[AIX] Handle ReadOnlyWithRel kind on AIX.

[Esme]

Summary

This patch handles the SectionKind of ReadOnlyWithRel.

[DiggerLin]

llvm/test/CodeGen/PowerPC/aix-relro-section.ll

25

we can delete the Name: <stdin> symbol , it is not relate the patch's functionality

55

we can delete the Name: , it is not relate the patch's functionality

103

ditto

132

ditto

[hubert.reinterpretcast]

llvm/lib/MC/MCSectionXCOFF.cpp

128

Is this correct for -mxcoff-roptr?

[Esme]

The storage-mapping class should be XCOFF::XMC_RO when -mxcoff-roptr is specified. Add check lines for it.

[hubert.reinterpretcast]

@Esme, can you add more info about the motivation for doing this (e.g., what fails?) to either the patch description (preferred) or as a comment (replying to this one)?
Information on whether this should be included for LLVM 17 (and why) would be useful.

[Esme]

In D157483#4612306, @hubert.reinterpretcast wrote:

@Esme, can you add more info about the motivation for doing this (e.g., what fails?) to either the patch description (preferred) or as a comment (replying to this one)?
Information on whether this should be included for LLVM 17 (and why) would be useful.

The issue was found by Zheng @shchenz during sanitizer enablement on AIX.

$ clang -fsanitize=address -m32 -fsanitize-coverage=control-flow llvm-project/compiler-rt/test/sanitizer_common/TestCases/sanitizer_coverage_control_flow.cpp
fatal error: error in backend: Printing for this SectionKind is unimplemented.
clang: error: clang frontend command failed with exit code 70 (use -v to see invocation)

[hubert.reinterpretcast]

llvm/lib/MC/MCSectionXCOFF.cpp

44–54

Move the code to here.

84–86

Update this because of the other proposed changes.

127–135

Given the structure of the function, I think the code should be moved to right after the isReadOnly block. Once moved, the XMC_TD case would need to be allowed in this code too.

[hubert.reinterpretcast]

In D157483#4612499, @Esme wrote:

The issue was found by Zheng @shchenz during sanitizer enablement on AIX.

It sounds like this is not a regression and can be left out of the LLVM 17 release then. Does that sound right?

[Esme]

In D157483#4612609, @hubert.reinterpretcast wrote:

In D157483#4612499, @Esme wrote:

The issue was found by Zheng @shchenz during sanitizer enablement on AIX.

It sounds like this is not a regression and can be left out of the LLVM 17 release then. Does that sound right?

I think so. This failure currently only occurs with -fsanitize-coverage and support for this option on AIX is not yet complete.

[hubert.reinterpretcast]

In D157483#4612870, @Esme wrote:

It sounds like this is not a regression and can be left out of the LLVM 17 release then. Does that sound right?

I think so. This failure currently only occurs with -fsanitize-coverage and support for this option on AIX is not yet complete.

It is clear from the added test that the failure can occur in other contexts, but we only discovered the issue in new coverage (associated with sanitizer enablement).

[hubert.reinterpretcast]

LGTM!

llvm/lib/MC/MCSectionXCOFF.cpp

void MCSectionXCOFF::printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
 
   if (getKind().isReadOnly()) {
     if (getMappingClass() != XCOFF::XMC_RO &&
         getMappingClass() != XCOFF::XMC_TD)
       report_fatal_error("Unhandled storage-mapping class for .rodata csect.");
     printCsectDirective(OS);
     return;
   }
 
+  if (getKind().isReadOnlyWithRel()) {
+    if (getMappingClass() != XCOFF::XMC_RW &&
+        getMappingClass() != XCOFF::XMC_RO &&
+        getMappingClass() != XCOFF::XMC_TD)
+      report_fatal_error(
+          "Unexepected storage-mapping class for ReadOnlyWithRel kind");
+    printCsectDirective(OS);
+    return;
+  }
+
   // Initialized TLS data.
   if (getKind().isThreadData()) {
     // We only expect XMC_TL here for initialized TLS data.
     if (getMappingClass() != XCOFF::XMC_TL)
       report_fatal_error("Unhandled storage-mapping class for .tdata csect.");
     printCsectDirective(OS);
     return;
   }
case XCOFF::XMC_TC0:
       break;
     default:
       report_fatal_error(
           "Unhandled storage-mapping class for .data csect.");
     }
     return;
   }
 
