[ELF] - Linkerscript: implemented ALIGN modificatior of output sections.

Output section description can contain ALIGN modificator: https://sourceware.org/binutils/docs/ld/Output-Section-Description.html#Output-Section-Description Patch implements it. Differential revision: https://reviews.llvm.org/D22674 llvm-svn: 276780
llvm · Jul 26, 2016 · 630c617 · 630c617
1 parent cb42ea0
commit 630c617
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diff --git a/lld/ELF/LinkerScript.cpp b/lld/ELF/LinkerScript.cpp
@@ -226,6 +226,9 @@ void LinkerScript<ELFT>::assignAddresses(
       if (Cmd->AddrExpr)
         Dot = Cmd->AddrExpr(Dot);
 
+      if (Cmd->AlignExpr)
+        Sec->updateAlignment(Cmd->AlignExpr(Dot));
+
       if ((Sec->getFlags() & SHF_TLS) && Sec->getType() == SHT_NOBITS) {
         uintX_t TVA = Dot + ThreadBssOffset;
         TVA = alignTo(TVA, Sec->getAlignment());
@@ -433,6 +436,7 @@ class elf::ScriptParser : public ScriptParserBase {
   std::vector<StringRef> readOutputSectionPhdrs();
   unsigned readPhdrType();
   void readProvide(bool Hidden);
+  void readAlign(OutputSectionCommand *Cmd);
 
   Expr readExpr();
   Expr readExpr1(Expr Lhs, int MinPrec);
@@ -671,6 +675,12 @@ void ScriptParser::readKeep(OutputSectionCommand *Cmd) {
   expect(")");
 }
 
+void ScriptParser::readAlign(OutputSectionCommand *Cmd) {
+  expect("(");
+  Cmd->AlignExpr = readExpr();
+  expect(")");
+}
+
 void ScriptParser::readOutputSectionDescription(StringRef OutSec) {
   OutputSectionCommand *Cmd = new OutputSectionCommand(OutSec);
   Opt.Commands.emplace_back(Cmd);
@@ -682,6 +692,9 @@ void ScriptParser::readOutputSectionDescription(StringRef OutSec) {
 
   expect(":");
 
+  if (skip("ALIGN"))
+    readAlign(Cmd);
+
   // Parse constraints.
   if (skip("ONLY_IF_RO"))
     Cmd->Constraint = ConstraintKind::ReadOnly;

diff --git a/lld/ELF/LinkerScript.h b/lld/ELF/LinkerScript.h
@@ -73,6 +73,7 @@ struct OutputSectionCommand : BaseCommand {
   static bool classof(const BaseCommand *C);
   StringRef Name;
   Expr AddrExpr;
+  Expr AlignExpr;
   std::vector<std::unique_ptr<BaseCommand>> Commands;
   std::vector<StringRef> Phdrs;
   std::vector<uint8_t> Filler;

diff --git a/lld/test/ELF/linkerscript/linkerscript-align.s b/lld/test/ELF/linkerscript/linkerscript-align.s
@@ -1,6 +1,7 @@
 # REQUIRES: x86
 # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
 
+## Check that ALIGN command workable using location counter
 # RUN: echo "SECTIONS { \
 # RUN:  . = 0x10000; \
 # RUN:  .aaa : \
@@ -27,6 +28,25 @@
 # CHECK-NEXT:   2 .bbb          00000008 0000000000011000 DATA
 # CHECK-NEXT:   3 .ccc          00000008 0000000000014000 DATA
 
+## Check output sections ALIGN modificator
+# RUN: echo "SECTIONS { \
+# RUN:  . = 0x10000; \
+# RUN:  .aaa : \
+# RUN:  { \
+# RUN:   *(.aaa) \
+# RUN:  } \
+# RUN:  .bbb : ALIGN(4096) \
+# RUN:  { \
+# RUN:   *(.bbb) \
+# RUN:  } \
+# RUN:  .ccc : ALIGN(4096 * 4) \
+# RUN:  { \
+# RUN:   *(.ccc) \
+# RUN:  } \
+# RUN: }" > %t2.script
+# RUN: ld.lld -o %t2 --script %t2.script %t
+# RUN: llvm-objdump -section-headers %t1 | FileCheck %s
+
 .global _start
 _start:
  nop