similar to: Semantics of LLVM IR intermediate variables

Hi Dustin, > I think I'm missing something basic about the semantics of returning an > aggregate type (in my case, a structure) from a function. Returning a > structure containing only compile-time constants is simple enough. But > I don't quite get how this works with a struct composed at run-time. If > I constructed it on the stack with alloca, would I be letting a

Dear LLVMdev, We have a question regarding the semantics of the undefined value in LLVM IR. As far as we understand, in order to give a semantics to the undefined value, the semantics of LLVM IR is generalized to a rather unusual set-based semantics. More specifically, the notion of value in LLVM IR is generalized to a set of values, rather than a single value. Then the undefined value is simply

I think I'm missing something basic about the semantics of returning an aggregate type (in my case, a structure) from a function. Returning a structure containing only compile-time constants is simple enough. But I don't quite get how this works with a struct composed at run-time. If I constructed it on the stack with alloca, would I be letting a stack variable escape to to a context

So, in hacking on mem2reg I noticed that it doesn't actually implement optimizations enabled by lifetime markers. I thought I might take a stab at teaching it about them, but I'm left with some questions about the semantics. Much of this may have been hash out when they were added, and if so I'll appreciate your help educating me, and maybe we can come up with improved documentation to

On Tue, 14 Apr 2020 at 21:24, Michael Kruse <llvmdev at meinersbur.de> wrote: > > Currently, LLVM often uses the *i8 type (pointer to char) to represent > a pointer to some not-specified type. We are also working on replacing > the pointer-to-type pointer types by a single pointer type without a > specific pointee-type. Look for "opaque pointer" on llvm-dev and the

All, I should have chimed in earlier, but have been working on two more side-channel variants of this conversation. At the beginning the PNaCl team was strongly pushing for trying to keep platform ABI compatibility on all platforms while taking one portable bitcode stream as input. During the discussions we've had over the past few weeks it became obvious that that is simply not tractable,

Hi Johannes, By following your directions, I can use your script as is to produce the .bc file now. Here's my command line for compiling s_sin.c into s_sin.bc file and the output: command line: ~/Downloads/newlib-2.1.0/newlib/libm/mathfp » python ~/llvm_link.py s_sin.c -I../common/ -I../../libc/include/ -o s_sin.bc output: Initiate CLANG (/path-to-clang): Options: 's_sin.c

Hi, I am looking for an IR that is similar to LLVM IR, with its SSA form, module->function->block->instruction etc. But, I wish a much reduced type model. I wish only three types: 1) An Integer of various bit-widths. 2) A pointer, but a pointer that does not need to point to a known type. A sort of "pointer to unknown type". 3) Floats of various varieties. For example, if we

I'm unintentionally allocating too much space on the stack by using `alloca` inside a loop. To fix this I will do my `alloca` outside of the loop itself.  I'm wondering if there is a way for this to be automatically done: given alloca a function scope, rather than loop scope. I'm curious also, since this actually allocates each time in the loop, is there a way to say the stack

It is possible to ask DataLayout about getTypeSizeInBits and also getTypeStoreSize. And there is a table showing an example of what it could look like: /// Size examples: /// /// Type SizeInBits StoreSizeInBits AllocSizeInBits[*] /// ---- ---------- --------------- --------------- /// i1 1 8 8 /// i8 8 8

Hi, While looking over the IR generated by my source code, I came across the following: %arr = alloca [30 x i8], align 1 In the source code this particular line of code is represented by: int arr[30]; I was wondering how I could change the capacity of arr from 30 to any other integral value via a function-pass. I know that 'alloca' can be used for reserving space on stack; further,

Hi, I want to edit LLVM generated IR file, like as given below, Original LLVM IR file, @.str2 = private unnamed_addr constant [17 x i8] c"\0AI am in one_11\0A\00", align 1 ; Function Attrs: nounwind define i32 @one_1(i32 %ivar1, i32 %ivar2) #0 { entry: %ivar1.addr = alloca i32, align 4 %ivar2.addr = alloca i32, align 4 %isum = alloca i32, align 4 store i32 %ivar1, i32*

Hi, Just had a simple question , The use-def and def-use chains provided by llvm::Value class , would they work for IR that has not been optimized by the "mem2reg" pass ? ( ie, IR code that contains memory interactions and is not in SSA form yet ) Thanks, Malhar -------------- next part -------------- An HTML attachment was scrubbed... URL:

Le 5 juil. 2013 à 17:48, Arnold Schwaighofer <aschwaighofer at apple.com> a écrit : > > On Jul 5, 2013, at 10:43 AM, Stéphane Letz <letz at grame.fr> wrote >> >> 1) "entry" block is the first block of the function right? > > Yes. OK > >> >> 2) do you mean *all* "alloca" in a function always have to be in the fist entry

Hi, sometimes when dealing with LLVM IR getting to a desired point of the code is a bit cumbersome, in particular if you're instrumenting existing code. A lot of nested loops and if checks. Maybe all of this could be avoided by employing a query language. Since an LLVM module can be seen as a sort of tree with attributes, I think that reusing an existing query language for XML would be

On Wed, 15 Apr 2020 at 17:28, David Blaikie <dblaikie at gmail.com> wrote: > > opaque pointers don't exist in the IR yet - the goal is to reduce the places that use non-opacity of pointer types already/today and then opacify the existing pointer type, rather than introducing an opaque pointer type & having it concurrently with non-opaque pointer types. (though in retrospect

Hi, I want to call/add some functions(that defined in another file) on top of some functions, and reflect the same changes in object file. No, I am not looking for contractor. Thanks, Deepika On Tue, Feb 9, 2016 at 7:04 PM, mats petersson <mats at planetcatfish.com> wrote: > What is the condition for adding this code? > > What have you tried so far? [Or are you looking for a

Create a new alloca instruction, insert it into the IR right before (or after) the old one, RAUW the value, then delete the old instruction. You should be able to find a variety of examples of this sort of thing in most of the IR level optimization passes. I’d look at InstCombine in particular. -Jim On Dec 4, 2013, at 1:40 PM, Shivam Bhagi <shivam.bhagi at outlook.com> wrote: > Hi,

> On Nov 17, 2014, at 5:50 PM, Reid Kleckner <rnk at google.com> wrote: > > On Mon, Nov 17, 2014 at 5:22 PM, Bob Wilson <bob.wilson at apple.com <mailto:bob.wilson at apple.com>> wrote: > I don’t know much about SEH and haven’t had time to really dig into this, but the idea of outlining functions that need to know about the frame layout sounds a bit scary. Is it

Hi, I'm trying to understand how virtual regs are assigned to operands in IR instructions. I looked into SelectionDAG but could not figure out where the assignment happens. How and where does this conversion happen? Furthermore, I want to build a map between variable and the virtual register (x corresponds to vreg11 in below code). I've been stuck here for a while. Any help is greatly