similar to: [LLVMdev] Possible bug in ScalarEvolution

Hi, Scalar evolution seems to be wrapping around the trip count in the following loop. void add (int *restrict a, int *restrict b, int *restrict c) { char i; for (i = 0; i < 255; i++) a[i] = b[i] + c[i]; } When I run scalar evolution on the bit code, I get a backedge-taken count which is obviously wrong. $> cat loop.ll ; Function Attrs: nounwind define void @add(i32* noalias

Hi, Seems pass scalar-evolution+indvars fail to get the loop trip count of the following case: int foo(int x, int y, int lam[256], int alp[256]) { int i; int z = y; for (i = 255; i >= 0; i--) { z += x; lam[i] = alp[i]; } return z; } The final optimized ll code is : define i32 @foo(i32 %x, i32 %y, i32* %lam, i32* %alp) nounwind { entry: br label %bb bb:

> > > Having the final .ll file doesn't help debug this. If you run opt > -analyze -scalar-evolution on the .ll you pasted, it will correctly > print out the loop trip count. > > I've modified llvm-gcc to remove all the passes after indvars. > > I updated my llvm and now it works. >> > Surely the loop trip count is 256, but the Loop::getTripCount()

Hi, I found issues with INDVARS <-> LSR passes interactions after https://reviews.llvm.org/rL346397. There were two main changes in this commit: 1. Previously we were propagating SCEV add expressions even if DefInst of exit value has hard uses inside the loop. After rL346397 we forbid propagation of SCEV add expressions if DefInst of exit value has hard use inside the loop. 2. Previously

On Mon, Sep 21, 2015 at 11:13 AM, Wei Mi <wmi at google.com> wrote: > Maybe it can follow the "Delete dead loops" pass which is after > Induction Variable Simplification pass, so it will not affect existing > exitvalue rewriting optimization in Induction Variable Simplification > to find out and delete dead loops? > > Existing pass pipeline: >

Hi, At the n2k10 OpenBSD network hackathon, I finally got some time to clean up and rewrite the ssh(1) client multiplexing code. The attached diffs (one for portable OpenSSH, one for OpenBSD) are the result, and they need some testing. The revised multiplexing code uses a better protocol between the master and slave processes and I even bothered to write it up :) It tracks the control sockets

This patch introduces a new generic queue spinlock implementation that can serve as an alternative to the default ticket spinlock. Compared with the ticket spinlock, this queue spinlock should be almost as fair as the ticket spinlock. It has about the same speed in single-thread and it can be much faster in high contention situations especially when the spinlock is embedded within the data

v6->v7: - Remove an atomic operation from the 2-task contending code - Shorten the names of some macros - Make the queue waiter to attempt to steal lock when unfair lock is enabled. - Remove lock holder kick from the PV code and fix a race condition - Run the unfair lock & PV code on overcommitted KVM guests to collect performance data. v5->v6: - Change the optimized

v6->v7: - Remove an atomic operation from the 2-task contending code - Shorten the names of some macros - Make the queue waiter to attempt to steal lock when unfair lock is enabled. - Remove lock holder kick from the PV code and fix a race condition - Run the unfair lock & PV code on overcommitted KVM guests to collect performance data. v5->v6: - Change the optimized

Hi Folks, Let's keep this optimization alive. To summarize: several folks voiced general support, but with questions about why existing optimizations do not already catch this case. Deep dive by Wei Mi showed that the optimization is most likely not a clean-up of LSR sloppiness, but something new. Follow-up by myself confirmed that the redundancy eliminated the LoopExitValues pass exists in

https://bugzilla.samba.org/show_bug.cgi?id=1652 Summary: rsync --timeout=n -> if timeout occurs, exits with no exitvalue Product: rsync Version: 2.6.0 Platform: x86 OS/Version: All Status: NEW Severity: normal Priority: P3 Component: core AssignedTo: wayned@samba.org

Hi all, first of all: Sorry for my bad englis, and now the Question: I have some problems with running R from Java. First i tried using rJava (JRI). But the examples didnt work properly. Now im trying to establish a connection by using Rserve and JRclient (RF503). I have the following code, which i`ve found: ------------------------------------------------------------------------ public

Dear All, Is the following patch to ScalarEvolution correct? It seems that without it, the enclosing for loop could skip over SCEVAddRecExpr's in the Ops[] array. -- John T. -------------- next part -------------- An embedded and charset-unspecified text was scrubbed... Name: scpatch URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20080222/3ff8edd7/attachment.ksh>

v7->v8: - Remove one unneeded atomic operation from the slowpath, thus improving performance. - Simplify some of the codes and add more comments. - Test for X86_FEATURE_HYPERVISOR CPU feature bit to enable/disable unfair lock. - Reduce unfair lock slowpath lock stealing frequency depending on its distance from the queue head. - Add performance data for IvyBridge-EX CPU.

v7->v8: - Remove one unneeded atomic operation from the slowpath, thus improving performance. - Simplify some of the codes and add more comments. - Test for X86_FEATURE_HYPERVISOR CPU feature bit to enable/disable unfair lock. - Reduce unfair lock slowpath lock stealing frequency depending on its distance from the queue head. - Add performance data for IvyBridge-EX CPU.

N.B. Sorry for the duplicate. This patch series were resent as the original one was rejected by the vger.kernel.org list server due to long header. There is no change in content. v7->v8: - Remove one unneeded atomic operation from the slowpath, thus improving performance. - Simplify some of the codes and add more comments. - Test for X86_FEATURE_HYPERVISOR CPU feature bit

N.B. Sorry for the duplicate. This patch series were resent as the original one was rejected by the vger.kernel.org list server due to long header. There is no change in content. v7->v8: - Remove one unneeded atomic operation from the slowpath, thus improving performance. - Simplify some of the codes and add more comments. - Test for X86_FEATURE_HYPERVISOR CPU feature bit

Hi! I would appreciate some feedback from someone with experience in SCEV/SE. D39346 tries to fix an issue in LV (PR34965) that exposes a limitation in SCEV/SE. The best solution to the LV issue might not be a fix at SCEV/SE level but we may want to report/address SCEV/SE limitation as well. For the snippet below, LV expects SE to return a SCEVAddRecExpr for %21. However, SE returns ((4 * (zext

Ever since a recent power failure I have been getting a Logrotate error. My machine is on a UPS -- it shutdown cleanly, but I suspect that its BIOS/RTC battery is dead, since the machine came up thinking it was 1982 :-(. I reset the clock and everything is fine, *except* I had to delete Logrotate's state files (which had bad dates). But now Logrotate is raising the error: error: error

Thanks for the feedback, Sanjoy. > SCEV is fairly conservative around PHI nodes that aren't recurrences and aren't obviously equivalent to a min-max branch-phi idiom. Is that the limitation you're running into here? Yes, that's exactly the problem. The problematic PHI nodes (%bc.resume.val and %bc.resume.val1) aren't either recurrences or related to min-max idioms. I