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Yuri

2010-Jun-01 19:34 UTC

[LLVMdev] How to create global string array? (user question)

I am trying to create such module with API (it's equivalent to c++: 
const char* ss[] = {"s1","s2"};):

@ss = global [2 x i8*] [i8* getelementptr inbounds ([3 x i8]* @.str1, 
i32 0, i32 0), i8* getelementptr inbounds ([3 x i8]* @.str2, i32 0, i32 
0)] ; <[2 x i8*]*> [#uses=0]
@.str1 = private constant [3 x i8] c"s1\00", align 1 ; <[3 x
i8]*> [#uses=1]
@.str2 = private constant [3 x i8] c"s2\00", align 1 ; <[3 x
i8]*> [#uses=1]

Code below doesn't compile because to initialize GlobalVariable I need 
ConstantArray*, ConstantArray::get requires vector<Constant*>, but 
getelementptr is an instruction and it's not Constant*, but Value*.

What is the correct way to create such module? It's really tye

Yuri

--- c++ code ---
#include "llvm/LLVMContext.h"
#include "llvm/Module.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Constants.h"
#include "llvm/Instructions.h"
#include "llvm/Analysis/Verifier.h"
#include <stdio.h>
#include <vector>
using namespace llvm;
using namespace std;

Constant* mk_string(Module *M, LLVMContext &Context, const string
&svalue) {
   ArrayType *Ty = ArrayType::get(Type::getInt8Ty(Context),svalue.size()+1);
   GlobalVariable *GV = new llvm::GlobalVariable(
     *M,
     Ty,
     true,
     GlobalValue::InternalLinkage,
     ConstantArray::get(Context,svalue),
     "str",
     0,
     false,
     0);

   vector<Constant*> idxs;
   idxs.push_back(ConstantInt::get(Type::getInt32Ty(Context), 0, false));
   idxs.push_back(ConstantInt::get(Type::getInt32Ty(Context), 0, false));
   return (GetElementPtrInst::Create(
     GV,
     idxs.begin(),
     idxs.end(),
     "gepi",
     (BasicBlock*)0
   ));
}

main() {
   LLVMContext Context;
   Module *M = new Module("test", Context);
   //
   vector<Constant*> strs;
   strs.push_back(mk_string(M, Context, "s1"));
   strs.push_back(mk_string(M, Context, "s2"));
   ArrayType *Ty = 
ArrayType::get(Type::getInt8Ty(Context)->getPointerTo(),2);
   new llvm::GlobalVariable(
     *M,
     Ty,
     true,
     GlobalValue::InternalLinkage,
     ConstantArray::get(Ty,strs),
     "ss",
     0,
     false,
     0);
   verifyModule(*M);
   delete M;
}

Eugene Toder

2010-Jun-01 19:41 UTC

head link

[LLVMdev] How to create global string array? (user question)

I think ConstantExpr::getGetElementPtr() returns a Constant*.

On Tue, Jun 1, 2010 at 8:34 PM, Yuri <yuri at rawbw.com>
wrote:> I am trying to create such module with API (it's equivalent to c++:
> const char* ss[] = {"s1","s2"};):
>
> @ss = global [2 x i8*] [i8* getelementptr inbounds ([3 x i8]* @.str1,
> i32 0, i32 0), i8* getelementptr inbounds ([3 x i8]* @.str2, i32 0, i32
> 0)] ; <[2 x i8*]*> [#uses=0]
> @.str1 = private constant [3 x i8] c"s1\00", align 1 ; <[3 x
i8]*> [#uses=1]
> @.str2 = private constant [3 x i8] c"s2\00", align 1 ; <[3 x
i8]*> [#uses=1]
>
> Code below doesn't compile because to initialize GlobalVariable I need
> ConstantArray*, ConstantArray::get requires vector<Constant*>, but
> getelementptr is an instruction and it's not Constant*, but Value*.
>
> What is the correct way to create such module? It's really tye
>
> Yuri
>
> --- c++ code ---
> #include "llvm/LLVMContext.h"
> #include "llvm/Module.h"
> #include "llvm/DerivedTypes.h"
> #include "llvm/Constants.h"
> #include "llvm/Instructions.h"
> #include "llvm/Analysis/Verifier.h"
> #include <stdio.h>
> #include <vector>
> using namespace llvm;
> using namespace std;
>
> Constant* mk_string(Module *M, LLVMContext &Context, const string
&svalue) {
>   ArrayType *Ty = ArrayType::get(Type::getInt8Ty(Context),svalue.size()+1);
>   GlobalVariable *GV = new llvm::GlobalVariable(
>     *M,
>     Ty,
>     true,
>     GlobalValue::InternalLinkage,
>     ConstantArray::get(Context,svalue),
>     "str",
>     0,
>     false,
>     0);
>
>   vector<Constant*> idxs;
>   idxs.push_back(ConstantInt::get(Type::getInt32Ty(Context), 0, false));
>   idxs.push_back(ConstantInt::get(Type::getInt32Ty(Context), 0, false));
>   return (GetElementPtrInst::Create(
>     GV,
>     idxs.begin(),
>     idxs.end(),
>     "gepi",
>     (BasicBlock*)0
>   ));
> }
>
> main() {
>   LLVMContext Context;
>   Module *M = new Module("test", Context);
>   //
>   vector<Constant*> strs;
>   strs.push_back(mk_string(M, Context, "s1"));
>   strs.push_back(mk_string(M, Context, "s2"));
>   ArrayType *Ty >
ArrayType::get(Type::getInt8Ty(Context)->getPointerTo(),2);
>   new llvm::GlobalVariable(
>     *M,
>     Ty,
>     true,
>     GlobalValue::InternalLinkage,
>     ConstantArray::get(Ty,strs),
>     "ss",
>     0,
>     false,
>     0);
>   verifyModule(*M);
>   delete M;
> }
>
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>

