diff --git a/nac3core/src/codegen/irrt/irrt.c b/nac3core/src/codegen/irrt/irrt.c
index fda9312..59c481f 100644
--- a/nac3core/src/codegen/irrt/irrt.c
+++ b/nac3core/src/codegen/irrt/irrt.c
@@ -8,6 +8,8 @@ typedef unsigned _BitInt(64) uint64_t;
 # define MAX(a, b) (a > b ? a : b)
 # define MIN(a, b) (a > b ? b : a)
 
+# define NULL ((void *) 0)
+
 // adapted from GNU Scientific Library: https://git.savannah.gnu.org/cgit/gsl.git/tree/sys/pow_int.c
 // need to make sure `exp >= 0` before calling this function
 #define DEF_INT_EXP(T) T __nac3_int_exp_##T( \
@@ -293,3 +295,87 @@ uint64_t __nac3_ndarray_flatten_index64(
     }
     return idx;
 }
+
+void __nac3_ndarray_calc_broadcast(
+    const uint32_t *lhs_dims,
+    uint32_t lhs_ndims,
+    const uint32_t *rhs_dims,
+    uint32_t rhs_ndims,
+    uint32_t *out_dims
+) {
+    uint32_t max_ndims = lhs_ndims > rhs_ndims ? lhs_ndims : rhs_ndims;
+
+    for (uint32_t i = 0; i < max_ndims; ++i) {
+        uint32_t *lhs_dim_sz = i < lhs_ndims ? &lhs_dims[lhs_ndims - i - 1] : NULL;
+        uint32_t *rhs_dim_sz = i < rhs_ndims ? &rhs_dims[rhs_ndims - i - 1] : NULL;
+        uint32_t *out_dim = &out_dims[max_ndims - i - 1];
+
+        if (lhs_dim_sz == NULL) {
+            *out_dim = *rhs_dim_sz;
+        } else if (rhs_dim_sz == NULL) {
+            *out_dim = *lhs_dim_sz;
+        } else if (*lhs_dim_sz == 1) {
+            *out_dim = *rhs_dim_sz;
+        } else if (*rhs_dim_sz == 1) {
+            *out_dim = *lhs_dim_sz;
+        } else if (*lhs_dim_sz == *rhs_dim_sz) {
+            *out_dim = *lhs_dim_sz;
+        } else {
+            __builtin_unreachable();
+        }
+    }
+}
+
+void __nac3_ndarray_calc_broadcast64(
+    const uint64_t *lhs_dims,
+    uint64_t lhs_ndims,
+    const uint64_t *rhs_dims,
+    uint64_t rhs_ndims,
+    uint64_t *out_dims
+) {
+    uint64_t max_ndims = lhs_ndims > rhs_ndims ? lhs_ndims : rhs_ndims;
+
+    for (uint64_t i = 0; i < max_ndims; ++i) {
+        uint64_t *lhs_dim_sz = i < lhs_ndims ? &lhs_dims[lhs_ndims - i - 1] : NULL;
+        uint64_t *rhs_dim_sz = i < rhs_ndims ? &rhs_dims[rhs_ndims - i - 1] : NULL;
+        uint64_t *out_dim = &out_dims[max_ndims - i - 1];
+
+        if (lhs_dim_sz == NULL) {
+            *out_dim = *rhs_dim_sz;
+        } else if (rhs_dim_sz == NULL) {
+            *out_dim = *lhs_dim_sz;
+        } else if (*lhs_dim_sz == 1) {
+            *out_dim = *rhs_dim_sz;
+        } else if (*rhs_dim_sz == 1) {
+            *out_dim = *lhs_dim_sz;
+        } else if (*lhs_dim_sz == *rhs_dim_sz) {
+            *out_dim = *lhs_dim_sz;
+        } else {
+            __builtin_unreachable();
+        }
+    }
+}
+
+void __nac3_ndarray_calc_broadcast_idx(
+    const uint32_t *src_dims,
+    uint32_t src_ndims,
+    const uint32_t *in_idx,
+    uint32_t *out_idx
+) {
+    for (uint32_t i = 0; i < src_ndims; ++i) {
+        uint32_t src_i = src_ndims - i - 1;
+        out_idx[src_i] = src_dims[src_i] == 1 ? 0 : in_idx[src_i];
+    }
+}
+
+void __nac3_ndarray_calc_broadcast_idx64(
+    const uint64_t *src_dims,
+    uint64_t src_ndims,
+    const uint32_t *in_idx,
+    uint32_t *out_idx
+) {
+    for (uint64_t i = 0; i < src_ndims; ++i) {
+        uint64_t src_i = src_ndims - i - 1;
+        out_idx[src_i] = src_dims[src_i] == 1 ? 0 : (uint32_t) in_idx[src_i];
+    }
+}
diff --git a/nac3core/src/codegen/irrt/mod.rs b/nac3core/src/codegen/irrt/mod.rs
index 6da048f..ce675ce 100644
--- a/nac3core/src/codegen/irrt/mod.rs
+++ b/nac3core/src/codegen/irrt/mod.rs
@@ -8,9 +8,11 @@ use super::{
         ListValue,
         NDArrayValue,
         TypedArrayLikeAdapter,
+        UntypedArrayLikeAccessor,
     },
