[llvm-branch-commits] [llvm] 2927649 - [MC][ELF] Do not error on parsing .debug_* section directive for MIPS

[Fangrui Song via llvm-branch-commits]

Author: Simon Atanasyan
Date: 2021-12-14T17:32:32-08:00
New Revision: 29276490d13c9368b556d109353b6091404a37a2

URL: https://github.com/llvm/llvm-project/commit/29276490d13c9368b556d109353b6091404a37a2
DIFF: https://github.com/llvm/llvm-project/commit/29276490d13c9368b556d109353b6091404a37a2.diff

LOG: [MC][ELF] Do not error on parsing .debug_* section directive for MIPS

MIPS .debug_* sections should have SHT_MIPS_DWARF section type to
distinguish among sections contain DWARF and ECOFF debug formats, but in
assembly files these sections have SHT_PROGBITS (@progbits) type. Now
assembler shows 'changed section type for ...' error when parsing
`.section .debug_*,"", at progbits` directive for MIPS targets.

The same problem exists for x86-64 target and this patch extends
workaround implemented in D76151. The patch adds one more case
when assembler ignores section types mismatch after `SwitchSection()`
call.

Differential Revision: https://reviews.llvm.org/D107707

(cherry picked from commit 990e8025b5fcac42da6e7ce082cd9bf81b4fbbf7)

Added: 
    

Modified: 
    llvm/lib/MC/MCParser/ELFAsmParser.cpp
    llvm/test/MC/Mips/elf-debug-section.s

Removed: 
    


################################################################################
diff  --git a/llvm/lib/MC/MCParser/ELFAsmParser.cpp b/llvm/lib/MC/MCParser/ELFAsmParser.cpp
index 70d69fc8dd321..fdaacb572f062 100644
--- a/llvm/lib/MC/MCParser/ELFAsmParser.cpp
+++ b/llvm/lib/MC/MCParser/ELFAsmParser.cpp
@@ -502,6 +502,23 @@ static bool hasPrefix(StringRef SectionName, StringRef Prefix) {
   return SectionName.startswith(Prefix) || SectionName == Prefix.drop_back();
 }
 
+static bool allowSectionTypeMismatch(const Triple &TT, StringRef SectionName,
+                                     unsigned Type) {
+  if (TT.getArch() == Triple::x86_64) {
+    // x86-64 psABI names SHT_X86_64_UNWIND as the canonical type for .eh_frame,
+    // but GNU as emits SHT_PROGBITS .eh_frame for .cfi_* directives. Don't
+    // error for SHT_PROGBITS .eh_frame
+    return SectionName == ".eh_frame" && Type == ELF::SHT_PROGBITS;
+  }
+  if (TT.isMIPS()) {
+    // MIPS .debug_* sections should have SHT_MIPS_DWARF section type to
+    // distinguish among sections contain DWARF and ECOFF debug formats,
+    // but in assembly files these sections have SHT_PROGBITS type.
+    return hasPrefix(SectionName, ".debug_") && Type == ELF::SHT_PROGBITS;
+  }
+  return false;
+}
+
 bool ELFAsmParser::ParseSectionArguments(bool IsPush, SMLoc loc) {
   StringRef SectionName;
 
@@ -659,11 +676,9 @@ bool ELFAsmParser::ParseSectionArguments(bool IsPush, SMLoc loc) {
       getContext().getELFSection(SectionName, Type, Flags, Size, GroupName,
                                  IsComdat, UniqueID, LinkedToSym);
   getStreamer().SwitchSection(Section, Subsection);
-  // x86-64 psABI names SHT_X86_64_UNWIND as the canonical type for .eh_frame,
-  // but GNU as emits SHT_PROGBITS .eh_frame for .cfi_* directives. Don't error
-  // for SHT_PROGBITS .eh_frame
   if (Section->getType() != Type &&
-      !(SectionName == ".eh_frame" && Type == ELF::SHT_PROGBITS))
+      !allowSectionTypeMismatch(getContext().getTargetTriple(), SectionName,
+                                Type))
     Error(loc, "changed section type for " + SectionName + ", expected: 0x" +
                    utohexstr(Section->getType()));
   // Check that flags are used consistently. However, the GNU assembler permits

diff  --git a/llvm/test/MC/Mips/elf-debug-section.s b/llvm/test/MC/Mips/elf-debug-section.s
index 237fef12703ca..ad477df7dd663 100644
--- a/llvm/test/MC/Mips/elf-debug-section.s
+++ b/llvm/test/MC/Mips/elf-debug-section.s
@@ -1,6 +1,42 @@
 # RUN: llvm-mc -filetype=obj -triple=mips-linux-gnu -g %s -o - \
 # RUN:   | llvm-readobj -S - | FileCheck %s
 
+# MIPS .debug_* sections should have SHT_MIPS_DWARF section type
+# to distinguish among sections contain DWARF and ECOFF debug formats,
+# but in assembly files these sections have SHT_PROGBITS type.
+
+.section        .debug_abbrev,"", at progbits
+.section        .debug_addr,"", at progbits
+.section        .debug_aranges,"", at progbits
+.section        .debug_info,"", at progbits
+.section        .debug_line,"", at progbits
+.section        .debug_loclists,"", at progbits
+.section        .debug_pubnames,"", at progbits
+.section        .debug_pubtypes,"", at progbits
+.section        .debug_ranges,"", at progbits
+.section        .debug_rnglists,"", at progbits
+.section        .debug_str,"MS", at progbits,1
+
 # CHECK:      Section {
+# CHECK:        Name: .debug_abbrev
+# CHECK-NEXT:   Type: SHT_MIPS_DWARF
+# CHECK:        Name: .debug_addr
+# CHECK-NEXT:   Type: SHT_MIPS_DWARF
+# CHECK:        Name: .debug_aranges
+# CHECK-NEXT:   Type: SHT_MIPS_DWARF
+# CHECK:        Name: .debug_info
+# CHECK-NEXT:   Type: SHT_MIPS_DWARF
 # CHECK:        Name: .debug_line
-# CHECK-NEXT:   Type: SHT_MIPS_DWARF (0x7000001E)
+# CHECK-NEXT:   Type: SHT_MIPS_DWARF
+# CHECK:        Name: .debug_loclists
+# CHECK-NEXT:   Type: SHT_MIPS_DWARF
+# CHECK:        Name: .debug_pubnames
+# CHECK-NEXT:   Type: SHT_MIPS_DWARF
+# CHECK:        Name: .debug_pubtypes
+# CHECK-NEXT:   Type: SHT_MIPS_DWARF
+# CHECK:        Name: .debug_ranges
+# CHECK-NEXT:   Type: SHT_MIPS_DWARF
+# CHECK:        Name: .debug_rnglists
+# CHECK-NEXT:   Type: SHT_MIPS_DWARF
+# CHECK:        Name: .debug_str
+# CHECK-NEXT:   Type: SHT_MIPS_DWARF