similar to: [LLVMdev] Some questions on the output formats of AliasSetTracker

Dear Staff, Here are some questions on the output formats of AliasSetTracker. The code is as below: int G1 = 9; int G2 = 5; int main() { int * XX; int * YY; XX = &G1; YY = XX; YY = &G2; XX = &G2; } The output for -anders-aa is: Alias Set Tracker: 5 alias sets for 4 pointer values. AliasSet[0xea6fb0,0] may alias, Mod/Ref 10 Call Sites: void ({ }*)*

Quoting Eli Friedman <eli.friedman at gmail.com>: Dear Eli, Thanks very much for your reply. I have modified the XX and YY to be global variables, but the output of AliasSetTracker are still MUST alias: Alias Set Tracker: 5 alias sets for 4 pointer values. AliasSet[0xea55d0,0] may alias, Mod/Ref 8 Call Sites: void ({ }*)* @llvm.dbg.func.start, void (i32, i32, { }*)*

On Thu, May 7, 2009 at 5:07 PM, <hc2428 at columbia.edu> wrote: > However, I am a little confused with these output. In Both anders-aa > and steens-aa, XX and YY should stay in the same AliasSet, and their > alias relationship should be May Alias, right? %XX and %YY are the results of alloca instructions (i.e. equivalent to the C expressions "&XX" and

Hi all, There is a problem about how AliasSetTracker merging AliasSet's when meet UnknownInst. When adding new pointer it looks for existing AliasSet's aliased with new pointer. And merging them together. It is ok for pointers: if %A mayalias %B and %B mayalias %C then %A mayalias %C. But the same logic when adding callsite is wrong ( findAliasSetForUnknownInst). Callsite may be known

Oliver Horst wrote: > Dear All, > > while willing to assist developers to adhere strictly to coding guidelines, I > wrote the attached program called "alias-detector". The program's intent is to > utilize the BasicAliasAnalysis to get a list of aliases for each pointer in a > certain program code. First it initializes clang as frontend, executes the >

Dear All, while willing to assist developers to adhere strictly to coding guidelines, I wrote the attached program called "alias-detector". The program's intent is to utilize the BasicAliasAnalysis to get a list of aliases for each pointer in a certain program code. First it initializes clang as frontend, executes the EmitLLVMOnlyAction, and then processes the produced Module with

I started using the AliasSetTracker, but I have a problem. I am using -basicaa -anders-aa and optimizations are enabled for llvm-gcc and llvm-ld. I use an instruction visitor to populate the alias set tracker, but two pointers end up in different alias sets. While investigating this I notice at one point that if I call: bool New = false; AliasSet &X = AST->getAliasSetForPointer(Pointer,

On Aug 17, 2009, at 4:16 PM, Marcus Hicks wrote: > I started using the AliasSetTracker, but I have a problem. Hi Marcus, At best, anders-aa is beta-quality. It probably has several bugs and is not really ready to be widely used. -Chris > > I am using -basicaa -anders-aa and optimizations are enabled for > llvm-gcc and llvm-ld. > I use an instruction visitor to populate the

On Wed, 17 May 2006, Nai Xia wrote: > Unfortunately, I did not locate the lines in steens-aa for "printf" special case. > In ds-aa, I found the lines below: Right, steens-aa and ds-aa share code for "local analysis", they just stitch it together into an interprocedural analysis in different ways. The code below is used for steens-aa. >

On Mon, 15 May 2006, Nai Xia wrote: > In other words, if I only use -steens-aa and the data_XXXs are all > external global variables( and so inComplete ), Sounds right! > the call to printf will > make the same effect, which I have tested it. > > Am I right ? :) If you've tested it then, yes you're right :). I haven't played with this stuff for a long time,

On Tuesday 16 May 2006 03:19, Chris Lattner wrote: > On Mon, 15 May 2006, Nai Xia wrote: > > > In other words, if I only use -steens-aa and the data_XXXs are all > > external global variables( and so inComplete ), > > Sounds right! > > > the call to printf will > > make the same effect, which I have tested it. > > > > Am I right ? :) >

Hi Chris, I took a haste look at the "Points-to Analysis in Almost Linear Time" by Steens , your PHD thesis and SteensGaard.cpp in LLVM this afternoon. So I think: 1. Actually the basic algorithm described originally by SteensGaard does not provide MOD/REF information for functions. 2. The context insensitive part of Data Structure Analysis (LocalAnalysis) can be deemed as an

Oh, I appologize that I should not have asked about __main() ---- it appears in FAQ. But the question remains that why call to __main() can alias stack location? I think the memory location pointed by data_X pointers are not visible to __main(). In comparison, calls to printf() do not have similar effect. On 5/14/06, Nai Xia <nelson.xia at gmail.com> wrote: > > In a code segment of

Hi together, i want to create a map containing a set of aliases for each value. For example, for a code like: int main() { int i; int *p1 = &i; int *p2 = &i; return 0; } the map should contain something like: {i --> (p1, p2), ..... } For that, i do followings in my pass: AliasAnalysis &AA = getAnalysis<AliasAnalysis>(); AliasSetTracker *tracker =

On 01/27/2016 07:53 AM, Daniel Berlin wrote: > > > On Wed, Jan 27, 2016 at 1:27 AM, Roman Gareev <gareevroman at gmail.com > <mailto:gareevroman at gmail.com>> wrote: > > Thank you for the idea! Could you please explain it? > > > Which part are you having trouble with, so i know where to concetrate? > > If I’m not > mistaken, you advise

In a code segment of my pass plugin, I try to gather AliasSets for all StoreInst, LoadInst and CallInst instructions in a function. Some behaviors of the pass puzzled me. Below is the *.ll of the test program which I run the pass on, it was get with "llvm-gcc -Wl,--disable-opt" from a rather simple *.c program. ---------------------------------- ; ModuleID = 'ptralias.bc'

Hello, I got a strange result when I used alias analysis DSAA, can you tell what is wrong? 1. The following is the primary body of my pass "fps.cpp": AliasAnalysis *AA = &getAnalysis<AliasAnalysis>(); AliasSetTracker AST(*AA); for (Module::iterator fi = M.begin(), fe = M.end(); fi != fe; ++fi ) for (Function::iterator bi = fi->begin(), be = fi->end(); bi

Hi all, I have a problem with alias aliasing results returned by the alias set tracker and the alias analysis evaluator. so i call opt tool to run my module with the following options "-anders-aa -aa-eval -print-alias-sets -print-all-alias-modref-info" i use 2 classes to print alias analysis, the AliasSetTracket and AliasAnalysisEvaluator. but they give different results. here is a

Oh, your meaning is pointers in a aliasset have equal address logically? But I think that two pointers are alias means they point to a same memory object, so if pointers "p" and "q" are alias, it seem as p = q, not &p = &q. Another question is about "forwarding". "AliasSet[XXXX, 0] may alias, Mod/Ref forwarding to YYYY" (XXXX != YYYY) means the

Thank you, Chris. The following is my comprehension about the AliasSetTracker, please correct me. 1. A aliasset "as" represents a memory object, and all pointer "p" in "as" represent values with the type of pointer that may/must point to the memory object "as". 2. If a aliasset is "forwarding", it has been merged to another aliasset and I