-
Notifications
You must be signed in to change notification settings - Fork 13.6k
Fix i1 array global crash in NVPTXAsmPrinter. #92506
New issue
Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.
By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.
Already on GitHub? Sign in to your account
Conversation
See the test file. At head, this crashes with ``` assertion failed at llvm/lib/Support/APInt.cpp:492 in uint64_t llvm::APInt::extractBitsAsZExtValue(unsigned int, unsigned int) const: bitPosition < BitWidth && (numBits + bitPosition) <= BitWidth && "Illegal bit extraction" ```
Cal you provide more details on why exactly that assertion got triggered with |
@@ -1847,9 +1847,13 @@ void NVPTXAsmPrinter::bufferLEByte(const Constant *CPV, int Bytes, | |||
auto AddIntToBuffer = [AggBuffer, Bytes](const APInt &Val) { | |||
size_t NumBytes = (Val.getBitWidth() + 7) / 8; | |||
SmallVector<unsigned char, 16> Buf(NumBytes); | |||
for (unsigned I = 0; I < NumBytes; ++I) { | |||
for (unsigned I = 0; I < NumBytes - 1; ++I) { |
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
This could certainly use a comment or two about what's going on, because it's not obvious. At all.
Why exactly are we special casing the last byte?
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
It's explained in the PR description, also look at the test. If the type's bitwidth is not a multiple of 8, the old code crashes.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
PR description only shows the expression for the failed assertion: bitPosition < BitWidth && (numBits + bitPosition) <= BitWidth
, but it was not clear which part of that assertion has failed.
The substance of the fix LGTM.
That said, If I ever need to look at this code in the future, I'm pretty sure I'll have to scratch my head, again, pondering what's going on here. Hence, my suggestion that a comment would be helpful. We already have way too many puzzles, we do not need more.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
Sounds good. Sent a follow-up.
This is a follow-up to llvm#92506.
This is a follow-up to llvm#92506.
This is a follow-up to #92506.
This is a follow-up to llvm#92506.
See the test file. At head, this crashes with