[ELF] - Implemented linkerscript ALIGN command

[grimar]

Summary

ALIGN(exp)
Return the location counter (.) aligned to the next exp boundary. (https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/4/html/Using_ld_the_GNU_Linker/expressions.html)

Patch implements this command.
This was requested in PR27406.

[• rafael]

LGTM with a nit.

test/ELF/linkerscript-align.s

9 ↗

(On Diff #54496)

Any reason for not just checking in the script in Inputs?

[grimar]

test/ELF/linkerscript-align.s

9 ↗

(On Diff #54496)

All (or at least most of) our tests has scripts inline atm. Actually I think it is
comfortable to have it in the same file. We have files with dozen
of little scripts, I don't think have dozen of inputs for them is better.

lld/trunk/ELF/LinkerScript.cpp

uint64_t LinkerScript<ELFT>::parsePrimary(ArrayRef<StringRef> &Tokens) {
   if (Tok == ".")
     return Dot;
   if (Tok == "(") {
     uint64_t V = parseExpr(Tokens);
     if (!expect(Tokens, ")"))
       return 0;
     return V;
   }
+  if (Tok == "ALIGN") {
+    if (!expect(Tokens, "("))
+      return 0;
+    uint64_t V = parseExpr(Tokens);
+    if (!expect(Tokens, ")"))
+      return 0;
+    return alignTo(Dot, V);
+  }
   return getInteger(Tok);
 }
 
 template <class ELFT>
 uint64_t LinkerScript<ELFT>::parseTernary(ArrayRef<StringRef> &Tokens,
                                           uint64_t Cond) {
   next(Tokens);
   uint64_t V = parseExpr(Tokens);

lld/trunk/test/ELF/linkerscript-align.s

+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
+
+# RUN: echo "SECTIONS { \
+# RUN:  . = 0x10000; \
+# RUN:  .aaa : \
+# RUN:  { \
+# RUN:   *(.aaa) \
+# RUN:  } \
+# RUN:  . = ALIGN(4096); \
+# RUN:  .bbb : \
+# RUN:  { \
+# RUN:   *(.bbb) \
+# RUN:  } \
+# RUN:  . = ALIGN(4096 * 4); \
+# RUN:  .ccc : \
+# RUN:  { \
+# RUN:   *(.ccc) \
+# RUN:  } \
+# RUN: }" > %t.script
+# RUN: ld.lld -o %t1 --script %t.script %t
+# 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 .aaa          00000008 0000000000010000 DATA
+# CHECK-NEXT:   2 .bbb          00000008 0000000000011000 DATA
+# CHECK-NEXT:   3 .ccc          00000008 0000000000014000 DATA
+
+.global _start
+_start:
+ nop
+
+.section .aaa, "a"
+.quad 0
+
+.section .bbb, "a"
+.quad 0
+
+.section .ccc, "a"
+.quad 0