lld: Put the header in the first PT_LOAD even if that PT_LOAD has a LMAExpr

The root problem is that we were creating a PT_LOAD just for the header.
That was technically valid, but inconvenient: we should not be making
the ELF discontinuous.

The solution is to allow a section with LMAExpr to be added to a PT_LOAD
if that PT_LOAD doesn't already have a LMAExpr.

LLVM PR:	36017
Obtained from:	LLVM r323625 by Rafael Espindola

2 files changed, 10 insertions, 2 deletions

diff --git a/contrib/llvm/tools/lld/ELF/Writer.cpp b/contrib/llvm/tools/lld/ELF/Writer.cpp
index 5715af94268e..1c3b6495a0d1 100644
--- a/contrib/llvm/tools/lld/ELF/Writer.cpp
+++ b/contrib/llvm/tools/lld/ELF/Writer.cpp
@@ -822,6 +822,8 @@ void PhdrEntry::add(OutputSection *Sec) {
   p_align = std::max(p_align, Sec->Alignment);
   if (p_type == PT_LOAD)
     Sec->PtLoad = this;
+  if (Sec->LMAExpr)
+    ASectionHasLMA = true;
 }
 
 // The beginning and the ending of .rel[a].plt section are marked
@@ -1626,8 +1628,9 @@ template <class ELFT> std::vector<PhdrEntry *> Writer<ELFT>::createPhdrs() {
     // different flags or is loaded at a discontiguous address using AT linker
     // script command.
     uint64_t NewFlags = computeFlags(Sec->getPhdrFlags());
-    if (Sec->LMAExpr || Sec->MemRegion != Load->FirstSec->MemRegion ||
-        Flags != NewFlags) {
+    if ((Sec->LMAExpr && Load->ASectionHasLMA) ||
+        Sec->MemRegion != Load->FirstSec->MemRegion || Flags != NewFlags) {
+
       Load = AddHdr(PT_LOAD, NewFlags);
       Flags = NewFlags;
     }
diff --git a/contrib/llvm/tools/lld/ELF/Writer.h b/contrib/llvm/tools/lld/ELF/Writer.h
index 6875dc514039..9902f0070cb4 100644
--- a/contrib/llvm/tools/lld/ELF/Writer.h
+++ b/contrib/llvm/tools/lld/ELF/Writer.h
@@ -44,6 +44,11 @@ struct PhdrEntry {
   OutputSection *FirstSec = nullptr;
   OutputSection *LastSec = nullptr;
   bool HasLMA = false;
+
+  // True if any of the sections in this program header as a LMA specified via
+  // linker script: AT(addr).
+  bool ASectionHasLMA = false;
+
   uint64_t LMAOffset = 0;
 };