similar to: [LLVMdev] basicaa result

Oh, got it. Thanks for your explain. I misunderstand what getLocation does. If I would like to get the result of alias analysis referring to the stored value, what should I do in llvm? On 2/16/15 1:42 PM, Hal Finkel wrote: > ----- Original Message ----- >> From: "Haopeng Liu" <hyliuhp at gmail.com> >> To: "Hal Finkel" <hfinkel at anl.gov> >>

Yes, in my example, %1 and %2 point to t. %3 points to t2. But t and t2 point to the same var, is it? That's where I'm confused. On 2/16/15 12:37 PM, Hal Finkel wrote: > ----- Original Message ----- >> From: "Haopeng Liu" <hyliuhp at gmail.com> >> To: "Hal Finkel" <hfinkel at anl.gov> >> Cc: llvmdev at cs.uiuc.edu >> Sent:

t and t2 are two pointers defined in .c file. The definitions in .bc are: %thd = alloc i64, align 8 %t = alloca i64*, align 8 %t2 = alloca i64*, align 8 .c file likes this: int thd; int *t = &thd; int *t2 = t; On 2/16/15 12:28 PM, Hal Finkel wrote: > ----- Original Message ----- >> From: "Haopeng Liu" <hyliuhp at gmail.com> >> To: llvmdev at cs.uiuc.edu

Hi all, I am implementing a pass which needs aliasanalysis in llvm. My pass firstly records all store or load instructions as follows: loc[cnt++] = AA.getLocation(si/li); Then, get each pairwise alias result. AliasAnalysis::AliasResult ar = AA.alias(loc[i], loc[j]); switch(ar){ case 0,1,2,3;} And the command is: opt -load mypass.so -mypass -basicaa test.bc The store/load in test.bc: (1):

I tried to compare two types. Because of renaming, the comparison result is not as expected. How to deal with renaming while comparing types? Best, Haopeng On 6/2/15 4:09 PM, Mehdi Amini wrote: > Hi Haopeng, > > One more element, I just noticed you are using LTO, I am not sure how it is implemented but my guess is that there is a shared LLVMContext. If multiple files include this

Hi Mehdi, Thanks for your reply. It seems caused by random rename because I saw %struct.StructTyName.692.475*, which might be twice renaming. Does this collision occur because this type is declared more than once? I encountered this problem when used clang to compile transmission 1.42 (http://download.transmissionbt.com/files/) with configuration: "./configure --disable-gtk". Then

Hi All, It seems that functions in callgraph remove all metadata info, such as dbg. Can I keep metadata in callgraph? Best, Haopeng

Hi All, I generated the following code with "clang -flto" command. void test(struct StruTyName *a) { ... } Then the type of test function is "void (%struct.StruTyName.100*)" by calling function::getFunctionType API. What's the meaning of number 100? Best, Haopeng

Got it, thanks. But in my pass, I use function name to locate. Can I disable mangling in clang? Best, Haopeng On 3/1/15 10:44 PM, John Criswell wrote: > On 3/1/15 11:38 PM, Haopeng Liu wrote: >> Hi, >> >> I compile a .cpp with cmd: >> clang++ -emit-llvm -c -g -O0 -w pbzip2.cpp -o pbzip2.bc -lbz2 >> llvm-dis pbzip2.bc >> >> One function in .cpp is

Hi I am completely new to LLVM, and I am trying to explore the alias analysis part of it. It seems to me that -basicaa is the most simple alias analysis pass in LLVM. So I would like to try and make it work (to see some alias analysis results of some sample bit code). What I have done is that I ---make lib/Analysis/BasicAliasAnalysis.cpp into a .so file ---write a sample c program, hello.c,

Hi, We've seen a similar case recently, where BasicAA returns PartialAlias for the access of two different fields of a structure. We noticed this since Lint complained about it when checking for aliasing beteen "noalias" attributed parameters: opt -S -lint ./alias.ll gave Unusual: noalias argument aliases another argument on the (silly) function: %rec7 = type { i16, i16, i16

On Thu, Nov 8, 2012 at 6:53 PM, Pranav Bhandarkar <pranavb at codeaurora.org> wrote: > Hi, > > I am observing some incorrect behavior in basicaa, wherein two pointers that > basicaa should determine to be MustAlias are ending up NoAlias - the other > extreme :( > I am blaming this on basicaa not handling inttoptr. Here is the relevant IR > snippet. >

Hi, I am observing some incorrect behavior in basicaa, wherein two pointers that basicaa should determine to be MustAlias are ending up NoAlias - the other extreme :( I am blaming this on basicaa not handling inttoptr. Here is the relevant IR snippet. -------------------- %sunkaddr36 = ptrtoint %struct.BitParams* %bs to i32 %sunkaddr37 = add i32 %sunkaddr36, 16 %sunkaddr38 = inttoptr i32

Hi, I'd like to understand if it makes sense to keep BasicAA as a not CFG-only pass, or if it can be updated to CFG-only. The change was made in D44564 <https://reviews.llvm.org/D44564>. >From what I gathered the motivation was PhiValuesAnalysis not being properly updated, and BasicAA having an instance of it. PhiValuesAnalysis now uses callback values to invalidate deleted values (

BasicAA treats it conservatively if used on its own. It will return mayalias for the two pointers. TBAA operates based on the guarantee that pointers to different types cannot alias (think C's strict aliasing rules). Therein lies its power but also its danger, that is, nothing prevents the programmer to write code that violates these rules (That's why we have -fno-strict-aliasing). So

> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] > On Behalf Of Arnold Schwaighofer > Subject: [LLVMdev] inttoptr and basicaa > BasicAA treats it conservatively if used on its own. It will return mayalias > for the two pointers. > TBAA operates based on the guarantee that pointers to different types cannot > alias (think C's strict

On 2/10/20 2:35 PM, Alina Sbirlea wrote: > Hi, > > Here's a tentative patch of the changes for this: D74353 > <https://reviews.llvm.org/D74353>. I suppose that, as expected, it's invalidated less often this way. Given that it's generally stateless, does this really represent a cost savings?  -Hal > > Thank you, > Alina > > > On Mon, Feb 10,

Hello all, I observed that BasicAA alias query returns PartialAlias between different fields of a structure. Following is the test program and -print–all-alias-modref-info output: --- ; test.ll target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" target triple = "x86_64-unknown-linux-gnu" %"type" = type { [10 x i32], i64 } define void

My understanding is that alias analysis returns results in the function scope, not in loop scope. Since both the phis access both global arrays, that should results in BasicAA conservatively returning MayAlias. I debugged this a little bit and narrowed it down to the section of the code in BasicAAResult::aliasPHI() which has this comment- // Analyse the PHIs' inputs under the assumption

Hi all, I have this test case- #define N 1000 extern double Ag[N]; extern double Bg[N]; void consume(double *A, double *B); void swap_deps() { double *A = Ag; double *B = Bg; for (int i = 0; i < 97; ++i) { for (int j = 0; j < N; ++j) { B[j] = A[j] + 1; } double *tmp = A; A = B; B = tmp; } consume(A, B); } BasicAA is returning 'NoAlias' when