[XCOFF][AIX] Fix for missing of undefined symbols from symbol table

[jasonliu]

Summary

When we use undefined symbol with its qualname, we are not able to generate that symbol because of the logic of early "continue" that skip the qualname symbol. This patch fixes it.

[DiggerLin]

LGTM

[hubert.reinterpretcast]

Looks fine here as well. Not sure if other reviewers would have comments though.

[DiggerLin]

llvm/test/CodeGen/PowerPC/aix-xcoff-toc.ll

0–1

minor: change to -mcpu=pwr4 ?

[daltenty]

llvm/test/CodeGen/PowerPC/aix-xcoff-toc.ll

73–151

My only concern here is that maybe these don't belong in this testcase. This test case tests exclusively TOC related functionality currently. Perhaps adding an undef test would be better (and possibly folding some of the undef function tests into it).

[jasonliu]

llvm/test/CodeGen/PowerPC/aix-xcoff-toc.ll

0–1

Addressed when landed. Thanks.

73–151

I thought about making a separate test case. But I figure I would write out similar llvm IR in order to trigger a undefined variable and undefined function descriptor generation.
So I think it's actually a good fit to put them together. In fact, it is precisely lack of those tests in this file so that we didn't find this bug in the first place.

[jasonliu]

llvm/test/CodeGen/PowerPC/aix-xcoff-toc.ll

73–151

As discussed offline, I will put comments in this unit test to indicate what we are testing here.

llvm/lib/MC/XCOFFObjectWriter.cpp

for (const auto &S : Asm) {
     Group.emplace_back(MCSec);
     WrapperMap[MCSec] = &Group.back();
   }
 
   for (const MCSymbol &S : Asm.symbols()) {
     // Nothing to do for temporary symbols.
     if (S.isTemporary())
       continue;
-    const MCSymbolXCOFF *XSym = cast<MCSymbolXCOFF>(&S);
 
-    // Map the symbol into its containing csect.
+    const MCSymbolXCOFF *XSym = cast<MCSymbolXCOFF>(&S);
     const MCSectionXCOFF *ContainingCsect = XSym->getContainingCsect();
 
+    // Handle undefined symbol.
+    if (ContainingCsect->getCSectType() == XCOFF::XTY_ER) {
+      UndefinedCsects.emplace_back(ContainingCsect);
+      continue;
+    }
+
     // If the symbol is the csect itself, we don't need to put the symbol
     // into csect's Syms.
     if (XSym == ContainingCsect->getQualNameSymbol())
       continue;
 
-    if (XSym->isUndefined(false)) {
-      UndefinedCsects.emplace_back(ContainingCsect);
-      continue;
-    }
-
     assert(WrapperMap.find(ContainingCsect) != WrapperMap.end() &&
            "Expected containing csect to exist in map");
 
     // Lookup the containing csect and add the symbol to it.
     WrapperMap[ContainingCsect]->Syms.emplace_back(XSym);
 
     // If the name does not fit in the storage provided in the symbol table
     // entry, add it to the string table.

llvm/test/CodeGen/PowerPC/aix-xcoff-toc.ll

-; RUN: llc  -verify-machineinstrs -mcpu=pwr7 -mtriple powerpc-ibm-aix-xcoff < %s | FileCheck --check-prefixes CHECK,CHECK32 %s
-; RUN: llc  -verify-machineinstrs -mcpu=pwr7 -mtriple powerpc64-ibm-aix-xcoff < %s 2>&1 | FileCheck --check-prefixes CHECK,CHECK64  %s
+; RUN: llc  -verify-machineinstrs -mcpu=pwr4 -mtriple powerpc-ibm-aix-xcoff < %s | FileCheck --check-prefixes CHECK,CHECK32 %s
+; RUN: llc  -verify-machineinstrs -mcpu=pwr4 -mtriple powerpc64-ibm-aix-xcoff < %s 2>&1 | FileCheck --check-prefixes CHECK,CHECK64  %s
 
