similar to: [LLVMdev] adding an optional flag edge to a BRIND node

I have changed the way in which the ARM backend generates a function return. Instead of expanding a RET to a CopyToReg;RETFLAG, it now expands into a CopyToReg;BRIND. I haven't commit it yet, but the patch is attached. In my opinion the resulting code is easier to understand, but I have some questions: Why all backends use RETFLAG? Why it is named RETFLAG? Why the Copy that places the

On Tue, 30 May 2006, [UTF-8] Rafael Esp?ndola wrote: > I have changed the way in which the ARM backend generates a function > return. Instead of expanding a RET to a CopyToReg;RETFLAG, it now > expands into a CopyToReg;BRIND. I haven't commit it yet, but the patch > is attached. Ok, I haven't looked at the code, but you're free to do whatever make sense. > In my

> > Why it is named RETFLAG? > > Historical reason. Originally we didn't have nodes that could > *optionally* have an input flag. A better design, e.g. on PPC would be to > have a PPCISD::RET node, which takes an optional input flag, and always > lower RET to it. I See. I will try to always lower to "(mov)*;bx lr" on ARM. > Flag in the SelectionDAG stuff is

On Wed, 31 May 2006, [UTF-8] Rafael Esp?ndola wrote: >> We don't want the copy and shift to wander apart from each other (e.g. we >> don't want another shift to get scheduled in between them), so we flag >> them together. In practice, these copies usually get coallesced away. > In the second case shl explicitly uses CL. Shouldn't the register > allocator be

On 5/31/06, Chris Lattner <sabre at nondot.org> wrote: > On Wed, 31 May 2006, [UTF-8] Rafael Esp?ndola wrote: > >> We don't want the copy and shift to wander apart from each other (e.g. we > >> don't want another shift to get scheduled in between them), so we flag > >> them together. In practice, these copies usually get coallesced away. > > In

I have just added a retflag to the ARM backend. I thought that using BRIND directly was to blame for a dummy move. But I the move wasn't removed. When compiling --------------------------------------- int %g() { entry: call void %f( ) ret int 42 } declare void %f() -------------------------------------- The ARM backend produces ------------------------------------------- g:

I am trying to make the ARM backend compile int f() {return 0;} I have added a custom expansion of ret that is similar to the one used in ppc and sparc. If I understand it correctly, it will expand the ret into an assignment to the return register (R0) and a RETFLAG node. I declared the bx instruction to match RETFLAG. Now the instruction selection says it can't match " i32 = Constant

I have started to add support for FP in the ARM backend. According to the ABI, 32 bit floating point numbers should be returned in R0 and 64bit ones in R0/R1. I have solved the 32 bit case by inserting bit_converts in LowerRET. For the 64bit case I considered two options: 1) Creating two nodes. fp_lo and fp_hi. I could then select fmrdh and fmrdl with (set IntRegs:$dst (bitconvert (fp_hi

Hi all, Our target does not have native support for 64-bit integers, so we rely on library calls for certain operations (like sdiv). We recently ran into a problem where these operations that are expanded to library calls aren't maintaining the proper ordering in relation to other chains in the DAG. The following snippet of a DAG demonstrates the problem. t0: ch = EntryToken t2:

Hello. I'm having problems at instruction selection with my back end with the following basic-block due to a vector add with immediate constant vector (obtained by vectorizing a simple C program doing vector sum map): vector.ph: ; preds = %vector.memcheck50 %.splatinsert = insertelement <8 x i64> undef, i64 %i.07.unr, i32 0

So if I first create the value in an entry BB and then build a CopyToReg but then I have to read it in a BB that loops back to itself, with it's own CopyToReg at the end, then I have two CopyToReg nodes for the same value. In this case, I need to create 3 virt regs, 1 for each CopyToReg and a third for the CopyFromReg in the beginning of the loop BB, right? And then I need to build a PHI

Well, that's the thing: I thought that was CopyToReg. I don't know what the name of the node is to load one value into a register, so I don't know how to construct such a pattern. On Sat, Nov 4, 2017 at 9:23 PM Craig Topper <craig.topper at gmail.com> wrote: > Do you have a pattern for loading an i16 immediate into a 16-bit register? > > ~Craig > > On Sat, Nov 4,

Hmm, okay. Then what's the problem being reported here? I'm not sure what I'm supposed to do with "LLVM ERROR: Cannot select: t1: i16 = Constant<127>".BTW, the function is: ; ModuleID = 'return.c' source_filename = "return.c" target datalayout = "E-m:e-p:16:16:16-i1:16:16-i8:16:16-i16:16:16-i32:16:16-i64:16:16-S16-n16" target triple =

Hi, On SystemZ there are a set of "access registers" that can be copied in and out of 32-bit GPRs with special instructions. These instructions can only perform the copy using low 32-bit parts of the 64-bit GPRs. As reported and discussed at https://bugs.llvm.org/show_bug.cgi?id=44254, this is currently broken due to the fact that the default register class for 32-bit integers is

So there's a DAG that looks like this in the debug output: Selecting: t3: ch,glue = CopyToReg t0, Register:i16 %R5, Constant:i16<127> In the instruction selection phase, what pattern would that match? I've constructed this so far: (??? REG16:$dst, i16imm:$src) but the problem is, I can't determine what to use as ???. There is an ISD::CopyToReg enum value, but I don't

Evan: What you requested was in the debug output (sans offending Node), but here it is, outside of the attachment. The offending node is highlighted: SU(0): 0xa908760: ch = EntryToken SU(1): 0xa907600: i32,ch,flag = CopyFromReg 0xa9095d0, 0xa9070e0, 0xa9095d0:1 0xa906e30: ch,flag = CopyToReg 0xa908760, 0xa9070e0, 0xa9071f0 <<--<<--<<--<<--<< Node

Sorry, still not enough information. I am guessing it's asserting in getVR() called from EmitNode()? The node is CopyToReg and it's trying to find the virtual register of operand 2? From the schedule, I don't see the definition of the operand. Can you do DAG.viewGraph()? That should gives us a better idea. Evan On Oct 16, 2007, at 9:06 PM, Scott Michel wrote: > Evan: >

Is there any way to get it to delay this optimization where it goes from this: Initial selection DAG: BB#0 'bclr64:entry' SelectionDAG has 14 nodes: t0: ch = EntryToken t2: i64,ch = CopyFromReg t0, Register:i64 %vreg0 t4: i64,ch = CopyFromReg t0, Register:i64 %vreg1 t6: i64 = sub t4, Constant:i64<1> t7: i64 = shl Constant:i64<1>, t6

Hi all, I am working on modeling an instruction similar to SystemZ's 'BRCT', which takes a register, decrements it, and branches if the register is nonzero. I saw that the LLVM backend for SystemZ generates the instruction in a MachineFunctionPass as part of a pass intended to eliminate or combine compares. I then looked at ARM, where it uses the HardwareLoops pass first, and then a

On Tue, Jul 14, 2009 at 6:48 PM, Bob Wilson <bob.wilson at apple.com> wrote: > > On Jul 2, 2009, at 10:48 AM, robert muth wrote: > > I spend over a day trying to follow your suggestion. In the end I was not > successful. Here is what Iearned: > > After setting > > ARMJITInfo::hasCustomJumpTables -> true > setOperationAction for ISD::BR_JT -> Expand >