[PATCH] D125074: [ELF] Change (NOLOAD) type mismatch to use the specified type instead of SHT_PROGBITS

[Fangrui Song via Phabricator via llvm-commits]

MaskRay created this revision.
MaskRay added a reviewer: peter.smith.
Herald added subscribers: StephenFan, arichardson, emaste.
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Placing a non-SHT_NOBITS input section in an output section specified with
(NOLOAD) is fishy but used by some projects. D118840 <https://reviews.llvm.org/D118840> changed the output type to
SHT_PROGBITS, but using the specified type seems to make more sense and improve
GNU ld compatibility: `(NOLOAD)` seems to change the output section type
regardless of input.

I think we should keep the current type mismatch warning as it does indicate an
error-prone usage.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D125074

Files:
  lld/ELF/OutputSections.cpp
  lld/test/ELF/linkerscript/custom-section-type.s
  lld/test/ELF/linkerscript/noload.s


Index: lld/test/ELF/linkerscript/noload.s
===================================================================
--- lld/test/ELF/linkerscript/noload.s
+++ lld/test/ELF/linkerscript/noload.s
@@ -24,7 +24,7 @@
 
 # WARN:   warning: section type mismatch for .data_noload_a
 # CHECK2:      Name                 Type     Address          Off               Size
-# CHECK2:      .data_noload_a       PROGBITS 0000000000000000 [[OFF:[0-9a-f]+]] 001001
+# CHECK2:      .data_noload_a       NOBITS   0000000000000000 [[OFF:[0-9a-f]+]] 001001
 
 #--- asm
 .section .text,"ax", at progbits
Index: lld/test/ELF/linkerscript/custom-section-type.s
===================================================================
--- lld/test/ELF/linkerscript/custom-section-type.s
+++ lld/test/ELF/linkerscript/custom-section-type.s
@@ -37,7 +37,7 @@
 ## Mismatched progbits and expr are changed to SHT_PROGBITS.
 # MISMATCH: progbits PROGBITS
 # MISMATCH: note     NOTE
-# MISMATCH: expr     PROGBITS
+# MISMATCH: expr     0x42: <unknown>
 
 # RUN: not ld.lld -T %t/unknown1.lds %t/a.o -o /dev/null 2>&1 | FileCheck %s --check-prefix=UNKNOWN1
 # UNKNOWN1: error: {{.*}}.lds:1: symbol not found: foo
Index: lld/ELF/OutputSections.cpp
===================================================================
--- lld/ELF/OutputSections.cpp
+++ lld/ELF/OutputSections.cpp
@@ -123,7 +123,8 @@
                  "\n>>> output section " + name + ": " +
                  getELFSectionTypeName(config->emachine, type));
       }
-      type = SHT_PROGBITS;
+      if (!typeIsSet)
+        type = SHT_PROGBITS;
     } else {
       type = isec->type;
     }


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