search for: pessimisations

On Wed, Feb 20, 2013 at 12:39 PM, Chris Lattner <clattner at apple.com> wrote: > On Feb 20, 2013, at 8:40 AM, David Blaikie <dblaikie at gmail.com> wrote: > > Sure, if you're willing to sacrifice the possible simplification of all > indirect calls in any function that has even one nobuiltin requirement. > > I don't understand what you mean by this. > 1)

On Feb 20, 2013, at 8:40 AM, David Blaikie <dblaikie at gmail.com> wrote: > Sure, if you're willing to sacrifice the possible simplification of all indirect calls in any function that has even one nobuiltin requirement. > I don't understand what you mean by this. > 1) annotate calls > Pro: you can inline calls without pessimizing the function you inline into > Con:

On 10 May 2014, at 16:18, Tim Northover <t.p.northover at gmail.com> wrote: > Actually, I really agree there. I considered it recently, but decided > to leave it as an intrinsic for now (the new IR expansion pass happens > after most optimisations so there wouldn't be much benefit, but if we > did it earlier and the mid-end understood what an ldrex/strex meant, I > could

Hi all, I have been looking at the `DependenceAnalysis` pass in `llvm/include/llvm/Analysis/DependenceAnalysis.h`. In order for this analysis to produce accurate dependence vectors for multi-dimensional arrays in nested loops, it needs to "delinearize" array element accesses to recover the subscripts in each dimension of the array. I believe that the current implementation of

Hi all, I've been making a number of changes to the summary representation recently, and I wanted to lay out some of my plans so that folks are aware of my ultimate direction with this. Basically I want to move the summary into the irsymtab that we will be storing to disk after D32061 lands. This would help solve a number of problems: - To read a summary, you need to read all summaries in a

...program compiled with -fhosted. With the proposed rule, the loop idiom recognizer may transform the body of the memset function into a self-call. So that leaves either compile in freestanding or error out. Freestanding would produce a conservatively correct result, but it may lead to unintentional pessimisations, so unless we error out we'd likely want to warn on mixed. In principle erroring out could break existing builds, but I suppose these builds are already wrong in LTO mode, so it may not matter. In my view the higher order bit is resolved: we should not support mixed hosted/freestanding "w...

Hi, On Wed, Jul 12, 2017 at 2:21 AM, Rui Ueyama via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > Thanks, Bruce. This is a very interesting optimization. > > lld doesn't currently have code to support that kind of code shrinking > optimization, but we can definitely add it. It seems that essentially we > need to iterate over all relocations while rewriting

Hi, i would like to ask you, if i can get a lower-level representation than the llvm IR.For example, having the following instruction in the llvm IR, call void @llvm.memcpy.i32(i8* %19, i8* getelementptr inbounds ([2 x [2 x [3 x i8]]]* @main.s, i32 0, i32 0, i32 0, i32 0), i32 12, i32 1) i would like to get something like this (in A-normal form (without nested instructions):%temp = i8*

Hi David, Thank you very much for your response. I also get correct results for my example (for a 64-bit target) if the upper bounds are changed to unsigned. The reason is simply because clang zero-extends `m` for address calculations but sign-extends it for the loop upper bound. This prevents SCEV from canceling out the 'm' term from the difference expression that looks like `(-3 +

On Mon, May 1, 2017 at 11:06 AM, Mehdi AMINI <joker.eph at gmail.com> wrote: > > > 2017-04-25 12:11 GMT-07:00 Peter Collingbourne <peter at pcc.me.uk>: > >> Hi all, >> >> I've been making a number of changes to the summary representation >> recently, and I wanted to lay out some of my plans so that folks are aware >> of my ultimate

On 10 May 2014, at 18:14, Tim Northover <t.p.northover at gmail.com> wrote: >> The easiest solution would be to extend the cmpxchg instruction with a >> weak variant. It is then trivial to map load, modify, weak-cmpxchg to >> load-linked, modify, store-conditional (that is what weak cmpxchg was >> intended for in the C[++]11 memory model). > > That would

Hi Peter, This is a great proposal, thanks!. If you were worried about making the abi change have you thought about just going for an array of symbol names or hashes of symbol names where any matching symbol is considered address significant? This would sidestep the problem of keeping the symbol table indices in sync. It would be pessimistic for local symbols if the input SHT_ADDRSIG sections

Hello Under the proviso that it's been a while since I looked into any of these things... On 05/15, Bardia Mahjour via llvm-dev wrote: > I also get correct results for my example (for a 64-bit target) if the upper > bounds are changed to unsigned. The reason is simply because clang zero-extends > `m` for address calculations but sign-extends it for the loop upper bound. This >

Hi, I found many references on the Web to the fact that "Rails is not thread-safe". However, I have not found an explanation _why_ it isn''t? What happens if multiple requests are handled concurrently by ActionPack? Assuming that the code I execute in my controller methods is thread safe, is this ok? If not -- what happens? The following makes it sound like the issue is

On 9 August 2017 at 19:38, Friedman, Eli <efriedma at codeaurora.org> wrote: > On 8/9/2017 9:11 AM, Alex Bradbury via llvm-dev wrote: >> >> Option 3: Teach va_arg to handle aggregates >> * In this option, va_arg might reasonably be expected to handle a >> struct, >> but would not be expected to have detailed ABI-specific knowledge. e.g. >> it

+Eric and Akira (for thoughts on module flags) > On 2016-Sep-16, at 12:47, Mehdi Amini <mehdi.amini at apple.com> wrote: > >> On Sep 16, 2016, at 12:30 PM, Peter Collingbourne <peter at pcc.me.uk> wrote: >> >> In PR30403 we've been discussing how to encode -ffreestanding when using LTO. This bit is currently dropped during LTO because its only

Hello Yes, I agree that the SCEV cannot be simplified. Is my understanding correct that it is passed to a function like "isKnownNegative"? Which could still be able to prove is always true. The delinearisation may be valid, depending on exactly how you define delinearisation (under what conditions it should be giving results). It would be invalid for DA to return a dependency of [0

This time around, the numbers are indeed looking better than in v1; and I like the interface better. Eric Blake (2): server: Prefer send() over write() server: Group related transmission send()s server/internal.h | 7 +++- server/connections.c | 51 +++++++++++++++++++++++++--- server/crypto.c | 11 ++++--

Hi all, Context: ld.gold has an --icf=safe flag which is intended to apply ICF only to sections which can be safely merged according to the guarantees provided by the language. It works using a set of heuristics (symbol name matching and relocation scanning). That's not only imprecise but it only works with certain languages and is slow due to the need to demangle symbols and scan

On Fri, May 29, 2020 at 4:00 PM Richard Smith <richard at metafoo.co.uk> wrote: > > On Fri, 29 May 2020 at 11:06, John McCall via llvm-dev <llvm-dev at lists.llvm.org> wrote: >> >> On 28 May 2020, at 18:42, Bill Wendling wrote: >> >> > On Tue, May 26, 2020 at 7:49 PM James Y Knight via llvm-dev >> > <llvm-dev at lists.llvm.org> wrote: