[llvm-commits] checking of inbounds for multi dimensional arrary and struct array on isInBoundsIndices()

[Jin Gu Kang]

Hi all

isBounsIndices() function decides to set inbounds flag and uses one-past-the-end
rule about index. I think one-past-the-end rule is applied to multi-dimensional
array and struct array.

What do you think about this?

I tested the following code.

char a[3][2];
struct test {
  char a;
  int b;
};
struct test foo[3];
int main(void) {
  a[2][1] = 1;
  a[3][0] = 2;
  a[3][1] = 3;
  a[3][2] = 4;
  foo[2].a = 5;
  foo[3].a = 6;
  foo[3].b = 7;
}
------------------------------------------------------------------
define i32 @main() nounwind {
entry:
  %retval = alloca i32
  %"alloca point" = bitcast i32 0 to i32
  store i8 1, i8* getelementptr inbounds ([3 x [2 x i8]]* @a, i32 0, i32 2, i32 1), align 1
  store i8 2, i8* getelementptr inbounds ([3 x [2 x i8]]* @a, i32 1, i32 0, i32 0), align 1
  store i8 3, i8* getelementptr ([3 x [2 x i8]]* @a, i32 1, i32 0, i32 1), align 1
  store i8 4, i8* getelementptr ([3 x [2 x i8]]* @a, i32 1, i32 1, i32 0), align 1
  store i8 5, i8* getelementptr inbounds ([3 x %struct.test]* @foo, i32 0, i32 2, i32 0), align 4
  store i8 6, i8* getelementptr inbounds ([3 x %struct.test]* @foo, i32 1, i32 0, i32 0), align 4
  store i32 7, i32* getelementptr ([3 x %struct.test]* @foo, i32 1, i32 0, i32 1), align 4
  br label %return
return:                                           ; preds = %entry
  %retval1 = load i32* %retval
  ret i32 %retval1
}
-------------------------------------------------------------------
isInBoundsIndices() doesn't return inbounds flag as true on
a[3][1] = 3,  a[3][2] = 4 and  foo[3].b = 7.

I made a patch to fix this.

This patch has a little "if-else" statements to process some of cases.
If you find a better solution, please let me know. :)

Please review the attached patch.

Thanks,
Jin-Gu Kang


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