[DebugInfo] In FastISel, convert llvm.dbg.label to DBG_LABEL MI.

[HsiangKai]

Summary

Convert llvm.dbg.label(!label_metadata) to DBG_LABEL !label_metadata.

lib/CodeGen/SelectionDAG/FastISel.cpp

if (!V) {
               DI->getVariable(), DI->getExpression());
     } else {
       // We can't yet handle anything else here because it would require
       // generating code, thus altering codegen because of debug info.
       LLVM_DEBUG(dbgs() << "Dropping debug info for " << *DI << "\n");
     }
     return true;
   }
+  case Intrinsic::dbg_label: {
+    const DbgLabelInst *DI = cast<DbgLabelInst>(II);
+    assert(DI->getLabel() && "Missing label");
+    if (!FuncInfo.MF->getMMI().hasDebugInfo()) {
+      LLVM_DEBUG(dbgs() << "Dropping debug info for " << *DI << "\n");
+      return true;
+    }
+
+    BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc,
+      TII.get(TargetOpcode::DBG_LABEL))
+  .addMetadata(DI->getLabel());
+    return true;
+  }
   case Intrinsic::objectsize: {
     ConstantInt *CI = cast<ConstantInt>(II->getArgOperand(1));
     unsigned long long Res = CI->isZero() ? -1ULL : 0;
     Constant *ResCI = ConstantInt::get(II->getType(), Res);
     unsigned ResultReg = getRegForValue(ResCI);
     if (!ResultReg)
       return false;
     updateValueMap(II, ResultReg);

test/DebugInfo/Generic/debug-label-mi.ll

 ; Test DBG_LABEL MachineInstr for label debugging.
 ; REQUIRES: asserts
-; RUN: llc -fast-isel=false -debug-only=isel %s -o /dev/null 2> %t.debug
+; RUN: llc -debug-only=isel %s -o /dev/null 2> %t.debug
 ; RUN: cat %t.debug | FileCheck %s --check-prefix=CHECKMI
 ;
 ; CHECKMI: DBG_LABEL "top", debug-location !9
 ; CHECKMI: DBG_LABEL "done", debug-location !11
 ;
-; RUN: llc -fast-isel=false %s -o - | FileCheck %s --check-prefix=CHECKASM
+; RUN: llc %s -o - | FileCheck %s --check-prefix=CHECKASM
 ;
 ; CHECKASM: DEBUG_LABEL: foo:top
 ; CHECKASM: DEBUG_LABEL: foo:done
 
 source_filename = "debug-label-mi.c"
 
 ; Function Attrs: noinline nounwind optnone
 define i32 @foo(i32 signext %a, i32 signext %b) #0 !dbg !4 {

test/DebugInfo/Generic/debug-label-opt.ll

 ; Test DBG_LABEL MachineInstr under optimization.
 ; The test case is generated by clang with -O2 is on.
 ; REQUIRES: asserts
-; RUN: llc -fast-isel=false -debug-only=isel %s -o /dev/null 2> %t.debug
+; RUN: llc -debug-only=isel %s -o /dev/null 2> %t.debug
 ; RUN: cat %t.debug | FileCheck %s --check-prefix=CHECKMI
 ;
 ; CHECKMI: DBG_LABEL "end_sum", debug-location !17
 ; CHECKMI: DBG_LABEL "end", debug-location !19
 source_filename = "debug-label-opt.c"
 
 define i32 @foo(i32* nocapture readonly %a, i32 %n) local_unnamed_addr !dbg !7 {
 entry:

test/DebugInfo/Generic/debug-label.ll

-; RUN: llc -fast-isel=false -O0 -filetype=obj -o - %s | llvm-dwarfdump -v - | FileCheck %s
+; RUN: llc -O0 -filetype=obj -o - %s | llvm-dwarfdump -v - | FileCheck %s
 ;
 ; CHECK: .debug_info contents:
 ; CHECK: DW_TAG_label
 ; CHECK-NEXT: DW_AT_name [DW_FORM_strp] {{.*}}"top"
 ; CHECK-NEXT: DW_AT_decl_file [DW_FORM_data1] {{.*}}debug-label.c
 ; CHECK-NEXT: DW_AT_decl_line [DW_FORM_data1] {{.*}}4
 ; CHECK-NEXT: DW_AT_low_pc [DW_FORM_addr] {{.*}}{{0x[0-9a-f]+}}
 ; CHECK: DW_TAG_label
 ; CHECK-NEXT: DW_AT_name [DW_FORM_strp] {{.*}}"done"
 ; CHECK-NEXT: DW_AT_decl_file [DW_FORM_data1] {{.*}}debug-label.c
 ; CHECK-NEXT: DW_AT_decl_line [DW_FORM_data1] {{.*}}7
 ; CHECK-NEXT: DW_AT_low_pc [DW_FORM_addr] {{.*}}{{0x[0-9a-f]+}}
 ; CHECK-NOT: DW_AT_name [DW_FORM_strp] {{.*}}"top"
 ;
-; RUN: llc -fast-isel=false -O0 -o - %s | FileCheck %s -check-prefix=ASM
+; RUN: llc -O0 -o - %s | FileCheck %s -check-prefix=ASM
 ;
 ; ASM: [[TOP_LOW_PC:[.0-9a-zA-Z]+]]:{{[[:space:]].*}}DEBUG_LABEL: foo:top
 ; ASM: [[DONE_LOW_PC:[.0-9a-zA-Z]+]]:{{[[:space:]].*}}DEBUG_LABEL: foo:done
 ; ASM-LABEL: .debug_str
 ; ASM: [[TOP_LABEL:[.0-9a-zA-Z]+]]:{{[[:space:]].*}}"top"
 ; ASM: [[DONE_LABEL:[.0-9a-zA-Z]+]]:{{[[:space:]].*}}"done"
 ; ASM-LABEL: .debug_info
 ; ASM: DW_TAG_label