similar to: [IR question] Switching on pointers

Thanks everyone for your answers. Mats, my goal is do an alternate implementation of the subtyping test in the Pony compiler. I'll try to keep the explanation short to avoid cluttering the mail with irrelevant information. Every object in Pony has a type descriptor, which is used in the subtyping test to determine the real type of an object. The current algorithm is suboptimal and

Hi, guys! I write a virtual machine which uses LLVM as back-end code generator. The following function code causes strange "UNREACHABLE executed!" error: define void @p1(%1*) { %2 = call i8* @llvm.stacksave() %3 = alloca %0 %4 = getelementptr %0* %3, i64 1 %5 = ptrtoint %0* %3 to i64 %6 = ptrtoint %0* %4 to i64 %7 = sub i64 %6, %5 %8 = bitcast %0* %3 to i8* call void

Here's a version that doesn't try to do block deletion on it's own. If you use -adce then -simplifycfg, you get what you want. It passes all tests except one, which is that we delete an invoke of a pure function, IE Transforms/ADCE/dce_pure_invoke.ll - I'm not sure why that's bad. The reason we delete it is because it returns false to I.mayHaveSideEffects(), and in particular,

Hi R-users, I'm trying to retrieve data from MS SQL database with RODBC's sqlQuery-function: temp <- sqlQuery(channel,"select *, (select text from table1 where koodi='paa' and koodi2=paa) as tempor from table2") str(temp) … $ var0 : num NA NA 1.6 NA NA 1.4 NA 1 NA NA ... $ var1 : Factor w/ 45 levels "

Hi, Recently 10% performance regression on an important benchmark showed up after we integrated https://reviews.llvm.org/rL318299. The analysis showed that rL318299 triggered loop rotation on an multi exits loop, and the loop rotation introduced code layout issue. The performance regression is a side-effect of rL318299. I got two testcases a.ll and b.ll attached to illustrate the problem. a.ll

On Mon, Dec 18, 2017 at 5:46 PM Xinliang David Li <davidxl at google.com> wrote: > The introduction of cleanup.cond block in b.ll without loop-rotation > already makes the layout worse than a.ll. > > > Without introducing cleanup.cond block, the layout out is > > entry->while.cond -> while.body->ret > > All the arrows are hot fall through edges which is

I'm going to show the same function, first normally, and then as a coroutine, and show how gdb can see the variable when it's a normal function, but not when it's a coroutine. I'd like to understand if this can be improved. I'm trying to debug a real world problem, but the lack of debug info on variables in coroutines is making it difficult. Should I file a bug? Is this a

Hello all, There is a missing vectorization opportunity issue with clang 4.0 with the file attached. Indeed, when compiled with -O2, the "op_distance" function get vectorized, but not the "op" one. For information, this test case has been reduced from a file generated by the Pythran compiler (https://github.com/serge-sans-paille/pythran). If we take a look at the generated

Hello, I have a minimal testcase which crashes RegisterCoalescer in my out-of-tree target. It only crashes in Debug builds of llc---not in Release builds. Also, interesting to note that the x86 backend lowers this same testcase successfully. I did a quick search of bugs.llvm.org and found no matches. This implies that the problem is in my backend and/or how my backend interacts with

Hi, I am trying to figure out how to read arguments of a call instruction. I had few questions based on that I have the following C Code 1 #include <stdio.h> 2 3 struct my_struct 4 { 5 int a; 6 int b; 7 }; 8 9 struct my_struct abc; 10 void p_ptr ( unsigned long j) 11 { 12 printf ( "%lx \n", j ); 13 } 14 15 void struct_ptr ( struct my_struct *

Note that I've set the SA_NODEFER flag for the SEGV handler in the ASan runtime only a couple of days ago. Not sure that could've affected this test though; without that flag the second SEGV would've simply crashed the program. But you can try removing the flag from compiler-rt/trunk/lib/sanitizer_common/sanitizer_posix_libcdep.cc and see if that makes any difference. HTH, Alex On

Using LLVM ToT and Hal's helpful slide deck [1], I've been trying to use `llvm.assume` to communicate pointer alignment guarantees to vector load and store instructions. For example, in [2] %5 and %9 are guaranteed to be 32-byte aligned. However, if I run this IR through `opt -O3 -datalayout -S`, the vectorized loads and stores are still 1-byte aligned [3]. What's going wrong? Do I

Hello, I found that GVN doesn't promote identical sequence of instructions in if and else branch to their common predecessors. For example, for the following code snippet pred: … br i1 %cmp, label %if, label %else if: %incdec.ptr.1 = getelementptr inbounds i8, i8* %ptr, i64 1 %cast1 = ptrtoint i8* %incdec.ptr.1 to i64 … else: %incdec.ptr.2 = getelementptr inbounds i8, i8* %ptr,

When zig updated to llvm 5 we started hitting this assertion: zig: /home/andy/downloads/llvm-project/llvm/include/llvm/Support/Casting.h:106: static bool llvm::isa_impl_cl<To, const From*>::doit(const From*) [with To = llvm::Instruction; From = llvm::Value]: Assertion `Val && "isa<> used on a null pointer"' failed. I wonder if however this was caused by an

I think this is the same underlying issue as https://bugs.llvm.org/show_bug.cgi?id=40320. CCing Reid, who's had a bunch of thoughts on this in the past. On 1/11/20, 10:25 AM, "llvm-dev on behalf of Chrulski, Christopher M via llvm-dev" <llvm-dev-bounces at lists.llvm.org on behalf of llvm-dev at lists.llvm.org> wrote: Hi, I've run into a bug with the LLVM

Can you please open a bug on bugzilla and attach the ir testcase? Your fix doesn't look right (just hiding the assertion failure) On Sep 17, 2017 10:45 AM, "Andrew Kelley via llvm-dev" < llvm-dev at lists.llvm.org> wrote: > What do you think about this patch? > > --- a/llvm/lib/Transforms/Scalar/NewGVN.cpp > +++ b/llvm/lib/Transforms/Scalar/NewGVN.cpp > @@

Hi Shankha, > 24 p_ptr ((unsigned long)&abc); > call void @p_ptr(i64 ptrtoint (%struct.my_struct* @abc to i64)) > nounwind, !dbg !31 > > Q.1 At line no 24 I try to read the address of global variable abc. > The address is type casted > from struct * to int * for which ptrtoint. I guess you mean "is type casted from struct * to unsigned

So, 90% of the time I've seen this, it was memory corruption, usually use after free. I know I fixed one after 5.0 branched. You should compile with address sanitizer enabled, and I suspect you will find the issue quicky. If not, we really need ir that reproduces it. On Sun, Sep 17, 2017, 12:27 PM Andrew Kelley via llvm-dev < llvm-dev at lists.llvm.org> wrote: > I think I forgot to

Hi everyone, I am wondering what¹s stopping the LLVM optimizer (opt -O3) from eliminating the apparently useless « icmp sgt » instruction in the following piece of LLVM IR. > ; ModuleID = 'lambda-opt.bc' > target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128" > target triple = "x86_64-apple-macosx10.10.0" > > ; Function

Hello, On the appended reasonably simple test case that has an fmul/fadd sequence on <8 x float> vector types, I don't see the x86-64 code generator (with cpu set to haswell or later types) turning it into an AVX2 FMA instructions. Here's the snippet in the output it generates: $ llc -O3 -mcpu=skylake --------------------- .LBB0_2: # =>This Inner