llvm dev - Mar 2017 - Let ctor of DiagnosticInfoWithLocationBase take Function* instead of Function& ?

Hi,

Currently the constructor of class DiagnosticInfoWithLocationBase takes 
a Function reference:

   /// \p Fn is the function where the diagnostic is being emitted. \p 
Loc is
   /// the location information to use in the diagnostic.
   DiagnosticInfoWithLocationBase(enum DiagnosticKind Kind,
                                  enum DiagnosticSeverity Severity,
                                  const Function &Fn,
                                  const DiagnosticLocation &Loc)

However, if we want to emit diagnostics via calls like 
emitUndefinedBehaviorOptimizedWarning, the Function object may be 
unavailable. For example, in the interim of inlining, under the context 
of Analysis/InstructionSimplify, the Instruction in the context has no 
parent BB.

So how about let the constructor takes a Function ptr? All the use of 
Function object is to print out function name. Using pointer, we can 
let  if print somthing like "<optimized out function>" if it is
null.

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On 03/24/2017 05:37 PM, Zhao, Weiming via llvm-dev
wrote:
> Hi,
>
> Currently the constructor of class DiagnosticInfoWithLocationBase 
> takes a Function reference:
>
>   /// \p Fn is the function where the diagnostic is being emitted. \p 
> Loc is
>   /// the location information to use in the diagnostic.
>   DiagnosticInfoWithLocationBase(enum DiagnosticKind Kind,
>                                  enum DiagnosticSeverity Severity,
>                                  const Function &Fn,
>                                  const DiagnosticLocation &Loc)
>
> However, if we want to emit diagnostics via calls like 
> emitUndefinedBehaviorOptimizedWarning, the Function object may be 
> unavailable. For example, in the interim of inlining, under the 
> context of Analysis/InstructionSimplify, the Instruction in the 
> context has no parent BB.
>
> So how about let the constructor takes a Function ptr? All the use of 
> Function object is to print out function name. Using pointer, we can 
> let  if print somthing like "<optimized out function>" if
it is null.
We might just not want to emit a warning at all in this case. 
Unfortunately, just printing a warning which says, "There's UB
somewhere
in your program", is not very helpful. If we'd like to do this, then we
need to think about how to feed enough information through the 
interfaces to make the reporting useful (functions and debug locations).

  -Hal

-- 
Hal Finkel
Lead, Compiler Technology and Programming Languages
Leadership Computing Facility
Argonne National Laboratory