MemoryBuffer::create_from_memory_range calls LLVMCreateMemoryBufferWithMemoryRange with RequiresNullTerminator set to false, while an LLVM memory buffer should always be null-terminated:
Please note that setting RequiresNullTerminator to true won't solve the issue; LLVM will simply throw an error. Instead, the function signature needs to be changed to require null-terminated buffers. There can be no zero-copy implementation of MemoryBuffer::create_from_memory_range for arbitrary &[u8].
The RequiresNullTerminator argument is truly baffling to me. It seems to mean "if true, check if the buffer is null-terminated" and not "I don't need this memory buffer to be null terminated" because it is always assumed to be so (perhaps you want to patch it after construction):
Create a memory buffer with MemoryBuffer::create_from_memory_range and attempt to use it in Context::create_module_from_ir for instance. The parser will behave oddly as it tries to read past the buffer.
Expected Behavior
MemoryBuffer::create_from_memory_range should always pass a null-terminated buffer to LLVMCreateMemoryBufferWithMemoryRange and set RequiresNullTerminator to true.
As this requires a copy in the general case, it should take a type that represents a buffer b of length N where b[N - 1] == b'\0' and set the buffer length to N-1 in LLVMCreateMemoryBufferWithMemoryRange.
Otherwise the documentation should be updated to ask the user to do the the necessary manipulation themselves before calling the function.
LLVM Version (please complete the following information):
LLVM Version: 17.0.6
Inkwell Branch Used: master
Desktop (please complete the following information):
TheDan64
commented
4 months ago
Describe the Bug
MemoryBuffer::create_from_memory_rangecallsLLVMCreateMemoryBufferWithMemoryRangewithRequiresNullTerminatorset tofalse, while an LLVM memory buffer should always be null-terminated:https://github.com/llvm/llvm-project/blob/adacb5010f5ca6e923b3cf2d8ea47cbaab96099d/llvm/include/llvm/Support/MemoryBuffer.h#L41-L51
Please note that setting
RequiresNullTerminatortotruewon't solve the issue; LLVM will simply throw an error. Instead, the function signature needs to be changed to require null-terminated buffers. There can be no zero-copy implementation ofMemoryBuffer::create_from_memory_rangefor arbitrary&[u8].The
RequiresNullTerminatorargument is truly baffling to me. It seems to mean "iftrue, check if the buffer is null-terminated" and not "I don't need this memory buffer to be null terminated" because it is always assumed to be so (perhaps you want to patch it after construction):https://github.com/llvm/llvm-project/blob/main/llvm/lib/Support/MemoryBuffer.cpp#L49-L57
To Reproduce
Create a memory buffer with
MemoryBuffer::create_from_memory_rangeand attempt to use it inContext::create_module_from_irfor instance. The parser will behave oddly as it tries to read past the buffer.Expected Behavior
MemoryBuffer::create_from_memory_rangeshould always pass a null-terminated buffer toLLVMCreateMemoryBufferWithMemoryRangeand setRequiresNullTerminatortotrue.As this requires a copy in the general case, it should take a type that represents a buffer
bof lengthNwhereb[N - 1] == b'\0'and set the buffer length toN-1inLLVMCreateMemoryBufferWithMemoryRange.Otherwise the documentation should be updated to ask the user to do the the necessary manipulation themselves before calling the function.
LLVM Version (please complete the following information):
Desktop (please complete the following information):
Additional Context
N/A