This change will allow to put code pointers in DWARF info fields that are larger than actual pointer size, e.g. 16-bit pointers into 32-bit fields.
The need for this came up while creating support for MSP430 in LLDB. MSP430-GCC already generates DWARF info with 32-bit fields, so this change is necessary for LLDB to maintain compatibility with both GCC and LLVM binaries. Moreover, right now in LLDB there is no support for having DWARF pointer size different from ELF header type, e.g. 16-bit DWARF info within ELF32, and it seems there is no such thing as ELF16.
Since other mainline targets are made to have the same pointer size in both MCAsmInfo and DataLayout, there is no need to change anything there.
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D148042
Implement emission of DWARF CFI instructions for MSP430. This includes descriptions of stack frame layout and location of callee-saved registers that could be used for backtracing.
Differential Revision: https://reviews.llvm.org/D146966
This reverts commit 256a52d9aac8a9e98fbfd6a3d91090bf127cef7d (and
also the follow-up commit 38eb4fe74b3843ab0d7fc1e that moved a test
case to a different directory).
As discussed in https://reviews.llvm.org/D126257 there is a suspicion
that something was wrong with this commit as text section range was
shortened to 1 byte rather than rounded up as shown in the
llvm/test/DebugInfo/X86/dwarf-aranges.ll test case.
This commit modifies the AsmPrinter to avoid emitting any zero-sized symbols to
the .debug_aranges table, by rounding their size up to 1. Entries with zero
length violate the DWARF 5 spec, which states:
> Each descriptor is a triple consisting of a segment selector, the beginning
> address within that segment of a range of text or data covered by some entry
> owned by the corresponding compilation unit, followed by the non-zero length
> of that range.
In practice, these zero-sized entries produce annoying warnings in lld and
cause GNU binutils to truncate the table when parsing it.
Other parts of LLVM, such as DWARFDebugARanges in the DebugInfo module
(specifically the appendRange method), already avoid emitting zero-sized
symbols to .debug_aranges, but not comprehensively in the AsmPrinter. In fact,
the AsmPrinter does try to avoid emitting such zero-sized symbols when labels
aren't involved, but doesn't when the symbol to emitted is a difference of two
labels; this patch extends that logic to handle the case in which the symbol is
defined via labels.
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D126257
Some dwarf loaders in LLVM are hard-coded to only accept 4-byte and 8-byte address sizes. This patch generalizes acceptance into `DWARFContext::isAddressSizeSupported` and provides a common way to generate rejection errors.
The MSP430 target has been given new tests to cover dwarf loading cases that previously failed due to 2-byte addresses.
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D111953
