[DwarfDebug] Refuse to emit DW_OP_LLVM_arg values wider than 64 bits #3665
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DwarfExpression::addUnsignedConstant(const APInt &Value) only supports wider-than-64-bit values when it is used to emit a top-level DWARF expression representing the location of a variable. Before this change, it was possible to call addUnsignedConstant on >64 bit values within a subexpression when substituting DW_OP_LLVM_arg values. This can trigger an assertion failure (e.g. PR52584, PR52333) when it happens in a fragment (DW_OP_LLVM_fragment) expression, as addUnsignedConstant on >64 bit values splits the constant into separate DW_OP_pieces, which modifies DwarfExpression::OffsetInBits. This change papers over the assertion errors by bailing on overly wide DW_OP_LLVM_arg values. A more comprehensive fix might be to be to split wide values into pointer-sized fragments. [0] https://github.com/llvm/llvm-project/blob/e71fa03/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp#L799-L805 Patch by Ricky Zhou! Differential Revision: https://reviews.llvm.org/D115343 (cherry picked from commit c7c84b9)
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DwarfExpression::addUnsignedConstant(const APInt &Value) only supports
wider-than-64-bit values when it is used to emit a top-level DWARF
expression representing the location of a variable. Before this change,
it was possible to call addUnsignedConstant on >64 bit values within a
subexpression when substituting DW_OP_LLVM_arg values.
This can trigger an assertion failure (e.g. PR52584, PR52333) when it
happens in a fragment (DW_OP_LLVM_fragment) expression, as
addUnsignedConstant on >64 bit values splits the constant into separate
DW_OP_pieces, which modifies DwarfExpression::OffsetInBits.
This change papers over the assertion errors by bailing on overly wide
DW_OP_LLVM_arg values. A more comprehensive fix might be to be to split
wide values into pointer-sized fragments.
[0] https://github.com/llvm/llvm-project/blob/e71fa03/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp#L799-L805
Patch by Ricky Zhou!
Differential Revision: https://reviews.llvm.org/D115343
(cherry picked from commit c7c84b9)