similar to: [LLVMdev] Question about intrinsic function llvm.objectsize

Hi, Regarding the definition of object for @llvm.objectsize, it is identical to gcc's __builtin_object_size(). So it's not wrong; it's just the way it was defined to be. Regarding the BasicAA's usage of these functions, I'm unsure. It seems to me that isObjectSmallerThan() also expects the same definition, but I didn't review the code carefully. When you do a

On Feb 27, 2013, at 4:05 AM, Nuno Lopes <nunoplopes at sapo.pt> wrote: > Hi, > > Regarding the definition of object for @llvm.objectsize, it is identical to gcc's __builtin_object_size(). So it's not wrong; it's just the way it was defined to be. > > Regarding the BasicAA's usage of these functions, I'm unsure. It seems to me that isObjectSmallerThan()

On Feb 27, 2013, at 12:37 PM, Shuxin Yang <shuxin.llvm at gmail.com> wrote: > Hi, Nuno and Arnold: > > Thank you all for the input. > > Let me coin a term, say "clique" for this discussion to avoid unnecessary confusion. > A clique is statically or dynamically allocated type-free stretch of memory. A "clique" > 1) is maximal in the sense

Hi, Nuno and Arnold: Thank you all for the input. Let me coin a term, say "clique" for this discussion to avoid unnecessary confusion. A clique is statically or dynamically allocated type-free stretch of memory. A "clique" 1) is maximal in the sense that a clique dose not have any enclosing data structure that can completely cover or, partially

On 2/27/13 11:21 AM, Arnold Schwaighofer wrote: > On Feb 27, 2013, at 12:37 PM, Shuxin Yang <shuxin.llvm at gmail.com> wrote: > >> Hi, Nuno and Arnold: >> >> Thank you all for the input. >> >> Let me coin a term, say "clique" for this discussion to avoid unnecessary confusion. >> A clique is statically or dynamically allocated

> In the "llvm.objectsize" context we pass an object "based on p" to getObjectSize: "p+50". In the basicaa context, we wanna know whether an access is beyond the bounds of an underlying object (undefined behavior land) so we pass the underlying object (which in your example would be the "p" returned from malloc) to the getObjectSize function. > > In

Hello All, I have met a case with restrict keyword and I have a question about it. Let's look at a simple example. char buf[4]; void test(char *restrict a, char *restrict b, int count) {   for (unsigned i = 0; i < count; i++) {     *a = *b;     a++;     b++;     buf[i] = i;   } } I think there are no aliasing among pointers such as 'a', 'b' and 'buf'

The documentation of LLVM says that "The llvm.objectsize intrinsic is lowered to a constant representing the size of the object concerned". I'm attempting to lower this intrinsic function to a constant in a pass. Below is the code snippet that I wrote: for (BasicBlock::iterator i = b.begin(), ie = b.end(); (i != ie) && (block_split == false);) { IntrinsicInst *ii =

Thanks for your reply. I'm attempting to expand KLEE to support this intrinsic function. That's why I need to handle this myself. According to the reply, the correct implementation should first find the definition of the object and then determine the size of the object. BTW, can I just refer to the implementation in InstCombineCalls.cpp. On Wed, Nov 5, 2014 at 2:24 PM, Matt Arsenault

Hello, On Nov 4, 2009, at 1:51 AM, Hans Wennborg wrote: > > > / Hans > Index: lib/Analysis/BasicAliasAnalysis.cpp > =================================================================== > --- lib/Analysis/BasicAliasAnalysis.cpp (revision 86023) > +++ lib/Analysis/BasicAliasAnalysis.cpp (working copy) > @@ -633,6 +633,15 @@ > AliasAnalysis::AliasResult >

This is the first patch I've sent to this project. Please be gentle :) LLVM fails to remove the dead load in the following code when running $./llvm-as -o - test.ll | ./opt -O3 -o - | ./llvm-dis -o - %t = type { i32 } declare void @foo(i8*) define void @f(%t* noalias nocapture %stuff ) { %p = getelementptr inbounds %t* %stuff, i32 0, i32 0 %before = load i32* %p call void

Am Di., 17. März 2020 um 16:56 Uhr schrieb Chawla, Pankaj via llvm-dev <llvm-dev at lists.llvm.org>: > All I am expecting from DA is a direction vector containing (*). There seems to be a bug in DI, see Felipe's answer. > I think the main problem is that currently there is no exact way DA can query AliasAnalysis in a ‘conservatively correct’ manner. > > Using UnknownSize

tl;dr: We'd like to add a bit to @llvm.objectsize to make it optionally be conservative when it's handed a null pointer. Happy Wednesday! We're trying to fix PR23277, which is a bug about how clang+LLVM treat __builtin_object_size when it's given a null pointer. For compatibility with GCC, clang would like to be able to hand back a conservative result (e.g. (size_t)-1), but the

Hi George, Have you considered changing our existing behavior to match GCC's builtin_object_size instead of adding a new parameter? That may be simpler overall. There's also a clear upgrade strategy -- fold every old style call to "<min> ? 0 : 1". You probably already know this, but GCC folds builtin_object_size(0, 0) to -1 and builtin_object_size(0, 2) to 0. We'll

Hi George, On Mon, Jan 2, 2017 at 10:41 AM, George Burgess IV <george.burgess.iv at gmail.com> wrote: > Thanks for the comments! > >> Have you considered changing our existing behavior to match GCC's >> builtin_object_size instead of adding a new parameter > > Yup! My issue with turning `i1 %min` into `i8 %flags` is that > __builtin_object_size would get

Hello LLVMer, I use dragonegg to generate LLVM bitcode. Then I use LLVM interpreter to execute what I get from compilation. However an error occurred and the error message is: "LLVM ERROR: Code generator does not support intrinsic function 'llvm.objectsize.i64'!." As far as I know, objectsize intrinsic is equivalent to gcc built-in function __builtin_object_size. But I don't

Dan Gohman wrote: > I tried out your patch on x86 and it didn't appear to need any special changes. it might be needed to look at the addressing modes of a load/store to get the right offset. but i think it should work, if the lowering does not rewrite loads/stores into custom DAG nodes. > For the [??], it looks like the IsFrameIndex isn't getting set for the first > instruction

On Mon, Jul 23, 2007 at 02:19:38PM +0200, Florian Brandner wrote: > hi, > > i know it took a while, but here is a patch that adds a list of source > values to machine instructions. Cool! > i've testet all this for our backend only, which is not public. i do not > know how much has to be done to integrate this with the other, e.g., the > x86, targets. does any of the

hi, i know it took a while, but here is a patch that adds a list of source values to machine instructions. i modified the DAGISelEmiter to automatically catch regular loads/stores. custom instructions and loads/stores rewritten by the lowering pass are not automatically captured. during the instruction selection a source value operand is added to the DAG for patterns matching a load/store.

On 11/17/2017 02:01 AM, Hongbin Zheng wrote: > Do you mean a and b are noalias if: > > static int foo(int *a, int *b) { > return a[0] + b[0]; > } > > int bar(int *x) { > return foo(x+1, x); > } > > ? > > To me, because "AA.alias((x+1, MemoryLocation::UnknownSize), > (x, MemoryLocation::UnknownSize)) != NoAlias", so a and b are not noalias.