Fix fast-interp "pre-compiled label offset out of range" issue #2659
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| #define FETCH_OPCODE_AND_DISPATCH() \ | ||
| do { \ | ||
| const void *p_label_addr; \ | ||
| bh_assert(((uintptr_t)frame_ip & 1) == 0); \ |
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No, the frame_ip must be 2-byte aligned, but not necessarily 4-byte aligned. If we force the frame_ip to be 4-byte aligned in wasm_loader, we need to add padding byte if needed, and here, we need to add code like frame_ip = align_uint(frame_ip, 4) or if (frame_ip & 2) frame_ip += 2, I had a try, it impacts performance a lot.
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Got it, Thanks!
I originally thought the CPU requires 4-bytes align, if 2-bytes align is OK, then no problem here.
core/iwasm/interpreter/wasm_loader.c
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| #else | ||
| #define emit_label(opcode) \ | ||
| do { \ | ||
| uint32 offset = (uint32)(uintptr_t)handle_table[opcode]; \ |
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had better rename offset to position or label_addr?
victoryang00
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May 27, 2024
…odealliance#2659) When labels-as-values is enabled in a target which doesn't support unaligned address access, 16-bit offset is used to store the relative offset between two opcode labels. But it is a little small and the loader may report "pre-compiled label offset out of range" error. Emitting 32-bit data instead to resolve the issue: emit label address in 32-bit target and emit 32-bit relative offset in 64-bit target. See also: bytecodealliance#2635
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When labels-as-values is enabled in a target which doesn't support
unaligned address access, 16-bit offset is used to store the relative
offset between two opcode labels. But it is a little small and the loader
may report "pre-compiled label offset out of range" error.
Emitting 32-bit data instead to resolve the issue: emit label address in
32-bit target and emit 32-bit relative offset in 64-bit target.
See also:
#2635