation(const DWARF_Attribute& attr, const Location* frameBase, int at)

+Location decodeLocation(const PEImage& img, const DWARF_Attribute& attr, const Location* frameBase, int at)

 {

 	static Location invalid = { Location::Invalid };

 

@@ -47,8 +47,10 @@ Location decodeLocation(const DWARF_Attribute& attr, const Location* frameBase,
 

 	if (attr.type != ExprLoc && attr.type != Block) // same memory layout

 		return invalid;

+	

+	byte*p = attr.expr.ptr;

+	byte*end = attr.expr.ptr + attr.expr.len;

 

-	byte* p = attr.expr.ptr;

 	Location stack[256];

 	int stackDepth = 0;

     if (at == DW_AT_data_member_location)

@@ -56,7 +58,7 @@ Location decodeLocation(const DWARF_Attribute& attr, const Location* frameBase,
 

 	for (;;)

 	{

-		if (p >= attr.expr.ptr + attr.expr.len)

+		if (p >= end)

 			break;

 

 		int op = *p++;

@@ -79,10 +81,10 @@ Location decodeLocation(const DWARF_Attribute& attr, const Location* frameBase,
 				stack[stackDepth++] = mkInReg(LEB128(p));

 				break;

 

-			case DW_OP_const1u: stack[stackDepth++] = mkAbs(*p); break;

+			case DW_OP_const1u: stack[stackDepth++] = mkAbs(*p++); break;

 			case DW_OP_const2u: stack[stackDepth++] = mkAbs(RD2(p)); break;

 			case DW_OP_const4u: stack[stackDepth++] = mkAbs(RD4(p)); break;

-			case DW_OP_const1s: stack[stackDepth++] = mkAbs((char)*p); break;

+			case DW_OP_const1s: stack[stackDepth++] = mkAbs((char)*p++); break;

 			case DW_OP_const2s: stack[stackDepth++] = mkAbs((short)RD2(p)); break;

 			case DW_OP_const4s: stack[stackDepth++] = mkAbs((int)RD4(p)); break;

 			case DW_OP_constu:  stack[stackDepth++] = mkAbs(LEB128(p)); break;

diff --git a/src/readDwarf.h b/src/readDwarf.h
index a259e3c..532d1c2 100644
--- a/src/readDwarf.h
+++ b/src/readDwarf.h
@@ -349,12 +349,12 @@ struct Location
 	bool is_regrel() const { return type == RegRel; }

 };

 

-// Attemots to partially evaluate DWARF location expressions.

+class PEImage;

+

+// Attempts to partially evaluate DWARF location expressions.

 // The only supported expressions are those, whose result may be represented

 // as either an absolute value, a register, or a register-relative address.

-Location decodeLocation(const DWARF_Attribute& attr, const Location* frameBase = 0, int at = 0);

-

-class PEImage;

+Location decodeLocation(const PEImage& img, const DWARF_Attribute& attr, const Location* frameBase = 0, int at = 0);

 

 // Debug Information Entry Cursor

 class DIECursor