similar to: [LLVMdev] What is the Use of "Implicit EFLAGS" in TableGen

Hello, Here is one question regarding the LLVM TableGen: Which file in the llvm/lib/Target/X86 folder describes how the bits in the EFLAGS register are modified by the x86 instructions? For example, in the "X86InstrInfo.td" file, lines 2134-2135, it says: let SchedRW = [WriteALU], Defs = [EFLAGS], Uses = [EFLAGS] in { def CLC : I<0xF8, RawFrm, (outs), (ins), "clc",

Hi, I'm trying to revive jacobly0's Z80 back-end (from https://github.com/jacobly0/llvm-z80) and build it with a current version of LLVM. Apart from some interface changes, I'm stuck at building the tables. Specifically, the generation of the DAG instruction selector causes an assertion in the table generator: Assertion failed: Ops.size() >= NumSrcResults &&

Hi Bill. Thank you very much! Now I see my understanding was incorrect :) A dependence from a single physreg-defining instruction (like CMP or TEST) is allowed to be shared in several instructions unless that register is not clobbered (and this is what we have with CMOV_FR64). Wouldn't it be safe then to not set the live-in flag in EmitLoweredSelect for instructions which are marked as

On Jun 1, 2011, at 9:18 AM, Galanov, Sergey wrote: > Hello. > > I am not sure this is the right place to ask but here is my question. About a year ago there was a fix of some obscure bug (rdar://problem/8030636 which is located on the internal Apple bugtracker I believe and so not available to the general public J) > Some discussion can be found here:

Hello. I am not sure this is the right place to ask but here is my question. About a year ago there was a fix of some obscure bug (rdar://problem/8030636 which is located on the internal Apple bugtracker I believe and so not available to the general public :)) Some discussion can be found here: http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20100531/102160.html. Unfortunately, no

Is there a backend to Tablegen which can dump a map of pattern-to-matched to instruction-to-be-generated? --help doesn't seem to indicate anything like that. On Tue, Jul 14, 2020 at 2:13 PM Rotate Right <rightrotate5 at gmail.com> wrote: > Thanks Matt and Thomas. I will go through them. > > On Tue, Jul 14, 2020, 1:35 PM Matt P. Dziubinski <matdzb at gmail.com> wrote:

A physical register cannot be live across the block. So it must have a use in the block or it must be marked dead. From your dump, it looks like the CCFLAGS defs are not being marked dead. It's unclear where things went wrong, but you can step through LiveVariables to debug this. Evan On Jan 9, 2009, at 2:50 AM, Christian Sayer wrote: > Hello, > > For my backend, I define and

Hi, Is there a way to specify the Integer type to be of 2Byte for a Target? LLVM IR produces 4Bytes(i32) for Integer type. Clang can be tweaked to make the integer to be of 2Byte(i16), but is there a way to specify in the LLVM CodeGen? -- Thanks and Regards, Shashidhar

Hi, Bill and Jakob. I don't quite understand. I am talking about CMOV_GR* instructions which are conservatively marked as clobbering EFLAGS in X86InstrCompiler.td. Doesn't that mean there cannot be any use of EFLAGS in subsequent instructions before it is defined by some other instruction? I also don't understand the remark about resetting EFLAGS. What kind of reset is meant? In case

Well, the point is CMOV_GR* are marked clobbering EFLAGS conservatively just in case they turn out to be lowered into a sequence containing XOR %reg,%reg which indeed clobbers EFLAGS. This means there might not be any instruction which actually uses this EFLAGS value. For an example we can look no further than the actual test which has been disabled after the fix

On Jun 2, 2011, at 3:53 AM, Galanov, Sergey wrote: > Hi Bill. > > Thank you very much! Now I see my understanding was incorrect :) A dependence from a single physreg-defining instruction (like CMP or TEST) is allowed to be shared in several instructions unless that register is not clobbered (and this is what we have with CMOV_FR64). Wouldn't it be safe then to not set the live-in

Hello, For my backend, I define and use a CC register similiarly to the EFLAGS register in X86 (I call it CCFLAGS). But if I make all arithmetic/logic instructions affect it ('let Defs = [CCFLAGS] in...' in InstrInfo.td) I run into // The only case we should have a dead physreg here without a killing or // instruction where we know it's dead is if it is live-in to the function

Hi Reed, The .td file "Defs = …" should be sufficient. The implicit uses and implicit defs are part of the MCInstrDesc data structure, which is shared by all instances of a given instruction. -Jim On Feb 17, 2013, at 2:22 PM, reed kotler <rkotler at mips.com> wrote: > If I put in my tablegen td file that a certain instruction implicitly sets a register, do I need to also do

You are right about your interpretation of "dead". The case here is that RSP is a reserved register and so its liveness isn't really tracked. The "implicit-def dead" is an idiom used to mean that the register (reserved or not) is clobbered. The other implicit uses/defs can come from instruction definitions to indicate that this instruction uses and/or modifies a given

On Aug 21, 2012, at 3:45 PM, Jakob Stoklund Olesen <stoklund at 2pi.dk> wrote: >> I don't understand what you're saying. Are you proposing that all properties (may load, store, side effects) be explicitly added to all instructions, and the pattern only be used to produce warnings? > > Yes. > > The side effect inference is worse than the load/store inference, but

Hi Hal, On Tuesday 01 October 2013 06:22 PM, Hal Finkel wrote: > ----- Original Message ----- >> Hi Hal, >> >> >> Our Architecture has indirect move instruction which increments >> the >> pointer implicitly and the target only has i8 type values. So the >> load >> of i16 will be converted to two i8 target loads wherein after the

Hi Jim, One thing that seems strange to me is that if do a BuildMI, if you put a register inside the first parens, then it will treat it as a def, but if you just .addReg it won't (by default), even though it should know from the instruction definition. Seems like it should do that. Why would you want it to not do that? Reed On 02/18/2013 01:22 PM, Jim Grosbach wrote: > Hi Reed,

On Aug 21, 2012, at 3:02 PM, Chris Lattner <clattner at apple.com> wrote: > > On Aug 21, 2012, at 2:02 PM, Jakob Stoklund Olesen <stoklund at 2pi.dk> wrote: > >> All, >> >> TableGen likes to infer the MCID::UnmodeledSideEffects flag from an instruction's pattern. When an instruction doesn't have a pattern, it is assumed to have side effects. >

----- Original Message ----- > From: "Jakob Stoklund Olesen" <stoklund at 2pi.dk> > To: "Hal Finkel" <hfinkel at anl.gov> > Cc: "LLVM Developers Mailing List" <llvmdev at cs.uiuc.edu> > Sent: Friday, April 12, 2013 11:36:49 AM > Subject: Re: [LLVMdev] TableGen list merging > > > On Apr 12, 2013, at 2:06 AM, Hal Finkel