search for: requiresregisterscaveng

...test case failures are due to this - not bad code or asserts). But inserting redundant code ofcourse bloats the generated code... Would it be possible to conditionally enable the register scavenger only if the function has a big stack? It now gets unconditionally enabled in SPURegisterInfo::requiresRegisterScavenging(const MachineFunction &MF). Just checking MF.getFrameInfo()->getStackSize() here doesn't seem to be the solution... kalle -------------- next part -------------- An embedded and charset-unspecified text was scrubbed... Name: bigstack.ll URL: <http://lists.llvm.org/pipermail/llv...

Hello > Would it be possible to conditionally enable the register scavenger only if > the function has a big stack? It now gets unconditionally enabled in >  SPURegisterInfo::requiresRegisterScavenging(const MachineFunction &MF). > Just checking MF.getFrameInfo()->getStackSize() here doesn't seem to be the > solution... Well, I think no. regscavenger should work well regardless of any settings. Currently it's heavily used for ARM, so, you might want to look how the stuff i...

I would like to maintain the livein information for physical registers on basic blocks past register allocation, or recreate it if possible. The goal is to be able to run a late pass of DeadMachineInstrElim, which requires valid livein information. The X86 target returns false for requiresRegisterScavenging so passes like BranchFolding don't update the livein information. At that point I gather that DeadMachineInstrElim will break. What are the requirements to return true for requiresRegisterScavenging? ARM does but I don't know if special care has been taken in that target to allow it....

Hi! I started writing a LLVM backend for a custom architecture. I have some register and instruction .td files and some other files/classes like a MCStreamer for assembler output. At the moment I can compile some empty programs so far. I implemented the method ::eliminateFrameIndex() similar to the Sparc and ARM backend. The method looks like this: // frame pointer is in reg of class

Thanks Jon and Hal for the helpful pointers. By returning true from requiresRegisterScavenging() and requiresFrameIndexScavenging(), LLVM handled all the scavenging effort. That is nearly painless for the target, so why do some targets seem to do scavenging on their own? When the scavenged register is loaded with a simple immediate, is it safe to search the BB and replace other uses of...

Hello all, For my custom processor backend I am trying add some instruction using BuildMI() inside eliminateFrameIndex(). I tried RegScavenger like this: unsigned RegUnused0 = RS->FindUnusedReg(&LASER::GNPRegsRegClass); if (!RegUnused0) RegUnused0 = RS->scavengeRegister(&LASER::GNPRegsRegClass, II, SPAdj); assert(RegUnused0 && "Register scavenger failed");

On 1/29/15 2:00 PM, Steve King wrote: > Hello LLVM, > The ARM target sometimes adds an instruction with a virtual register > in eliminateFrameIndex(): > > https://github.com/llvm-mirror/llvm/blob/master/lib/Target/ARM/ARMBaseRegisterInfo.cpp > > This looks late for a virtual register to appear. Where is this vreg made real? The register scavenger should take care of such

...steve at metrokings.com> > To: jonathan at codesourcery.com > Cc: llvmdev at cs.uiuc.edu > Sent: Friday, January 30, 2015 10:52:19 AM > Subject: Re: [LLVMdev] creating a vreg in eliminateFrameIndex() > > Thanks Jon and Hal for the helpful pointers. By returning true from > requiresRegisterScavenging() and requiresFrameIndexScavenging(), LLVM > handled all the scavenging effort. That is nearly painless for the > target, so why do some targets seem to do scavenging on their own? Some of the targets pre-date the introduction of that feature. > > When the scavenged register is l...

On Feb 22, 2010, at 6:08 AM, Kalle.Raiskila at nokia.com wrote: > Hello all, > > currently the SPU backend does not handle big stack frames (>16*511 > bytes) nicely. llc asserts on malformed machine instructions. > (Assertion `MI->getOperand(OpNo).isImm() && "printDFormAddr first > operand is not immediate") Sounds fine to me in general. Please write a

Hello LLVM, The ARM target sometimes adds an instruction with a virtual register in eliminateFrameIndex(): https://github.com/llvm-mirror/llvm/blob/master/lib/Target/ARM/ARMBaseRegisterInfo.cpp This looks late for a virtual register to appear. Where is this vreg made real? Thanks, -steve

I need to use ‘createVirtualRegister’ for a specific case in my ‘eliminateFrameIndex’ function implementation. However, whenever that code is executed, I get the assertion "MachineCopyPropagation should be run after register allocation!” at a later stage. I have seen that at least a couple of backend implementations (including ARM Thumb) create virtual registers in ‘eliminatedFrameIndex’.

Hello all, currently the SPU backend does not handle big stack frames (>16*511 bytes) nicely. llc asserts on malformed machine instructions. (Assertion `MI->getOperand(OpNo).isImm() && "printDFormAddr first operand is not immediate") E.g. the function: define i32 @foo() nounwind { entry: %retval = alloca i32 %big_data = alloca [1000 x i32] store i32 3840, i32*