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fix: incorrect error message in ASTree::BuildFromCode(...)
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* `opcode` was incorrectly clamped causing misleading output.

* modified output with additional info about offending bytecode and position so end-user submissions can become more informative.

* for `EXTENDED_ARG` bytecode the position will be off by a few bytes, but, at least the bytecode printed will be correct.
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@wilson0x4d
wilson0x4d committed Aug 14, 2024
1 parent dc6ca4a commit c650559
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Showing 3 changed files with 23 additions and 11 deletions.
9 changes: 5 additions & 4 deletions ASTree.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -85,6 +85,7 @@ PycRef<ASTNode> BuildFromCode(PycRef<PycCode> code, PycModule* mod)
PycRef<ASTBlock> curblock = defblock;
blocks.push(defblock);

unsigned char bytecode;
int opcode, operand;
int curpos = 0;
int pos = 0;
Expand All @@ -108,7 +109,7 @@ PycRef<ASTNode> BuildFromCode(PycRef<PycCode> code, PycModule* mod)
#endif

curpos = pos;
bc_next(source, mod, opcode, operand, pos);
bc_next(source, mod, bytecode, opcode, operand, pos);

if (need_try && opcode != Pyc::SETUP_EXCEPT_A) {
need_try = false;
Expand Down Expand Up @@ -1788,7 +1789,7 @@ PycRef<ASTNode> BuildFromCode(PycRef<PycCode> code, PycModule* mod)
curblock = blocks.top();
curblock->append(prev.cast<ASTNode>());

bc_next(source, mod, opcode, operand, pos);
bc_next(source, mod, bytecode, opcode, operand, pos);
}
}
break;
Expand All @@ -1811,7 +1812,7 @@ PycRef<ASTNode> BuildFromCode(PycRef<PycCode> code, PycModule* mod)
curblock = blocks.top();
curblock->append(prev.cast<ASTNode>());

bc_next(source, mod, opcode, operand, pos);
bc_next(source, mod, bytecode, opcode, operand, pos);
}
}
break;
Expand Down Expand Up @@ -2474,7 +2475,7 @@ PycRef<ASTNode> BuildFromCode(PycRef<PycCode> code, PycModule* mod)
}
break;
default:
fprintf(stderr, "Unsupported opcode: %s\n", Pyc::OpcodeName(opcode & 0xFF));
fprintf(stderr, "Unsupported opcode: %s (bytecode=%02Xh) at position %d.\n", Pyc::OpcodeName(opcode), bytecode, curpos);
cleanBuild = false;
return new ASTNodeList(defblock->nodes());
}
Expand Down
23 changes: 17 additions & 6 deletions bytecode.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -276,14 +276,16 @@ void print_const(std::ostream& pyc_output, PycRef<PycObject> obj, PycModule* mod
}
}

void bc_next(PycBuffer& source, PycModule* mod, int& opcode, int& operand, int& pos)
void bc_next(PycBuffer& source, PycModule* mod, unsigned char& bytecode, int& opcode, int& operand, int& pos)
{
opcode = Pyc::ByteToOpcode(mod->majorVer(), mod->minorVer(), source.getByte());
bytecode = source.getByte();
opcode = Pyc::ByteToOpcode(mod->majorVer(), mod->minorVer(), bytecode);
if (mod->verCompare(3, 6) >= 0) {
operand = source.getByte();
pos += 2;
if (opcode == Pyc::EXTENDED_ARG_A) {
opcode = Pyc::ByteToOpcode(mod->majorVer(), mod->minorVer(), source.getByte());
bytecode = source.getByte();
opcode = Pyc::ByteToOpcode(mod->majorVer(), mod->minorVer(), bytecode);
operand = (operand << 8) | source.getByte();
pos += 2;
}
Expand All @@ -292,7 +294,8 @@ void bc_next(PycBuffer& source, PycModule* mod, int& opcode, int& operand, int&
pos += 1;
if (opcode == Pyc::EXTENDED_ARG_A) {
operand = source.get16() << 16;
opcode = Pyc::ByteToOpcode(mod->majorVer(), mod->minorVer(), source.getByte());
bytecode = source.getByte();
opcode = Pyc::ByteToOpcode(mod->majorVer(), mod->minorVer(), bytecode);
pos += 3;
}
if (opcode >= Pyc::PYC_HAVE_ARG) {
Expand Down Expand Up @@ -340,17 +343,25 @@ void bc_disasm(std::ostream& pyc_output, PycRef<PycCode> code, PycModule* mod,

PycBuffer source(code->code()->value(), code->code()->length());

unsigned char bytecode;
int opcode, operand;
int pos = 0;
while (!source.atEof()) {
int start_pos = pos;
bc_next(source, mod, opcode, operand, pos);
bc_next(source, mod, bytecode, opcode, operand, pos);
if (opcode == Pyc::CACHE && (flags & Pyc::DISASM_SHOW_CACHES) == 0)
continue;

for (int i=0; i<indent; i++)
pyc_output << " ";
formatted_print(pyc_output, "%-7d %-30s ", start_pos, Pyc::OpcodeName(opcode));

auto opcode_name = Pyc::OpcodeName(opcode);
if (opcode == Pyc::Opcode::PYC_INVALID_OPCODE) {
// attempt to generate a more informative output for anyone doing copy-pasta Issue creation
formatted_print(pyc_output, "%-7d %-30s (bytecode=%02Xh)", start_pos, opcode_name, bytecode);
} else {
formatted_print(pyc_output, "%-7d %-30s ", start_pos, opcode_name);
}

if (opcode >= Pyc::PYC_HAVE_ARG) {
switch (opcode) {
Expand Down
2 changes: 1 addition & 1 deletion bytecode.h
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Original file line number Diff line number Diff line change
Expand Up @@ -29,6 +29,6 @@ int ByteToOpcode(int maj, int min, int opcode);

void print_const(std::ostream& pyc_output, PycRef<PycObject> obj, PycModule* mod,
const char* parent_f_string_quote = nullptr);
void bc_next(PycBuffer& source, PycModule* mod, int& opcode, int& operand, int& pos);
void bc_next(PycBuffer& source, PycModule* mod, unsigned char& bytecode, int& opcode, int& operand, int& pos);
void bc_disasm(std::ostream& pyc_output, PycRef<PycCode> code, PycModule* mod,
int indent, unsigned flags);

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