o.j.sivart at gmail.com

2010-Jun-01 21:57 UTC

head link

[LLVMdev] How to create global string array? (user question)

I have found an invaluable way to find an answer (not necessarily the best
answer, but an initial answer at least) is to write a simple c source file,
compile it to bitcode (clang -S -emit-llvm sourcefile.c), then get llc to
produce a cpp file containing the calls required to produce that bitcode (llc
-march=cpp sourcefile.s). I find that the resulting source file
(sourcefile.s.cpp) is usually enough to make an initial start on figuring out
how to do what I want if I can't otherwise find it in the docs.

In your case sourcefile.c would simply be:
const char* ss[] = {"s1","s2"};

On 02/06/2010, at 5:04 AM, Yuri wrote:
> I am trying to create such module with API (it's equivalent to c++: 
> const char* ss[] = {"s1","s2"};):
> 
> @ss = global [2 x i8*] [i8* getelementptr inbounds ([3 x i8]* @.str1, 
> i32 0, i32 0), i8* getelementptr inbounds ([3 x i8]* @.str2, i32 0, i32 
> 0)] ; <[2 x i8*]*> [#uses=0]
> @.str1 = private constant [3 x i8] c"s1\00", align 1 ; <[3 x
i8]*> [#uses=1]
> @.str2 = private constant [3 x i8] c"s2\00", align 1 ; <[3 x
i8]*> [#uses=1]
> 
> Code below doesn't compile because to initialize GlobalVariable I need 
> ConstantArray*, ConstantArray::get requires vector<Constant*>, but 
> getelementptr is an instruction and it's not Constant*, but Value*.
> 
> What is the correct way to create such module? It's really tye
> 
> Yuri
> 
> --- c++ code ---
> #include "llvm/LLVMContext.h"
> #include "llvm/Module.h"
> #include "llvm/DerivedTypes.h"
> #include "llvm/Constants.h"
> #include "llvm/Instructions.h"
> #include "llvm/Analysis/Verifier.h"
> #include <stdio.h>
> #include <vector>
> using namespace llvm;
> using namespace std;
> 
> Constant* mk_string(Module *M, LLVMContext &Context, const string
&svalue) {
>   ArrayType *Ty = ArrayType::get(Type::getInt8Ty(Context),svalue.size()+1);
>   GlobalVariable *GV = new llvm::GlobalVariable(
>     *M,
>     Ty,
>     true,
>     GlobalValue::InternalLinkage,
>     ConstantArray::get(Context,svalue),
>     "str",
>     0,
>     false,
>     0);
> 
>   vector<Constant*> idxs;
>   idxs.push_back(ConstantInt::get(Type::getInt32Ty(Context), 0, false));
>   idxs.push_back(ConstantInt::get(Type::getInt32Ty(Context), 0, false));
>   return (GetElementPtrInst::Create(
>     GV,
>     idxs.begin(),
>     idxs.end(),
>     "gepi",
>     (BasicBlock*)0
>   ));
> }
> 
> main() {
>   LLVMContext Context;
>   Module *M = new Module("test", Context);
>   //
>   vector<Constant*> strs;
>   strs.push_back(mk_string(M, Context, "s1"));
>   strs.push_back(mk_string(M, Context, "s2"));
>   ArrayType *Ty = 
> ArrayType::get(Type::getInt8Ty(Context)->getPointerTo(),2);
>   new llvm::GlobalVariable(
>     *M,
>     Ty,
>     true,
>     GlobalValue::InternalLinkage,
>     ConstantArray::get(Ty,strs),
>     "ss",
>     0,
>     false,
>     0);
>   verifyModule(*M);
>   delete M;
> }
> 
> 
> 
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

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