-; RUN: llc -verify-machineinstrs -mcpu=pwr7 -mtriple powerpc-ibm-aix-xcoff -filetype=obj -o %t.o < %s
+; RUN: llc -verify-machineinstrs -mcpu=pwr4 -mtriple powerpc-ibm-aix-xcoff -filetype=obj -o %t.o < %s
 ; RUN: llvm-readobj --syms %t.o | FileCheck --check-prefix=SYM %s
 
-; RUN: not llc -verify-machineinstrs -mcpu=pwr7 -mtriple powerpc64-ibm-aix-xcoff -filetype=obj -o %t.o 2>&1 \
+; RUN: not llc -verify-machineinstrs -mcpu=pwr4 -mtriple powerpc64-ibm-aix-xcoff -filetype=obj -o %t.o 2>&1 \
 ; RUN: < %s | FileCheck --check-prefix=XCOFF64 %s
 ; XCOFF64: LLVM ERROR: 64-bit XCOFF object files are not supported yet.
 
 @a = external global i32, align 4
 @b = external global i64, align 8
 @c = external global i16, align 2
 @globa = common global i32 0, align 4
 

 ; CHECK-NEXT: LC5:
 ; CHECK-NEXT: .tc   bar[TC],bar[DS]
 ; CHECK-NEXT: LC6:
 ; CHECK-NEXT: .tc   foo[TC],foo[DS]
 ; CHECK-NEXT: LC7:
 ; CHECK-NEXT: .tc   foobar[TC],foobar[DS]
 
