Assert valid target data string in LLVMCreateTargetData

[thielema]

Bugzilla Link	8998
Version	2.8
OS	All
CC	@thielema

Extended Description

Please add an assert to LLVMCreateTargetData (i.e. the C++ function that it calls), that checks whether the input string is correct. It seems that there is no way to find out, if an input string is actually valid. If I pass "nonsense" I get a non-NULL pointer as result (that is, the TargetDataRef does not show me, that the input was wrong), and if I pass that to LLVMAddTargetData then things go silently wrong in a very awful way.
See ticket #​6394 for an example.
http://llvm.org/bugs/show_bug.cgi?id=6394

[JOE1994]

(checked with llvmorg-17.0.6)

Function LLVMTargetDataRef LLVMCreateTargetData (const char *StringRep) feeds its input string to the following constructor of llvm::DataLayout:

explicit DataLayout(StringRef LayoutDescription) {
  reset(LayoutDescription);
}

DataLayout::reset performs validation checks on input parameter StringRef LayoutDescription, via function DataLayout::parseSpecifier.

llvm-project/llvm/lib/IR/DataLayout.cpp

Lines 195 to 221 in 6009708

	void DataLayout::reset(StringRef Desc) {
	clear();
	LayoutMap = nullptr;
	BigEndian = false;
	AllocaAddrSpace = 0;
	StackNaturalAlign.reset();
	ProgramAddrSpace = 0;
	DefaultGlobalsAddrSpace = 0;
	FunctionPtrAlign.reset();
	TheFunctionPtrAlignType = FunctionPtrAlignType::Independent;
	ManglingMode = MM_None;
	NonIntegralAddressSpaces.clear();
	StructAlignment = LayoutAlignElem::get(Align(1), Align(8), 0);
	// Default alignments
	for (const auto &[Kind, Layout] : DefaultAlignments) {
	if (Error Err = setAlignment(Kind, Layout.ABIAlign, Layout.PrefAlign,
	Layout.TypeBitWidth))
	return report_fatal_error(std::move(Err));
	}
	if (Error Err = setPointerAlignmentInBits(0, Align(8), Align(8), 64, 64))
	return report_fatal_error(std::move(Err));
	if (Error Err = parseSpecifier(Desc))
	return report_fatal_error(std::move(Err));
	}

As there are validation checks in place as requested, I think this ticket can be closed.