     CodeGenContext,
     CodeGenerator,
+    llvm_intrinsics,
 };
 use inkwell::{
     attributes::{Attribute, AttributeLoc},
@@ -23,6 +25,8 @@ use inkwell::{
 };
 use itertools::Either;
 use nac3parser::ast::Expr;
+use crate::codegen::classes::TypedArrayLikeAccessor;
+use crate::codegen::stmt::gen_for_callback_incrementing;
 
 #[must_use]
 pub fn load_irrt(ctx: &Context) -> Module {
@@ -783,4 +787,195 @@ pub fn call_ndarray_flatten_index<'ctx, G, Index>(
         ndarray,
         indices,
     )
+}
+
+/// Generates a call to `__nac3_ndarray_calc_broadcast`. Returns a tuple containing the number of
+/// dimension and size of each dimension of the resultant `ndarray`.
+pub fn call_ndarray_calc_broadcast<'ctx, G: CodeGenerator + ?Sized>(
+    generator: &mut G,
+    ctx: &mut CodeGenContext<'ctx, '_>,
+    lhs: NDArrayValue<'ctx>,
+    rhs: NDArrayValue<'ctx>,
+) -> TypedArrayLikeAdapter<'ctx, IntValue<'ctx>> {
+    let llvm_usize = generator.get_size_type(ctx.ctx);
+    let llvm_pusize = llvm_usize.ptr_type(AddressSpace::default());
+
+    let ndarray_calc_broadcast_fn_name = match llvm_usize.get_bit_width() {
+        32 => "__nac3_ndarray_calc_broadcast",
+        64 => "__nac3_ndarray_calc_broadcast64",
+        bw => unreachable!("Unsupported size type bit width: {}", bw)
+    };
+    let ndarray_calc_broadcast_fn = ctx.module.get_function(ndarray_calc_broadcast_fn_name).unwrap_or_else(|| {
+        let fn_type = llvm_usize.fn_type(
+            &[
+                llvm_pusize.into(),
+                llvm_usize.into(),
+                llvm_pusize.into(),
+                llvm_usize.into(),
+                llvm_pusize.into(),
+            ],
+            false,
+        );
+
+        ctx.module.add_function(ndarray_calc_broadcast_fn_name, fn_type, None)
+    });
+
+    let lhs_ndims = lhs.load_ndims(ctx);
+    let rhs_ndims = rhs.load_ndims(ctx);
+    let min_ndims = llvm_intrinsics::call_int_umin(ctx, lhs_ndims, rhs_ndims, None);
+
+    gen_for_callback_incrementing(
+        generator,
+        ctx,
+        llvm_usize.const_zero(),
+        (min_ndims, false),
+        |generator, ctx, idx| {
+            let idx = ctx.builder.build_int_sub(min_ndims, idx, "").unwrap();
+            let (lhs_dim_sz, rhs_dim_sz) = unsafe {
+                (
+                    lhs.dim_sizes().get_typed_unchecked(ctx, generator, idx, None),
+                    rhs.dim_sizes().get_typed_unchecked(ctx, generator, idx, None),
+                )
+            };
+
+            let llvm_usize_const_one = llvm_usize.const_int(1, false);
+            let lhs_eqz = ctx.builder.build_int_compare(
+                IntPredicate::EQ,
+                lhs_dim_sz,
+                llvm_usize_const_one,
+                "",
+            ).unwrap();
+            let rhs_eqz = ctx.builder.build_int_compare(
+                IntPredicate::EQ,
+                rhs_dim_sz,
+                llvm_usize_const_one,
+                "",
+            ).unwrap();
+            let lhs_or_rhs_eqz = ctx.builder.build_or(
+                lhs_eqz,
+                rhs_eqz,
+                ""
+            ).unwrap();
+
+            let lhs_eq_rhs = ctx.builder.build_int_compare(
+                IntPredicate::EQ,
+                lhs_dim_sz,
+                rhs_dim_sz,
+                ""
+            ).unwrap();
+
+            let is_compatible = ctx.builder.build_or(
+                lhs_or_rhs_eqz,
+                lhs_eq_rhs,
+                ""
+            ).unwrap();
+
+            ctx.make_assert(
+                generator,
+                is_compatible,
+                "0:ValueError",
+                "operands could not be broadcast together",
