[lld] [LLD] [ELF] Add support for linker script unary plus operator (PR #121508)

[Parth Arora via llvm-commits]

https://github.com/partaror updated https://github.com/llvm/llvm-project/pull/121508

>From f35c48f75e0ebdbe6dfb797fc9c1ca14d1f6dfcf Mon Sep 17 00:00:00 2001
From: Parth Arora <quic_partaror at quicinc.com>
Date: Thu, 2 Jan 2025 09:32:23 -0800
Subject: [PATCH] [LLD] [ELF] Add support for linker script unary plus operator

This commit adds support for linker script unary plus ('+') operator.
It is helpful for improving compatibility between LLD and GNU LD.

Fixes #118047
---
 lld/ELF/ScriptParser.cpp                 | 3 +++
 lld/test/ELF/linkerscript/diag.test      | 4 ++--
 lld/test/ELF/linkerscript/operators.test | 2 ++
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/lld/ELF/ScriptParser.cpp b/lld/ELF/ScriptParser.cpp
index f53515cc3f3c0d..49ddd5e7999cfd 100644
--- a/lld/ELF/ScriptParser.cpp
+++ b/lld/ELF/ScriptParser.cpp
@@ -1489,6 +1489,9 @@ Expr ScriptParser::readPrimary() {
     Expr e = readPrimary();
     return [=] { return -e().getValue(); };
   }
+  if (consume("+")) {
+    return readPrimary();
+  }
 
   StringRef tok = next();
   std::string location = getCurrentLocation();
diff --git a/lld/test/ELF/linkerscript/diag.test b/lld/test/ELF/linkerscript/diag.test
index fbc24659a53114..114f5c2c0820b7 100644
--- a/lld/test/ELF/linkerscript/diag.test
+++ b/lld/test/ELF/linkerscript/diag.test
@@ -12,9 +12,9 @@ SECTIONS {
 }
 
 # RUN: not ld.lld -shared 0.o -T 1.lds 2>&1 | FileCheck %s --check-prefix=CHECK1 --match-full-lines --strict-whitespace
-#      CHECK1:{{.*}}:2: malformed number: +
+#      CHECK1:{{.*}}:2: malformed number: {
 # CHECK1-NEXT:>>>   .text + { *(.text) }
-# CHECK1-NEXT:>>>         ^
+# CHECK1-NEXT:>>>           ^
 
 #--- 2.lds
 
diff --git a/lld/test/ELF/linkerscript/operators.test b/lld/test/ELF/linkerscript/operators.test
index 27209a2e40f598..d7b3becf36d706 100644
--- a/lld/test/ELF/linkerscript/operators.test
+++ b/lld/test/ELF/linkerscript/operators.test
@@ -73,6 +73,7 @@ SECTIONS {
   log2ceil100000000 = LOG2CEIL(0x100000000);
   log2ceil100000001 = LOG2CEIL(0x100000001);
   log2ceilmax = LOG2CEIL(0xffffffffffffffff);
+  unaryadd = +3 + ++5;
 }
 
 # CHECK:      0000000000000002 A unary
@@ -126,6 +127,7 @@ SECTIONS {
 # CHECK-NEXT: 0000000000000020 A log2ceil100000000
 # CHECK-NEXT: 0000000000000021 A log2ceil100000001
 # CHECK-NEXT: 0000000000000040 A log2ceilmax
+# CHECK-NEXT: 0000000000000008 A unaryadd
 
 ## Mailformed number error.
 # RUN: echo "SECTIONS { . = 0x12Q41; }" > %t.script