[MC] Set defaults based on section names and support name suffixes

[phosek]

Summary

Set correct default flags and section type based on its name for .text, .data, .bss, .init_array, .fini_array, .preinit_array, .tdata, and .tbss and support section name suffixes for .data.*, .rodata.*, .text.*, .bss.*, .tdata.* and .tbss.* which matches the behavior of GAS.

This addresses PR31888.

[mcgrathr]

Isn't PROGBITS the default type anyway?

The GNU behavior is not startswith(".text"); it's == ".text" || startswith(".text."). Exactly analogous to the .bss cases I reported earlier.

[phosek]

In D30229#682890, @mcgrathr wrote:

Isn't PROGBITS the default type anyway?

The GNU behavior is not startswith(".text"); it's == ".text" || startswith(".text."). Exactly analogous to the .bss cases I reported earlier.

The .text case is handled by a directive handler (line 57) which only supports the exact match which is why this is being handled separately.

[mcgrathr]

The point is you are matching ".textfoo" whereas GNU only matches ".text.foo". And I was talking about ".section .text", not ".text".,

[phosek]

In D30229#682913, @mcgrathr wrote:

The point is you are matching ".textfoo" whereas GNU only matches ".text.foo". And I was talking about ".section .text", not ".text".,

Got it! I'll expand the implementation to match the GAS behavior for other sections and expand the test.

[mcgrathr]

It looks right to me. It would be more in keeping with the existing code to merge into each existing if rather than adding another whose then statement is identical, but that's a trivial thing.

[phosek]

Updated to use the new hasPrefix function. I'm fine using the existing code, my only concern are the duplicated checks for each if then condition, is that fine with you?

llvm/trunk/lib/MC/MCParser/ELFAsmParser.cpp

bool ELFAsmParser::ParseSectionArguments(bool IsPush, SMLoc loc) {
   unsigned Flags = 0;
   const MCExpr *Subsection = nullptr;
   bool UseLastGroup = false;
   StringRef UniqueStr;
   MCSymbolELF *Associated = nullptr;
   int64_t UniqueID = ~0;
 
   // Set the defaults first.
-  if (SectionName == ".fini" || SectionName == ".init" ||
-      SectionName == ".rodata")
+  if (hasPrefix(SectionName, ".rodata.") || SectionName == ".rodata1")
     Flags |= ELF::SHF_ALLOC;
-  if (SectionName == ".fini" || SectionName == ".init")
-    Flags |= ELF::SHF_EXECINSTR;
+  if (SectionName == ".fini" || SectionName == ".init" ||
+      hasPrefix(SectionName, ".text."))
+    Flags |= ELF::SHF_ALLOC | ELF::SHF_EXECINSTR;
+  if (hasPrefix(SectionName, ".data.") || SectionName == ".data1" ||
+      hasPrefix(SectionName, ".bss.") ||
+      hasPrefix(SectionName, ".init_array.") ||
+      hasPrefix(SectionName, ".fini_array.") ||
+      hasPrefix(SectionName, ".preinit_array."))
+    Flags |= ELF::SHF_ALLOC | ELF::SHF_WRITE;
+  if (hasPrefix(SectionName, ".tdata.") ||
+      hasPrefix(SectionName, ".tbss."))
+    Flags |= ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_TLS;
 
   if (getLexer().is(AsmToken::Comma)) {
     Lex();
 
     if (IsPush && getLexer().isNot(AsmToken::String)) {
       if (getParser().parseExpression(Subsection))
         return true;
       if (getLexer().isNot(AsmToken::Comma))
if (TypeName.empty()) {
     if (SectionName.startswith(".note"))
       Type = ELF::SHT_NOTE;
     else if (hasPrefix(SectionName, ".init_array."))
       Type = ELF::SHT_INIT_ARRAY;
     else if (hasPrefix(SectionName, ".bss."))
       Type = ELF::SHT_NOBITS;
     else if (hasPrefix(SectionName, ".tbss."))
       Type = ELF::SHT_NOBITS;
-    else if (SectionName == ".fini_array")
+    else if (hasPrefix(SectionName, ".fini_array."))
       Type = ELF::SHT_FINI_ARRAY;
-    else if (SectionName == ".preinit_array")
+    else if (hasPrefix(SectionName, ".preinit_array."))
       Type = ELF::SHT_PREINIT_ARRAY;
   } else {
     if (TypeName == "init_array")
       Type = ELF::SHT_INIT_ARRAY;
     else if (TypeName == "fini_array")
       Type = ELF::SHT_FINI_ARRAY;
     else if (TypeName == "preinit_array")
       Type = ELF::SHT_PREINIT_ARRAY;

llvm/trunk/test/MC/ELF/section.s

 // CHECK-NEXT:     SHF_ALLOC
 // CHECK-NEXT:     SHF_LINK_ORDER
 // CHECK-NEXT:   ]
 // CHECK-NEXT:   Address:
 // CHECK-NEXT:   Offset:
 // CHECK-NEXT:   Size:
 // CHECK-NEXT:   Link:    22
 // CHECK-NEXT:   Info:    0
+
+.section  .text.foo
+// CHECK:        Section {
+// CHECK:          Name: .text.foo
+// CHECK-NEXT:     Type: SHT_PROGBITS
+// CHECK-NEXT:     Flags [
+// CHECK-NEXT:       SHF_ALLOC
+// CHECK-NEXT:       SHF_EXECINSTR
+// CHECK-NEXT:     ]
+
+.section .bss
+// CHECK:        Section {
+// CHECK:          Name: .bss
+// CHECK-NEXT:     Type: SHT_NOBITS
+// CHECK-NEXT:     Flags [
+// CHECK-NEXT:       SHF_ALLOC
+// CHECK-NEXT:       SHF_WRITE
+// CHECK-NEXT:     ]
+
+.section .bss.foo
+// CHECK:        Section {
+// CHECK:          Name: .bss.foo
+// CHECK-NEXT:     Type: SHT_NOBITS
+// CHECK-NEXT:     Flags [
+// CHECK-NEXT:       SHF_ALLOC
+// CHECK-NEXT:       SHF_WRITE
+// CHECK-NEXT:     ]
+
+.section .tbss
+// CHECK:        Section {
+// CHECK:          Name: .tbss
+// CHECK-NEXT:     Type: SHT_NOBITS
+// CHECK-NEXT:     Flags [
+// CHECK-NEXT:       SHF_ALLOC
+// CHECK-NEXT:       SHF_TLS
+// CHECK-NEXT:       SHF_WRITE
+// CHECK-NEXT:     ]
+
+.section .tbss.foo
+// CHECK:        Section {
+// CHECK:          Name: .tbss.foo
+// CHECK-NEXT:     Type: SHT_NOBITS
+// CHECK-NEXT:     Flags [
+// CHECK-NEXT:       SHF_ALLOC
+// CHECK-NEXT:       SHF_TLS
+// CHECK-NEXT:       SHF_WRITE
+// CHECK-NEXT:     ]