Question

所以我有以下C代码：

#include<stdio.h>

int main(int argc, char *argv[]) {

    printf("%s\n", argv[0]);
    return argc;
}

翻译成

; ModuleID = 'argv.bc'
source_filename = "argv.c"
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-linux-gnu"

@.str = private unnamed_addr constant [4 x i8] c"%s\0A\00", align 1

; Function Attrs: noinline nounwind optnone uwtable
define i32 @main(i32, i8**) #0 {
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  %5 = alloca i8**, align 8
  store i32 0, i32* %3, align 4
  store i32 %0, i32* %4, align 4
  store i8** %1, i8*** %5, align 8
  %6 = load i8**, i8*** %5, align 8
  %7 = getelementptr inbounds i8*, i8** %6, i64 0
  %8 = load i8*, i8** %7, align 8
  %9 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i32 0, i32 0), i8* %8)
  %10 = load i32, i32* %4, align 4
  ret i32 %10
}

declare i32 @printf(i8*, ...) #1

attributes #0 = { noinline nounwind optnone uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #1 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }

!llvm.module.flags = !{!0}
!llvm.ident = !{!1}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{!"clang version 6.0.1-svn334776-1~exp1~20181018152737.116 (branches/release_60)"}

此刻我正在尝试Interpreter类，我想在执行代码时从内存中提取值。

在这种情况下，我知道％8持有指向argv [0]的指针，我想提取该值。虽然正确的方法应该是在visitLoadInst内部完成它：

ExecutionContext &SF = ECStack.back();
  GenericValue SRC = getOperandValue(I.getPointerOperand(), SF);
  GenericValue *Ptr = (GenericValue*)GVTOP(SRC);
  GenericValue Result;
  LoadValueFromMemory(Result, Ptr, I.getType());

我使用了getInt32Ty（context）而不是I.getType（），而是使用了第一个LoadValueFromMemory返回的结果来代替Ptr。之后，我打印“ newResult.Int”，但结果始终为0。我不明白为什么。

有人可以帮我从内存中取出argv [0]吗？

非常感谢

如何获得i8 *

0 个答案: