5.3. The extension register bank

NEON and VFP use the same extension register bank. This is distinct from the ARM register bank.

The VFP coprocessor has 32 single-precision registers, each of which can contain either a single-precision floating-point value, or a 32-bit integer.

These 32 registers are also treated as 16 double-precision registers. However, some VFPv3 variants add 16 further double-precision registers to the VFP register set. These do not overlap with any single-precision VFP registers.

The extension register bank can be referenced using three explicitly aliased views, as described in the following sections.

Figure 5.1 shows the three views of the extension register bank, and the way the word, doubleword, and quadword registers overlap.


If your processor has both NEON and VFP, all the NEON registers overlap with the VFP registers.

You can use:

Do not attempt to use corresponding single-precision and double-precision registers at the same time. No damage is caused but the results are meaningless.

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