[ELF] Fix precedence of == and != in expressions

In GNU ld, the == and != operators have lower precedence than < > <= >=.
This behavior matches C.

Author: MaskRay

lld/ELF/ScriptParser.cpp

@@ -636,14 +636,15 @@ void ScriptParser::readTarget() {
 
 static int precedence(StringRef op) {
   return StringSwitch<int>(op)
-      .Cases("*", "/", "%", 8)
-      .Cases("+", "-", 7)
-      .Cases("<<", ">>", 6)
-      .Cases("<", "<=", ">", ">=", "==", "!=", 5)
-      .Case("&", 4)
-      .Case("|", 3)
-      .Case("&&", 2)
-      .Case("||", 1)
+      .Cases("*", "/", "%", 10)
+      .Cases("+", "-", 9)
+      .Cases("<<", ">>", 8)
+      .Cases("<", "<=", ">", ">=", 7)
+      .Cases("==", "!=", 6)
+      .Case("&", 5)
+      .Case("|", 4)
+      .Case("&&", 3)
+      .Case("||", 2)
       .Default(-1);
 }
 

lld/test/ELF/linkerscript/operators.test

@@ -20,7 +20,7 @@ SECTIONS {
   greater = 0 > 1 ? 1 : 2;
   greatereq = 1 >= 1 ? 1 : 2;
   eq = 1 == 1 ? 1 : 2;
-  neq = 1 != 1 ? 1 : 2;
+  neq = (1 != 1 <= 1) ? 1 : 2;
   plusassign = 1;
   plusassign += 2;
   unary = -1 + 3;