Add an entry for rodata constant merge sections to the default

section flags in the ELF assembler. This matches the defaults
given in the rest of MC.

Fixes PR37997 where we couldn't assemble our own assembly output
without warnings.

llvm-svn: 336072

llvm/lib/MC/MCParser/ELFAsmParser.cpp

@@ -486,6 +486,9 @@ static bool hasPrefix(StringRef SectionName, StringRef Prefix) {
 // defaults.
 static unsigned defaultSectionFlags(StringRef SectionName) {
 
+  if (hasPrefix(SectionName, ".rodata.cst"))
+    return ELF::SHF_ALLOC | ELF::SHF_MERGE;
+
   if (hasPrefix(SectionName, ".rodata.") || SectionName == ".rodata1")
     return ELF::SHF_ALLOC;
 

llvm/test/MC/ELF/extra-section-flags.s

@@ -1,10 +1,12 @@
 # RUN: llvm-mc -triple x86_64-unknown-unknown -filetype=obj %s -o /dev/null 2>&1 | FileCheck %s
-	
+
 .section .rodata, "ax"
 # CHECK: warning: setting incorrect section attributes for .rodata
 nop
 
 .section .rodata, "a"
-# CHECK-NOT: warning:
 nop
+.section .rodata.cst4, "aM",@progbits,8
+nop
+# CHECK-NOT: warning: