similar to: [LLVMdev] Pointer sizes, GetElementPtr, and offset sizes

On Fri, May 2, 2008 at 1:22 PM, Marc de Kruijf <dekruijf at cs.wisc.edu> wrote: > The LLVA and LLVM papers motivate the GetElementPtr instruction by arguing > that it abstracts implementation details, in particular pointer size, from > the compiler. While it does this fine for pointer addresses, it does not > manage it for address offsets. Consider the following code: > >

Hello everybody, I have stumbled upon a test case (the attached module is a slightly reduced version) that shows extremely reduced performance on linux compared to windows when executed using LLVM's JIT. We narrowed the problem down to the actual code being generated, the source IR on both systems is the same. Try compiling the attached module: llc -O3 -filetype=asm -o BAD.s BAD.ll Under

Hello, I want to compile a LLVM file into an executable running on ARM platform. I use LLVM 2.0 with the following command lines: llvm-as -f -o test.bc test.ll llc -march=arm -mcpu=arm1136j-s -mattr=+v6 -f -o test.s test.bc arm-linux-gnu-as -mcpu=arm1136j-s test.s With the last command, I obtain the following error: rd and rm should be different in mul The bad instruction is

Hi Mikael, You are obtaining warning, not an error, right? The most arm cores, including arm1136, can execute mul with rd = rm. So, you can ignore this warning. Lauro 2007/6/12, Peltier, Mikael <m-peltier at ti.com>: > > > > > Hello, > > > > I want to compile a LLVM file into an executable running on ARM platform. > > I use LLVM 2.0 with the following

Hi, I have been trying to output my graphs to a file (jpeg, pdf, ps, it doesnt matter) but i cant seem to be able to get it to output. I tried a few things but none of them worked and am lost as what to do now. I am using the scatter3d function, and it prints out the graphs on tot he screen without any problems, but when it comes to writing them to a file i cant make it work. Is there any

Thanks, Sanjay, that makes sense. The opportunity for improving instcombining splat sounds promising. Another question about shuffle simplification. This is a testcase from test/Transforms/InstCombine/vec_shuffle.ll: define <4 x i32> @test10(<4 x i32> %tmp5) nounwind { %tmp6 = shufflevector <4 x i32> %tmp5, <4 x i32> undef, <4 x i32> <i32 1, i32 undef, i32

Hi, I'm using LLVM 2.7 right now, and I found "opt -std-compile-opts" has missed some opportunities for optimization: define void @spa.main() readonly { entry: %tmp = load i32* @dst-ip ; <i32> [#uses=3] %tmp1 = and i32 %tmp, -16777216 ; <i32> [#uses=1] %tmp2 = icmp eq i32 %tmp1, 167772160 ; <i1> [#uses=2]

I am testing vectorization on the following test case: float x[1024], y[1024]; void myloop1() { for (long int k = 0; k < 512; k++) { x[2*k] = x[2*k]+y[k]; } } Vectorization failed due to "unsafe dependent memory operation". I traced the LoopAccessAnalysis.cpp and found the reason is the NoWrapFlag for SCEVAddRecExpr is not set and consequently the

[+Arnold] > On Jun 10, 2015, at 1:29 PM, Sanjoy Das <sanjoy at playingwithpointers.com> wrote: > > [+CC Andy] > >> Can anyone familiar with ScalarRevolution tell me whether this is an >> expected behavior or a bug? > > Assuming you're talking about 2*k, this is a bug. ScalarEvolution > should be able to prove that {0,+,4} is <nsw> and

Hello, How can I compute the functions on the loop iterators used as array indices?  For example: for i = 0, N       for j = 0, M             A[2*i + j - 10] = ...  Can I obtain that this instruction A[2*i + j - 10]= .. always accesses memory using a function       f(i,j)   =   2*i + j - 10 + base_address_of_A If I run the scalar evolution pass on this code I obtain: %arrayidx =

Hello, I've come across another example: I'm compiling with clang -S -emit-llvm -std=gnu99 -O3 clang version 2.9 (trunk 118238) Target: x86_64-unknown-linux-gnu Thread model: posix I take the code: int loops(int x) { int ret = 0; for(int i = 0; i < x; i++) { for(int j = 0; j < x; j++) { ret += 1; } } return ret; } and the

The following piece of IR is a fixed point for opt -std-compile-opts/-O3: --- target datalayout = "e-p:64:64:64-S128-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f16:16:16-f32:32:32-f64:64:64-f128:128:128-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64" target triple = "x86_64-unknown-linux-gnu" ; Function Attrs: nounwind readonly define i32 @get32Bits(i8*

Hello all, My app is using LLVM JIT as a runtime engine for image analysis (similar to opencl). I'm placing values into a struct to pass byref to a series of functions. After running the createStandardModulePasses(...) set of optimizations, the function calls are all inlined but the struct store/load pairs haven't been optimized away. I've attached the code below. What I'd like to

Hello all, My app is using LLVM JIT as a runtime engine for image analysis (similar to opencl). I'm placing values into a struct to pass byref to a series of functions. After running the createStandardModulePasses(...) set of optimizations, the function calls are all inlined but the struct store/load pairs haven't been optimized away. I've attached the code below. What I'd like to

Hey again) Now I have next code: ; ModuleID = 'sample.lz' @.str1 = internal global [8 x i8] c" world!\00" ; <[8 x i8]*> [#uses=1] @.str2 = internal global [8 x i8] c"hello, \00" ; <[8 x i8]*> [#uses=1] @.str7 = internal global [21 x i8] c"welcome to out hall!\00" ; <[21 x i8]*> [#uses=1] declare i32 @puts(i8*)

As Sanjay noted in D31426<https://reviews.llvm.org/D31426#712701>, InstructionSimplify is missing the following simplification: This function: define <4 x i32> @splat_operand(<4 x i32> %x) { %splat = shufflevector <4 x i32> %x, <4 x i32> undef, <4 x i32> zeroinitializer %shuf = shufflevector <4 x i32> %splat, <4 x i32> undef, <4 x i32>

On Jul 23, 2008, at 8:47 PM, kapil anand wrote: > > Specifically, I need a way to represent indirect branch instruction > (in binary) as an equivalent LLVM instruction. With switch > instruction , I would have to list all the possible targets and then > initialize the corresponding instruction. I was just thinking > whether it might be possible to have some kind of

It's invalid for the same reason that char *foobar = strcat("foo", "bar"); is invalid in C. Please make sure you understand what you're asking LLVM to do before going any further down this path. A good approach is to write out the correct code in C and then use llvm-gcc (or the demo page at http://llvm.org/demo ) to see what it looks like in LLVM assembly. Nick

hm.... I think, that is valid in c but next code too doesn't works right: ; ModuleID = 'sample.lz' @.str1 = internal global [6 x i8] c"world\00" ; <[6 x i8]*> [#uses=1] @.str2 = internal global [7 x i8] c"hello \00" ; <[7 x i8]*> [#uses=1] @.str7 = internal global [7 x i8] c"father\00" ; <[7 x i8]*> [#uses=1]

I'm attempting to modify a parser generator to emit LLVM code instead of C. So far the experience has been trivial, but I am now running into an error regarding labels that I can't seem to solve. Situation 1: A label is used immediately after a void function call (l6 in this case): <snip> %tmp26 = load i32* @yybegin, align 4 %tmp27 = load i32* @yyend, align 4 call void