similar to: [LLVMdev] predefined pass for transforming a module to SSA?

Hi all: I'm writing a research prototype on LLVM 1.9. Given a module ,what is the right way to get the SSA-based llvm-IR? As I know , llvmgcc generates SSA-based bytecode. But if a module is constructed by hand, how can I transform it into a SSA-based llvm? Thanks. Ying -------------- next part -------------- An HTML attachment was scrubbed... URL:

Hi, I am emitting llvm bit code using llvm-gcc -c -emit-llvm -O0 -o test.bc test.c and then optimizing it with opt -O3 -print-module test.bc in order to obtain a dump of generated IR. The resulting code has Phi nodes and is perhaps in SSA form. I want to undo the SSA form while retaining all the other optimizations. Is mem2reg the right optimization to be added after -O3, i.e., opt -O3

Hi, Silly question from an LLVM newbie: the LLVM LRM say that the bytecode is "is an SSA based representation". Indeed, my experience with llvm-gcc is that the generated code is not necessarily SSA, while the one given by "llvm-gcc -O1" is. Is this assumption correct? Is there a non-SSA to SSA translator available? Thanks, -- Matthieu

On 3/29/11 12:26 PM, George Baah wrote: > Hi All, > When I run the following command > llvm-gcc -03 -emit-llvm test.cpp -c -o test.bc or llvm-gcc -emit-llvm > test.cpp -c -o test.bc > > on the program test.cpp, the IR representation is not in SSA form. > I do not see any phi functions. Actually, it is in SSA form (or more precisely, the virtual registers are in SSA form;

Hello, for some my use case, I'd like to temporary break SSA property and then ask LLVM to restore it. Here's more details: if (i < 0) { i = -i; } This is a C code example. I'm trying to create a value range analysis, which will determine, that after this code, 'i' is non-negative. In SSA form, this will become i = 0; if (i < 0) { i.2 = -i; }

But, the mem2reg pass removes all load store instructions. It replaces all variables by their if possible (kind of constant propagation). I have generated the bitcode of the source program and the applied the mem2reg pass and obviously not getting desired thing. What I want is convert it into SSA form without replacing any variable by their constant value. Please elaborate on your point. Also,

[ sorry for the late reply ] Patrick Meredith <pmeredit at uiuc.edu> wrote: > All register uses are SSA. Memory is not in SSA. The mem2reg pass > which promotes stack variables to registers effectively converts non- > SSA to SSA. There was a reg2mem pass, written by Andrew Lenharth, I'm > not sure if it's still being maintained. What is the difference between

Well, it *is* in SSA form, but it "cheats" by keeping values in memory. --Sean Silva On Wed, Jun 13, 2012 at 2:00 PM, Jiesheng Wei <jwei at ece.ubc.ca> wrote: > Hi Amruth, > > If you do not specify any optimization flag for 'clang' and do not run > 'opt -mem2reg' pass on the generated IR file, it is in non-SSA form. > However, many variables stay

Ricardo wrote: > Hi, > > I have been looking into the code that generates the LLVM assembly in the LLVM front end, but I am > not very sure if at the time that the llvm_c_expand_body_1 function is called, the SSA form was > already constructed (each definition dominates all the uses). Can somebody please tell me? The LLVM GCC frontend does not translate variables directly into

All register uses are SSA. Memory is not in SSA. The mem2reg pass which promotes stack variables to registers effectively converts non- SSA to SSA. There was a reg2mem pass, written by Andrew Lenharth, I'm not sure if it's still being maintained. On Jul 7, 2008, at 8:47 AM, Matthieu Moy wrote: > Hi, > > Silly question from an LLVM newbie: the LLVM LRM say that the

On 01/22/2011 10:30 PM, Surinder wrote: > Hi, > > I am emitting llvm bit code using > > llvm-gcc -c -emit-llvm -O0 -o test.bc test.c > > and then optimizing it with > > opt -O3 -print-module test.bc > > in order to obtain a dump of generated IR. > > > The resulting code has Phi nodes and is perhaps in SSA form. I want > to undo the SSA form while

Thanks for the explanation. It's more clear now The only thing that seems strange is that in the function llvm_expand_shortcircuit_truth_expr in the front end, there is the creation of a PHI instruction. If there is no SSA yet, why do you do that? Thanks in advance --- John Criswell <criswell at cs.uiuc.edu> wrote: > Ricardo wrote: > > Hi, > > > > I have been

LLVM IR is always in SSA form. If you *really* don't want it to be, use allocas for everything and then don't run the mem2reg optimization pass. This will represent all of your variables as stack locations instead of registers, and it will not be SSA. Reid On Sat, Sep 26, 2009 at 3:55 PM, ivtm <martinaide1 at yahoo.com> wrote: > > I tried the -O0 option and I am still

I tried using the mem2reg pass with opt, e.g. opt -reg2mem x.bc > x2.bc where x.bc was produced with: llvm-gcc -O2 -emit-llvm -c x.c -o x.bc This did not reduce the # of variables in x2.bc I use -O2 because it produces the least # of instructions and hence the least # of new SSA virtual registers. Do you have a set of options to give to llvm-gcc or opt in mind ? My goal is to take a .c

Hi, I have been looking into the code that generates the LLVM assembly in the LLVM front end, but I am not very sure if at the time that the llvm_c_expand_body_1 function is called, the SSA form was already constructed (each definition dominates all the uses). Can somebody please tell me? Thanks

Hi Amruth, If you do not specify any optimization flag for 'clang' and do not run 'opt -mem2reg' pass on the generated IR file, it is in non-SSA form. However, many variables stay in memory instead of registers in this case. Thanks, Jiesheng On Wed, Jun 13, 2012 at 1:17 PM, <amruth.rd at knights.ucf.edu> wrote: > I am experimenting with LLVM optimizer and found that

I am experimenting with LLVM optimizer and found that the bit code file clang emits is already in SSA form, but I want to generate it in non-SSA form. Would you let me know if there is any way of doing it? Cheera,Amruth -------------- next part -------------- An HTML attachment was scrubbed... URL:

Hi All, When I run the following command llvm-gcc -03 -emit-llvm test.cpp -c -o test.bc or llvm-gcc -emit-llvm test.cpp -c -o test.bc on the program test.cpp, the IR representation is not in SSA form. I do not see any phi functions. program: test.cpp int main(int argc, char **argv) { int a[2],i,j; for(i=0;i<2;i++) { a[i] = i; } return a[1]; } Any clarifications will be

Hi, Can anyone tell me, whether it is possible to convert a program into SSA form without considering algebric equivalence ? regards, Chayan

Hi, does LLVM have a mechanism to automatically update SSA form, e.g. after insertion of additional definitions of a variable? This would recursively traverse the dominance tree of all uses of the definition backwards and insert phi-functions where ever they are needed. http://portal.acm.org/citation.cfm?id=277656&dl=GUIDE, (Paragraph 4.5) provides an algorithm for such an incremental SSA