How to load an address that was allocated in a separate function using IRBuilder - LLVM 6.0
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Working on a research project that requires to add load instructions to an analyzed LLVM IR code to load in a function func_A addresses that were allocated in a separate function func_B using IRBuilder. An example is shown as follows.
define void @func_B() {
%1 = alloca [1 x i32], align 4
}
define void @func_A() {
// load the address allocated above here using IRBuilder in an analysis pass
// to the IR code, something like the following:
// IRBuilder<> builder();
// builder.CreateLoad(val);
}
I've been able to find the to-be-loaded llvm:value*, i.e., val in the above example, but the problem is val is a local identifier declared in func_B and may conflict with func_A's identifiers (say func_A declares a local identifier named %1 too) when loaded in func_A.
How can I load func_B's %1 without conflicts in func_A? Note that I can't pass %1 to func_A as a function parameter since I don't want to change anything of the IR code but adding some load instructions.
Any help would be greatly appreciated!
llvm llvm-ir
asked Nov 16 '18 at 21:39
RuiRui
184
add a comment |
Working on a research project that requires to add load instructions to an analyzed LLVM IR code to load in a function func_A addresses that were allocated in a separate function func_B using IRBuilder. An example is shown as follows.
define void @func_B() {
%1 = alloca [1 x i32], align 4
}
define void @func_A() {
// load the address allocated above here using IRBuilder in an analysis pass
// to the IR code, something like the following:
// IRBuilder<> builder();
// builder.CreateLoad(val);
}
I've been able to find the to-be-loaded llvm:value*, i.e., val in the above example, but the problem is val is a local identifier declared in func_B and may conflict with func_A's identifiers (say func_A declares a local identifier named %1 too) when loaded in func_A.
How can I load func_B's %1 without conflicts in func_A? Note that I can't pass %1 to func_A as a function parameter since I don't want to change anything of the IR code but adding some load instructions.
Any help would be greatly appreciated!
llvm llvm-ir
asked Nov 16 '18 at 21:39
RuiRui
184
add a comment |
Working on a research project that requires to add load instructions to an analyzed LLVM IR code to load in a function func_A addresses that were allocated in a separate function func_B using IRBuilder. An example is shown as follows.
define void @func_B() {
%1 = alloca [1 x i32], align 4
}
define void @func_A() {
// load the address allocated above here using IRBuilder in an analysis pass
// to the IR code, something like the following:
// IRBuilder<> builder();
// builder.CreateLoad(val);
}
I've been able to find the to-be-loaded llvm:value*, i.e., val in the above example, but the problem is val is a local identifier declared in func_B and may conflict with func_A's identifiers (say func_A declares a local identifier named %1 too) when loaded in func_A.
How can I load func_B's %1 without conflicts in func_A? Note that I can't pass %1 to func_A as a function parameter since I don't want to change anything of the IR code but adding some load instructions.
Any help would be greatly appreciated!
llvm llvm-ir
asked Nov 16 '18 at 21:39
RuiRui
184
Working on a research project that requires to add load instructions to an analyzed LLVM IR code to load in a function func_A addresses that were allocated in a separate function func_B using IRBuilder. An example is shown as follows.
define void @func_B() {
%1 = alloca [1 x i32], align 4
}
define void @func_A() {
// load the address allocated above here using IRBuilder in an analysis pass
// to the IR code, something like the following:
// IRBuilder<> builder();
// builder.CreateLoad(val);
}
I've been able to find the to-be-loaded llvm:value*, i.e., val in the above example, but the problem is val is a local identifier declared in func_B and may conflict with func_A's identifiers (say func_A declares a local identifier named %1 too) when loaded in func_A.
How can I load func_B's %1 without conflicts in func_A? Note that I can't pass %1 to func_A as a function parameter since I don't want to change anything of the IR code but adding some load instructions.
Any help would be greatly appreciated!
llvm llvm-ir
llvm llvm-ir
asked Nov 16 '18 at 21:39
RuiRui
184
asked Nov 16 '18 at 21:39
RuiRui
184
asked Nov 16 '18 at 21:39
RuiRui
184
asked Nov 16 '18 at 21:39
RuiRui
184
asked Nov 16 '18 at 21:39
RuiRui
184
184
add a comment |
add a comment |
1 Answer
1
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oldest
votes
You, obviously, can't do that. It is as if you wanted to access int a from the bar() in the following example:
int foo()
{
int a = 5;
}
int bar()
{
...
