How to differentiate stack/heap addresses in llvm IR code?
I'd like to find a way to determine if a load/store operand in LLVM IR is a stack address or a heap address in an LLVM pass (the pass coded in C++), i.e.
if (inst is a store) {
if (inst->getOperand(1) is a heap address) {
// do something with the heap address
}
}
And operate similarly for loads. Looking in the IR code, they are referenced the same:
store i32 5, i32* %c, align 4 // storing value to a local variable
store i32 1, i32* %4, align 4 // storing value to something on the heap, do something with the heap address
Any ideas?
c++ llvm llvm-ir llvm-c++-api
asked Nov 19 '18 at 17:48
user3043904user3043904
112
add a comment |
I'd like to find a way to determine if a load/store operand in LLVM IR is a stack address or a heap address in an LLVM pass (the pass coded in C++), i.e.
if (inst is a store) {
if (inst->getOperand(1) is a heap address) {
// do something with the heap address
}
}
And operate similarly for loads. Looking in the IR code, they are referenced the same:
store i32 5, i32* %c, align 4 // storing value to a local variable
store i32 1, i32* %4, align 4 // storing value to something on the heap, do something with the heap address
Any ideas?
c++ llvm llvm-ir llvm-c++-api
asked Nov 19 '18 at 17:48
user3043904user3043904
112
add a comment |
I'd like to find a way to determine if a load/store operand in LLVM IR is a stack address or a heap address in an LLVM pass (the pass coded in C++), i.e.
if (inst is a store) {
if (inst->getOperand(1) is a heap address) {
// do something with the heap address
}
}
And operate similarly for loads. Looking in the IR code, they are referenced the same:
store i32 5, i32* %c, align 4 // storing value to a local variable
store i32 1, i32* %4, align 4 // storing value to something on the heap, do something with the heap address
Any ideas?
c++ llvm llvm-ir llvm-c++-api
asked Nov 19 '18 at 17:48
user3043904user3043904
112
I'd like to find a way to determine if a load/store operand in LLVM IR is a stack address or a heap address in an LLVM pass (the pass coded in C++), i.e.
if (inst is a store) {
if (inst->getOperand(1) is a heap address) {
// do something with the heap address
}
}
And operate similarly for loads. Looking in the IR code, they are referenced the same:
store i32 5, i32* %c, align 4 // storing value to a local variable
store i32 1, i32* %4, align 4 // storing value to something on the heap, do something with the heap address
Any ideas?
c++ llvm llvm-ir llvm-c++-api
c++ llvm llvm-ir llvm-c++-api
asked Nov 19 '18 at 17:48
user3043904user3043904
112
asked Nov 19 '18 at 17:48
user3043904user3043904
112
asked Nov 19 '18 at 17:48
user3043904user3043904
112
asked Nov 19 '18 at 17:48
user3043904user3043904
112
asked Nov 19 '18 at 17:48
user3043904user3043904
112
112
add a comment |
add a comment |
1 Answer
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My frontend does this (well, something a little like it). You may not be able to do it well enough to reach your goals, but if you do, this is one approach:
Regard each return result of malloc() (or whatever your allocator is called) as a heap variable and each result of alloca() as a stack variable. For each of those, classify more values by looking at for(auto x : y->users()); a getelementptr or cast of a malloc() is also a heap variable.
However, this doesn't classify every value. Loading a pointer from a struct/array on the heap may return something on the stack and vice versa. Function arguments may be either. But perhaps you don't need to classify every value.
answered Nov 20 '18 at 6:51
arntarnt
5,06431728
add a comment |
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My frontend does this (well, something a little like it). You may not be able to do it well enough to reach your goals, but if you do, this is one approach:
Regard each return result of malloc() (or whatever your allocator is called) as a heap variable and each result of alloca() as a stack variable. For each of those, classify more values by looking at for(auto x : y->users()); a getelementptr or cast of a malloc() is also a heap variable.
However, this doesn't classify every value. Loading a pointer from a struct/array on the heap may return something on the stack and vice versa. Function arguments may be either. But perhaps you don't need to classify every value.
answered Nov 20 '18 at 6:51
arntarnt
5,06431728
add a comment |
My frontend does this (well, something a little like it). You may not be able to do it well enough to reach your goals, but if you do, this is one approach:
Regard each return result of malloc() (or whatever your allocator is called) as a heap variable and each result of alloca() as a stack variable. For each of those, classify more values by looking at for(auto x : y->users()); a getelementptr or cast of a malloc() is also a heap variable.
However, this doesn't classify every value. Loading a pointer from a struct/array on the heap may return something on the stack and vice versa. Function arguments may be either. But perhaps you don't need to classify every value.
answered Nov 20 '18 at 6:51
arntarnt
5,06431728
add a comment |
My frontend does this (well, something a little like it). You may not be able to do it well enough to reach your goals, but if you do, this is one approach:
Regard each return result of malloc() (or whatever your allocator is called) as a heap variable and each result of alloca() as a stack variable. For each of those, classify more values by looking at for(auto x : y->users()); a getelementptr or cast of a malloc() is also a heap variable.
However, this doesn't classify every value. Loading a pointer from a struct/array on the heap may return something on the stack and vice versa. Function arguments may be either. But perhaps you don't need to classify every value.
answered Nov 20 '18 at 6:51
arntarnt
5,06431728
My frontend does this (well, something a little like it). You may not be able to do it well enough to reach your goals, but if you do, this is one approach:
Regard each return result of malloc() (or whatever your allocator is called) as a heap variable and each result of alloca() as a stack variable. For each of those, classify more values by looking at for(auto x : y->users()); a getelementptr or cast of a malloc() is also a heap variable.
However, this doesn't classify every value. Loading a pointer from a struct/array on the heap may return something on the stack and vice versa. Function arguments may be either. But perhaps you don't need to classify every value.
answered Nov 20 '18 at 6:51
arntarnt
5,06431728
edited Nov 20 '18 at 7:31
answered Nov 20 '18 at 6:51
arntarnt
5,06431728
answered Nov 20 '18 at 6:51
arntarnt
5,06431728
answered Nov 20 '18 at 6:51
arntarnt
5,06431728
5,06431728
add a comment |
add a comment |
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