qdrawhelper crash rendering with ARM NEON

When running an ARM native app using QT, the qdrawhelper.cpp crashes at the following breakpoint. Was previously working in 6.7.2.

Error message is: Run-Time Check Failure #3 - The variable 'v_top' is being used without being initialized

And debugging via VS:

#elif defined(_ARM_NEON_)
        const int16x8_t colorMask = vdupq_n_s16(0x00ff);
        const int16x8_t invColorMask = vmvnq_s16(colorMask);
        const int16x8_t v_256 = vdupq_n_s16(256);
        const int16x8_t v_disty = vdupq_n_s16(disty4);
        const int16x8_t v_disty_ = vshlq_n_s16(v_disty, 4);
        int32x4_t v_fdx = vdupq_n_s32(fdx*4);

        int32x4_t v_fx = vmovq_n_s32(fx);
        v_fx = vsetq_lane_s32(fx + fdx, v_fx, 1);
        v_fx = vsetq_lane_s32(fx + fdx * 2, v_fx, 2);
        v_fx = vsetq_lane_s32(fx + fdx * 3, v_fx, 3);

        const int32x4_t v_ffff_mask = vdupq_n_s32(0x0000ffff);
        const int32x4_t v_fx_r = vdupq_n_s32(0x0800);

        while (b < boundedEnd - 3) {
            uint32x4x2_t v_top, v_bot;

            int x1 = (fx >> 16);
            fx += fdx;
            v_top = vld2q_lane_u32(s1 + x1, v_top, 0); < this is the break point
            v_bot = vld2q_lane_u32(s2 + x1, v_bot, 0);