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- Don't use GlobalAliases with non-0 GEPs (GNU runtime) - this was unsupported and LLVM will be generating errors if you do it soon. This also simplifies the code generated by the GNU runtime a bit.
- Make GetSelector() return a constant (GNU runtime), not a load of a store of a constant.
- Recognise @selector() expressions as valid static initialisers (as GCC does).
- Add methods to GCObjCRuntime to emit selectors as constants (needed for using @selector() expressions as constants. These need implementing for the Mac runtimes - I couldn't figure out how to do this, they seem to require a load.
- Store an ObjCMethodDecl in an ObjCSelectorExpr so that we can get at the type information for the selector. This is needed for generating typed selectors from @selector() expressions (as GCC does). Ideally, this information should be stored in the Selector, but that would be an invasive change. We should eventually add checks for common uses of @selector() expressions. Possibly adding an attribute that can be applied to method args providing the types of a selector so, for example, you'd do something like this:
- (id)performSelector: __attribute__((selector_types(id, SEL, id)))(SEL)
withObject: (id)object;
Then, any @selector() expressions passed to the method will be check to ensure that it conforms to this signature. We do this at run time on the GNU runtime already, but it would be nice to do it at compile time on all runtimes.
- Made @selector() expressions emit type info if available and the runtime supports it.
Someone more familiar with the Mac runtime needs to implement the GetConstantSelector() function in CGObjCMac. This currently just assert()s.
llvm-svn: 95189
IRgen optimization opportunities. //===---------------------------------------------------------------------===// The common pattern of -- short x; // or char, etc (x == 10) -- generates an zext/sext of x which can easily be avoided. //===---------------------------------------------------------------------===// Bitfields accesses can be shifted to simplify masking and sign extension. For example, if the bitfield width is 8 and it is appropriately aligned then is is a lot shorter to just load the char directly. //===---------------------------------------------------------------------===// It may be worth avoiding creation of alloca's for formal arguments for the common situation where the argument is never written to or has its address taken. The idea would be to begin generating code by using the argument directly and if its address is taken or it is stored to then generate the alloca and patch up the existing code. In theory, the same optimization could be a win for block local variables as long as the declaration dominates all statements in the block. NOTE: The main case we care about this for is for -O0 -g compile time performance, and in that scenario we will need to emit the alloca anyway currently to emit proper debug info. So this is blocked by being able to emit debug information which refers to an LLVM temporary, not an alloca. //===---------------------------------------------------------------------===// We should try and avoid generating basic blocks which only contain jumps. At -O0, this penalizes us all the way from IRgen (malloc & instruction overhead), all the way down through code generation and assembly time. On 176.gcc:expr.ll, it looks like over 12% of basic blocks are just direct branches! //===---------------------------------------------------------------------===//