[PATCH] D120805: [LLD] [COFF] Order .debug_* sections at the end, to avoid leaving gaps if stripped

[Martin Storsjö via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG4c3b74b7f5d6: [LLD] [COFF] Order .debug_* sections at the end, to avoid leaving gaps if… (authored by mstorsjo).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D120805/new/

https://reviews.llvm.org/D120805

Files:
  lld/COFF/Writer.cpp
  lld/test/COFF/sort-debug.test


Index: lld/test/COFF/sort-debug.test
===================================================================
--- lld/test/COFF/sort-debug.test
+++ lld/test/COFF/sort-debug.test
@@ -10,6 +10,7 @@
 
 # CHECK: Name: .text
 # CHECK: Name: .reloc
+# CHECK: Name: .rmeta
 # CHECK: Name: .debug_abbrev
 # CHECK: Name: .debug_info
 # CHECK: Name: .debug_line
@@ -18,6 +19,7 @@
 
 # NODEBUG: Name: .text
 # NODEBUG: Name: .reloc
+# NODEBUG: Name: .rmeta
 # NODEBUG-NOT: Name: .debug_abbrev
 # NODEBUG-NOT: Name: .debug_info
 # NODEBUG-NOT: Name: .debug_line
@@ -183,6 +185,10 @@
       - VirtualAddress:  43
         SymbolName:      .text
         Type:            IMAGE_REL_I386_DIR32
+  - Name:            .rmeta
+    Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_MEM_DISCARDABLE, IMAGE_SCN_MEM_READ ]
+    Alignment:       1
+    SectionData:     00112233
 symbols:
   - Name:            .text
     Value:           0
Index: lld/COFF/Writer.cpp
===================================================================
--- lld/COFF/Writer.cpp
+++ lld/COFF/Writer.cpp
@@ -928,8 +928,14 @@
     // Move DISCARDABLE (or non-memory-mapped) sections to the end of file
     // because the loader cannot handle holes. Stripping can remove other
     // discardable ones than .reloc, which is first of them (created early).
-    if (s->header.Characteristics & IMAGE_SCN_MEM_DISCARDABLE)
+    if (s->header.Characteristics & IMAGE_SCN_MEM_DISCARDABLE) {
+      // Move discardable sections named .debug_ to the end, after other
+      // discardable sections. Stripping only removes the sections named
+      // .debug_* - thus try to avoid leaving holes after stripping.
+      if (s->name.startswith(".debug_"))
+        return 3;
       return 2;
+    }
     // .rsrc should come at the end of the non-discardable sections because its
     // size may change by the Win32 UpdateResources() function, causing
     // subsequent sections to move (see https://crbug.com/827082).


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