In the ELFWriter when writing aliased (.set) symbols dont blindly

take type from the new symbol but merge them so that the type
is never "downgraded".

This is probably quite rare, except for IFUNC symbols which
we used to misassemble, losing the IFUNC type.

Fixes #18372.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198706 91177308-0d34-0410-b5e6-96231b3b80d8

lib/MC/ELFObjectWriter.cpp

@@ -532,6 +532,41 @@ void ELFObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
   }
 }
 
+static uint8_t mergeTypeForSet(uint8_t origType, uint8_t newType) {
+  uint8_t Type = newType;
+
+  // Propagation rules:
+  // IFUNC > FUNC > OBJECT > NOTYPE
+  // TLS_OBJECT > OBJECT > NOTYPE
+  //
+  // dont let the new type degrade the old type
+  switch (origType) {
+  default:
+    break;
+  case ELF::STT_GNU_IFUNC:
+    if (Type == ELF::STT_FUNC || Type == ELF::STT_OBJECT ||
+        Type == ELF::STT_NOTYPE || Type == ELF::STT_TLS)
+      Type = ELF::STT_GNU_IFUNC;
+    break;
+  case ELF::STT_FUNC:
+    if (Type == ELF::STT_OBJECT || Type == ELF::STT_NOTYPE ||
+        Type == ELF::STT_TLS)
+      Type = ELF::STT_FUNC;
+    break;
+  case ELF::STT_OBJECT:
+    if (Type == ELF::STT_NOTYPE)
+      Type = ELF::STT_OBJECT;
+    break;
+  case ELF::STT_TLS:
+    if (Type == ELF::STT_OBJECT || Type == ELF::STT_NOTYPE ||
+        Type == ELF::STT_GNU_IFUNC || Type == ELF::STT_FUNC)
+      Type = ELF::STT_TLS;
+    break;
+  }
+
+  return Type;
+}
+
 void ELFObjectWriter::WriteSymbol(MCDataFragment *SymtabF,
                                   MCDataFragment *ShndxF,
                                   ELFSymbolData &MSD,
@@ -545,7 +580,7 @@ void ELFObjectWriter::WriteSymbol(MCDataFragment *SymtabF,
 
   // Binding and Type share the same byte as upper and lower nibbles
   uint8_t Binding = MCELF::GetBinding(OrigData);
-  uint8_t Type = MCELF::GetType(Data);
+  uint8_t Type = mergeTypeForSet(MCELF::GetType(OrigData), MCELF::GetType(Data));
   uint8_t Info = (Binding << ELF_STB_Shift) | (Type << ELF_STT_Shift);
 
   // Other and Visibility share the same byte with Visibility using the lower

test/MC/ELF/type.s

@@ -41,6 +41,95 @@ tls_upper_case:
         .global tls_upper_case
         .type tls_upper_case,STT_TLS
 
