similar to: RFC] Shrink-wrapping improvement

Hi Francis, Thanks for getting back to me. Could you please provide more details about the problems you encounter with those tools and what improvements required to improve compact unwinding format? Most of my experience is in the mid end, but it is still surprising to me that an improved shrink wrap will break that many tools, considering the fact that gcc has a good shrink wrapping pass and

Hi all, We've seen several examples recently of performance opportunities on POWER if we can improve the location of save/restore code for callee-saved registers. Both Nemanja and myself have discussed this with several people, and it seems that there are two possibilities for improving this: 1. Extend shrink wrapping to make the analysis of callee-saved registers more precise. 2.

Hello Momchil, (CC’ing more people that could correct me if I’m wrong) Thanks for looking into this. More answers below: > On 9 Apr 2018, at 17:57, Momchil Velikov via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > Hello, > > So, I have this testcase: > > void f(int n, int x[]) { > if (n < 0) > return; > > int a[n]; >

Thanks for sharing the known problem. I think to solve the problem properly, we need to fully understand why that assumption about dominance is there and the implications of removing it. It would be good if you could be more specific about your idea of nullptr or SCEV_unknown (eg which function would return those values and when), but returning nullptr from getAddExpr or getSCEVAtScope may be

Hi All, I wrote a very crude and simple AsmParser for my backend. llvm-tablegen also generates asm-matcher .inc file without any error. I have included the .inc file in my class for AsmParser. However, while building llvm, in linking stage for LTO, i am getting error - undefined reference to functions - ComputeAvailableFeatures, MatchInstructionImpl, MatchRegisterName and

Hello, So, I have this testcase: void f(int n, int x[]) { if (n < 0) return; int a[n]; for (int i = 0; i < n; i++) a[i] = x[n - i - 1]; for (int i = 0; i < n; i++) x[i] = a[i] + 1; } that, compiled with -O1/-Os for AArch64 and X86, generates machine code, which fails to properly restore the stack pointer upon function return.

Hi Jimmy, It's good to know that the problem is not specific to the case I ran into. May be you can provide your example as well, since Philip seems to be interested in some specific examples. If the assertion in getAddrExpr is deemed necessary, then I think a condition check would be the next best solution as it helps client code guard against such cases and make alternative arrangements to

Hi LLVM developers, llc -march=mips -debug-only=isel was able to work in Nov 8 2017 https://reviews.llvm.org/D39723 But it doesn't work now: $ clang --version LLVM China clang version 6.0.0 (git at github.com:llvm-mirror/clang.git 9b7b03045ee9b5622028537266aafeb9ea218ac1) (git at github.com:llvm-mirror/llvm.git 3a26601a88394c02603b8756527c55df9ab94d78) (based on LLVM 6.0.0svn) Target:

Cool this is better than I expected - I never thought about the YAML support. And the document reference is really very good. Thanks Francis, MartinO -----Original Message----- From: Francis Visoiu Mistrih [mailto:francisvm at yahoo.com] Sent: 05 February 2018 21:43 To: Martin J. O'Riordan <MartinO at theheart.ie> Cc: LLVM Developers <llvm-dev at lists.llvm.org>; Adam Nemet

Hi, We have a significant regression since llvm 5.0.0 in the x86 assembler. The following snippets fail: 1) .intel_syntax 0: jmp 0b 2) .intel_syntax and edi, 0b010101 when running through `llvm-mc -arch x86-64`. This regression was introduced in r301390, which was driven by PR27884. I think https://llvm.org/PR36144 describes this very well, and I think we should get this fixed, since

Hi Martin, > On Feb 5, 2018, at 11:46 AM, Martin J. O'Riordan via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > I would like to be able to emit a list of functions by name and their fixed stack reservation size information, so that a programmer can gauge how much stack they are likely to need in tightly constrained embedded systems. Despite the rich number of options, the

> I'm not following your example.  If you have two sibling loops with the same parent, one will frequently, but not always dominate the other.  Can you give a specific example of when forming a recurrence between two siblings (without one dominating the other), is useful? The situation can happen with guarded loops or with a user guard like below: if (c) { for (i = 0; i < n; i++)

Hi Adam, Thanks for your input. If I understand correctly, you’re saying that we can handle the loop versioning issue by explicitly identifying new loops as they are created. So, the unswitching optimization, for example, would report that it unswitched loop-0 at source location X, creating loop-1 and loop-2, and then later the vectorizer would report that it was unable to vectorize loop-1 at

Thanks for the details! How should we think of the case where an instruction has memory operands (in the sense that X86II::getMemoryOperandNo >=0), but doesn't have MachineMemOperands? I'm seeing an example in the case of __builtin_prefetch (lowered via SelectionDAG::getMemIntrinsicNode, which produces a MachineMemOperand) vs __builtin_ia32_gatherpfdpd, lowered through getPrefetchNode

I would like to be able to emit a list of functions by name and their fixed stack reservation size information, so that a programmer can gauge how much stack they are likely to need in tightly constrained embedded systems. Despite the rich number of options, the only option I can find that is even relatively close is: -warn-stack-size=<uint> Is there some existing way of getting this

Hello everyone, In the file *lib/CodeGen/AsmPrinter/AsmPrinter.cpp*, I would like to obtain an MCInst corresponding to its MachineInstr. Can anyone tell me a way to do that? If that is not possible, then, I would like to know if a given MachineInstr is an *lea *instruction and I would like to know if the symbol involved with this lea instruction is a jump-table. For instance, given a

Hello Mircea, > On 8 Mar 2018, at 18:52, Mircea Trofin via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > Hello, > > I'm trying to understand the relationship between MachineMemOperand and, on X86, memory operands of machine instructions. The latter seem to be operands held in order by the MachineInstr, from an offset onwards - Base, Scale, Index, Displacement,

Hello all, During the compilation process, LLVM automatically derives various attributes about functions and values (for example that a pointer is nonnull, a function is constant, etc) that are used within a translation unit. I propose adding a pass to LLVM that allows front-ends to output derived attributes. Such a pass would be useful both for developers and end users to debug programs,

Hi, I'm new to llvm and am trying to run benchmarks from the test-suite using lnt to check loop-vectorization for various benchmarks. Test are compiling and executing fine, but I am not getting optimization remarks while using flags like -Rpass-missed=loop-vectorize and -Rpass-analysis=loop-vectorize I've tried running it like this: lnt runtest test-suite --sandbox SANDBOX --cc

Hello, I'm trying to understand the relationship between MachineMemOperand and, on X86, memory operands of machine instructions. The latter seem to be operands held in order by the MachineInstr, from an offset onwards - Base, Scale, Index, Displacement, Segment. The former, if I understand it correctly, is used to hold a relationship back to IR load/store instructions. Is it possible to have