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Jiong Wang says: ==================== NFP eBPF JIT is missing logic indirect shifts (both left and right) and arithmetic right shift (both indirect shift and shift by constant). This patch adds support for them. For indirect shifts, shift amount is not specified as constant, NFP needs to get the shift amount through the low 5 bits of source A operand in PREV_ALU, therefore extra instructions are needed compared with shifts by constants. Because NFP is 32-bit, so we are using register pair for 64-bit shifts and therefore would need different instruction sequences depending on whether shift amount is less than 32 or not. NFP branch-on-bit-test instruction emitter is added by this patch set and is used for efficient runtime check on shift amount. We'd think the shift amount is less than 32 if bit 5 is clear and greater or equal then 32 otherwise. Shift amount is greater than or equal to 64 will result in undefined behavior. This patch also use range info to avoid generating unnecessary runtime code if we are certain shift amount is less than 32 or not. ==================== Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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