llvm dev - Nov 2020 - Question about LLVM Rel10 llvm/IR/AsmWriter.cpp

Hi,

See fuller extract below.
I am curious about the for loop.
    for (unsigned i = 1, e = CA->getNumElements(); i != e; ++i) {
What happens when CA->getNumElements() is zero ? Infinite loop????
Wouldn't the following be better. i.e. safer:
    for (unsigned i = 1; i < CA->getNumElements(); i++) {

Kind Regards

James


At about line 1429:
    Type *ETy = CA->getType()->getElementType();
    Out << '[';
    TypePrinter.print(ETy, Out);
    Out << ' ';
    WriteAsOperandInternal(Out, CA->getElementAsConstant(0),
                           &TypePrinter, Machine,
                           Context);
    for (unsigned i = 1, e = CA->getNumElements(); i != e; ++i) {
      Out << ", ";
      TypePrinter.print(ETy, Out);
      Out << ' ';
      WriteAsOperandInternal(Out, CA->getElementAsConstant(i),
&TypePrinter,
                             Machine, Context);
    }
    Out << ']';
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On Wed, 11 Nov 2020 at 23:58, James Courtier-Dutton via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> What happens when CA->getNumElements() is zero ? Infinite loop????
It looks like a ConstantArray can't exist with zero elements,
ConstantArray::get produces a ConstantAggregateZero instead. Actually
parsing a .ll file seems to go for UndefValue.
> Wouldn't the following be better. i.e. safer:
>    for (unsigned i = 1; i < CA->getNumElements(); i++) {
The code above has already dereferenced CA[0] so I think it's no real
improvement.

Cheers.

Tim.