skan marked an inline comment as done.
skan added inline comments.
================
Comment at: clang/lib/Headers/ia32intrin.h:421
+ if (__c != 0) {
\
+ *(a) = (unsigned)__bsfd(__c);
\
+ __d = 1;
\
----------------
craig.topper wrote:
> skan wrote:
> > craig.topper wrote:
> > > Should (a) have a cast to (unsigned *)?
> > No. Using a cast here may cause pointer aliasing problem.
> >
> > https://stackoverflow.com/questions/98650/what-is-the-strict-aliasing-rule
> >
> > If a is not `unsigned *`, letting the compiler do auto integer conversion
> > for `*(a)` is the correct way, from my perspective.
> But if we implemented this as an inline function instead of a macro wouldn't
> the argument have been an unsigned *?
Yes, it would have been. But I don't known the motivation to use a cast
`(unsigned *)` here, is there any case using cast here works correctly while
not using cast here fails?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D75723/new/
https://reviews.llvm.org/D75723
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