[ELF] - Do not create 4gb output when -obinary -Ttext and -omagic used together. (variant 2)

[grimar]

Summary

This is the same like D27200 but uses a different approach.
D27200 eliminates the excessive PT_LOAD, but this one has less changes.
What does look better ?

[emaste]

ELF/Writer.cpp

1239

It seems a tad confusing. Could we avoid adding an empty PT_LOAD? To me, having the extra complexity in createPhdrs instead of here would make the overall operation more clear.

test/ELF/oformat-binary-ttext.s

7–9

If there's only one, use regular CHECK, CHECK-NEXT?

[emaste]

ELF/Writer.cpp

1239

Oh, now I understand, and will comment in D27200.

[grimar]

ELF/Writer.cpp

1239

That what I do in D27200 :)

test/ELF/oformat-binary-ttext.s

7–9

Ok.

[grimar]

I'll post different solution.

ELF/Writer.cpp

template <class ELFT> std::vector<PhdrEntry<ELFT>> Writer<ELFT>::createPhdrs() {
   if (OutputSectionBase *Sec = findSection(".interp")) {
     Phdr &Hdr = *AddHdr(PT_INTERP, Sec->getPhdrFlags());
     Hdr.add(Sec);
   }
 
   // Add the first PT_LOAD segment for regular output sections.
   uintX_t Flags = computeFlags<ELFT>(PF_R);
   Phdr *Load = AddHdr(PT_LOAD, Flags);
-  if (!ScriptConfig->HasSections) {
+  if (!Config->OFormatBinary && !ScriptConfig->HasSections) {
     Load->add(Out<ELFT>::ElfHeader);
     Load->add(Out<ELFT>::ProgramHeaders);
   }
 
   Phdr TlsHdr(PT_TLS, PF_R);
   Phdr RelRo(PT_GNU_RELRO, PF_R);
   Phdr Note(PT_NOTE, PF_R);
   for (OutputSectionBase *Sec : OutputSections) {
void Writer<ELFT>::addPtArmExid(std::vector<PhdrEntry<ELFT>> &Phdrs) {
   Phdr ARMExidx(PT_ARM_EXIDX, PF_R);
   ARMExidx.add(*I);
   Phdrs.push_back(ARMExidx);
 }
 
 // The first section of each PT_LOAD and the first section after PT_GNU_RELRO
 // have to be page aligned so that the dynamic linker can set the permissions.
 template <class ELFT> void Writer<ELFT>::fixSectionAlignments() {
+  // Load can be empty if we produce binary output.
   for (const Phdr &P : Phdrs)
-    if (P.H.p_type == PT_LOAD)
+    if (P.H.p_type == PT_LOAD && P.First)
       P.First->PageAlign = true;
 
   for (const Phdr &P : Phdrs) {
     if (P.H.p_type != PT_GNU_RELRO)
       continue;
     // Find the first section after PT_GNU_RELRO. If it is in a PT_LOAD we
     // have to align it to a page.
     auto End = OutputSections.end();

test/ELF/oformat-binary-ttext.s

+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
+
+# RUN: ld.lld -N -Ttext 0x100 -o %t.out %t --oformat binary
+# RUN: od -t x1 -v %t.out | FileCheck %s --check-prefix=BIN
+
+# BIN:      0000000 90 00 00 00 00 00 00 00
+# BIN-NEXT: 0000010
+# BIN-NOT:  0000020
+
+## The same but without OMAGIC.
+# RUN: ld.lld -Ttext 0x100 -o %t.out %t --oformat binary
+# RUN: od -t x1 -v %t.out | FileCheck %s --check-prefix=BIN
+
+.text
+.globl _start
+_start:
+ nop