 ; SYM:       File: {{.*}}aix-xcoff-toc.ll.tmp.o
-; SYM:       Symbol {{[{][[:space:]] *}}Index: [[#INDX:]]{{[[:space:]] *}}Name: TOC
+; SYM:       Symbol {{[{][[:space:]] *}}Index: [[#UNDEF_INDX:]]{{[[:space:]] *}}Name: a
+; SYM-NEXT:   Value (RelocatableAddress): 0x0
+; SYM-NEXT:   Section: N_UNDEF
+; SYM-NEXT:   Type: 0x0
+; SYM-NEXT:   StorageClass: C_EXT (0x2)
+; SYM-NEXT:   NumberOfAuxEntries: 1
+; SYM-NEXT:   CSECT Auxiliary Entry {
+; SYM-NEXT:     Index: [[#UNDEF_INDX+1]]
+; SYM-NEXT:     SectionLen: 0
+; SYM-NEXT:     ParameterHashIndex: 0x0
+; SYM-NEXT:     TypeChkSectNum: 0x0
+; SYM-NEXT:     SymbolAlignmentLog2: 0
+; SYM-NEXT:     SymbolType: XTY_ER (0x0)
+; SYM-NEXT:     StorageMappingClass: XMC_UA (0x4)
+; SYM-NEXT:     StabInfoIndex: 0x0
+; SYM-NEXT:     StabSectNum: 0x0
+; SYM-NEXT:   }
+; SYM-NEXT: }
+; SYM-NEXT: Symbol {
+; SYM-NEXT:   Index: [[#UNDEF_INDX+2]]
+; SYM-NEXT:   Name: b
+; SYM-NEXT:   Value (RelocatableAddress): 0x0
+; SYM-NEXT:   Section: N_UNDEF
+; SYM-NEXT:   Type: 0x0
+; SYM-NEXT:   StorageClass: C_EXT (0x2)
+; SYM-NEXT:   NumberOfAuxEntries: 1
+; SYM-NEXT:   CSECT Auxiliary Entry {
+; SYM-NEXT:     Index: [[#UNDEF_INDX+3]]
+; SYM-NEXT:     SectionLen: 0
+; SYM-NEXT:     ParameterHashIndex: 0x0
+; SYM-NEXT:     TypeChkSectNum: 0x0
+; SYM-NEXT:     SymbolAlignmentLog2: 0
+; SYM-NEXT:     SymbolType: XTY_ER (0x0)
+; SYM-NEXT:     StorageMappingClass: XMC_UA (0x4)
+; SYM-NEXT:     StabInfoIndex: 0x0
+; SYM-NEXT:     StabSectNum: 0x0
+; SYM-NEXT:   }
+; SYM-NEXT: }
+; SYM-NEXT: Symbol {
+; SYM-NEXT:   Index: [[#UNDEF_INDX+4]]
+; SYM-NEXT:   Name: c
+; SYM-NEXT:   Value (RelocatableAddress): 0x0
+; SYM-NEXT:   Section: N_UNDEF
+; SYM-NEXT:   Type: 0x0
+; SYM-NEXT:   StorageClass: C_EXT (0x2)
+; SYM-NEXT:   NumberOfAuxEntries: 1
+; SYM-NEXT:   CSECT Auxiliary Entry {
+; SYM-NEXT:     Index: [[#UNDEF_INDX+5]]
+; SYM-NEXT:     SectionLen: 0
+; SYM-NEXT:     ParameterHashIndex: 0x0
+; SYM-NEXT:     TypeChkSectNum: 0x0
+; SYM-NEXT:     SymbolAlignmentLog2: 0
+; SYM-NEXT:     SymbolType: XTY_ER (0x0)
+; SYM-NEXT:     StorageMappingClass: XMC_UA (0x4)
+; SYM-NEXT:     StabInfoIndex: 0x0
+; SYM-NEXT:     StabSectNum: 0x0
+; SYM-NEXT:   }
+; SYM-NEXT: }
+; SYM-NEXT: Symbol {
+; SYM-NEXT:   Index: [[#UNDEF_INDX+6]]
+; SYM-NEXT:   Name: foo
+; SYM-NEXT:   Value (RelocatableAddress): 0x0
+; SYM-NEXT:   Section: N_UNDEF
+; SYM-NEXT:   Type: 0x0
+; SYM-NEXT:   StorageClass: C_EXT (0x2)
+; SYM-NEXT:   NumberOfAuxEntries: 1
