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

[grimar]

Summary

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.

[grimar]

• Updated test case.

[jhenderson]

The changes in this patch look good, but you should probably also add a test case to section-filter-disasm.test. The section-filter-relocs.test case is more intended to test the interaction with -r.

[grimar]

• Addressed review comment.
• Removed excessive comment from the test case.

[grimar]

• Remove Address of sections from the test case added.

[MaskRay]

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

6

Nit: typo disassembled

[grimar]

• Fixed comment.

James, are you OK with this version?

[jhenderson]

LGTM, with one minor nit.

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

4

with use of -> with the use of the

[grimar]

rL362596

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

+# RUN: yaml2obj %s -o %t.o
+
+## By default, only executable sections are disassembled,
+## but with use of --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'

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

 ## 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:
 # DISASM-NEXT:  0000000000000400 .text:
 # 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:
   Class:   ELFCLASS64
   Data:    ELFDATA2LSB
   Type:    ET_REL
   Machine: EM_X86_64
 Sections:

tools/llvm-objdump/llvm-objdump.cpp

static void disassembleObject(const Target *TheTarget, const ObjectFile *Obj,
 
   // Sort all the symbols, this allows us to use a simple binary search to find
   // a symbol near an address.
   for (std::pair<const SectionRef, SectionSymbolsTy> &SecSyms : AllSymbols)
     array_pod_sort(SecSyms.second.begin(), SecSyms.second.end());
   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();
     uint64_t SectSize = Section.getSize();
     if (!SectSize)
       continue;
 
     // Get the list of all the symbols in this section.