[ELF] - Linkerscript: implemented ADDR command.

ADDR(section)
Return the absolute address (the VMA) of the named section.

Used in the wild, eg.: https://searchcode.com/file/53617342/arch/x86/kernel/vmlinux.lds.S

Differential revision: https://reviews.llvm.org/D23913

llvm-svn: 280070

lld/ELF/LinkerScript.cpp

@@ -532,6 +532,16 @@ template <class ELFT> bool LinkerScript<ELFT>::hasPhdrsCommands() {
   return !Opt.PhdrsCommands.empty();
 }
 
+template <class ELFT>
+typename ELFT::uint
+LinkerScript<ELFT>::getOutputSectionAddress(StringRef Name) {
+  for (OutputSectionBase<ELFT> *Sec : *OutputSections)
+    if (Sec->getName() == Name)
+      return Sec->getVA();
+  error("undefined section " + Name);
+  return 0;
+}
+
 template <class ELFT>
 typename ELFT::uint LinkerScript<ELFT>::getOutputSectionSize(StringRef Name) {
   for (OutputSectionBase<ELFT> *Sec : *OutputSections)
@@ -1044,6 +1054,21 @@ static uint64_t getSectionSize(StringRef Name) {
   }
 }
 
+static uint64_t getSectionAddress(StringRef Name) {
+  switch (Config->EKind) {
+  case ELF32LEKind:
+    return Script<ELF32LE>::X->getOutputSectionAddress(Name);
+  case ELF32BEKind:
+    return Script<ELF32BE>::X->getOutputSectionAddress(Name);
+  case ELF64LEKind:
+    return Script<ELF64LE>::X->getOutputSectionAddress(Name);
+  case ELF64BEKind:
+    return Script<ELF64BE>::X->getOutputSectionAddress(Name);
+  default:
+    llvm_unreachable("unsupported target");
+  }
+}
+
 static uint64_t getHeaderSize() {
   switch (Config->EKind) {
   case ELF32LEKind:
@@ -1154,6 +1179,12 @@ Expr ScriptParser::readPrimary() {
 
   // Built-in functions are parsed here.
   // https://sourceware.org/binutils/docs/ld/Builtin-Functions.html.
+  if (Tok == "ADDR") {
+    expect("(");
+    StringRef Name = next();
+    expect(")");
+    return [=](uint64_t Dot) { return getSectionAddress(Name); };
+  }
   if (Tok == "ASSERT")
     return readAssert();
   if (Tok == "ALIGN") {

lld/ELF/LinkerScript.h

@@ -151,6 +151,7 @@ public:
   void assignAddresses();
   int compareSections(StringRef A, StringRef B);
   bool hasPhdrsCommands();
+  uintX_t getOutputSectionAddress(StringRef Name);
   uintX_t getOutputSectionSize(StringRef Name);
   uintX_t getHeaderSize();
 

lld/test/ELF/linkerscript/linkerscript-addr.s

@@ -0,0 +1,32 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
+# RUN: echo "SECTIONS { \
+# RUN:  . = 0x1000; \
+# RUN:  .text  : { *(.text*) } \
+# RUN: .foo.1 : { *(.foo.1) }  \
+# RUN: .foo.2 ADDR(.foo.1) + 0x100 : { *(.foo.2) } \
+# RUN: .foo.3 : { *(.foo.3) } \
+# RUN: }" > %t.script
+# RUN: ld.lld %t --script %t.script -o %t1
+# RUN: llvm-objdump -section-headers %t1 | FileCheck %s
+
+# CHECK:      Sections:
+# CHECK-NEXT: Idx Name          Size      Address          Type
+# CHECK-NEXT:   0               00000000 0000000000000000
+# CHECK-NEXT:   1 .text         00000000 0000000000001000 TEXT DATA
+# CHECK-NEXT:   2 .foo.1        00000008 0000000000001000 DATA
+# CHECK-NEXT:   3 .foo.2        00000008 0000000000001100 DATA
+# CHECK-NEXT:   4 .foo.3        00000008 0000000000001108 DATA
+
+.text
+.globl _start
+_start:
+
+.section .foo.1,"a"
+ .quad 1
+
+.section .foo.2,"a"
+ .quad 2
+
+.section .foo.3,"a"
+ .quad 3