TCA emitSmashableMovq(CodeBlock& cb, uint64_t imm, PhysReg d) {
auto const start = EMIT_BODY(cb, movq, Movq, 0xdeadbeeffeedface, d);
auto immp = reinterpret_cast<uint64_t*>(
cb.frontier() - smashableMovqLen() + kSmashMovqImmOff
);
*immp = imm;
return start;
}
TCA funcGuardFromPrologue(TCA prologue, const Func* /*func*/) {
if (!isPrologueStub(prologue)) {
// Typically a func guard is a smashable movq followed by an ldr, cmp, b.eq,
// ldr, br, and a 32 bit target. However, relocation can shorten the sequence,
// so search backwards until the smashable movq is found.
for (int length = 0; length <= (5 * 4) + 4; length += 4) {
TCA inst = prologue - (smashableMovqLen() + length);
if (isSmashableMovq(inst)) return inst;
}
always_assert(false);
}
return prologue;
}
