Recover elf32-bigmips and elf32-powerpc support in LLD

[vit9696]

Summary

This fixes a 7.0 -> 8.0 regression when parsing OUTPUT_FORMAT("elf32-powerpc"); or elf32-bigmips directive in ldscripts as well as an unknown emulation error when lld is invoked by clang due to missed elf32ppclinux case.

I request this to be backported to LLD 8.0, as it is a regression breaking ldscripts that worked fine with LLD 7.0.

[grimar]

Testcase?

[vit9696]

Sorry, did not realise that we have tests for this functionality in such an undescriptive place. Added tests and merged with D58007 as suggested by Rui.

[ruiu]

lld/ELF/Driver.cpp

132

Do you know where elf32ppclinux came from? Is this really correct to handle it as a synonym for elf32ppc?

lld/ELF/ScriptParser.cpp

398

Ditto -- do you know if this correct to handle elf32-bigmips as a synonym for elf32-tradbigmips?

lld/test/ELF/emulation-ppc.s

107–108

Please test -m elf32ppclinux as well.

[vit9696]

Done with the test update. As for your other comments, there are some minor differences in section handling for different output types in GNU binutils, but I believe they have little to do with LLD abilities as of now. ppclinux one is chosen when clang is used for linking under Linux target. You can get some more details by checking ld/emulation folder, but I believe it is just fine to have these as synonyms for a long while to let most of the code continue building just fine.

[ruiu]

Yeah maybe it is fine to add elf32ppclinux as a synonym for elf32ppc.

One last thing: please add a test to lld/test/ELF/emulation-mips.s for the mips synonym.

[vit9696]

Done, I must have been quite tired yesterday, thought I included it.

Would you take the effort with the merge request?

[ruiu]

LGTM

In order to have this cherry-picked, please commit this patch first and then file a cherry pick request as a new bug and make the new bug depend on https://bugs.llvm.org/show_bug.cgi?id=40331.

[vit9696]

I am fine to create bugs, but I am yet to ask for commit access, and somebody needs to commit the patch for the time being. For this reason I thought it would be faster to leave the rest up to you.

[ruiu]

Oh sorry, I'll commit and merge this to 8.0 for you.

[vit9696]

Thanks a lot!

[ruiu]

Submitted this patch and filed a merge request as https://bugs.llvm.org/show_bug.cgi?id=40721.

lld/ELF/Driver.cpp

std::pair<ELFKind, uint16_t> Ret =
       StringSwitch<std::pair<ELFKind, uint16_t>>(S)
           .Cases("aarch64elf", "aarch64linux", "aarch64_elf64_le_vec",
                  {ELF64LEKind, EM_AARCH64})
           .Cases("armelf", "armelf_linux_eabi", {ELF32LEKind, EM_ARM})
           .Case("elf32_x86_64", {ELF32LEKind, EM_X86_64})
           .Cases("elf32btsmip", "elf32btsmipn32", {ELF32BEKind, EM_MIPS})
           .Cases("elf32ltsmip", "elf32ltsmipn32", {ELF32LEKind, EM_MIPS})
           .Case("elf32lriscv", {ELF32LEKind, EM_RISCV})
-          .Case("elf32ppc", {ELF32BEKind, EM_PPC})
+          .Cases("elf32ppc", "elf32ppclinux", {ELF32BEKind, EM_PPC})
           .Case("elf64btsmip", {ELF64BEKind, EM_MIPS})
           .Case("elf64ltsmip", {ELF64LEKind, EM_MIPS})
           .Case("elf64lriscv", {ELF64LEKind, EM_RISCV})
           .Case("elf64ppc", {ELF64BEKind, EM_PPC64})
           .Case("elf64lppc", {ELF64LEKind, EM_PPC64})
           .Cases("elf_amd64", "elf_x86_64", {ELF64LEKind, EM_X86_64})
           .Case("elf_i386", {ELF32LEKind, EM_386})
           .Case("elf_iamcu", {ELF32LEKind, EM_IAMCU})

lld/ELF/ScriptParser.cpp

 static std::pair<ELFKind, uint16_t> parseBfdName(StringRef S) {
   return StringSwitch<std::pair<ELFKind, uint16_t>>(S)
       .Case("elf32-i386", {ELF32LEKind, EM_386})
       .Case("elf32-iamcu", {ELF32LEKind, EM_IAMCU})
       .Case("elf32-littlearm", {ELF32LEKind, EM_ARM})
       .Case("elf32-x86-64", {ELF32LEKind, EM_X86_64})
       .Case("elf64-aarch64", {ELF64LEKind, EM_AARCH64})
       .Case("elf64-littleaarch64", {ELF64LEKind, EM_AARCH64})
+      .Case("elf32-powerpc", {ELF32BEKind, EM_PPC})
       .Case("elf64-powerpc", {ELF64BEKind, EM_PPC64})
       .Case("elf64-powerpcle", {ELF64LEKind, EM_PPC64})
       .Case("elf64-x86-64", {ELF64LEKind, EM_X86_64})
-      .Case("elf32-tradbigmips", {ELF32BEKind, EM_MIPS})
+      .Cases("elf32-tradbigmips", "elf32-bigmips", {ELF32BEKind, EM_MIPS})
       .Case("elf32-ntradbigmips", {ELF32BEKind, EM_MIPS})
       .Case("elf32-tradlittlemips", {ELF32LEKind, EM_MIPS})
       .Case("elf32-ntradlittlemips", {ELF32LEKind, EM_MIPS})
       .Case("elf64-tradbigmips", {ELF64BEKind, EM_MIPS})
       .Case("elf64-tradlittlemips", {ELF64LEKind, EM_MIPS})
       .Default({ELFNoneKind, EM_NONE});
 }
 