   if (isCsect() && getMappingClass() == XCOFF::XMC_TD) {
-    assert((getKind().isBSSExtern() || getKind().isBSSLocal() ||
-            getKind().isReadOnlyWithRel()) &&
+    assert((getKind().isBSSExtern() || getKind().isBSSLocal()) &&
            "Unexepected section kind for toc-data");
     printCsectDirective(OS);
     return;
   }
   // Common csect type (uninitialized storage) does not have to print csect
   // directive for section switching.
   if (isCsect() && getCSectType() == XCOFF::XTY_CM) {
     assert((getMappingClass() == XCOFF::XMC_RW ||
             getMappingClass() == XCOFF::XMC_BS ||
void MCSectionXCOFF::printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
   // XCOFF debug sections.
   if (getKind().isMetadata() && isDwarfSect()) {
     OS << "\n\t.dwsect " << format("0x%" PRIx32, *getDwarfSubtypeFlags())
        << '\n';
     OS << MAI.getPrivateLabelPrefix() << getName() << ':' << '\n';
     return;
   }
 
   report_fatal_error("Printing for this SectionKind is unimplemented.");
 }
 
 bool MCSectionXCOFF::useCodeAlign() const { return getKind().isText(); }
 
 bool MCSectionXCOFF::isVirtualSection() const {
   // DWARF sections are always not virtual.
   if (isDwarfSect())
     return false;
   assert(isCsect() &&
          "Handling for isVirtualSection not implemented for this section!");
   return XCOFF::XTY_CM == CsectProp->Type;
 }

