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// 107 instruction bytes _objc_msgSend: cmpq $0xfffffffffffeb010, %rsi if (_cmd is ignored) je IGNORED return self testq %rdi, %rdi if (self == nil) je NIL return zero movq (%rdi), %r11 class = self->isa movq %rcx, -32(%rsp) save non-volatile registers movq %r8, -24(%rsp) movq %r9, -16(%rsp) movq 16(%r11), %rcx cache = class->cache leaq 8(%rcx), %r8 buckets = cache->buckets movl (%rcx), %r9d mask = cache->mask shlq $3, %r9 mask *= 8 movq %rsi, %rcx andq %r9, %rcx offset = _cmd & mask LOOP: movq (%r8, %rcx), %r11 method = buckets[index] testq %r11, %r11 if (method == nil) je MISS goto cache miss addq $8, %rcx offset += 8 andq %r9, %rcx offset &= mask cmpq (%r11), %rsi if (method->sel != _cmd) jne LOOP scan more movq -32(%rsp), %rcx restore saved registers movq -24(%rsp), %r8 movq -16(%rsp), %r9 movq 16(%r11), %r11 imp = method->imp jmpq *%r11 jump to imp |
Leopard introduced 64-bit Intel. This implementation was structured in the same way as the PowerPC code, instead of being adapted directly from the 32-bit Intel code. The cache scanning loop in particular is structured like the PowerPC version rather than the i386 version. Like the i386 version, this code does not take advantage of the x86-64 instruction set's register-memory architecture.
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