Hi,
I want to ask for a small help for creating an instruction that calls
e member method of an object. I suppose that this is not a headache
but I am impatient in learning :) I would be very thankful if you can
show me an example snippet code that does this in LLVM. Below is
described my case.
Let's say I have a class TestClass
class TestClass
{
int testMethod(int a);
}
and I want to create a call instruction that calls
obj.testMethod(input) where obj is an instance of TestClass
TestClass obj; // I have this declared prior
int input = 1; // I have declared prior
int output; // I have this declared prior too
output = obj.testObject(input); // I want to create this instruction
Thanks,
Ferad
--
Ferad Zyulkyarov
Barcelona Supercomputing Center
Ferad Zyulkyarov wrote:> Hi, > > I want to ask for a small help for creating an instruction that calls > e member method of an object. I suppose that this is not a headache > but I am impatient in learning :) I would be very thankful if you can > show me an example snippet code that does this in LLVM. Below is > described my case. > > Let's say I have a class TestClass > > class TestClass > { > int testMethod(int a); > } > > and I want to create a call instruction that calls > obj.testMethod(input) where obj is an instance of TestClass > > TestClass obj; // I have this declared prior > int input = 1; // I have declared prior > int output; // I have this declared prior too > output = obj.testObject(input); // I want to create this instruction > > Thanks, > Ferad >You can use the LLVM demo page ( http://llvm.org/demo/index.cgi ) to find out what LLVM code is generated for some C++ code. For example, the above produces: ; ModuleID = '/tmp/webcompile/_6207_0.bc' target datalayout = "e-p:32:32" target endian = little target pointersize = 32 target triple = "i686-pc-linux-gnu" %struct.TestClass = type { ubyte } implementation ; Functions: void %_Z4funcv() { entry: %obj = alloca %struct.TestClass, align 1 ; <%struct.TestClass*> [#uses=1] %tmp1 = call int %_ZN9TestClass10testMethodEi( %struct.TestClass* %obj, int 1 ) ; <int> [#uses=0] ret void } declare int %_ZN9TestClass10testMethodEi(%struct.TestClass*, int) The object on which you call the method becomes the first argument to the method.
Hi Ferad, On Wed, 2007-04-04 at 19:48 +0200, Ferad Zyulkyarov wrote:> Hi, > > I want to ask for a small help for creating an instruction that calls > e member method of an object. I suppose that this is not a headache > but I am impatient in learning :) I would be very thankful if you can > show me an example snippet code that does this in LLVM. Below is > described my case. > > Let's say I have a class TestClass > > class TestClass > { > int testMethod(int a); > } > > and I want to create a call instruction that calls > obj.testMethod(input) where obj is an instance of TestClass > > TestClass obj; // I have this declared prior > int input = 1; // I have declared prior > int output; // I have this declared prior too > output = obj.testObject(input); // I want to create this instruction >Why not just code this up into a C++ function and submit it to the online demo to see what is produced? I submitted this: class TestClass { public: int testMethod(int a); virtual int testMethod2(int a); }; int doit() { TestClass obj; // I have this declared prior int input = 1; // I have declared prior int output; // I have this declared prior too output = obj.testMethod(input); // I want to create this inst output += obj.testMethod2(input); // Try virtual too return output; } to http://llvm.org/demo/ and got: target datalayout = "e-p:32:32" target endian = little target pointersize = 32 target triple = "i686-pc-linux-gnu" %struct.TestClass = type { int (...)** } %vtable for TestClass = external constant [3 x int (...)*] ; <[3 x int (...)*]*> [#uses=1] implementation ; Functions: int %doit()() { entry: %obj = alloca %struct.TestClass, align 16 ; <%struct.TestClass*> [#uses=3] %tmp = getelementptr %struct.TestClass* %obj, int 0, uint 0 ; <int (...)