similar to: [LLVMdev] SSA in the Front End

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

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

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 Wed, 11 Jan 2006, Reid Spencer wrote: > llvm-as file.bc | opt -mem2reg | llvm-dis > file.ll llvm-as < file.bc | opt -mem2reg | llvm-dis > file.ll Note the extra "<". -Chris > On Wed, 2006-01-04 at 09:12 +0800, lizhuo wrote: >> meone tell me how to convert LLVM bytecode into minimal SSA form ? >> or just depend on GCC frontend ? > -Chris --

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,

On Wed, Jan 11, 2006 at 02:04:36PM -0600, Chris Lattner wrote: > On Wed, 11 Jan 2006, Reid Spencer wrote: > >llvm-as file.bc | opt -mem2reg | llvm-dis > file.ll > > llvm-as < file.bc | opt -mem2reg | llvm-dis > file.ll > > Note the extra "<". Strictly speaking, llvm-as converts .ll to .bc so that would be: llvm-as < input.ll | opt -mem2reg |

Suppose my Input function is like : myfunc(int x,int y){ int a=2, b=3,c=5; if(x>y) { c=a+b; a=6; } else { c=a*b; b=4; } a=c+a; c=a+b; } and the output should be : myfunc(int x,int y){ int a.0=2, b.0=3,c.0=5; if(x>y) { c.1=a.0+b.0; a.1=6; } else { c.2=a.0*b.0; b.1=4; }

[ 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

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

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

There is no existing pass to do this in LLVM, mostly because it wouldn't be useful for optimizing programs. From your input, mem2reg produces: define i32 @myfunc(i32 %x, i32 %y) nounwind { entry: %cmp = icmp sgt i32 %x, %y ; <i1> [#uses=1] br i1 %cmp, label %if.then, label %if.else if.then: ; preds = %entry %add = add

Hello, Ying. > But if a module is constructed by hand, how can I transform it into a > SSA-based llvm? LLVM IR is *always* in SSA form, even if you're constructing module by hands (Verifier pass actually does the check and reject invalid code). If you want to eliminate memory accesses and transform them to registers & phi's you might want to run mem2reg pass also. -- With best

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

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; }

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

You can use STOREs and LOADs on memory and then use mem2reg pass. 2010/6/1 Chayan Sarkar <chayan.ju at gmail.com>: > Hi, > > Can anyone tell me, whether it is possible to convert a program into > SSA form without considering algebric equivalence ? > > regards, > Chayan > _______________________________________________ > LLVM Developers mailing list > LLVMdev at

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

Dear All, Could someone tell me how to convert LLVM bytecode into minimal SSA form ? or just depend on GCC frontend ? thanks aqex

> > Here's 'foo' is always called with positive value. However, the value > range > assigned to 'i' variable can be only [-inf, +inf], because uses of 'i' > outside of condition can get any value. So, I'd like to convert the > above to: > > i = 0; > if (i > 0) { > i = change_value_range(i); > foo(i); > } I

On Sat, Jun 5, 2010 at 2:03 AM, Chayan Sarkar <chayan.ju at gmail.com> wrote: > 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