[llvm-objdump] - Disassemble non-executable sections if specifically requested.

This is https://bugs.llvm.org/show_bug.cgi?id=41897.

Previously -d + -j .data had no effect, that wasn't consistent with GNU,
which proccesses .data in that case. With this patch we follow this behavior.

Diffeential revision: https://reviews.llvm.org/D62848

llvm-svn: 362596

llvm/test/tools/llvm-objdump/X86/section-filter-disasm.test

@@ -0,0 +1,43 @@
+# RUN: yaml2obj %s -o %t.o
+
+## By default, only executable sections are disassembled,
+## but with the use of the --section flag, we can change this behavior.
+## Show that llvm-objdump can disassemble the specified sections.
+
+# RUN: llvm-objdump -d %t.o | FileCheck %s --check-prefix=TEXT \
+# RUN:   --implicit-check-not=.rodata --implicit-check-not=.data
+
+# RUN: llvm-objdump -d %t.o --section=.rodata \
+# RUN:   | FileCheck %s --check-prefix=RODATA \
+# RUN:   --implicit-check-not=.text --implicit-check-not=.data
+
+# RUN: llvm-objdump -d %t.o --section=.rodata --section=.text \
+# RUN:   | FileCheck %s --check-prefixes=RODATA,TEXT \
+# RUN:   --implicit-check-not=.data
+
+# RUN: llvm-objdump -d %t.o --section=.rodata --section=.text --section=.data \
+# RUN:   | FileCheck %s --check-prefixes=RODATA,TEXT,DATA
+
+# RODATA: Disassembly of section .rodata
+# TEXT:   Disassembly of section .text
+# DATA:   Disassembly of section .data
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_REL
+  Machine: EM_X86_64
+Sections:
+  - Name:    .rodata
+    Type:    SHT_PROGBITS
+    Flags:   [SHF_ALLOC]
+    Content: '00'
+  - Name:    .text
+    Type:    SHT_PROGBITS
+    Flags:   [SHF_ALLOC, SHF_EXECINSTR]
+    Content: '00'
+  - Name:    .data
+    Type:    SHT_PROGBITS
+    Flags:   [SHF_ALLOC, SHF_WRITE]
+    Content: '00'

llvm/test/tools/llvm-objdump/X86/section-filter-relocs.test

@@ -1,16 +1,11 @@
 ## Test that --section works correctly for -d with -r.
 # RUN: yaml2obj %s -o %t.o
 
-## Show non-executable sections are not disassembled even if specified,
-## and that only the specified executable sections are disassembled.
+## Show that only the specified sections are disassembled.
 ## Also show that no relocation sections are dumped because none are
 ## specified.
-## FIXME: This is different behaviour to GNU objdump, which dumps the non-
-##        executable sections if requested explicitly.
-##        See https://bugs.llvm.org/show_bug.cgi?id=41897.
 # RUN: llvm-objdump -d -r %t.o --section=.text --section=.rodata \
-# RUN:   | FileCheck %s --check-prefixes=DISASM,RELOC --implicit-check-not=.text2 \
-# RUN:           --implicit-check-not=.rodata
+# RUN:   | FileCheck %s --check-prefixes=DISASM,RELOC --implicit-check-not=.text2
 
 # DISASM:       Disassembly of section .text:
 # DISASM-EMPTY:
@@ -18,6 +13,12 @@
 # DISASM-NEXT:  400: e8 00 00 00 00                callq   0 <.text+0x5>
 # RELOC-NEXT:                      00000401:  R_X86_64_PC32        foo+1
 # RELOC-NEXT:                      00000401:  R_X86_64_GOT32       foo
+# DISASM:       Disassembly of section .rodata:
+# DISASM-EMPTY:
+# DISASM-NEXT:  0000000000000000 .rodata:
+# DISASM-NEXT:  0: 00 00                           addb    %al, (%rax)
+# RELOC-NEXT:              0000000000000000:  R_X86_64_NONE        foo
+# DISASM-NEXT:  2: 00 00                           addb    %al, (%rax)
 
 --- !ELF
 FileHeader:

llvm/tools/llvm-objdump/llvm-objdump.cpp

@@ -1095,7 +1095,8 @@ static void disassembleObject(const Target *TheTarget, const ObjectFile *Obj,
   array_pod_sort(AbsoluteSymbols.begin(), AbsoluteSymbols.end());
 
   for (const SectionRef &Section : ToolSectionFilter(*Obj)) {
-    if (!DisassembleAll && (!Section.isText() || Section.isVirtual()))
+    if (FilterSections.empty() && !DisassembleAll &&
+        (!Section.isText() || Section.isVirtual()))
       continue;
 
     uint64_t SectionAddr = Section.getAddress();