Tag-Protector: An Effective and Dynamic Detection of Illegal Memory Accesses through Compile Time Code Instrumentation

Listing 3

LLVM-IR code (uninstrumented) for C code presented in Listing 2.

  //Lines 1-3 represent LLV-IR code for line 1 of C code in Listing 2

1:  %call = call noalias i8  @malloc (i64 800) #2

2:  %0 = bitcast i8  % call to i8

3:  store i8  %0, i8***  @buffer, align 8

4:  br label %for.cond

  //Lines 5-8 represent LLV-IR code for line 2 of C code in Listing 2

5: for.cond:        ; preds = %for.inc, %entry

6:  %index .0 = phi i32 [0, % entry], [%inc, %for.incs]

7:  %cmp = icmp slt i32 %index .0, 101

8:  br i1 %cmp, label %for.body, label %for.end

  //Lines 9-14 represent LLV-IR code for line 3 of C code in Listing 2

9: for.body:            ; preds = %for.cond

10:  %idxprom = sext i32 %index .0 to i64

11:  %1 = load i8   @buffer, align 8

12:  %arrayidx = getelementptr inbounds i8  %1, i64 %idxprom

13:  store i8  null, i8  %arrayidx, align 8

14:  br label %for.inc

15: for.inc:

; preds = %for.body

16:  %inc = add nsw i32 %index.0, 1

17:  br label %for.cond

18: for.end:

; preds = %for.cond