[mips] Handle MipsMCExpr sub-expression for the MEK_DTPREL tag

This is a fix for a regression introduced by the rL348194 commit. In
that change new type (MEK_DTPREL) of MipsMCExpr expression was added,
but in some places of the code this type of expression considered as
unexpected.

This change fixes the bug. The MEK_DTPREL type of expression is used for
marking TLS DIEExpr only and contains a regular sub-expression. Where we
need to handle the expression, we retrieve the sub-expression and
handle it in a common way.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@351987 91177308-0d34-0410-b5e6-96231b3b80d8

Author: atanasyan

lib/Target/Mips/MCTargetDesc/MipsMCCodeEmitter.cpp

@@ -613,8 +613,9 @@ getExprOpValue(const MCExpr *Expr, SmallVectorImpl<MCFixup> &Fixups,
       llvm_unreachable("Unhandled fixup kind!");
       break;
     case MipsMCExpr::MEK_DTPREL:
-      llvm_unreachable("MEK_DTPREL is used for TLS DIEExpr only");
-      break;
+      // MEK_DTPREL is used for marking TLS DIEExpr only
+      // and contains a regular sub-expression.
+      return getExprOpValue(MipsExpr->getSubExpr(), Fixups, STI);
     case MipsMCExpr::MEK_CALL_HI16:
       FixupKind = Mips::fixup_Mips_CALL_HI16;
       break;

lib/Target/Mips/MCTargetDesc/MipsMCExpr.cpp

@@ -43,8 +43,10 @@ void MipsMCExpr::printImpl(raw_ostream &OS, const MCAsmInfo *MAI) const {
     llvm_unreachable("MEK_None and MEK_Special are invalid");
     break;
   case MEK_DTPREL:
-    llvm_unreachable("MEK_DTPREL is used for TLS DIEExpr only");
-    break;
+    // MEK_DTPREL is used for marking TLS DIEExpr only
+    // and contains a regular sub-expression.
+    getSubExpr()->print(OS, MAI, true);
+    return;
   case MEK_CALL_HI16:
     OS << "%call_hi";
     break;
@@ -160,7 +162,9 @@ MipsMCExpr::evaluateAsRelocatableImpl(MCValue &Res,
     case MEK_Special:
       llvm_unreachable("MEK_None and MEK_Special are invalid");
     case MEK_DTPREL:
-      llvm_unreachable("MEK_DTPREL is used for TLS DIEExpr only");
+      // MEK_DTPREL is used for marking TLS DIEExpr only
+      // and contains a regular sub-expression.
+      return getSubExpr()->evaluateAsRelocatable(Res, Layout, Fixup);
     case MEK_DTPREL_HI:
     case MEK_DTPREL_LO:
     case MEK_GOT:
@@ -248,9 +252,6 @@ void MipsMCExpr::fixELFSymbolsInTLSFixups(MCAssembler &Asm) const {
   case MEK_Special:
     llvm_unreachable("MEK_None and MEK_Special are invalid");
     break;
-  case MEK_DTPREL:
-    llvm_unreachable("MEK_DTPREL is used for TLS DIEExpr only");
-    break;
   case MEK_CALL_HI16:
   case MEK_CALL_LO16:
   case MEK_GOT:
@@ -273,6 +274,7 @@ void MipsMCExpr::fixELFSymbolsInTLSFixups(MCAssembler &Asm) const {
     if (const MipsMCExpr *E = dyn_cast<const MipsMCExpr>(getSubExpr()))
       E->fixELFSymbolsInTLSFixups(Asm);
     break;
+  case MEK_DTPREL:
   case MEK_DTPREL_HI:
   case MEK_DTPREL_LO:
   case MEK_TLSLDM:

test/DebugInfo/Mips/dwarfdump-tls.ll

@@ -1,12 +1,34 @@
-; RUN: llc -O0 -march=mips -mcpu=mips32r2 -filetype=obj -o=%t-32.o < %s
+; RUN: llc -O0 -march=mips -mcpu=mips32r2 -filetype=obj \
+; RUN:     -split-dwarf-file=foo.dwo -o=%t-32.o < %s
 ; RUN: llvm-dwarfdump %t-32.o 2>&1 | FileCheck %s
-; RUN: llc -O0 -march=mips64 -mcpu=mips64r2 -filetype=obj -o=%t-64.o < %s
+; RUN: llc -O0 -march=mips64 -mcpu=mips64r2 -filetype=obj \
+; RUN:     -split-dwarf-file=foo.dwo -o=%t-64.o < %s
 ; RUN: llvm-dwarfdump %t-64.o 2>&1 | FileCheck %s
 
+; RUN: llc -O0 -march=mips -mcpu=mips32r2 -filetype=asm \
+; RUN:     -split-dwarf-file=foo.dwo < %s | FileCheck -check-prefix=ASM32 %s
+; RUN: llc -O0 -march=mips64 -mcpu=mips64r2 -filetype=asm \
+; RUN:     -split-dwarf-file=foo.dwo < %s | FileCheck -check-prefix=ASM64 %s
+
 @x = thread_local global i32 5, align 4, !dbg !0
 
 ; CHECK-NOT: error: failed to compute relocation: R_MIPS_TLS_DTPREL
 
+; CHECK:      DW_AT_name      ("x")
+; CHECK-NEXT: DW_AT_type      (0x00000025 "int")
+; CHECK-NEXT: DW_AT_external  (true)
+; CHECK-NEXT: DW_AT_decl_file (0x01)
+; CHECK-NEXT: DW_AT_decl_line (1)
+; CHECK-NEXT: DW_AT_location  (DW_OP_GNU_const_index 0x0, DW_OP_GNU_push_tls_address)
+
+; ASM32:              .section        .debug_addr
+; ASM32-NEXT: $addr_table_base0:
+; ASM32-NEXT:         .4byte  x+32768
+
+; ASM64:              .section        .debug_addr
+; ASM64-NEXT: .Laddr_table_base0:
+; ASM64-NEXT:         .8byte  x+32768
+
 !llvm.dbg.cu = !{!2}
 !llvm.module.flags = !{!7, !8}