similar to: Spare Register at one Machine Instruction

There is also the LivePhysReg facility that I would recomment if you just want to query for a free register and do not need the full feature set of the RegisterScavenger. - Matthias > On Jan 19, 2017, at 5:50 AM, Nemanja Ivanovic via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > I believe what you're after is the register scavenger. > It's in:

I'm not sure exactly what you're after. I was under the impression that you want to know which register is live at a specific point (an instruction). If that's the case, how do one of the two suggested solutions not suffice? If a register is live-in to a block and not killed before your instruction or it has a def and no kill within the block, it is live. Otherwise it is dead and

You mean when I "explicity" use it by calling methods of register scavenger? Right now I'm just allocating virtual registers that will be resolved by the use of register scavenger and I'm also providing an override of the virtual method saveScavengerRegister. In Mips16, I have an extra mips 32 register (not usually very useful since it can only be used in a move instruction)

I ran into another issue with register scavenger. In my case, I don't need a place on the stack for an emergency spill slot. I have these free mips32 registers, that are not in general very useful for other things, for the emergency spill slot. I can move to and from mips16 (subset of mips32) registers and mips32 registers. I also have a situation where I need two free registers so then

Hi, I would like to know what register scavenging is, but reading RegisterScavenging.h [1] and googling don't help too much. Could someone explain it a little bit (what it is and when we need it), or point me to some nice link, I will be very appreciated. :-) [1] http://llvm.org/docs/doxygen/html/RegisterScavenging_8h_source.html Regards, chenwj -- Wei-Ren Chen (陳韋任) Homepage:

Hi, I'm a bit unsure of the semantics of undef physical registers. The explanations I've seen in the code and in the langref seems to pertain more to constant values and virtual registers. What I really want to achieve is a push-pop of a register to have a temporary to work with, without having to check if this register is defined or not. However, whenever the reg is not defined before

Where is the liveness analysis pass? I have been looking for days but cannot find anything. I just want to know transfer variables in and out of basic blocks, that are calculated using simple data flow equations. Thanks! -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20180920/529bce15/attachment.html>

So what is the status about LiveVariables. Is there a plan to remove it? After searching in old lvm-dev-mails it is mentioned that LiveVariable still exists due to one pass needing it. And a comment in TargetPassConfig.cpp indicates that the pass in question is TwoAddressInstruction: // FIXME: Once TwoAddressInstruction pass no longer uses kill flags, // LiveVariables can be removed

> On Jan 22, 2016, at 1:23 PM, Matthias Braun <mbraun at apple.com> wrote: > >> >> On Jan 22, 2016, at 12:29 PM, Derek Schuff <dschuff at google.com <mailto:dschuff at google.com>> wrote: >> >> Here are 2 patches, which are independent of each other. >> >> The first splits PrologEpilogInserter into 2 parts :

Kalle: Your patch is similar to what I'd coded (and am testing, which means a couple of hours before I consider committing). Other than cosmetic changes and changing 'NULL' to '0' (it's an integer list, after all). This patch now causes new problems in the CellSPU backend (more stqd's and lqd's), so I have to investigate those before committing the patch.

On Feb 28, 2010, at 11:49 PM, <Kalle.Raiskila at nokia.com> <Kalle.Raiskila at nokia.com> wrote: > Jakob Stoklund Olesen skrev: >> On Feb 26, 2010, at 10:09 AM, Scott Michel wrote: >>> This patch now causes new problems in the CellSPU >>> backend (more stqd's and lqd's), so I have to investigate those >>> before committing the patch. >

Hi, I'm trying to implement my ideas about better garbage collection support [1]. The hardest problem seems to be to find all registers that are live at safe points (for example, during a call) and spilling them. Since nobody responded on the original thread, I decided to start a new thread specifically for this question. The problem is to safe registers that contain gc pointers to the stack

Thanks Quentin. I'm trying to examine from the operands of the return instruction, and then to get the last assignment of those. I thought use_iterator/reg_iterator may suit better than just loop through the machine basicblock in the reverse order. Cheng-Chih On Thu, Sep 25, 2014 at 1:51 PM, Quentin Colombet <qcolombet at apple.com> wrote: > Hi Cheng-Chih, > > On Sep 25,

Hi, I have ported LLC to a risc cpu. It can pass benchmark that I have at current. But I want do some optimization after register alloction by adjusting register using. I scan MachineBasicBlock to analyze operand's IsKill, IsDead , IsDef attribute to get a physical register's liverange. But I get a strange case at MBB.jpg. R4 is marked <kill> at MBB0. If I scan R4's

On Sep 3, 2013, at 17:21 , Manuel Jacob <me at manueljacob.de> wrote: > The problem is to safe registers that contain gc pointers to the stack > before a call and reload them after the call. Is there an Analysis Pass > that computes information about which registers are live during a > specific instruction? I looked at LiveIntervals and LiveVariables, but > they seem to be for

On Jan 14, 2010, at 6:39 PM, 任坤 wrote: > But I want do some optimization after register alloction by adjusting > register using. I scan MachineBasicBlock to analyze operand's IsKill, IsDead , IsDef attribute to get a physical register's liverange. But I get a strange case at MBB.jpg. You can also look at RegisterScavenging.cpp and MachineVerifier.cpp. They are doing the same

>It should be possible to get llvm to produce very good code for the Z80... Yes, I was thinking that too. These techniques didn't exist back then, so I'm really looking forward to the point where the first regular C sources can be compiled and see the magic happening in action live :) ------------------------------------------------------------------------ *From:* Bruce Hoult

Hi All, I have a question regarding LLVM backend. I appreciate a lot if anyone can provide some hints. My work here is to avoid base+index address mode for X86 target, to allow base-register only or index-register only address mode. For example, "mov (%rsi), %rbx" is allowed, but "mov (%rsi, %rax), %rbx" is not allowed. I understand LLVM backend is a complex system. Can any

Hi, Is there a way to print the register liveness information into the assembly file or as some intermediate listing? To be more precise, I am looking at figuring out the following information in an assembly file/listing. Say, for simplicity, our register set is only { rsp, rbp, eax } subq $16, %rsp // rsp is killed here, eax and rbp are live movl $0, -4(%rbp) // rbp is killed here,

There's an assert at line 192, lib/CodeGen/RegisterScavenging.cpp that appears to get tripped on targets that don't have subregisters defined: bool SubUsed = false; for (const unsigned *SubRegs = TRI->getSubRegisters(Reg); unsigned SubReg = *SubRegs; ++SubRegs) if (isUsed(SubReg)) { SubUsed = true; break; }