[ELF] Support quoted symbols in symbol assignments

glibc/elf/tst-absolute-zero-lib.lds uses `"absolute" = 0;`

Author: MaskRay

lld/ELF/ScriptParser.cpp

@@ -1001,6 +1001,7 @@ SymbolAssignment *ScriptParser::readAssignment(StringRef tok) {
 }
 
 SymbolAssignment *ScriptParser::readSymbolAssignment(StringRef name) {
+  name = unquote(name);
   StringRef op = next();
   assert(op == "=" || op == "+=");
   Expr e = readExpr();
@@ -1350,7 +1351,7 @@ Expr ScriptParser::readPrimary() {
     return [=] { return alignTo(script->getDot(), e().getValue()); };
   }
   if (tok == "DEFINED") {
-    StringRef name = readParenLiteral();
+    StringRef name = unquote(readParenLiteral());
     return [=] {
       Symbol *b = symtab->find(name);
       return (b && b->isDefined()) ? 1 : 0;
@@ -1428,6 +1429,7 @@ Expr ScriptParser::readPrimary() {
     return [=] { return *val; };
 
   // Tok is a symbol name.
+  tok = unquote(tok);
   if (!isValidSymbolName(tok))
     setError("malformed number: " + tok);
   script->referencedSymbols.push_back(tok);

lld/test/ELF/linkerscript/symbol-name.test

@@ -1,8 +1,15 @@
 # REQUIRES: x86
-## Test that . and $ can be used by symbol names in expressions.
+## Test that ., $ and " can be used by symbol names in expressions.
 
 # RUN: llvm-mc -filetype=obj -triple=x86_64 /dev/null -o %t.o
-# RUN: ld.lld -T %s %t.o -o /dev/null
+# RUN: ld.lld -T %s %t.o -o %t
+# RUN: llvm-readelf -s %t | FileCheck %s
+
+# CHECK:      Value            Size Type   Bind   Vis     Ndx Name
+# CHECK-DAG:  0000000000000000    0 NOTYPE GLOBAL DEFAULT ABS a1
+# CHECK-DAG:  0000000000000000    0 NOTYPE GLOBAL DEFAULT ABS a0
+# CHECK-DAG:  0000000000000003    0 NOTYPE GLOBAL DEFAULT ABS a2
 
 a0 = DEFINED(.TOC.) ? .TOC. : 0;
-a1 = DEFINED(__global_pointer$) ? __global_pointer$ : 0;
+"a1" = DEFINED(__global_pointer$) ? __global_pointer$ : 0;
+"a2" = DEFINED("a1") ? "a1" + 3 : 0;

lld/test/ELF/linkerscript/symbolreferenced.s

@@ -13,6 +13,10 @@
 # RUN: llvm-objdump -t %t1 | FileCheck --check-prefix=HIDDEN1 %s
 # HIDDEN1: 0000000000000001 l       *ABS*  0000000000000000 .hidden newsym
 
+# RUN: echo 'SECTIONS { PROVIDE_HIDDEN("newsym" = 1);}' > %t.script
+# RUN: ld.lld -o %t1 --script %t.script %t
+# RUN: llvm-objdump -t %t1 | FileCheck --check-prefix=HIDDEN1 %s
+
 .global _start
 _start:
  nop