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Thanks to your help I've actually made some progress... Especially the SelectionDAGNodes.h was a good hint. But there are still some things that I can't figure out: // 'mov eax, 41' Chain = DAG.getCopyToReg(Chain, DAG.getRegister(X86::EAX, MVT::i32), DAG.getConstant(41, MVT::i32), InFlag); InFlag = Chain.getValue(1); // 'inc eax' SDValue eaxVal =

On Jul 1, 2009, at 2:22 PMPDT, Dan Gohman wrote: >> Ops.push_back(DAG.getConstant(1, MVT::i32)); >> Chain = DAG.getNode(ISD::ADD, DAG.getVTList(MVT::Other, MVT::i32), >> &Ops[0], Ops.size()); >> >> Isn't that the way how it is supposed to work? > > ADD does not use a chain, so there's no chain operand, or > MVT::Other result for it in an ADD

Dan Gohman wrote: > There certainly are wishlist items for TableGen and TableGen-based > instruction descriptions, though I don't know of an official list. > Offhand, > a few things that come to mind are the ability to handle nodes with > multiple results, Is there an official workaround, BTW? - Volodya

Thank you for your help. I think I managed to create the instruction I wanted: // mov eax, 41 Chain = DAG.getCopyToReg(Chain, DAG.getRegister(X86::EAX, MVT::i32), DAG.getConstant(41, MVT::i32), InFlag); InFlag = Chain.getValue(1); I don't understand though what InFlag is for. As I read the code, it even remains uninitialized when first passed to some node creation method.

>>Note that the isCommutable flag is only really useful for two-address instructions. If the two inputs are not constrained, nothing is really won by swapping them. Ahh i see, good to know that. >> Does the -view-*-dags output look correct? They do look correct, there are three Xmul_lohi blocks, one returns the low part copied into R14 and the rest of combinations get added and merged

On Sep 9, 2010, at 12:59 PM, Borja Ferrer wrote: > Hello, i've noticed a new possible missed optimization while testing more trivial code. > This time it's not a with a xor but with a multiplication instruction and the example is little bit more involved. > > C code: > > typedef short t; > t foo(t a, t b) > { > t a4 = a*b; > return a4; > } >

Hello everybody, hi Evan, this patch changes the lowering of arguments for tail call optimized calls. Before arguments that could be overwritten by each other were explicitly lowered to a stack slot, not giving the register allocator a chance to optimize. Now a sequence of copyto/copyfrom virtual registers ensures that arguments are loaded in (virtual) registers before they are lowered to the

On Jun 25, 2009, at 2:05 PM, Artjom K. wrote: > > Greetings, > > I am rather new to LLVM, so please excuse my limited knowledge about > it. > > Currently I am trying to modify the X86TargetLowering::LowerCALL > method by > inserting additional instructions before the call. > As far as I understand, nodes are created by calling the getNode > method on >

On Fri, 12 Jan 2007, Nicolas Geoffray wrote: > I'm currently implementing a linux/ppc target in llvm. The abis between cool > Darwin/ppc and linux/ppc are different and I'm running into problems > with vararg calls. ok > Before a variadic method is called, an extra instruction must be > executed (which is creqv 6, 6, 6). This instruction is not necessary in >

Greetings, I am rather new to LLVM, so please excuse my limited knowledge about it. Currently I am trying to modify the X86TargetLowering::LowerCALL method by inserting additional instructions before the call. As far as I understand, nodes are created by calling the getNode method on the DAG. If, for example, I insert the following code Ops.push_back(Chain); Chain = DAG.getNode(ISD::TRAP,

> > Basically, flag operands are a hack used to handle resources that > are not > > accurately modeled in the scheduler (e.g. condition codes, explicit > > register assignments, etc). The basic idea of the flag operand is > that > > they require the scheduler to keep the "flagged" nodes stuck > together in > > the output machine instructions. >

Hi all, I'm currently implementing a linux/ppc target in llvm. The abis between Darwin/ppc and linux/ppc are different and I'm running into problems with vararg calls. Before a variadic method is called, an extra instruction must be executed (which is creqv 6, 6, 6). This instruction is not necessary in Darwin/ppc. I looked into the PowerPC target implementation and the code generation

On Jun 26, 2009, at 4:49 AM, Artjom K. wrote: > > Thank you for your help. > > I think I managed to create the instruction I wanted: > > // mov eax, 41 > Chain = DAG.getCopyToReg(Chain, DAG.getRegister(X86::EAX, MVT::i32), > DAG.getConstant(41, MVT::i32), InFlag); > InFlag = Chain.getValue(1); > > I don't understand though what InFlag is for. As I read the

Hello, i've noticed a new possible missed optimization while testing more trivial code. This time it's not a with a xor but with a multiplication instruction and the example is little bit more involved. C code: typedef short t; t foo(t a, t b) { t a4 = a*b; return a4; } argument "a" is passed in R15:R14, argument "b" in R13:R12, the return value is stored in

On Sat, 14 Oct 2006, Roman Levenstein wrote: >> On Sat, 14 Oct 2006, Roman Levenstein wrote: >>> Is it possible to dynamically define implicit defs for some >>> instructions? >> >> Yes! This is what explicit operands are :). Specifically, if you >> want to >> vary on a per-opcode basis what registers are used/def'd by the >> instruction,

Hi Evan, I incoporated the changes you request but to the following i have got a question: > Also, moving the option > there will allow us to change fastcc ABI (callee popping arguments) > only when this option is on. See Chris' email: I am not to sure on that. because that would make modules compiled with the flag on incompatible with ones compiled without the flag off as

Hi Chris, Thanks for your response. > On Sat, 14 Oct 2006, Roman Levenstein wrote: > > Is it possible to dynamically define implicit defs for some > > instructions? > > Yes! This is what explicit operands are :). Specifically, if you > want to > vary on a per-opcode basis what registers are used/def'd by the > instruction, you can just add those registers

On Mon, 9 Oct 2006, Roman Levenstein wrote: > But your previous explanations were so good that I implemented in my > backend last week almost the same that you've done now in the > X86InstrSSE.td. I even introduced isCommutable parameter to indicate > this property, just as you did. So, by now integer arithmetic and > general purpose instructions are implemented. I'm working

> Basically, flag operands are a hack used to handle resources that are not > accurately modeled in the scheduler (e.g. condition codes, explicit > register assignments, etc). The basic idea of the flag operand is that > they require the scheduler to keep the "flagged" nodes stuck together in > the output machine instructions. >From an user point of view, flags have

I am working the AVR backend. It is still in the early stage. I got the following error:[ 86%] Building CXX object lib/Target/AVR/CMakeFiles/LLVMAVRCodeGen.dir/AVRISelDAGToDAG.cpp.obj AVRISelDAGToDAG.cpp C:\llvm-build\lib\Target\AVR\AVRGenDAGISel.inc(596) : error C2664: 'llvm::SDNode *llvm::SelectionDAG::SelectNodeTo(llvm::SDNode *,unsigned int,llvm::MVT,llvm::MVT,llvm::MVT,const llvm::SDValue