change semantics of nsz so it only makes the input sign non-deterministic

Per llvm/llvm-project#180906

Author: nunoplopes

ir/instr.cpp

@@ -676,7 +676,7 @@ static expr fminimum_fmaximum(State &s, const expr &a, const expr &b,
   return expr::mkIf(a.isNaN(), a, expr::mkIf(b.isNaN(), b, e));
 }
 
-static expr any_fp_zero(State &s, const expr &v) {
+static expr any_fp_zero(State &s, expr v) {
   expr is_zero = v.isFPZero();
   if (is_zero.isFalse())
     return v;
@@ -688,7 +688,7 @@ static expr any_fp_zero(State &s, const expr &v) {
       expr a, b;
       if (cond.isAnd(a, b) && a.isVar() && a.fn_name().starts_with("anyzero") &&
           b.isIsFPZero())
-        return any_fp_zero(s, val);
+        return any_fp_zero(s, std::move(val));
     }
   }
 
@@ -767,11 +767,11 @@ static StateValue fm_poison(State &s, expr a, const expr &ap, expr b,
   auto &fpty = *from_ty.getAsFloatType();
 
   if (fmath.flags & FastMathFlags::NSZ) {
-    a = any_fp_zero(s, a);
+    a = any_fp_zero(s, std::move(a));
     if (nary >= 2) {
-      b = any_fp_zero(s, b);
+      b = any_fp_zero(s, std::move(b));
       if (nary == 3)
-        c = any_fp_zero(s, c);
+        c = any_fp_zero(s, std::move(c));
     }
   }
 
@@ -824,8 +824,6 @@ static StateValue fm_poison(State &s, expr a, const expr &ap, expr b,
     val = expr::mkUF("afn", { val }, val);
     s.doesApproximation("afn", val);
   }
-  if (!flags_in_only && fmath.flags & FastMathFlags::NSZ)
-    val = any_fp_zero(s, std::move(val));
 
   if (!bitwise && val.isFloat()) {
     val = handle_subnormal(s,