Comments (3)
dequeb
commented on July 2, 2024
1
Thank you.
…________________________________
De : Robin ***@***.***>
Envoyé : Sunday, March 10, 2024 8:38:13 PM
À : llir/llvm ***@***.***>
Cc : dequeb ***@***.***>; Mention ***@***.***>
Objet : Re: [llir/llvm] Hello 10 instead of Hello world. Passing a IntPtr to printf (go - LLIR/LLVM) (Issue #234)
Hi @dequeb<https://github.com/dequeb>,
I updated the example code you posted to make it print "Hello, 10!". The random value that was printed was the pointer address, rather than the value stored within the local variable. Hope this helps!
Contents of foo.go:
package main
import (
"fmt"
"github.com/llir/llvm/ir"
"github.com/llir/llvm/ir/constant"
"github.com/llir/llvm/ir/types"
)
func main() {
// Create a new LLVM IR module.
m := ir.NewModule()
hello := constant.NewCharArrayFromString("Hello, %d!\n\x00")
ten := constant.NewInt(types.I32, 10)
numb := m.NewGlobalDef("ten", ten)
str := m.NewGlobalDef("str", hello)
// Add external function declaration of printf.
printf := m.NewFunc("printf", types.I32, ir.NewParam("", types.NewPointer(types.I8)))
printf.Sig.Variadic = true
main := m.NewFunc("main", types.I32)
entry := main.NewBlock("")
// Cast *[15]i8 to *i8.
zero := constant.NewInt(types.I64, 0)
// allocate memory for ten
tenVal := entry.NewLoad(types.I32, numb)
gep := constant.NewGetElementPtr(hello.Typ, str, zero, zero)
entry.NewCall(printf, gep, tenVal)
entry.NewRet(constant.NewInt(types.I32, 0))
fmt.Println(m)
}
Output LLVM IR (foo.ll):
@ten = global i32 10
@str = global [12 x i8] c"Hello, %d!\0A\00"
declare i32 @printf(i8* %0, ...)
define i32 @main() {
0:
%1 = load i32, i32* @ten
%2 = call i32 (i8*, ...) @printf(i8* getelementptr ([12 x i8], [12 x i8]* @str, i64 0, i64 0), i32 %1)
ret i32 0
}
Output from lli:
$ go run foo.go > foo.ll
$ lli foo.ll
Hello, 10!
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dequeb
commented on July 2, 2024
I modified my code. It compiles but the result is not what is expected:
func TestIntGEN(*testing.T) {
// Create a new LLVM IR module.
m := ir.NewModule()
hello := constant.NewCharArrayFromString("Hello, %d!\n\x00")
ten := constant.NewInt(types.I32, 10)
numb := m.NewGlobalDef("ten", ten)
str := m.NewGlobalDef("str", hello)
// Add external function declaration of printf.
printf := m.NewFunc("printf", types.I32, ir.NewParam("", types.NewPointer(types.I8)))
printf.Sig.Variadic = true
main := m.NewFunc("main", types.I32)
entry := main.NewBlock("")
// Cast *[15]i8 to *i8.
zero := constant.NewInt(types.I64, 0)
// allocate memory for ten
tenPtr := entry.NewAlloca(numb.Typ)
// store the pointer to ten in tenPtr
entry.NewStore(numb, tenPtr)
gep := constant.NewGetElementPtr(hello.Typ, str, zero, zero)
entry.NewCall(printf, gep, tenPtr)
entry.NewRet(constant.NewInt(types.I32, 0))
fmt.Println(m)
}
It looks like the pointer is accessing a random value instead. Someone could help?
The resulting LLVM-IR is:
@ten = global i32 10
@str = global [12 x i8] c"Hello, %d!\0A\00"
declare i32 @printf(i8* %0, ...)
define i32 @main() {
0:
%1 = alloca i32*
store i32* @ten, i32** %1
%2 = call i32 (i8*, ...) @printf(i8* getelementptr ([12 x i8], [12 x i8]* @str, i64 0, i64 0), i32** %1)
ret i32 0
}
from llvm.
mewmew
commented on July 2, 2024
Hi @dequeb,
I updated the example code you posted to make it print "Hello, 10!". The random value that was printed was the pointer address, rather than the value stored within the local variable. Hope this helps!
Contents of foo.go:
package main
import (
"fmt"
"github.com/llir/llvm/ir"
"github.com/llir/llvm/ir/constant"
"github.com/llir/llvm/ir/types"
)
func main() {
// Create a new LLVM IR module.
m := ir.NewModule()
hello := constant.NewCharArrayFromString("Hello, %d!\n\x00")
ten := constant.NewInt(types.I32, 10)
numb := m.NewGlobalDef("ten", ten)
str := m.NewGlobalDef("str", hello)
// Add external function declaration of printf.
printf := m.NewFunc("printf", types.I32, ir.NewParam("", types.NewPointer(types.I8)))
printf.Sig.Variadic = true
main := m.NewFunc("main", types.I32)
entry := main.NewBlock("")
// Cast *[15]i8 to *i8.
zero := constant.NewInt(types.I64, 0)
// load value of global variable to local variable.
tenVal := entry.NewLoad(types.I32, numb)
gep := constant.NewGetElementPtr(hello.Typ, str, zero, zero)
entry.NewCall(printf, gep, tenVal)
entry.NewRet(constant.NewInt(types.I32, 0))
fmt.Println(m)
}Output LLVM IR (foo.ll):
@ten = global i32 10
@str = global [12 x i8] c"Hello, %d!\0A\00"
declare i32 @printf(i8* %0, ...)
define i32 @main() {
0:
%1 = load i32, i32* @ten
%2 = call i32 (i8*, ...) @printf(i8* getelementptr ([12 x i8], [12 x i8]* @str, i64 0, i64 0), i32 %1)
ret i32 0
}Output from lli:
$ go run foo.go > foo.ll
$ lli foo.ll
Hello, 10!from llvm.
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