By default, qcc provides only ARMv7 instructions.
The ARMv7 architecture introduces a number of new instructions that may provide performance benefits for certain code. For example, DSP algorithms can take advantage of the new media instructions.
For ARMv7, the -Vgcc_ntoarmv7le option makes qcc use ARMv7 instructions and generate VFPv3-d16 code for floating point. This is the default for the ARMle-v7 variant. This means that the ARMle-v7 variant can run only on ARMv7 targets with a VFP unit; it's been compiled for VFPv3-d16, which is the lowest common denominator for VFP. For example, if you use a VFPv3-d32 FPU, your compiled code will use only half of the available double-precision registers.