llvm/test/CodeGen/PowerPC/aix-relro-section.ll

+; RUN: llc -mtriple powerpc-ibm-aix-xcoff < %s | FileCheck %s --check-prefix CHECK
+; RUN: llc -mtriple powerpc64-ibm-aix-xcoff < %s | FileCheck %s --check-prefix CHECK
+; RUN: llc -mtriple powerpc-ibm-aix-xcoff -mxcoff-roptr < %s | FileCheck %s --check-prefix CHECK-RO
+; RUN: llc -mtriple powerpc64-ibm-aix-xcoff -mxcoff-roptr < %s | FileCheck %s --check-prefix CHECK-RO
+
+; RUN: llc -filetype=obj -mtriple powerpc-ibm-aix-xcoff -verify-machineinstrs < %s -o %t32.o
+; RUN: llvm-readobj %t32.o --syms --relocs | FileCheck %s --check-prefix=OBJ32
+
+; RUN: llc -filetype=obj -mtriple powerpc64-ibm-aix-xcoff -verify-machineinstrs < %s -o %t64.o
+; RUN: llvm-readobj %t64.o --syms --relocs | FileCheck %s --check-prefix=OBJ64
+
+@var = external constant i32
+@ptr = private constant ptr @var, section "relro-section"
+
+; CHECK: .extern var[UA]
+; CHECK: .csect _Renamed..2drelro_section[RW]
+
+; CHECK-RO: .extern var[UA]
+; CHECK-RO: .csect _Renamed..2drelro_section[RO]
+
+; OBJ32:      Relocations [
+; OBJ32-NEXT:   Section (index: 2) .data {
+; OBJ32-NEXT:     0x0 R_POS var(1) 0x1F
+; OBJ32-NEXT:   }
+; OBJ32-NEXT: ]
+; OBJ32-NEXT: Symbols [
+; OBJ32:          Index: 1
+; OBJ32-NEXT:     Name: var
+; OBJ32-NEXT:     Value (RelocatableAddress): 0x0
+; OBJ32-NEXT:     Section: N_UNDEF
+; OBJ32-NEXT:     Type: 0x0
+; OBJ32-NEXT:     StorageClass: C_EXT (0x2)
+; OBJ32-NEXT:     NumberOfAuxEntries: 1
+; OBJ32-NEXT:     CSECT Auxiliary Entry {
+; OBJ32-NEXT:       Index: 2
+; OBJ32-NEXT:       SectionLen: 0
+; OBJ32-NEXT:       ParameterHashIndex: 0x0
+; OBJ32-NEXT:       TypeChkSectNum: 0x0
+; OBJ32-NEXT:       SymbolAlignmentLog2: 0
+; OBJ32-NEXT:       SymbolType: XTY_ER (0x0)
+; OBJ32-NEXT:       StorageMappingClass: XMC_UA (0x4)
+; OBJ32-NEXT:       StabInfoIndex: 0x0
+; OBJ32-NEXT:       StabSectNum: 0x0
+; OBJ32-NEXT:     }
+; OBJ32:          Index: 5
+; OBJ32-NEXT:     Name: relro-section
+; OBJ32-NEXT:     Value (RelocatableAddress): 0x0
+; OBJ32-NEXT:     Section: .data
+; OBJ32-NEXT:     Type: 0x0
+; OBJ32-NEXT:     StorageClass: C_HIDEXT (0x6B)
+; OBJ32-NEXT:     NumberOfAuxEntries: 1
+; OBJ32-NEXT:     CSECT Auxiliary Entry {
+; OBJ32-NEXT:       Index: 6
+; OBJ32-NEXT:       SectionLen: 4
+; OBJ32-NEXT:       ParameterHashIndex: 0x0
+; OBJ32-NEXT:       TypeChkSectNum: 0x0
+; OBJ32-NEXT:       SymbolAlignmentLog2: 2
+; OBJ32-NEXT:       SymbolType: XTY_SD (0x1)
+; OBJ32-NEXT:       StorageMappingClass: XMC_RW (0x5)
+; OBJ32-NEXT:       StabInfoIndex: 0x0
+; OBJ32-NEXT:       StabSectNum: 0x0
+; OBJ32-NEXT:     }
+; OBJ32:       ]
+
+; OBJ64:      Relocations [
+; OBJ64-NEXT:   Section (index: 2) .data {
+; OBJ64-NEXT:     0x0 R_POS var(1) 0x3F
+; OBJ64-NEXT:   }
+; OBJ64-NEXT: ]
+; OBJ64-NEXT: Symbols [
+; OBJ64:          Index: 1
+; OBJ64-NEXT:     Name: var
+; OBJ64-NEXT:     Value (RelocatableAddress): 0x0
+; OBJ64-NEXT:     Section: N_UNDEF
+; OBJ64-NEXT:     Type: 0x0
+; OBJ64-NEXT:     StorageClass: C_EXT (0x2)
+; OBJ64-NEXT:     NumberOfAuxEntries: 1
+; OBJ64-NEXT:     CSECT Auxiliary Entry {
+; OBJ64-NEXT:       Index: 2
+; OBJ64-NEXT:       SectionLen: 0
+; OBJ64-NEXT:       ParameterHashIndex: 0x0
+; OBJ64-NEXT:       TypeChkSectNum: 0x0
+; OBJ64-NEXT:       SymbolAlignmentLog2: 0
+; OBJ64-NEXT:       SymbolType: XTY_ER (0x0)
+; OBJ64-NEXT:       StorageMappingClass: XMC_UA (0x4)
+; OBJ64-NEXT:       Auxiliary Type: AUX_CSECT (0xFB)
+; OBJ64-NEXT:     }
+; OBJ64:          Index: 5
+; OBJ64-NEXT:     Name: relro-section
+; OBJ64-NEXT:     Value (RelocatableAddress): 0x0
+; OBJ64-NEXT:     Section: .data
+; OBJ64-NEXT:     Type: 0x0
+; OBJ64-NEXT:     StorageClass: C_HIDEXT (0x6B)
+; OBJ64-NEXT:     NumberOfAuxEntries: 1
+; OBJ64-NEXT:     CSECT Auxiliary Entry {
+; OBJ64-NEXT:       Index: 6
+; OBJ64-NEXT:       SectionLen: 8
+; OBJ64-NEXT:       ParameterHashIndex: 0x0
+; OBJ64-NEXT:       TypeChkSectNum: 0x0
+; OBJ64-NEXT:       SymbolAlignmentLog2: 3
+; OBJ64-NEXT:       SymbolType: XTY_SD (0x1)
+; OBJ64-NEXT:       StorageMappingClass: XMC_RW (0x5)
+; OBJ64-NEXT:       Auxiliary Type: AUX_CSECT (0xFB)
+; OBJ64-NEXT:     }
+; OBJ64:      ]