+; SYM-NEXT:   CSECT Auxiliary Entry {
+; SYM-NEXT:     Index: [[#UNDEF_INDX+7]]
+; SYM-NEXT:     SectionLen: 0
+; SYM-NEXT:     ParameterHashIndex: 0x0
+; SYM-NEXT:     TypeChkSectNum: 0x0
+; SYM-NEXT:     SymbolAlignmentLog2: 0
+; SYM-NEXT:     SymbolType: XTY_ER (0x0)
+; SYM-NEXT:     StorageMappingClass: XMC_DS (0xA)
+; SYM-NEXT:     StabInfoIndex: 0x0
+; SYM-NEXT:     StabSectNum: 0x0
+; SYM-NEXT:   }
+; SYM-NEXT: }
+; SYM:       Symbol {{[{][[:space:]] *}}Index: [[#TOC_INDX:]]{{[[:space:]] *}}Name: TOC
 ; SYM-NEXT:    Value (RelocatableAddress): 0xA8
 ; SYM-NEXT:    Section: .data
 ; SYM-NEXT:    Type: 0x0
 ; SYM-NEXT:    StorageClass: C_HIDEXT (0x6B)
 ; SYM-NEXT:    NumberOfAuxEntries: 1
 ; SYM-NEXT:    CSECT Auxiliary Entry {
-; SYM-NEXT:      Index: [[#INDX+1]]
+; SYM-NEXT:      Index: [[#TOC_INDX+1]]
 ; SYM-NEXT:      SectionLen: 0
 ; SYM-NEXT:      ParameterHashIndex: 0x0
 ; SYM-NEXT:      TypeChkSectNum: 0x0
 ; SYM-NEXT:      SymbolAlignmentLog2: 2
 ; SYM-NEXT:      SymbolType: XTY_SD (0x1)
 ; SYM-NEXT:      StorageMappingClass: XMC_TC0 (0xF)
 ; SYM-NEXT:      StabInfoIndex: 0x0
 ; SYM-NEXT:      StabSectNum: 0x0
 ; SYM-NEXT:    }
 ; SYM-NEXT:  }
 ; SYM-NEXT:  Symbol {
-; SYM-NEXT:    Index: [[#INDX+2]]
+; SYM-NEXT:    Index: [[#TOC_INDX+2]]
 ; SYM-NEXT:    Name: a
 ; SYM-NEXT:    Value (RelocatableAddress): 0xA8
 ; SYM-NEXT:    Section: .data
 ; SYM-NEXT:    Type: 0x0
 ; SYM-NEXT:    StorageClass: C_HIDEXT (0x6B)
 ; SYM-NEXT:    NumberOfAuxEntries: 1
 ; SYM-NEXT:    CSECT Auxiliary Entry {
-; SYM-NEXT:      Index: [[#INDX+3]]
+; SYM-NEXT:      Index: [[#TOC_INDX+3]]
 ; SYM-NEXT:      SectionLen: 4
 ; SYM-NEXT:      ParameterHashIndex: 0x0
 ; SYM-NEXT:      TypeChkSectNum: 0x0
 ; SYM-NEXT:      SymbolAlignmentLog2: 2
 ; SYM-NEXT:      SymbolType: XTY_SD (0x1)
 ; SYM-NEXT:      StorageMappingClass: XMC_TC (0x3)
 ; SYM-NEXT:      StabInfoIndex: 0x0
 ; SYM-NEXT:      StabSectNum: 0x0
 ; SYM-NEXT:    }
 ; SYM-NEXT:  }
 ; SYM-NEXT:  Symbol {
-; SYM-NEXT:    Index: [[#INDX+4]]
+; SYM-NEXT:    Index: [[#TOC_INDX+4]]
 ; SYM-NEXT:    Name: b
 ; SYM-NEXT:    Value (RelocatableAddress): 0xAC
 ; SYM-NEXT:    Section: .data
 ; SYM-NEXT:    Type: 0x0
 ; SYM-NEXT:    StorageClass: C_HIDEXT (0x6B)
 ; SYM-NEXT:    NumberOfAuxEntries: 1
 ; SYM-NEXT:    CSECT Auxiliary Entry {
-; SYM-NEXT:      Index: [[#INDX+5]]
+; SYM-NEXT:      Index: [[#TOC_INDX+5]]
 ; SYM-NEXT:      SectionLen: 4
 ; SYM-NEXT:      ParameterHashIndex: 0x0
 ; SYM-NEXT:      TypeChkSectNum: 0x0