***> [#uses=1] store int (...)** getelementptr ([3 x int (...)*]* %vtable for TestClass, int 0, long 2), int (...)*** %tmp %tmp1 = call int %TestClass::testMethod(int)( %struct.TestClass* %obj, int 1 ) ; <int> [#uses=1] %tmp3 = call int %TestClass::testMethod2(int)( %struct.TestClass* %obj, int 1 ) ; <int> [#uses=1] %tmp5 = add int %tmp3, %tmp1 ; <int> [#uses=1] ret int %tmp5 } declare int %TestClass::testMethod(int)(%struct.TestClass*, int) declare int %TestClass::testMethod2(int)(%struct.TestClass*, int) Note the "%vtable for TestClass" external constant array. Hope this helps, Reid.> Thanks, > Ferad >
Reid, Jeff thanks for the quick response. This will help. I didn't think of this way when sending the mail.. just blocked :) Thanks again, Ferad On 4/4/07, Reid Spencer <rspencer at reidspencer.com> wrote:> Hi Ferad, > > On Wed, 2007-04-04 at 19:48 +0200, Ferad Zyulkyarov wrote: > > Hi, > > > > I want to ask for a small help for creating an instruction that calls > > e member method of an object. I suppose that this is not a headache > > but I am impatient in learning :) I would be very thankful if you can > > show me an example snippet code that does this in LLVM. Below is > > described my case. > > > > Let's say I have a class TestClass > > > > class TestClass > > { > > int testMethod(int a); > > } > > > > and I want to create a call instruction that calls > > obj.testMethod(input) where obj is an instance of TestClass > > > > TestClass obj; // I have this declared prior > > int input = 1; // I have declared prior > > int output; // I have this declared prior too > > output = obj.testObject(input); // I want to create this instruction > > > > Why not just code this up into a C++ function and submit it to the > online demo to see what is produced? I submitted this: > > class TestClass { > public: > int testMethod(int a); > virtual int testMethod2(int a); > }; > > int doit() { > TestClass obj; // I have this declared prior > int input = 1; // I have declared prior > int output; // I have this declared prior too > output = obj.testMethod(input); // I want to create this inst > output += obj.testMethod2(input); // Try virtual too > return output; > } > > to http://llvm.org/demo/ and got: > > target datalayout = "e-p:32:32" > target endian = little > target pointersize = 32 > target triple = "i686-pc-linux-gnu" > %struct.TestClass = type { int (...)** } > %vtable for TestClass = external constant [3 x int (...)*] ; <[3 x int (...)*]*> [#uses=1] > > implementation ; Functions: > > int %doit()() { > entry: > %obj = alloca %struct.TestClass, align 16 ; <%struct.TestClass*> [#uses=3] > %tmp = getelementptr %struct.TestClass* %obj, int 0, uint 0 ; <int (...)***> [#uses=1] > store int (...)** getelementptr ([3 x int (...)*]* %vtable for TestClass, int 0, long 2), int (...)*** %tmp > %tmp1 = call int %TestClass::testMethod(int)( %struct.TestClass* %obj, int 1 ) ; <int> [#uses=1] > %tmp3 = call int %TestClass::testMethod2(int)( %struct.TestClass* %obj, int 1 ) ; <int> [#uses=1] > %tmp5 = add int %tmp3, %tmp1 ; <int> [#uses=1] > ret int %tmp5 > } > > declare int %TestClass::testMethod(int)(%struct.TestClass*, int) > > declare int %TestClass::testMethod2(int)(%struct.TestClass*, int) > > Note the "%vtable for TestClass" external constant array. > > Hope this helps, > > Reid. > > > > > Thanks, > > Ferad > > > > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >-- Ferad Zyulkyarov Barcelona Supercomputing Center
On 4 Apr 2007, at 20:10, Jeff Cohen wrote:> […] > %obj = alloca %struct.TestClass, align 1 ; <%struct.TestClass*> > [#uses=1] > %tmp1 = call int %_ZN9TestClass10testMethodEi( %struct.TestClass* % > obj, int 1 ) ; <int> [#uses=0] > ret void > } > > declare int %_ZN9TestClass10testMethodEi(%struct.TestClass*, int)The name mangling is not very pretty though and it is specific to the C++ front-end. What is the best manner to deal with that problem? Luc Bourhis