+// Test that .set doesnt downgrade the type:
+// IFUNC > FUNC > OBJECT > NOTYPE
+// TLS_OBJECT > OBJECT > NOTYPE
+// also TLS_OBJECT is incompatible with IFUNC and FUNC
+
+        .global sym1
+        .type sym1, @gnu_indirect_function
+alias1:
+        .global alias1
+        .type alias1, @function
+        .set sym1, alias1
+
+        .global sym2
+        .type sym2, @gnu_indirect_function
+alias2:
+        .global alias2
+        .type alias2, @object
+        .set sym2, alias2
+
+        .global sym3
+        .type sym3, @gnu_indirect_function
+alias3:
+        .global alias3
+        .type alias3, @notype
+        .set sym3, alias3
+
+        .global sym4
+        .type sym4, @function
+alias4:
+        .global alias4
+        .type alias4, @object
+        .set sym4, alias4
+
+        .global sym5
+        .type sym5, @function
+alias5:
+        .global alias5
+        .type alias5, @notype
+        .set sym5, alias5
+
+        .global sym6
+        .type sym6, @object
+alias6:
+        .global alias6
+        .type alias6, @notype
+        .set sym6, alias6
+
+        .global sym7
+        .type sym7, @gnu_indirect_function
+alias7:
+        .global alias7
+        .type alias7, @tls_object
+        .set sym7, alias7
+
+        .global sym8
+        .type sym8, @function
+        .global alias8
+alias8:
+        .type alias8, @tls_object
+        .set sym8, alias8
+
+        .global sym9
+        .type sym9, @tls_object
+alias9:
+        .global alias9
+        .type alias9, @object
+        .set sym9, alias9
+
+        .global sym10
+        .type sym10, @tls_object
+alias10:
+        .global alias10
+        .type alias10, @notype
+        .set sym10, alias10
+
+        .global sym11
+        .type sym11, @tls_object
+alias11:
+        .global alias11
+        .type alias11, @gnu_indirect_function
+        .set sym11, alias11
+
+        .global sym12
+        .type sym12, @tls_object
+alias12:        
+        .global alias12
+        .type alias12, @function
+        .set sym12, alias12
+
 // CHECK:        Symbol {
 // CHECK:          Name: bar
 // CHECK-NEXT:     Value: 0x0
@@ -86,6 +175,114 @@ tls_upper_case:
 // CHECK-NEXT:     Other: 0
 // CHECK-NEXT:     Section: .text (0x1)
 // CHECK-NEXT:   }
+// CHECK-NEXT:  Symbol {
+// CHECK-NEXT:    Name: sym1 (54)
+// CHECK-NEXT:    Value: 0x0
+// CHECK-NEXT:    Size: 0
+// CHECK-NEXT:    Binding: Global (0x1)
+// CHECK-NEXT:    Type: GNU_IFunc (0xA)
+// CHECK-NEXT:    Other: 0
+// CHECK-NEXT:    Section: .text (0x1)
+// CHECK-NEXT:  }
+// CHECK-NEXT:  Symbol {
+// CHECK-NEXT:    Name: sym10 (162)
+// CHECK-NEXT:    Value: 0x0
+// CHECK-NEXT:    Size: 0
+// CHECK-NEXT:    Binding: Global (0x1)
+// CHECK-NEXT:    Type: TLS (0x6)
+// CHECK-NEXT:    Other: 0
+// CHECK-NEXT:    Section: .text (0x1)
+// CHECK-NEXT:  }
+// CHECK-NEXT:  Symbol {
+// CHECK-NEXT:    Name: sym11 (176)
+// CHECK-NEXT:    Value: 0x0
+// CHECK-NEXT:    Size: 0
+// CHECK-NEXT:    Binding: Global (0x1)
+// CHECK-NEXT:    Type: TLS (0x6)
+// CHECK-NEXT:    Other: 0
+// CHECK-NEXT:    Section: .text (0x1)
+// CHECK-NEXT:  }
+// CHECK-NEXT:  Symbol {
+// CHECK-NEXT:    Name: sym12 (190)
+// CHECK-NEXT:    Value: 0x0
+// CHECK-NEXT:    Size: 0
+// CHECK-NEXT:    Binding: Global (0x1)
+// CHECK-NEXT:    Type: TLS (0x6)
+// CHECK-NEXT:    Other: 0
+// CHECK-NEXT:    Section: .text (0x1)
+// CHECK-NEXT:  }
+// CHECK-NEXT:  Symbol {
+// CHECK-NEXT:    Name: sym2 (66)
+// CHECK-NEXT:    Value: 0x0
+// CHECK-NEXT:    Size: 0
+// CHECK-NEXT:    Binding: Global (0x1)
+// CHECK-NEXT:    Type: GNU_IFunc (0xA)
+// CHECK-NEXT:    Other: 0
+// CHECK-NEXT:    Section: .text (0x1)
+// CHECK-NEXT:  }
+// CHECK-NEXT:  Symbol {
+// CHECK-NEXT:    Name: sym3 (78)
+// CHECK-NEXT:    Value: 0x0
+// CHECK-NEXT:    Size: 0
+// CHECK-NEXT:    Binding: Global (0x1)
+// CHECK-NEXT:    Type: GNU_IFunc (0xA)
+// CHECK-NEXT:    Other: 0
+// CHECK-NEXT:    Section: .text (0x1)
+// CHECK-NEXT:  }
+// CHECK-NEXT:  Symbol {
+// CHECK-NEXT:    Name: sym4 (90)
+// CHECK-NEXT:    Value: 0x0
+// CHECK-NEXT:    Size: 0
+// CHECK-NEXT:    Binding: Global (0x1)
+// CHECK-NEXT:    Type: Function (0x2)
+// CHECK-NEXT:    Other: 0
+// CHECK-NEXT:    Section: .text (0x1)
+// CHECK-NEXT:  }
+// CHECK-NEXT:  Symbol {
+// CHECK-NEXT:    Name: sym5 (102)
+// CHECK-NEXT:    Value: 0x0
+// CHECK-NEXT:    Size: 0
+// CHECK-NEXT:    Binding: Global (0x1)
+// CHECK-NEXT:    Type: Function (0x2)
+// CHECK-NEXT:    Other: 0
+// CHECK-NEXT:    Section: .text (0x1)
+// CHECK-NEXT:  }
+// CHECK-NEXT:  Symbol {
+// CHECK-NEXT:    Name: sym6 (114)
+// CHECK-NEXT:    Value: 0x0
+// CHECK-NEXT:    Size: 0
+// CHECK-NEXT:    Binding: Global (0x1)
+// CHECK-NEXT:    Type: Object (0x1)
+// CHECK-NEXT:    Other: 0
+// CHECK-NEXT:    Section: .text (0x1)
+// CHECK-NEXT:  }
+// CHECK-NEXT:  Symbol {
+// CHECK-NEXT:    Name: sym7 (126)
+// CHECK-NEXT:    Value: 0x0
+// CHECK-NEXT:    Size: 0
+// CHECK-NEXT:    Binding: Global (0x1)
+// CHECK-NEXT:    Type: GNU_IFunc (0xA)
+// CHECK-NEXT:    Other: 0
+// CHECK-NEXT:    Section: .text (0x1)
+// CHECK-NEXT:  }
+// CHECK-NEXT:  Symbol {
+// CHECK-NEXT:    Name: sym8 (138)
+// CHECK-NEXT:    Value: 0x0
+// CHECK-NEXT:    Size: 0
+// CHECK-NEXT:    Binding: Global (0x1)
+// CHECK-NEXT:    Type: Function (0x2)
+// CHECK-NEXT:    Other: 0
+// CHECK-NEXT:    Section: .text (0x1)
+// CHECK-NEXT:  }
+// CHECK-NEXT:  Symbol {
+// CHECK-NEXT:    Name: sym9 (150)
+// CHECK-NEXT:    Value: 0x0
+// CHECK-NEXT:    Size: 0
+// CHECK-NEXT:    Binding: Global (0x1)
+// CHECK-NEXT:    Type: TLS (0x6)
+// CHECK-NEXT:    Other: 0
+// CHECK-NEXT:    Section: .text (0x1)
+// CHECK-NEXT:  }
 // CHECK-NEXT:   Symbol {
 // CHECK-NEXT:     Name: tls
 // CHECK-NEXT:     Value: 0x0