[GR-17457] Use the same fix as upstream for bigdecimal RB_GC_GUARD

PullRequest: truffleruby/3665

Author: eregon

src/main/c/bigdecimal/bigdecimal.c

@@ -3955,12 +3955,9 @@ BigMath_s_log(VALUE klass, VALUE x, VALUE vprec)
 
     one = VpCheckGetValue(VpCreateRbObject(1, "1", true));
     two = VpCheckGetValue(VpCreateRbObject(1, "2", true));
-    RB_GC_GUARD(one);
-    RB_GC_GUARD(two);
 
     n = prec + BIGDECIMAL_DOUBLE_FIGURES;
     vn = SSIZET2NUM(n);
-    RB_GC_GUARD(vn);
     expo = VpExponent10(vx);
     if (expo < 0 || expo >= 3) {
 	char buf[DECIMAL_SIZE_OF_BITS(SIZEOF_VALUE * CHAR_BIT) + 4];
@@ -3975,9 +3972,6 @@ BigMath_s_log(VALUE klass, VALUE x, VALUE vprec)
     x2 = BigDecimal_mult2(x, x, vn);
     y = x;
     d = y;
-    RB_GC_GUARD(x2);
-    RB_GC_GUARD(y);
-    RB_GC_GUARD(d);
     i = 1;
     while (!VpIsZero((Real*)DATA_PTR(d))) {
 	SIGNED_VALUE const ey = VpExponent10(DATA_PTR(y));
@@ -4005,6 +3999,13 @@ BigMath_s_log(VALUE klass, VALUE x, VALUE vprec)
 	y = BigDecimal_add(y, dy);
     }
 
+    RB_GC_GUARD(one);
+    RB_GC_GUARD(two);
+    RB_GC_GUARD(vn);
+    RB_GC_GUARD(x2);
+    RB_GC_GUARD(y);
+    RB_GC_GUARD(d);
+
     return y;
 }