 ; SYM-NEXT:      SymbolAlignmentLog2: 2
 ; SYM-NEXT:      SymbolType: XTY_SD (0x1)
 ; SYM-NEXT:      StorageMappingClass: XMC_TC (0x3)
 ; SYM-NEXT:      StabInfoIndex: 0x0
 ; SYM-NEXT:      StabSectNum: 0x0
 ; SYM-NEXT:    }
 ; SYM-NEXT:  }
 ; SYM-NEXT:  Symbol {
-; SYM-NEXT:    Index: [[#INDX+6]]
+; SYM-NEXT:    Index: [[#TOC_INDX+6]]
 ; SYM-NEXT:    Name: c
 ; SYM-NEXT:    Value (RelocatableAddress): 0xB0
 ; SYM-NEXT:    Section: .data
 ; SYM-NEXT:    Type: 0x0
 ; SYM-NEXT:    StorageClass: C_HIDEXT (0x6B)
 ; SYM-NEXT:    NumberOfAuxEntries: 1
 ; SYM-NEXT:    CSECT Auxiliary Entry {
-; SYM-NEXT:      Index: [[#INDX+7]]
+; SYM-NEXT:      Index: [[#TOC_INDX+7]]
 ; SYM-NEXT:      SectionLen: 4
 ; SYM-NEXT:      ParameterHashIndex: 0x0
 ; SYM-NEXT:      TypeChkSectNum: 0x0
 ; SYM-NEXT:      SymbolAlignmentLog2: 2
 ; SYM-NEXT:      SymbolType: XTY_SD (0x1)
 ; SYM-NEXT:      StorageMappingClass: XMC_TC (0x3)
 ; SYM-NEXT:      StabInfoIndex: 0x0
 ; SYM-NEXT:      StabSectNum: 0x0
 ; SYM-NEXT:    }
 ; SYM-NEXT:  }
 ; SYM-NEXT:  Symbol {
-; SYM-NEXT:    Index: [[#INDX+8]]
+; SYM-NEXT:    Index: [[#TOC_INDX+8]]
 ; SYM-NEXT:    Name: globa
 ; SYM-NEXT:    Value (RelocatableAddress): 0xB4
 ; SYM-NEXT:    Section: .data
 ; SYM-NEXT:    Type: 0x0
 ; SYM-NEXT:    StorageClass: C_HIDEXT (0x6B)
 ; SYM-NEXT:    NumberOfAuxEntries: 1
 ; SYM-NEXT:    CSECT Auxiliary Entry {
-; SYM-NEXT:      Index: [[#INDX+9]]
+; SYM-NEXT:      Index: [[#TOC_INDX+9]]
 ; SYM-NEXT:      SectionLen: 4
 ; SYM-NEXT:      ParameterHashIndex: 0x0
 ; SYM-NEXT:      TypeChkSectNum: 0x0
 ; SYM-NEXT:      SymbolAlignmentLog2: 2
 ; SYM-NEXT:      SymbolType: XTY_SD (0x1)
 ; SYM-NEXT:      StorageMappingClass: XMC_TC (0x3)
 ; SYM-NEXT:      StabInfoIndex: 0x0
 ; SYM-NEXT:      StabSectNum: 0x0
 ; SYM-NEXT:    }
 ; SYM-NEXT:  }
 ; SYM-NEXT:  Symbol {
-; SYM-NEXT:    Index: [[#INDX+10]]
+; SYM-NEXT:    Index: [[#TOC_INDX+10]]
 ; SYM-NEXT:    Name: ptr
 ; SYM-NEXT:    Value (RelocatableAddress): 0xB8
 ; SYM-NEXT:    Section: .data
 ; SYM-NEXT:    Type: 0x0
 ; SYM-NEXT:    StorageClass: C_HIDEXT (0x6B)
 ; SYM-NEXT:    NumberOfAuxEntries: 1
 ; SYM-NEXT:    CSECT Auxiliary Entry {
-; SYM-NEXT:      Index: [[#INDX+11]]
+; SYM-NEXT:      Index: [[#TOC_INDX+11]]
 ; SYM-NEXT:      SectionLen: 4
 ; SYM-NEXT:      ParameterHashIndex: 0x0
 ; SYM-NEXT:      TypeChkSectNum: 0x0
 ; SYM-NEXT:      SymbolAlignmentLog2: 2
 ; SYM-NEXT:      SymbolType: XTY_SD (0x1)
 ; SYM-NEXT:      StorageMappingClass: XMC_TC (0x3)
