Add "%" operator to the linker script.

[ruiu]

Summary

This patch improves compatibility with GNU linkers.

lld/trunk/ELF/ScriptParser.cpp

 
 static ExprValue div(ExprValue A, ExprValue B) {
   if (uint64_t BV = B.getValue())
     return A.getValue() / BV;
   error("division by zero");
   return 0;
 }
 
+static ExprValue mod(ExprValue A, ExprValue B) {
+  if (uint64_t BV = B.getValue())
+    return A.getValue() % BV;
+  error("modulo by zero");
+  return 0;
+}
+
 static ExprValue bitAnd(ExprValue A, ExprValue B) {
   moveAbsRight(A, B);
   return {A.Sec, A.ForceAbsolute,
           (A.getValue() & B.getValue()) - A.getSecAddr(), A.Loc};
 }
 
 static ExprValue bitOr(ExprValue A, ExprValue B) {
   moveAbsRight(A, B);
if (!Cmd) {
         Cmd = readOutputSectionDescription(Tok);
     }
     Script->SectionCommands.push_back(Cmd);
   }
 }
 
 static int precedence(StringRef Op) {
   return StringSwitch<int>(Op)
-      .Cases("*", "/", 5)
+      .Cases("*", "/", "%", 5)
       .Cases("+", "-", 4)
       .Cases("<<", ">>", 3)
       .Cases("<", "<=", ">", ">=", "==", "!=", 2)
       .Cases("&", "|", 1)
       .Default(-1);
 }
 
 StringMatcher ScriptParser::readFilePatterns() {
static Expr combine(StringRef Op, Expr L, Expr R) {
   if (Op == "+")
     return [=] { return add(L(), R()); };
   if (Op == "-")
     return [=] { return sub(L(), R()); };
   if (Op == "*")
     return [=] { return L().getValue() * R().getValue(); };
   if (Op == "/")
     return [=] { return div(L(), R()); };
+  if (Op == "%")
+    return [=] { return mod(L(), R()); };
   if (Op == "<<")
     return [=] { return L().getValue() << R().getValue(); };
   if (Op == ">>")
     return [=] { return L().getValue() >> R().getValue(); };
   if (Op == "<")
     return [=] { return L().getValue() < R().getValue(); };
   if (Op == ">")
     return [=] { return L().getValue() > R().getValue(); };

lld/trunk/test/ELF/linkerscript/operators.s

 # REQUIRES: x86
 # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
 # RUN: echo "SECTIONS { \
 # RUN:  _start = .; \
 # RUN:  plus = 1 + 2 + 3; \
 # RUN:  minus = 5 - 1; \
 # RUN:  div = 6 / 2; \
+# RUN:  mod = 20 % 7; \
 # RUN:  mul = 1 + 2 * 3; \
 # RUN:  nospace = 1+2*6/3; \
 # RUN:  braces = 1 + (2 + 3) * 4; \
 # RUN:  and = 0xbb & 0xee; \
 # RUN:  ternary1 = 1 ? 1 : 2; \
 # RUN:  ternary2 = 0 ? 1 : 2; \
 # RUN:  less = 1 < 0 ? 1 : 2; \
 # RUN:  lesseq = 1 <= 1 ? 1 : 2; \

 # RUN:  minus_abs = _end - _start; \
 # RUN: }" > %t.script
 # RUN: ld.lld %t --script %t.script -o %t2
 # RUN: llvm-objdump -t %t2 | FileCheck %s
 
 # CHECK: 00000000000006 *ABS* 00000000 plus
 # CHECK: 00000000000004 *ABS* 00000000 minus
 # CHECK: 00000000000003 *ABS* 00000000 div
+# CHECK: 00000000000006 *ABS* 00000000 mod
 # CHECK: 00000000000007 *ABS* 00000000 mul
 # CHECK: 00000000000005 *ABS* 00000000 nospace
 # CHECK: 00000000000015 *ABS* 00000000 braces
 # CHECK: 000000000000aa *ABS* 00000000 and
 # CHECK: 00000000000001 *ABS* 00000000 ternary1
 # CHECK: 00000000000002 *ABS* 00000000 ternary2
 # CHECK: 00000000000002 *ABS* 00000000 less
 # CHECK: 00000000000001 *ABS* 00000000 lesseq