Fixed bug: load array or struct variable failed at AssignStmt.

[OrchidRock]

For the following input program to tinylang:

MODULE Point;

TYPE Point = RECORD X, Y: INTEGER END;

VAR p: Point;

PROCEDURE AssignX(a: INTEGER);
BEGIN
  p.X := a;
  p.Y := p.X + a;
END AssignX;

END Point.

I got a program crash:

tinylang: /usr/lib/llvm-12/include/llvm/Support/Casting.h:269: typename llvm::cast_retty<X, Y*>::ret_type llvm::cast(Y*) [with X = llvm::PointerType; Y = llvm::Type; typename llvm::cast_retty<X, Y*>::ret_type = llvm::PointerType*]: Assertion `isa<X>(Val) && "cast<Ty>() argument of incompatible type!"' failed.

it came from the struct reference for p.Xat p.Y := p.X + a. The program calls readVariable method when emitting p.X expression, but it didn't send the argument for LoadVal. After I fixed it, the program is working.

However, It's not enough. Then I got the following IR code:

; ModuleID = 'Point.mod'
source_filename = "Point.mod"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-linux-gnu"

%Point = type { i64, i64 }

@_t5Point1p = private global %Point zeroinitializer

define void @_t5Point7AssignX(i64 %a) {
entry:
  store i64 %a, i64* getelementptr inbounds (%Point, %Point* @_t5Point1p, i32 0, i32 0), align 8
  %0 = load %Point, %Point* @_t5Point1p, align 8
  %1 = add nsw %Point %0, i64 %a
  store %Point %1, i64* getelementptr inbounds (%Point, %Point* @_t5Point1p, i32 0, i32 1), align 8
  ret void
}

But the load instruction is incorrect because we didn't construct the correct IdxList when calling Builder::CreateInBoundsGEP(val, IdxList) .

After fixed the program, I got the working IR code:

; ModuleID = 'Point.mod'
source_filename = "Point.mod"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-linux-gnu"

%Point = type { i64, i64 }

@_t5Point1p = private global %Point zeroinitializer

define void @_t5Point7AssignX(i64 %a) {
entry:
  store i64 %a, i64* getelementptr inbounds (%Point, %Point* @_t5Point1p, i32 0, i32 0), align 8
  %0 = load i64, i64* getelementptr inbounds (%Point, %Point* @_t5Point1p, i32 0, i32 0), align 8
  %1 = add nsw  %0, i64 %a
  store i64 %1, i64* getelementptr inbounds (%Point, %Point* @_t5Point1p, i32 0, i32 1), align 8
  ret void
}