lld/test/ELF/emulation-mips.s

 # REQUIRES: mips
 # RUN: llvm-mc -filetype=obj -triple=mips-unknown-linux %s -o %tmips
 # RUN: ld.lld -m elf32btsmip -e _start %tmips -o %t2mips
 # RUN: llvm-readobj -file-headers %t2mips | FileCheck --check-prefix=MIPS %s
 # RUN: ld.lld %tmips -e _start -o %t3mips
 # RUN: llvm-readobj -file-headers %t3mips | FileCheck --check-prefix=MIPS %s
 # RUN: echo 'OUTPUT_FORMAT(elf32-tradbigmips)' > %tmips.script
 # RUN: ld.lld %tmips.script -e _start %tmips -o %t4mips
 # RUN: llvm-readobj -file-headers %t4mips | FileCheck --check-prefix=MIPS %s
+# RUN: echo 'OUTPUT_FORMAT(elf32-bigmips)' > %tmips2.script
+# RUN: ld.lld %tmips2.script -e _start %tmips -o %t5mips
+# RUN: llvm-readobj -file-headers %t5mips | FileCheck --check-prefix=MIPS %s
 # MIPS:      ElfHeader {
 # MIPS-NEXT:   Ident {
 # MIPS-NEXT:     Magic: (7F 45 4C 46)
 # MIPS-NEXT:     Class: 32-bit (0x1)
 # MIPS-NEXT:     DataEncoding: BigEndian (0x2)
 # MIPS-NEXT:     FileVersion: 1
 # MIPS-NEXT:     OS/ABI: SystemV (0x0)
 # MIPS-NEXT:     ABIVersion: 1

lld/test/ELF/emulation-ppc.s

 # PPC64LE-NEXT:   HeaderSize: 64
 # PPC64LE-NEXT:   ProgramHeaderEntrySize: 56
 # PPC64LE-NEXT:   ProgramHeaderCount:
 # PPC64LE-NEXT:   SectionHeaderEntrySize: 64
 # PPC64LE-NEXT:   SectionHeaderCount:
 # PPC64LE-NEXT:   StringTableSectionIndex:
 # PPC64LE-NEXT: }
 
+# RUN: llvm-mc -filetype=obj -triple=powerpc-unknown-linux %s -o %tppc32
+# RUN: ld.lld -m elf32ppc %tppc32 -o %t2ppc32
+# RUN: llvm-readobj -file-headers %t2ppc32 | FileCheck --check-prefix=PPC32 %s
+# RUN: ld.lld %tppc32 -o %t3ppc32
+# RUN: llvm-readobj -file-headers %t3ppc32 | FileCheck --check-prefix=PPC32 %s
+# RUN: echo 'OUTPUT_FORMAT(elf32-powerpc)' > %tppc32.script
+# RUN: ld.lld %tppc32.script  %tppc32 -o %t4ppc32
+# RUN: llvm-readobj -file-headers %t4ppc32 | FileCheck --check-prefix=PPC32 %s
+# RUN: ld.lld -m elf32ppclinux %tppc32 -o %t5ppc32
+# RUN: llvm-readobj -file-headers %t5ppc32 | FileCheck --check-prefix=PPC32 %s
+
+# PPC32:      ElfHeader {
+# PPC32-NEXT:   Ident {
+# PPC32-NEXT:     Magic: (7F 45 4C 46)
+# PPC32-NEXT:     Class: 32-bit (0x1)
+# PPC32-NEXT:     DataEncoding: BigEndian (0x2)
+# PPC32-NEXT:     FileVersion: 1
+# PPC32-NEXT:     OS/ABI: SystemV (0x0)
+# PPC32-NEXT:     ABIVersion: 0
+# PPC32-NEXT:     Unused: (00 00 00 00 00 00 00)
+# PPC32-NEXT:   }
+# PPC32-NEXT:   Type: Executable (0x2)
+# PPC32-NEXT:   Machine: EM_PPC (0x14)
+# PPC32-NEXT:   Version: 1
+# PPC32-NEXT:   Entry:
+# PPC32-NEXT:   ProgramHeaderOffset: 0x34
+# PPC32-NEXT:   SectionHeaderOffset:
+# PPC32-NEXT:   Flags [ (0x0)
+# PPC32-NEXT:   ]
+# PPC32-NEXT:   HeaderSize: 52
+# PPC32-NEXT:   ProgramHeaderEntrySize: 32
+# PPC32-NEXT:   ProgramHeaderCount:
+# PPC32-NEXT:   SectionHeaderEntrySize: 40
+# PPC32-NEXT:   SectionHeaderCount:
+# PPC32-NEXT:   StringTableSectionIndex:
+# PPC32-NEXT: }
+
 .globl _start
 _start: