[lld] r304925 - [ELF] - Linkerscript: implement NOLOAD section type.

[George Rimar via llvm-commits]

Author: grimar
Date: Wed Jun  7 11:31:08 2017
New Revision: 304925

URL: http://llvm.org/viewvc/llvm-project?rev=304925&view=rev
Log:
[ELF] - Linkerscript: implement NOLOAD section type.

This is PR32351

Each output section may have a type. The type is a keyword in parentheses.
(https://sourceware.org/binutils/docs/ld/Output-Section-Type.html#Output-Section-Type)
This patch support only one type, it is NOLOAD.
If output section has such type, we force it to be SHT_NOBITS. 

More details are available on a review page.

Differential revision: https://reviews.llvm.org/D33647

Added:
    lld/trunk/test/ELF/linkerscript/noload.s
Modified:
    lld/trunk/ELF/LinkerScript.cpp
    lld/trunk/ELF/LinkerScript.h
    lld/trunk/ELF/ScriptParser.cpp

Modified: lld/trunk/ELF/LinkerScript.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/LinkerScript.cpp?rev=304925&r1=304924&r2=304925&view=diff
==============================================================================
--- lld/trunk/ELF/LinkerScript.cpp (original)
+++ lld/trunk/ELF/LinkerScript.cpp Wed Jun  7 11:31:08 2017
@@ -431,6 +431,8 @@ void LinkerScript::processCommands(Outpu
       if (OutputSection *Sec = Cmd->Sec) {
         assert(Sec->SectionIndex == INT_MAX);
         Sec->SectionIndex = I;
+        if (Cmd->Noload)
+          Sec->Type = SHT_NOBITS;
         SecToCommand[Sec] = Cmd;
       }
     }

Modified: lld/trunk/ELF/LinkerScript.h
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/LinkerScript.h?rev=304925&r1=304924&r2=304925&view=diff
==============================================================================
--- lld/trunk/ELF/LinkerScript.h (original)
+++ lld/trunk/ELF/LinkerScript.h Wed Jun  7 11:31:08 2017
@@ -134,6 +134,7 @@ struct OutputSectionCommand : BaseComman
   ConstraintKind Constraint = ConstraintKind::NoConstraint;
   std::string Location;
   std::string MemoryRegionName;
+  bool Noload = false;
 
   template <class ELFT> void finalize();
   template <class ELFT> void writeTo(uint8_t *Buf);

Modified: lld/trunk/ELF/ScriptParser.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/ELF/ScriptParser.cpp?rev=304925&r1=304924&r2=304925&view=diff
==============================================================================
--- lld/trunk/ELF/ScriptParser.cpp (original)
+++ lld/trunk/ELF/ScriptParser.cpp Wed Jun  7 11:31:08 2017
@@ -568,10 +568,20 @@ ScriptParser::readOutputSectionDescripti
   OutputSectionCommand *Cmd =
       Script->createOutputSectionCommand(OutSec, getCurrentLocation());
 
-  // Read an address expression.
-  // https://sourceware.org/binutils/docs/ld/Output-Section-Address.html
-  if (peek() != ":")
-    Cmd->AddrExpr = readExpr();
+  if (peek() != ":") {
+    // Read an address expression.
+    // https://sourceware.org/binutils/docs/ld/Output-Section-Address.html
+    if (peek() != "(")
+      Cmd->AddrExpr = readExpr();
+
+    // Read a section type. Currently, only NOLOAD is supported.
+    // https://sourceware.org/binutils/docs/ld/Output-Section-Type.html
+    if (consume("(")) {
+      expect("NOLOAD");
+      expect(")");
+      Cmd->Noload = true;
+    }
+  }
 
   expect(":");
 

Added: lld/trunk/test/ELF/linkerscript/noload.s
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/ELF/linkerscript/noload.s?rev=304925&view=auto
==============================================================================
--- lld/trunk/test/ELF/linkerscript/noload.s (added)
+++ lld/trunk/test/ELF/linkerscript/noload.s Wed Jun  7 11:31:08 2017
@@ -0,0 +1,46 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t.o
+# RUN: echo "SECTIONS { \
+# RUN:        .data_noload_a (NOLOAD) : { *(.data_noload_a) } \
+# RUN:        .data_noload_b 0x10000 (NOLOAD) : { *(.data_noload_b) } };" > %t.script
+# RUN: ld.lld -o %t --script %t.script %t.o
+# RUN: llvm-readobj --symbols -sections %t
+
+# CHECK:      Section {
+# CHECK-NEXT:   Index: 2
+# CHECK-NEXT:   Name: .data_noload_a
+# CHECK-NEXT:   Type: SHT_NOBITS
+# CHECK-NEXT:   Flags [
+# CHECK-NEXT:     SHF_ALLOC
+# CHECK-NEXT:     SHF_WRITE
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   Address: 0x0
+# CHECK-NEXT:   Offset: 0x1000
+# CHECK-NEXT:   Size: 4096
+# CHECK-NEXT:   Link: 0
+# CHECK-NEXT:   Info: 0
+# CHECK-NEXT:   AddressAlignment: 1
+# CHECK-NEXT:   EntrySize: 0
+# CHECK-NEXT: }
+# CHECK-NEXT: Section {
+# CHECK-NEXT:   Index: 3
+# CHECK-NEXT:   Name: .data_noload_b
+# CHECK-NEXT:   Type: SHT_NOBITS
+# CHECK-NEXT:   Flags [
+# CHECK-NEXT:     SHF_ALLOC
+# CHECK-NEXT:     SHF_WRITE
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   Address: 0x10000
+# CHECK-NEXT:   Offset: 0x1000
+# CHECK-NEXT:   Size: 4096
+# CHECK-NEXT:   Link: 0
+# CHECK-NEXT:   Info: 0
+# CHECK-NEXT:   AddressAlignment: 1
+# CHECK-NEXT:   EntrySize: 0
+# CHECK-NEXT: }
+
+.section .data_noload_a,"aw", at progbits
+.zero 4096
+
+.section .data_noload_b,"aw", at progbits
+.zero 4096