Drop conflicting sh_entsize

[grimar]

LGTM.

test/ELF/merge-entsize.s

27

I would check only EntrySize here, other values are not important for this test.

[• espindola]

318311

ELF/OutputSections.cpp

static bool canMergeToProgbits(unsigned Type) {
   return Type == SHT_NOBITS || Type == SHT_PROGBITS || Type == SHT_INIT_ARRAY ||
          Type == SHT_PREINIT_ARRAY || Type == SHT_FINI_ARRAY ||
          Type == SHT_NOTE;
 }
 
 void OutputSection::addSection(InputSection *IS) {
   if (!Live) {
     // If IS is the first section to be added to this section,
-    // initialize Type by IS->Type.
+    // initialize Type and Entsize from IS.
     Live = true;
     Type = IS->Type;
+    Entsize = IS->Entsize;
   } else {
     // Otherwise, check if new type or flags are compatible with existing ones.
     if ((Flags & (SHF_ALLOC | SHF_TLS)) != (IS->Flags & (SHF_ALLOC | SHF_TLS)))
       error("incompatible section flags for " + Name + "\n>>> " + toString(IS) +
             ": 0x" + utohexstr(IS->Flags) + "\n>>> output section " + Name +
             ": 0x" + utohexstr(Flags));
 
     if (Type != IS->Type) {
void OutputSection::addSection(InputSection *IS) {
   // The actual offsets will be computed by assignAddresses. For now, use
   // crude approximation so that it is at least easy for other code to know the
   // section order. It is also used to calculate the output section size early
   // for compressed debug sections.
   IS->OutSecOff = alignTo(Size, IS->Alignment);
   this->Size = IS->OutSecOff + IS->getSize();
 
   // If this section contains a table of fixed-size entries, sh_entsize
-  // holds the element size. Consequently, if this contains two or more
-  // input sections, all of them must have the same sh_entsize. However,
-  // you can put different types of input sections into one output
-  // section by using linker scripts. I don't know what to do here.
-  // Probably we sholuld handle that as an error. But for now we just
-  // pick the largest sh_entsize.
-  this->Entsize = std::max(this->Entsize, IS->Entsize);
+  // holds the element size. If it contains elements of different size we
+  // set sh_entsize to 0.
+  if (Entsize != IS->Entsize)
+    Entsize = 0;
 
   if (!IS->Assigned) {
     IS->Assigned = true;
     if (SectionCommands.empty() ||
         !isa<InputSectionDescription>(SectionCommands.back()))
       SectionCommands.push_back(make<InputSectionDescription>(""));
     auto *ISD = cast<InputSectionDescription>(SectionCommands.back());
     ISD->Sections.push_back(IS);

test/ELF/linkerscript/merge-sections.s

 # CHECK-NEXT:     SHF_STRINGS
 # CHECK-NEXT:   ]
 # CHECK-NEXT:   Address: 0x[[ADDR1:.*]]
 # CHECK-NEXT:   Offset: 0x[[ADDR1]]
 # CHECK-NEXT:   Size: 14
 # CHECK-NEXT:   Link: 0
 # CHECK-NEXT:   Info: 0
 # CHECK-NEXT:   AddressAlignment: 2
-# CHECK-NEXT:   EntrySize: 2
+# CHECK-NEXT:   EntrySize: 0
 # CHECK-NEXT: }
 
 # CHECK:      Name: begin
 # CHECK-NEXT: Value: 0x[[ADDR1]]
 
 # CHECK:      Name: end
 # 0x19E = begin + sizeof(.foo) = 0x190 + 0xE
 # CHECK-NEXT: Value: 0x19E

test/ELF/merge-entsize.s

+// REQUIRES: x86
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
+// RUN: ld.lld %t.o -o %t
+// RUN: llvm-readobj -s %t | FileCheck %s
+
+        .section  .rodata.1,"aM",@progbits,1
+        .byte 0x42
+
+        .section  .rodata.2,"aM",@progbits,2
+        .short 0x42
+
+// Since the output section has both .rodata.1 and .rodata.2, it
+// contains elements of different sizes and we use an entsize of 0.
+
+// CHECK:      Name: .rodata (
+// CHECK-NEXT: Type: SHT_PROGBITS
+// CHECK-NEXT: Flags [
+// CHECK-NEXT:   SHF_ALLOC
+// CHECK-NEXT:   SHF_MERGE
+// CHECK-NEXT: ]
+// CHECK-NEXT: Address:
+// CHECK-NEXT: Offset:
+// CHECK-NEXT: Size: 4
+// CHECK-NEXT: Link: 0
+// CHECK-NEXT: Info: 0
+// CHECK-NEXT: AddressAlignment: 2
+// CHECK-NEXT: EntrySize: 0