 ; SYM-NEXT:      StabInfoIndex: 0x0
 ; SYM-NEXT:      StabSectNum: 0x0
 ; SYM-NEXT:    }
 ; SYM-NEXT:  }
 ; SYM-NEXT:  Symbol {
-; SYM-NEXT:    Index: [[#INDX+12]]
+; SYM-NEXT:    Index: [[#TOC_INDX+12]]
 ; SYM-NEXT:    Name: bar
 ; SYM-NEXT:    Value (RelocatableAddress): 0xBC
 ; SYM-NEXT:    Section: .data
 ; SYM-NEXT:    Type: 0x0
 ; SYM-NEXT:    StorageClass: C_HIDEXT (0x6B)
 ; SYM-NEXT:    NumberOfAuxEntries: 1
 ; SYM-NEXT:    CSECT Auxiliary Entry {
-; SYM-NEXT:      Index: [[#INDX+13]]
+; SYM-NEXT:      Index: [[#TOC_INDX+13]]
 ; SYM-NEXT:      SectionLen: 4
 ; SYM-NEXT:      ParameterHashIndex: 0x0
 ; SYM-NEXT:      TypeChkSectNum: 0x0
 ; SYM-NEXT:      SymbolAlignmentLog2: 2
 ; SYM-NEXT:      SymbolType: XTY_SD (0x1)
 ; SYM-NEXT:      StorageMappingClass: XMC_TC (0x3)
 ; SYM-NEXT:      StabInfoIndex: 0x0
 ; SYM-NEXT:      StabSectNum: 0x0
 ; SYM-NEXT:    }
 ; SYM-NEXT:  }
 ; SYM-NEXT:  Symbol {
-; SYM-NEXT:    Index: [[#INDX+14]]
+; SYM-NEXT:    Index: [[#TOC_INDX+14]]
 ; SYM-NEXT:    Name: foo
 ; SYM-NEXT:    Value (RelocatableAddress): 0xC0
 ; SYM-NEXT:    Section: .data
 ; SYM-NEXT:    Type: 0x0
 ; SYM-NEXT:    StorageClass: C_HIDEXT (0x6B)
 ; SYM-NEXT:    NumberOfAuxEntries: 1
 ; SYM-NEXT:    CSECT Auxiliary Entry {
-; SYM-NEXT:      Index: [[#INDX+15]]
+; SYM-NEXT:      Index: [[#TOC_INDX+15]]
 ; SYM-NEXT:      SectionLen: 4
 ; SYM-NEXT:      ParameterHashIndex: 0x0
 ; SYM-NEXT:      TypeChkSectNum: 0x0
 ; SYM-NEXT:      SymbolAlignmentLog2: 2
 ; SYM-NEXT:      SymbolType: XTY_SD (0x1)
 ; SYM-NEXT:      StorageMappingClass: XMC_TC (0x3)
 ; SYM-NEXT:      StabInfoIndex: 0x0
 ; SYM-NEXT:      StabSectNum: 0x0
 ; SYM-NEXT:    }
 ; SYM-NEXT:  }
 ; SYM-NEXT:  Symbol {
-; SYM-NEXT:    Index: [[#INDX+16]]
+; SYM-NEXT:    Index: [[#TOC_INDX+16]]
 ; SYM-NEXT:    Name: foobar
 ; SYM-NEXT:    Value (RelocatableAddress): 0xC4
 ; SYM-NEXT:    Section: .data
 ; SYM-NEXT:    Type: 0x0
 ; SYM-NEXT:    StorageClass: C_HIDEXT (0x6B)
 ; SYM-NEXT:    NumberOfAuxEntries: 1
 ; SYM-NEXT:    CSECT Auxiliary Entry {
-; SYM-NEXT:      Index: [[#INDX+17]]
+; SYM-NEXT:      Index: [[#TOC_INDX+17]]
 ; SYM-NEXT:      SectionLen: 4
 ; SYM-NEXT:      ParameterHashIndex: 0x0
 ; SYM-NEXT:      TypeChkSectNum: 0x0
 ; SYM-NEXT:      SymbolAlignmentLog2: 2
 ; SYM-NEXT:      SymbolType: XTY_SD (0x1)
 ; SYM-NEXT:      StorageMappingClass: XMC_TC (0x3)
 ; SYM-NEXT:      StabInfoIndex: 0x0
 ; SYM-NEXT:      StabSectNum: 0x0
 ; SYM-NEXT:    }
 ; SYM-NEXT:  }