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Analyzing why GCC failed to build LLVM recently, one root cause lies in definition of ArrayRef: // ArrayRef.h: ArrayRef(const T &OneElt) : Data(&OneElt), Length(1) {} Here address of const reference is taken and stored to an object. It is believed that live range of const reference is only at the function call site, escaping of its address to an object with a longer live range is invalid. Referring to the case and discussion h...

...cpp prints: "Expected behaviour." I think (as a quick fix) we should remove the const qualifier from ArrayRef's CTor argument, so that the above code won't compile anymore and thus avoiding a silent failure. To be precise: Change llvm/ADT/ArrayRef.h:57 from ArrayRef(const T &OneElt) : Data(&OneElt), Length(1) {} to ArrayRef(T &OneElt) : Data(&OneElt), Length(1) {} Best regards, Andreas -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20140718/7ac8f807/attachment.h...

...> --- a/include/llvm/ADT/ArrayRef.h > +++ b/include/llvm/ADT/ArrayRef.h > @@ -68,7 +68,7 @@ namespace llvm { > /*implicit*/ ArrayRef(NoneType) : Data(nullptr), Length(0) {} > > /// Construct an ArrayRef from a single element. > - /*implicit*/ ArrayRef(const T &OneElt) > + __attribute__((deprecated)) /*implicit*/ ArrayRef(const T &OneElt) > : Data(&OneElt), Length(1) {} > > /// Construct an ArrayRef from a pointer and length. > > and rebuilding LLVM and Clang gives me: > > $ ninja 2>&1 | grep -e Wdeprecated-d...

...ussion to continue from there. > > On Aug 19, 2014 11:18 PM, "Joey Ye" <joey.ye.cc at gmail.com> wrote: > > Analyzing why GCC failed to build LLVM recently, one root cause lies > in definition of ArrayRef: > // ArrayRef.h: > ArrayRef(const T &OneElt) : Data(&OneElt), Length(1) {} > > Here address of const reference is taken and stored to an object. It > is believed that live range of const reference is only at the function > call site, escaping of its address to an object with a longer live > range is inv...

...assertions, etc)). Of course that would be thwarted by moving the string into a local variable. Nothing perfect here. > If we remove the `ArrayRef` constructor AND the helper, and add a new > helper like: > > template <class T> ArrayRef<T> makeTempArrayRef(const T &OneElt) { > return ArrayRef<T>(&OneElt, &OneElt + 1); > } > > then both types of bugs will be more rare and obvious. > > For the OP's case, the name "Temp" makes it more clear that the ArrayRef > shouldn't be named. For my case, since the cal...

...m> wrote: >> >> > >> >> > Analyzing why GCC failed to build LLVM recently, one root cause >> >> > lies >> >> > in definition of ArrayRef: >> >> > // ArrayRef.h: >> >> > ArrayRef(const T &OneElt) : Data(&OneElt), Length(1) {} >> >> > >> >> > Here address of const reference is taken and stored to an object. >> >> > It >> >> > is believed that live range of const reference is only at the >> >> > function &...

...ug 19, 2014 11:18 PM, "Joey Ye" <joey.ye.cc at gmail.com> wrote: >> > >> > Analyzing why GCC failed to build LLVM recently, one root cause lies >> > in definition of ArrayRef: >> > // ArrayRef.h: >> > ArrayRef(const T &OneElt) : Data(&OneElt), Length(1) {} >> > >> > Here address of const reference is taken and stored to an object. It >> > is believed that live range of const reference is only at the >> > function >> > call site, escaping of its address to an o...

Hi all, How can I create an llvm::GetElementPtrInst in which the pointer and the index are in registers previously loaded with llvm::LoadInst ? I mean, the generated instruction will be like this: %1 = getelementptr i8* %myreg1, i32 %myreg2 here, %myreg1 and %myreg2 are previously created by load instructions (llvm::LoadInst). Please, let me know if there is an example of something similar.

...the context of the prior discussion to continue from there. On Aug 19, 2014 11:18 PM, "Joey Ye" <joey.ye.cc at gmail.com> wrote: > Analyzing why GCC failed to build LLVM recently, one root cause lies > in definition of ArrayRef: > // ArrayRef.h: > ArrayRef(const T &OneElt) : Data(&OneElt), Length(1) {} > > Here address of const reference is taken and stored to an object. It > is believed that live range of const reference is only at the function > call site, escaping of its address to an object with a longer live > range is invalid. Referring to t...

...cussion to continue from there. > On Aug 19, 2014 11:18 PM, "Joey Ye" <joey.ye.cc at gmail.com> wrote: > > > Analyzing why GCC failed to build LLVM recently, one root cause lies > > in definition of ArrayRef: > > // ArrayRef.h: > > ArrayRef(const T &OneElt) : Data(&OneElt), Length(1) {} > > > > Here address of const reference is taken and stored to an object. It > > is believed that live range of const reference is only at the function > > call site, escaping of its address to an object with a longer live > > range i...

.... > > On Aug 19, 2014 11:18 PM, "Joey Ye" <joey.ye.cc at gmail.com> wrote: > > > > > Analyzing why GCC failed to build LLVM recently, one root cause lies > > > in definition of ArrayRef: > > > // ArrayRef.h: > > > ArrayRef(const T &OneElt) : Data(&OneElt), Length(1) {} > > > > > > Here address of const reference is taken and stored to an object. It > > > is believed that live range of const reference is only at the function > > > call site, escaping of its address to an object with a longer li...

...14 11:18 PM, "Joey Ye" <joey.ye.cc at gmail.com> wrote: > > > > > > > Analyzing why GCC failed to build LLVM recently, one root cause lies > > > > in definition of ArrayRef: > > > > // ArrayRef.h: > > > > ArrayRef(const T &OneElt) : Data(&OneElt), Length(1) {} > > > > > > > > Here address of const reference is taken and stored to an object. It > > > > is believed that live range of const reference is only at the function > > > > call site, escaping of its address to an obj...