[ELF] Don't put NOLOAD section into PT_LOAD

[evgeny777]

Summary

This conforms to behavior of GNU linkers (2.29.51.20171212)

[ruiu]

LGTM

[grimar]

LGTM

ELF/Writer.cpp

void Writer<ELFT>::addStartStopSymbols(OutputSection *Sec) {
   StringRef S = Sec->Name;
   if (!isValidCIdentifier(S))
     return;
   addOptionalRegular(Saver.save("__start_" + S), Sec, 0, STV_DEFAULT);
   addOptionalRegular(Saver.save("__stop_" + S), Sec, -1, STV_DEFAULT);
 }
 
 static bool needsPtLoad(OutputSection *Sec) {
-  if (!(Sec->Flags & SHF_ALLOC))
+  if (!(Sec->Flags & SHF_ALLOC) || Sec->Noload)
     return false;
 
   // Don't allocate VA space for TLS NOBITS sections. The PT_TLS PHDR is
   // responsible for allocating space for them, not the PT_LOAD that
   // contains the TLS initialization image.
   if (Sec->Flags & SHF_TLS && Sec->Type == SHT_NOBITS)
     return false;
   return true;

test/ELF/linkerscript/noload.s

 # 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:        .data_noload_b (0x10000) (NOLOAD) : { *(.data_noload_b) } \
+# RUN:        .text (0x20000) : { *(.text) } };" > %t.script
 # RUN: ld.lld -o %t --script %t.script %t.o
-# RUN: llvm-readobj --symbols -sections %t | FileCheck %s
+# RUN: llvm-readobj -sections -program-headers  %t | FileCheck %s
 
 # CHECK:      Section {
-# CHECK:        Index: 2
+# CHECK:        Index: 1
 # 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:   Offset: 0xE8
 # 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:   Index: 2
 # 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:   Offset: 0xE8
 # CHECK-NEXT:   Size: 4096
 # CHECK-NEXT:   Link: 0
 # CHECK-NEXT:   Info: 0
 # CHECK-NEXT:   AddressAlignment: 1
 # CHECK-NEXT:   EntrySize: 0
 # CHECK-NEXT: }
+# CHECK:      ProgramHeader {
+# CHECK-NEXT:   Type: PT_LOAD (0x1)
+# CHECK-NEXT:   Offset: 0x1000
+# CHECK-NEXT:   VirtualAddress: 0x20000
+# CHECK-NEXT:   PhysicalAddress: 0x20000
+# CHECK-NEXT:   FileSize: 1
+# CHECK-NEXT:   MemSize: 1
+# CHECK-NEXT:   Flags [ (0x5)
+# CHECK-NEXT:     PF_R (0x4)
+# CHECK-NEXT:     PF_X (0x1)
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   Alignment: 4096
+# CHECK-NEXT: }
+
+.section .text,"ax",@progbits
+  nop
 
 .section .data_noload_a,"aw",@progbits
 .zero 4096
 
 .section .data_noload_b,"aw",@progbits
 .zero 4096