similar to: [LLVMdev] Loop unswitching creates dead code

Hi, I would like to test a sorting method that is in the user model, it''s a class method called search. What I would like to do is create 2 users and load the test database with just those 2 users, so that I can call User.search("john") and it would return those two users. Not sure how to clear the test database and populate it just with these 2 users for that specific

For void test0(unsigned short a, unsigned short * in, unsigned short * out) { for (unsigned short w = 1; w < a - 1; w++) //this will never overflow out[w] = in[w+7] * 2; } I think it will be sufficient to add a couple of new cases to ScalarEvolution::HowManyLessThans -- zext(A) ult zext(B) == A ult B sext(A) slt sext(B) == A slt B Currently it bails out if it sees a non-add

On 5/10/2018 10:44 PM, Gopalasubramanian, Ganesh via llvm-dev wrote: > > Hi, > > I am going through analysis on unswitching + vectorization. > > For the below test, llvm unswitches successfully but fails to > vectorize the loop after unswitching. > > Llvm bails out saying “Found an outside user” apparently which is the > value of ‘tmp’. > > int i, w, x[1000],

Hi, I am going through analysis on unswitching + vectorization. For the below test, llvm unswitches successfully but fails to vectorize the loop after unswitching. Llvm bails out saying "Found an outside user" apparently which is the value of 'tmp'. int i, w, x[1000], y[1000],tmp; void fn() { for (i = 0; i < 1000; i++) { if (w==1) { y[i] = 1; tmp = i*2; }

* Looks like some sort of pass ordering issue; it will vectorize if indvars runs sometime between loop unswitch and the vectorizer. That insight is helpful. I scheduled Canonicalization of induction variable before loop vectorization and could get the loop vectorized. The indvars are heavily dependent on SCEV. If there a scalar like tmp which is of real type, we may not be able to get the

Hi, This is somewhat similar to the previous thread regarding missed vectorization opportunities (http://lists.cs.uiuc.edu/pipermail/llvmdev/2015-April/084765.html), but maybe different enough to require a new thread. I'm seeing some missed vectorization opportunities in the loop vectorizer because SCEV is not able to fold sext/zext expressions into recurrence expressions (AddRecExpr). This

I am investigating changing BoundsChecking to use address-based rather than size- & offset-based tests. To explain, here is a short code sample cribbed from one of the tests: %mem = tail call i8* @calloc(i64 1, i64 %elements) %memobj = bitcast i8* %mem to i64* %ptr = getelementptr inbounds i64* %memobj, i64 %index %4 = load i64* %ptr, align 8 Currently, the IR for bounds checking

I am using the shovel deploy.rb from http://nubyonrails.com/pages/shovel I have SwitchTower-ized my app, copied the shovel deploy.rb file and put my settings in it. But when I run "rake remote_exec ACTION=setup_lighty" from the local app root it has no effect. It should prompt for a password for at least throw an error? I just get returned to the DOS prompt. If I do "rake

If I give instcombine the following IR: define i1 @f([1 x i8]* %a, [1 x i8]* %b) { %c = getelementptr [1 x i8]* %a, i32 0, i32 0 %d = getelementptr [1 x i8]* %b, i32 0, i32 0 %cmp = icmp ult i8* %c, %d ret i1 %cmp } It optimizes it into: define i1 @f([1 x i8]* %a, [1 x i8]* %b) { %cmp = icmp slt [1 x i8]* %a, %b ret i1 %cmp } Is this a bug, or are there some semantics of icmp

Hi Kevin, Thanks for your interest and for your deep analysis. Unfortunately, your approach doesn't catch all bugs and is vulnerable to an attack. Consider the following case: ...................... | ----- obj --- | | end ^ ptr ^ ^ end-of-memory The scenario is as follows: - an object is allocated in the last page of the address space - obj is byte

Hi, I am investigating a performance degradation between llvm-3.1 and llvm-3.2 (Note: current top-of-tree shows a similar degradation) One issue I see is the following: - 'loop invariant code motion' seems to be depending on the result of the 'reassociate expression' pass: In the samples below I observer the following behavior: Both start with the same expression: %add = add

I have one of those new little NUC's and installed Centos 7.1 on it. lspci shows 00:00.0 Host bridge: Intel Corporation Haswell-ULT DRAM Controller (rev 09) 00:02.0 VGA compatible controller: Intel Corporation Haswell-ULT Integrated Graphics Controller (rev 09) 00:03.0 Audio device: Intel Corporation Haswell-ULT HD Audio Controller (rev 09) 00:14.0 USB controller: Intel Corporation 8 Series

It's an interesting problem. The best stuff I've seen published is by Cooper, Eckhart, & Kennedy, in PACT '08. Cooper gives a nice intro in one of his lectures: http://www.cs.rice.edu/~keith/512/2012/Lectures/26ReassocII-1up.pdf I can't tell, quickly, what's going on in Reassociate; as usual, the documentation resolutely avoids giving any credit for the ideas. Why is that?

Example: define i8 @narrow_add(i8 %x, i8 %y) { %x32 = zext i8 %x to i32 %y32 = zext i8 %y to i32 %add = add nsw i32 %x32, %y32 %tr = trunc i32 %add to i8 ret i8 %tr } With no data-layout or with an x86 target where 8-bit integer is in the data-layout, we reduce to: $ ./opt -instcombine narrowadd.ll -S define i8 @narrow_add(i8 %x, i8 %y) { %add = add i8 %x, %y ret i8 %add } But on

As far as I can understand of the code, the Reassociate tries to achieve this result by its "ranking" mechanism. If it dose not, it is not hard to achieve this result, just restructure the expression in a way such that the earlier definition of the sub-expression is permute earlier in the resulting expr. e.g. outer-loop1 x= outer-loop2 y =

Thanks for the perf testing. I assume that DAG legalization is equipped to handle these cases fairly well, or someone would've complained by now... FWIW (and at least some of this can be blamed on me), instcombine already does the narrowing transforms without checking shouldChangeType() for binops like and/or/xor/udiv. The justification was that narrower ops are always better for

On Apr 25, 2013, at 10:51 AM, Preston Briggs <preston.briggs at gmail.com> wrote: > It's an interesting problem. > The best stuff I've seen published is by Cooper, Eckhart, & Kennedy, in PACT '08. > Cooper gives a nice intro in one of his lectures: http://www.cs.rice.edu/~keith/512/2012/Lectures/26ReassocII-1up.pdf > I can't tell, quickly, what's going on

Hi, I'm working on OpenCL and I'm using clang as compiler (based on clang 3.7.0). I have a issue, I'm generating a bitcode file (that I can print before before the generation). But when I'm trying to read it again with clang, I have this issue: "error: Invalid record" How can I managed to know where it comes from? Thank you, Romaric Here is what is print before the

Hi David, My question is: why both #ifdef and #else branches are missing? I think at least one of the two should be present... In fact there is a case where the width could be greater then PNG_USER_WIDTH_MAX but not greater then PNG_UINT_31_MAX. That's why I was expecting at least one of the two... Thanks Alberto On Wed, Dec 18, 2019, 22:12 David Blaikie <dblaikie at gmail.com>

Hello Thanks for looking into this. I can't be very confident what the knock on result of a change like that would be, especially on architectures that are not Arm. What I can do though, is run some benchmarks and look at that results. Using this patch: --- a/lib/Transforms/InstCombine/InstructionCombining.cpp +++ b/lib/Transforms/InstCombine/InstructionCombining.cpp @@ -150,6 +150,9 @@