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7369c14b6a
This is something of a hack, the problem is as follows: 1. we instantiate both copied of RetainPtr with the two different argument types (an id and protocol-qualified id). 2. We refer to the ctor of one of the instantiations when introducing global "x", this causes us to emit an llvm::Function for a prototype whose "this" has type "RetainPtr<id<bork> >*". 3. We refer to the ctor of the other instantiation when introducing global "y", however, because it *mangles to the same name as the other ctor* we just use a bitcasted version of the llvm::Function we previously emitted. 4. We emit deferred declarations, causing us to emit the body of the ctor, however the body we emit is for RetainPtr<id>, which expects its 'this' to have an IR type of "RetainPtr<id>*". Because of the mangling collision, we don't have this case, and explode. This is really some sort of weird AST invariant violation or something, but hey a bitcast makes the pain go away. llvm-svn: 135572
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! //===---------------------------------------------------------------------===//