[ELF] Bypass section type check #2

Differential revision: https://reviews.llvm.org/D29278

llvm-svn: 293613

lld/ELF/OutputSections.cpp

@@ -640,6 +640,18 @@ static uint64_t getIncompatibleFlags(uint64_t Flags) {
   return Flags & (SHF_ALLOC | SHF_TLS);
 }
 
+// We allow sections of types listed below to merged into a
+// single progbits section. This is typically done by linker
+// scripts. Merging nobits and progbits will force disk space
+// to be allocated for nobits sections. Other ones don't require
+// any special treatment on top of progbits, so there doesn't
+// seem to be a harm in merging them.
+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;
+}
+
 template <class ELFT>
 std::pair<OutputSectionBase *, bool>
 OutputSectionFactory<ELFT>::create(const SectionKey &Key,
@@ -650,14 +662,13 @@ OutputSectionFactory<ELFT>::create(const SectionKey &Key,
     if (getIncompatibleFlags(Sec->Flags) != getIncompatibleFlags(C->Flags))
       error("Section has flags incompatible with others with the same name " +
             toString(C));
-    // Convert notbits to progbits if they are mixed. This happens is some
-    // linker scripts.
-    if (Sec->Type == SHT_NOBITS && C->Type == SHT_PROGBITS)
-      Sec->Type = SHT_PROGBITS;
-    if (Sec->Type != C->Type &&
-        !(Sec->Type == SHT_PROGBITS && C->Type == SHT_NOBITS))
-      error("Section has different type from others with the same name " +
-            toString(C));
+    if (Sec->Type != C->Type) {
+      if (canMergeToProgbits(Sec->Type) && canMergeToProgbits(C->Type))
+        Sec->Type = SHT_PROGBITS;
+      else
+        error("Section has different type from others with the same name " +
+              toString(C));
+    }
     Sec->Flags |= Flags;
     return {Sec, false};
   }

lld/test/ELF/compatible-section-types.s

@@ -0,0 +1,20 @@
+// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
+// RUN: ld.lld -shared %t.o -o %t
+// RUN: llvm-objdump -section-headers %t | FileCheck %s
+
+// CHECK: .foo {{0*}}28
+
+.section .foo, "aw", @progbits, unique, 1
+.quad 0
+
+.section .foo, "aw", @init_array, unique, 2
+.quad 0
+
+.section .foo, "aw", @preinit_array, unique, 3
+.quad 0
+
+.section .foo, "aw", @fini_array, unique, 4
+.quad 0
+
+.section .foo, "aw", @note, unique, 5
+.quad 0

lld/test/ELF/incompatible-section-types.s

@@ -1,10 +0,0 @@
-// RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
-// RUN: not ld.lld -shared %t.o -o %t 2>&1 | FileCheck %s
-
-// CHECK: error: Section has different type from others with the same name {{.*}}incompatible-section-types.s.tmp.o:(.foo)
-
-.section .foo, "aw", @progbits, unique, 1
-.quad 0
-
-.section .foo, "aw", @init_array, unique, 2
-.quad 0