}
Since %1 is allocated on the stack, its memory get freed when the function func_B finishes, so it may not even exist during func_A execution.
The only thing you can do is to store the value of %1 into a global variable in func_B and load it in func_A:
@var = [1 x i32] zeroinitializer
define void @func_B() {
%1 = alloca [1 x i32], align 4
store %1, @var
}
define void @func_A() {
// load the address allocated above here using IRBuilder in an analysis pass
// to the IR code, something like the following:
// IRBuilder<> builder();
// builder.CreateLoad(val);
%1 = load @var
}
answered Nov 17 '18 at 8:44
arrowdarrowd
23.2k45584
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
You, obviously, can't do that. It is as if you wanted to access int a from the bar() in the following example:
int foo()
{
int a = 5;
}
int bar()
{
...
}
Since %1 is allocated on the stack, its memory get freed when the function func_B finishes, so it may not even exist during func_A execution.
The only thing you can do is to store the value of %1 into a global variable in func_B and load it in func_A:
@var = [1 x i32] zeroinitializer
define void @func_B() {
%1 = alloca [1 x i32], align 4
store %1, @var
}
define void @func_A() {
// load the address allocated above here using IRBuilder in an analysis pass
// to the IR code, something like the following:
// IRBuilder<> builder();
// builder.CreateLoad(val);
%1 = load @var
}
answered Nov 17 '18 at 8:44
arrowdarrowd
23.2k45584
add a comment |
You, obviously, can't do that. It is as if you wanted to access int a from the bar() in the following example:
int foo()
{
int a = 5;
}
int bar()
{
...
}
Since %1 is allocated on the stack, its memory get freed when the function func_B finishes, so it may not even exist during func_A execution.
The only thing you can do is to store the value of %1 into a global variable in func_B and load it in func_A:
@var = [1 x i32] zeroinitializer
define void @func_B() {
%1 = alloca [1 x i32], align 4
store %1, @var
}
define void @func_A() {
// load the address allocated above here using IRBuilder in an analysis pass
// to the IR code, something like the following:
// IRBuilder<> builder();
// builder.CreateLoad(val);
%1 = load @var
}
answered Nov 17 '18 at 8:44
arrowdarrowd
23.2k45584
add a comment |
You, obviously, can't do that. It is as if you wanted to access int a from the bar() in the following example:
int foo()
{
int a = 5;
}
int bar()
{
...
}
Since %1 is allocated on the stack, its memory get freed when the function func_B finishes, so it may not even exist during func_A execution.
The only thing you can do is to store the value of %1 into a global variable in func_B and load it in func_A:
@var = [1 x i32] zeroinitializer
define void @func_B() {
%1 = alloca [1 x i32], align 4
store %1, @var
}
define void @func_A() {
// load the address allocated above here using IRBuilder in an analysis pass
// to the IR code, something like the following:
// IRBuilder<> builder();
// builder.CreateLoad(val);
%1 = load @var
}
answered Nov 17 '18 at 8:44
arrowdarrowd
23.2k45584
You, obviously, can't do that. It is as if you wanted to access int a from the bar() in the following example:
int foo()
{
int a = 5;
}
int bar()
{
...
}
Since %1 is allocated on the stack, its memory get freed when the function func_B finishes, so it may not even exist during func_A execution.
The only thing you can do is to store the value of %1 into a global variable in func_B and load it in func_A:
@var = [1 x i32] zeroinitializer
define void @func_B() {
%1 = alloca [1 x i32], align 4
store %1, @var
}
define void @func_A() {
// load the address allocated above here using IRBuilder in an analysis pass
// to the IR code, something like the following:
// IRBuilder<> builder();
// builder.CreateLoad(val);
%1 = load @var
}
answered Nov 17 '18 at 8:44
arrowdarrowd
23.2k45584
answered Nov 17 '18 at 8:44
arrowdarrowd
23.2k45584
answered Nov 17 '18 at 8:44
arrowdarrowd
23.2k45584
answered Nov 17 '18 at 8:44
arrowdarrowd
23.2k45584
23.2k45584
add a comment |
add a comment |
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