support __hip_bfloat16 type alias (fixes #65)

[GauthamMK-0]

Fix: HIP __hip_bfloat16 Type Alias Support (Issue #65)

Problem

Previously, BarraCUDA only recognized the CUDA native __nv_bfloat16 type. When encountering HIP's __hip_bfloat16 type alias, it was passed as int

Solution

Added __hip_bfloat16 type alias resolution mappings within the semantic analyzer and intermediate representation

• src/fe/sema.c
• src/ir/bir_lower.c

Verification

Test Code Sample

The following snippet was used to verify semantic type inference of __hip_bfloat16

#include <hip/hip_runtime.h>
#include <hip/hip_bfloat16.h>

__global__ void test_bf16(__hip_bfloat16 *out, __hip_bfloat16 a, __hip_bfloat16 b) {
    int id = blockIdx.x * blockDim.x + threadIdx.x;
    out[id] = a + b;
}

Before __hip_bfloat16 mapping:

; Sema: 19 types interned, 1 symbols, 0 structs, 0 error(s)
; Symbols:
;   test_bf16            func       func(int*, int, int) -> void
; Annotated expressions:
;   node[20] var_decl @ 5:12 → int
;   node[22] member @ 5:22 → unsigned int
;   node[24] binary @ 5:25 → unsigned int
;   node[26] member @ 5:35 → unsigned int
;   node[28] binary @ 5:38 → unsigned int
;   node[30] member @ 5:49 → unsigned int
;   node[32] ident @ 6:5 → int*
;   node[33] subscript @ 6:8 → int
;   node[34] ident @ 6:9 → int
;   node[35] binary @ 6:13 → int
;   node[36] ident @ 6:15 → int
;   node[37] binary @ 6:17 → int
;   node[38] ident @ 6:19 → int
; 13 nodes annotated

After __hip_bfloat16 mapping:

; Sema: 20 types interned, 1 symbols, 0 structs, 0 error(s)
; Symbols:
;   test_bf16            func       func(__bfloat16*, __bfloat16, __bfloat16) -> void
; Annotated expressions:
;   node[20] var_decl @ 5:12 → int
;   node[22] member @ 5:22 → unsigned int
;   node[24] binary @ 5:25 → unsigned int
;   node[26] member @ 5:35 → unsigned int
;   node[28] binary @ 5:38 → unsigned int
;   node[30] member @ 5:49 → unsigned int
;   node[32] ident @ 6:5 → __bfloat16*
;   node[33] subscript @ 6:8 → __bfloat16
;   node[34] ident @ 6:9 → int
;   node[35] binary @ 6:13 → __bfloat16
;   node[36] ident @ 6:15 → __bfloat16
;   node[37] binary @ 6:17 → __bfloat16
;   node[38] ident @ 6:19 → __bfloat16
; 13 nodes annotated