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AArch64: Fold movtqb + movzbq into just a movzbq #9659

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AArch64: Fold movtqb + movzbq into just a movzbq #9659

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17 changes: 17 additions & 0 deletions hphp/runtime/vm/jit/vasm-simplify-arm.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -134,6 +134,23 @@ bool simplify(Env& env, const ldimmq& inst, Vlabel b, size_t i) {

///////////////////////////////////////////////////////////////////////////////

bool simplify(Env& env, const movtqb& inst, Vlabel b, size_t i) {
if (env.use_counts[inst.d] != 1)
return false;

if (if_inst<Vinstr::movzbq>(env, b, i + 1, [&](const movzbq& ext) {
if (ext.s != inst.d)
return false;

return simplify_impl(env, b, i, [&] (Vout& v) {
v << movzbq{Vreg8((Vreg)inst.s), ext.d};
return 2;
});
})) {
}
return false;
}

bool simplify(Env& env, const movzbl& inst, Vlabel b, size_t i) {
// movzbl{s, d}; shrli{2, s, d} --> ubfmli{2, 7, s, d}
return if_inst<Vinstr::shrli>(env, b, i + 1, [&](const shrli& sh) {
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