[PATCH] D113238: [llvm-profgen] Fix index out of bounds error while using ip.advance

[Wenlei He via Phabricator via llvm-commits]

wenlei added inline comments.


================
Comment at: llvm/tools/llvm-profgen/ProfileGenerator.cpp:388
     // can be Addr1+1 to Addr2-1. We should ignore such range.
     while (IP.Address <= RangeEnd) {
       uint64_t Offset = Binary->virtualAddrToOffset(IP.Address);
----------------
wlei wrote:
> wenlei wrote:
> > Before the loop, `RangeBegin <= RangeEnd` should be guaranteed, right? Would this look cleaner?
> > 
> > ```
> > do {
> > 
> >   ...
> > } while (IP.advance() && IP.Address <= RangeEnd);
> > 
> > ```
> Seems not guaranteed, see the comments: 
> ```
>     // Disjoint ranges may have range in the middle of two instr,
>     // e.g. If Instr1 at Addr1, and Instr2 at Addr2, disjoint range
>     // can be Addr1+1 to Addr2-1. We should ignore such range.
>     if (IP.Address > RangeEnd)
>       continue;
> ```
> or change to ?
> ```
> if (IP.Address > RangeEnd)
>      continue;
> do {
> 
>   ...
> } while (IP.advance() && IP.Address <= RangeEnd);
> 
> ```
Ok, I see. Yeah, that works. We could have `if (RangeStart > RangeEnd)` check before constructing the `IP`, and together with that comment.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D113238/new/

https://reviews.llvm.org/D113238