[PATCH] Added new functionality to LLVM C API to use DiagnosticInfo to handle errors

[Tom Stellard]

On Fri, Apr 04, 2014 at 10:59:11AM -0700, Eric Christopher wrote:
> I'd very much prefer not to expose the severity for now. This is a
> fairly well thought out, but very new interface and we guarantee
> stability of the C interface so we'd be locking the current severity
> interface down.
>
> I'm not, honestly, a huge fan of opening this up to the C API in
> general - is there a good reason to do so?
> 

We would like to use this in Mesa so we can report backend compiler
errors to the graphics drivers.  The most important use case is reporting
when the verifier detects an illegal instruction, because executing
illegal instructions has a good chance of locking up the system.

We'd also like to query the severity level, but we really only care about Errors
and not the others.  In fact we probably could just use the severity and not
worry about the error message.  What if we limited the C API to just:

LLVMContextSetDiagnosticHandler(LLVMContextRef C, LLVMDiagnosticHandler Handler,
                                void *DiagnosticContext);
/// @returns true if DiagnosticSeverity is DS_Error and false otherwise.
bool LLVMDiagInfoHasError(LLVMDiagnosticInfoRef DI);

Would this work?

-Tom

> 
> On Fri, Apr 4, 2014 at 10:39 AM, Quentin Colombet <qcolombet at apple.com> wrote:
> > Hi Darren,
> >
> > This LGTM with two comments:
> > - LLVMPrintDiagInfoToString should state that the string has to be freed
> > (see inline comment).
> > - Should we provide an API to expose the severity as well? What would do the
> > users of LLVMPrintDiagInfoToString if we do not?
> >
> > Note that I'm not super familiar with the C API, so you may want to wait for
> > another review.
> >
> > Thanks,
> > -Quentin
> >
> > On Apr 2, 2014, at 8:32 PM, Tom Stellard <tom at stellard.net> wrote:
> >
> > From: Darren Powell <darren.powell at amd.com>
> >
> > ---
> > include/llvm-c/Core.h            | 20 ++++++++++++++++++++
> > include/llvm/IR/DiagnosticInfo.h |  3 +++
> > lib/IR/Core.cpp                  | 20 ++++++++++++++++++++
> > 3 files changed, 43 insertions(+)
> >
> > diff --git a/include/llvm-c/Core.h b/include/llvm-c/Core.h
> > index 50c5e3a..17367ff 100644
> > --- a/include/llvm-c/Core.h
> > +++ b/include/llvm-c/Core.h
> > @@ -124,6 +124,12 @@ typedef struct LLVMOpaquePassRegistry
> > *LLVMPassRegistryRef;
> >  * @see llvm::Use */
> > typedef struct LLVMOpaqueUse *LLVMUseRef;
> >
> > +
> > +/**
> > + * @see llvm::DiagnosticInfo
> > + */
> > +typedef struct LLVMOpaqueDiagnosticInfo *LLVMDiagnosticInfoRef;
> > +
> > typedef enum {
> >     LLVMZExtAttribute       = 1<<0,
> >     LLVMSExtAttribute       = 1<<1,
> > @@ -453,6 +459,8 @@ void LLVMEnablePrettyStackTrace(void);
> >  * @{
> >  */
> >
> > +typedef void (*LLVMDiagnosticHandler)(LLVMDiagnosticInfoRef, void *);
> > +
> > /**
> >  * Create a new context.
> >  *
> > @@ -467,6 +475,13 @@ LLVMContextRef LLVMContextCreate(void);
> > LLVMContextRef LLVMGetGlobalContext(void);
> >
> > /**
> > + * Set the diagnostic handler for this context.
> > + */
> > +void LLVMContextSetDiagnosticHandler(LLVMContextRef C,
> > +                                     LLVMDiagnosticHandler Handler,
> > +                                     void *DiagnosticContext);
> > +
> > +/**
> >  * Destroy a context instance.
> >  *
> >  * This should be called for every call to LLVMContextCreate() or memory
> > @@ -474,6 +489,11 @@ LLVMContextRef LLVMGetGlobalContext(void);
> >  */
> > void LLVMContextDispose(LLVMContextRef C);
> >
> > +/**
> > + * Extract string description from DiagnosticInfo.
> >
> >
> > Add a comment here saying that the string should be freed using
> > LLVMDisposeMessage.
> >
> > + */
> > +char *LLVMPrintDiagInfoToString(LLVMDiagnosticInfoRef DI);
> > +
> > unsigned LLVMGetMDKindIDInContext(LLVMContextRef C, const char* Name,
> >                                   unsigned SLen);
> > unsigned LLVMGetMDKindID(const char* Name, unsigned SLen);
> > diff --git a/include/llvm/IR/DiagnosticInfo.h
> > b/include/llvm/IR/DiagnosticInfo.h
> > index de2a9d8..5fd6636 100644
> > --- a/include/llvm/IR/DiagnosticInfo.h
> > +++ b/include/llvm/IR/DiagnosticInfo.h
> > @@ -193,6 +193,9 @@ public:
> >   }
> > };
> >
> > +// Create wrappers for C Binding types (see CBindingWrapping.h).
> > +DEFINE_SIMPLE_CONVERSION_FUNCTIONS(DiagnosticInfo, LLVMDiagnosticInfoRef)
> > +
> > } // End namespace llvm
> >
> > #endif
> > diff --git a/lib/IR/Core.cpp b/lib/IR/Core.cpp
> > index 4f3d8b1..e3b70c7 100644
> > --- a/lib/IR/Core.cpp
> > +++ b/lib/IR/Core.cpp
> > @@ -17,6 +17,8 @@
> > #include "llvm/IR/Attributes.h"
> > #include "llvm/IR/CallSite.h"
> > #include "llvm/IR/Constants.h"
> > +#include "llvm/IR/DiagnosticInfo.h"
> > +#include "llvm/IR/DiagnosticPrinter.h"
> > #include "llvm/IR/DerivedTypes.h"
> > #include "llvm/IR/GlobalAlias.h"
> > #include "llvm/IR/GlobalVariable.h"
> > @@ -76,6 +78,14 @@ LLVMContextRef LLVMGetGlobalContext() {
> >   return wrap(&getGlobalContext());
> > }
> >
> > +void LLVMContextSetDiagnosticHandler(LLVMContextRef C,
> > +                                     LLVMDiagnosticHandler Handler,
> > +                                     void *DiagnosticContext) {
> > +  unwrap(C)->setDiagnosticHandler(
> > +      LLVM_EXTENSION
> > reinterpret_cast<LLVMContext::DiagnosticHandlerTy>(Handler),
> > +      DiagnosticContext);
> > +}
> > +
> > void LLVMContextDispose(LLVMContextRef C) {
> >   delete unwrap(C);
> > }
> > @@ -89,6 +99,16 @@ unsigned LLVMGetMDKindID(const char* Name, unsigned SLen)
> > {
> >   return LLVMGetMDKindIDInContext(LLVMGetGlobalContext(), Name, SLen);
> > }
> >
> > +char *LLVMPrintDiagInfoToString(LLVMDiagnosticInfoRef DI) {
> > +  std::string MsgStorage;
> > +  raw_string_ostream Stream(MsgStorage);
> > +  DiagnosticPrinterRawOStream DP(Stream);
> > +
> > +  unwrap(DI)->print(DP);
> > +  Stream.flush();
> > +
> > +  return strdup(MsgStorage.c_str());
> > +}
> >
> > /*===-- Operations on modules
> > ---------------------------------------------===*/
> >
> > --
> > 1.8.3.2
> >
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