similar to: [LLVMdev] X86 Frame info question

On Wed, 9 Jun 2004, Vladimir Prus wrote: > > The X86 backend has this code: > > X86TargetMachine::X86TargetMachine(const Module &M, IntrinsicLowering *IL) > : .... > FrameInfo(TargetFrameInfo::StackGrowsDown, 8/*16 for SSE*/, 4), > > That is, it uses "4" as local area offset. Based on prior discussion this > should mean that the local

Hello, it seems the Prolog/Epilog insertion does not correctly align stack for me. Consider the PEI::calculateFrameObjectOffsets method. It only aligns the stack if FFI->hasCalls() is true. The only place where MachineFrameInfo::setHasCalls is invoked is PEI::saveCallerSavedRegisters and the value 'true' is only passed when there are instructions with opcodes equal

Hi All, I'm dealing with a problem where the spill/restore instructions inserted during scavenging span an adjustment of the SP/FP register. The result is that despite the base register (SP/FP) being changed between the spill and the restore, both store and load use the same immediate offset. I see code in the PEI (replaceFrameIndices) that is supposed to track the SP/FP adjustment:

CallFrameSetupOpcode is a pseudo opcode like X86::ADJCALLSTACKDOWN64. That means when the code is expected to be called before the pseudo instructions are eliminated. I don't know why it's not the case for you. A quick look at PEI code indicates the pseudo's should not have been removed at the time when replaceFrameIndices are run. Evan On Sep 25, 2013, at 8:57 AM, Krzysztof

Paolo Invernizzi wrote: > There was a similar problem some time ago, and was resolved with alloca. > I think it's a better solution to use the stack instead of the heap... I tend to agree, but the constructors won't get called if it's an object array -- anyway, this particular case there was no objects, just pointers and bools so alloca should be fine. I'll leave it to

Consider this example: --- ex.ll --- declare void @bar() ; Function Attrs: nounwind optsize define void @main() { entry: %hin = alloca [256 x i32], align 4 %xin = alloca [256 x i32], align 4 call void @bar() ret void } ------------- Freshly built llc: llc -O2 -march=x86 < ex.ll -print-before-all # *** IR Dump Before Prologue/Epilogue Insertion & Frame Finalization ***: #

On Mar 28, 2008, at 5:17 PM, Chuck Rose III wrote: > I was curious about the state of stack alignment on x86. I noticed > there are a few bugs outstanding on the issue. I recently added > some code which had the effect of throwing an extra function > parameter on our stack at runtime, a 4 byte pointer. > > Esp is now not 16-byte aligned, so instructions like unpcklps

Hello, the calculateFrameObjectOffsets methods in CodeGen/PrologEpilogEmitter.cpp does not work for me, since it asserts if stack grows up, and when assert is commented out, allocates spill slots in the same location as function arguments, which is not right. I've tried to fix that, and a patches. It merely adds if (StackGrowsDown) everywhere, so that the current logic should not be

The code has changed a lot over the years. Looks like at some point of time the assumption was broken. calculateCallsInformation() may have eliminated the pseudo set up instructions already. // If call frames are not being included as part of the stack frame, and

Hola LLVMers, I was curious about the state of stack alignment on x86. I noticed there are a few bugs outstanding on the issue. I recently added some code which had the effect of throwing an extra function parameter on our stack at runtime, a 4 byte pointer. Esp is now not 16-byte aligned, so instructions like unpcklps xmm1, dword ptr [eps] cause grief. My AllocaInstr instructions are

Thanks, I'll look into that. Still, the case where the function does not call anything remains---in such a situation there are no ADJCALLSTACK pseudos, so regardless of what that function you pointed at does, there won't be any target-independent information about the SP adjustment by the time the frame index elimination runs. Would it make sense to have ADJCALLSTACK pseudos every

In ARM the stack should be 8 bytes aligned during function calls. A function that has at least one function call then has a stack size of 8 bytes. PEI::calculateFrameObjectOffsets corretly computes this correctly. The problem is that the alignment is computed before adding space for the call frame size. This is done in emitProlog. Currently the ARM backend has a bug in that it doesn't align

> That is irrelevant. The PEI code needs to know how much stack space is > required for each call to allocate and align the stack frame properly. It > gets this info from the ADJCALLSTACK instructions. I see. Looking at PEI::calculateCalleeSavedRegisters shows that the ADJCALLSTACK instructions is used to set up MaxCallFrameSize. Adding debug prints also show that in the example code

On Sat, 7 Oct 2006, [UTF-8] Rafael Esp?ndola wrote: >> This sounds like the ADJCALLSTACK DOWN/UP 'instructions' around the call >> aren't set right, or you have declared a SP offset. It doesn't look like >> the ARM backend does this, so this is probably the problem. > The ARM backend currently doesn't use a frame pointer. It uses the > same technique

> This sounds like the ADJCALLSTACK DOWN/UP 'instructions' around the call > aren't set right, or you have declared a SP offset. It doesn't look like > the ARM backend does this, so this is probably the problem. The ARM backend currently doesn't use a frame pointer. It uses the same technique of the PPC backend to avoid add/subs around calls. In the PPC backend we

Hello, I'd like to upstream our work over the time which the community would benefit from. This is a part of effort toward minimizing code size presented in here <https://llvm.org/devmtg/2020-02-23/slides/Kyungwoo-GlobalMachineOutlinerForThinLTO.pdf>. In particular, this RFC is about optimizing prolog and epilog for size. *Homogeneous Prolog and Epilog for Size Optimization, D76570

Hi, I'm looking for some pointers on how to troubleshoot this problem. I'm trying to write a backend for the AVR. There is an undefined reference at line 48 which is the line FrameInfo() is on. I've tried to use the MSP430 and other targets as references so I'm not sure what changes I did would cause a problem on this line? AVRTargetMachine::AVRTargetMachine(const Target &T,

Hi Vedant, Thanks for your interest and comment. Size-optimization improves page-faults and a start-up time for a large application, which this enabling also followed. Even though I didn't see a large regression/complaint on a CPU-bound case, which is not a typical case for mobile workload, I wanted to be precautious of enabling it by default. However, as with default outlining case, I

I started to implement inlining of the stack probe function based on Microsoft's inlined stack probes in https://github.com/Microsoft/llvm/tree/MS. Do we know why the stack pointer cannot be updated in a loop (which results in ideal code)? I noticed that was commented in Microsoft's code. I suspect this is due to debug or unwinding information, since it is allowed on Windows x86-32. I

On 6/24/20 11:21 AM, Matt Arsenault via llvm-dev wrote: > > >> On Jun 24, 2020, at 14:13, Arthur Eubanks via llvm-dev >> <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote: >> >> Hi, >> >> As part of new pass manager work, I've been trying to get something >> like `opt -foo` working under the NPM, where `foo` is