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dwarf-reader: Support DW_OP_GNU_variable_value

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This solves a crash that happened with self-comparing the package
'aws' in Fedora by doing:

    $ fedabipkgdiff  --self-compare -a --from fc37 aws

When evaluating a DWARF expression with
eval_last_constant_dwarf_sub_expr, indirectly called from
die_member_offset, the DW_OP_GNU_variable_value appears not being
supported.

This patch adds the support for that.

To help with figuring that kind of issue in the future, I
have added a few asserts in the code of op_is_arith_logic.

	* src/abg-dwarf-reader.cc (op_pushes_non_constant_value): Support
	DW_OP_GNU_variable_value.
	(op_is_arith_logic): Add a number of asserts and guards here.

Signed-off-by: Dodji Seketeli <dodji@redhat.com>
This commit is contained in:
Dodji Seketeli 2023-04-05 14:03:06 +02:00
parent eb272db9dc
commit 97d5ae80c0
1 changed files with 39 additions and 5 deletions
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38
src/abg-dwarf-reader.cc
View File

@ -7952,6 +7952,10 @@ op_pushes_non_constant_value(Dwarf_Op* ops,
next_index = index + 1;
break;
case DW_OP_GNU_variable_value:
next_index = index + 1;
break;
default:
return false;
}
@ -8119,13 +8123,16 @@ op_is_arith_logic(Dwarf_Op* expr,
Dwarf_Op& op = expr[index];
expr_result val1, val2;
bool result = false;
switch (op.atom)
{
case DW_OP_abs:
ABG_ASSERT(ctxt.stack.size() > 0);
val1 = ctxt.pop();
val1 = val1.abs();
ctxt.push(val1);
result = true;
break;
case DW_OP_and:
@ -8136,87 +8143,114 @@ op_is_arith_logic(Dwarf_Op* expr,
break;
case DW_OP_div:
ABG_ASSERT(ctxt.stack.size() > 1);
val1 = ctxt.pop();
val2 = ctxt.pop();
if (!val1.is_const())
val1 = 1;
ctxt.push(val2 / val1);
result = true;
break;
case DW_OP_minus:
ABG_ASSERT(ctxt.stack.size() > 1);
val1 = ctxt.pop();
val2 = ctxt.pop();
ctxt.push(val2 - val1);
result = true;
break;
case DW_OP_mod:
ABG_ASSERT(ctxt.stack.size() > 1);
val1 = ctxt.pop();
val2 = ctxt.pop();
ctxt.push(val2 % val1);
result = true;
break;
case DW_OP_mul:
ABG_ASSERT(ctxt.stack.size() > 1);
val1 = ctxt.pop();
val2 = ctxt.pop();
ctxt.push(val2 * val1);
result = true;
break;
case DW_OP_neg:
ABG_ASSERT(ctxt.stack.size() > 0);
val1 = ctxt.pop();
ctxt.push(-val1);
result = true;
break;
case DW_OP_not:
ABG_ASSERT(ctxt.stack.size() > 0);
val1 = ctxt.pop();
ctxt.push(~val1);
result = true;
break;
case DW_OP_or:
ABG_ASSERT(ctxt.stack.size() > 1);
val1 = ctxt.pop();
val2 = ctxt.pop();
ctxt.push(val1 | val2);
result = true;
break;
case DW_OP_plus:
ABG_ASSERT(ctxt.stack.size() > 1);
val1 = ctxt.pop();
val2 = ctxt.pop();
ctxt.push(val2 + val1);
result = true;
break;
case DW_OP_plus_uconst:
ABG_ASSERT(ctxt.stack.size() > 0);
val1 = ctxt.pop();
val1 += op.number;
ctxt.push(val1);
result = true;
break;
case DW_OP_shl:
ABG_ASSERT(ctxt.stack.size() > 1);
val1 = ctxt.pop();
val2 = ctxt.pop();
ctxt.push(val2 << val1);
result = true;
break;
case DW_OP_shr:
case DW_OP_shra:
ABG_ASSERT(ctxt.stack.size() > 1);
val1 = ctxt.pop();
val2 = ctxt.pop();
ctxt.push(val2 >> val1);
result = true;
break;
case DW_OP_xor:
ABG_ASSERT(ctxt.stack.size() > 1);
val1 = ctxt.pop();
val2 = ctxt.pop();
ctxt.push(val2 ^ val1);
result = true;
break;
default:
return false;
break;
}
if (result == true)
{
if (ctxt.stack.front().is_const())
ctxt.accum = ctxt.stack.front();
next_index = index + 1;
return true;
}
return result;;
}
/// If the current operation in the dwarf expression represents a push