+                [None, None, None],
+                ctx.current_loc,
+            );
+
+            Ok(())
+        },
+        llvm_usize.const_int(1, false),
+    ).unwrap();
+
+    let max_ndims = llvm_intrinsics::call_int_umax(ctx, lhs_ndims, rhs_ndims, None);
+    let lhs_dims = lhs.dim_sizes().base_ptr(ctx, generator);
+    let lhs_ndims = lhs.load_ndims(ctx);
+    let rhs_dims = rhs.dim_sizes().base_ptr(ctx, generator);
+    let rhs_ndims = rhs.load_ndims(ctx);
+    let out_dims = ctx.builder.build_array_alloca(llvm_usize, max_ndims, "").unwrap();
+    let out_dims = ArraySliceValue::from_ptr_val(out_dims, max_ndims, None);
+
+    ctx.builder
+        .build_call(
+            ndarray_calc_broadcast_fn,
+            &[
+                lhs_dims.into(),
+                lhs_ndims.into(),
+                rhs_dims.into(),
+                rhs_ndims.into(),
+                out_dims.base_ptr(ctx, generator).into(),
+            ],
+            "",
+        )
+        .unwrap();
+
+    TypedArrayLikeAdapter::from(
+        out_dims,
+        Box::new(|_, v| v.into_int_value()),
+        Box::new(|_, v| v.into()),
+    )
+}
+
+/// Generates a call to `__nac3_ndarray_calc_broadcast_idx`. Returns an [`ArrayAllocaValue`]
+/// containing the indices used for accessing `array` corresponding to the index of the broadcasted
+/// array `broadcast_idx`.
+pub fn call_ndarray_calc_broadcast_index<'ctx, G: CodeGenerator + ?Sized, BroadcastIdx: UntypedArrayLikeAccessor<'ctx>>(
+    generator: &mut G,
+    ctx: &mut CodeGenContext<'ctx, '_>,
+    array: NDArrayValue<'ctx>,
+    broadcast_idx: &BroadcastIdx,
+) -> TypedArrayLikeAdapter<'ctx, IntValue<'ctx>> {
+    let llvm_i32 = ctx.ctx.i32_type();
+    let llvm_usize = generator.get_size_type(ctx.ctx);
+    let llvm_pi32 = llvm_i32.ptr_type(AddressSpace::default());
+    let llvm_pusize = llvm_usize.ptr_type(AddressSpace::default());
+
+    let ndarray_calc_broadcast_fn_name = match llvm_usize.get_bit_width() {
+        32 => "__nac3_ndarray_calc_broadcast_idx",
+        64 => "__nac3_ndarray_calc_broadcast_idx64",
+        bw => unreachable!("Unsupported size type bit width: {}", bw)
+    };
+    let ndarray_calc_broadcast_fn = ctx.module.get_function(ndarray_calc_broadcast_fn_name).unwrap_or_else(|| {
+        let fn_type = llvm_usize.fn_type(
+            &[
+                llvm_pusize.into(),
+                llvm_usize.into(),
+                llvm_pi32.into(),
+                llvm_pi32.into(),
+            ],
+            false,
+        );
+
+        ctx.module.add_function(ndarray_calc_broadcast_fn_name, fn_type, None)
+    });
+
+    let broadcast_size = broadcast_idx.size(ctx, generator);
+    let out_idx = ctx.builder.build_array_alloca(llvm_i32, broadcast_size, "").unwrap();
+
+    let array_dims = array.dim_sizes().base_ptr(ctx, generator);
+    let array_ndims = array.load_ndims(ctx);
+    let broadcast_idx_ptr = unsafe {
+        broadcast_idx.ptr_offset_unchecked(
+            ctx,
+            generator,
+            llvm_usize.const_zero(),
+            None
+        )
+    };
+
+    ctx.builder
+        .build_call(
+            ndarray_calc_broadcast_fn,
+            &[
+                array_dims.into(),
+                array_ndims.into(),
+                broadcast_idx_ptr.into(),
+                out_idx.into(),
+            ],
+            "",
+        )
+        .unwrap();
+
+    TypedArrayLikeAdapter::from(
+        ArraySliceValue::from_ptr_val(out_idx, broadcast_size, None),
+        Box::new(|_, v| v.into_int_value()),
+        Box::new(|_, v| v.into()),
+    )
 }
\ No newline at end of file