Debug info: Get rid of the VLA indirection hack in FastISel.

Use the DIVariable::isIndirect() flag set by the frontend instead of
guessing whether to set the machine location's indirection bit.
Paired commit with CFE.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190961 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MachineLocation.h

@@ -44,7 +44,8 @@ class MachineLocation {
         Offset == Other.Offset;
   }
 
-  // Accessors
+  // Accessors.
+  /// \return true iff this is a register-indirect location.
   bool isIndirect()      const { return !IsRegister; }
   bool isReg()           const { return IsRegister; }
   unsigned getReg()      const { return Register; }

lib/CodeGen/SelectionDAG/FastISel.cpp

@@ -638,29 +638,24 @@ bool FastISel::SelectCall(const User *I) {
         (!isa<AllocaInst>(Address) ||
          !FuncInfo.StaticAllocaMap.count(cast<AllocaInst>(Address))))
       Op = MachineOperand::CreateReg(FuncInfo.InitializeRegForValue(Address),
-                                      false);
+                                     false);
 
-    if (Op)
+    if (Op) {
       if (Op->isReg()) {
-        // Set the indirect flag if the type and the DIVariable's
-        // indirect field are in disagreement: Indirectly-addressed
-        // variables that are nonpointer types should be marked as
-        // indirect, and VLAs should be marked as indirect eventhough
-        // they are a pointer type.
-        bool IsIndirect = DI->getAddress()->getType()->isPointerTy()
-          ^ DIVar.isIndirect();
         Op->setIsDebug(true);
         BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
                 TII.get(TargetOpcode::DBG_VALUE),
-                IsIndirect, Op->getReg(), Offset, DI->getVariable());
-      } else
-        BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
-                TII.get(TargetOpcode::DBG_VALUE)).addOperand(*Op).addImm(0)
-          .addMetadata(DI->getVariable());
-    else
+                false, Op->getReg(), 0, DI->getVariable());
+    } else
+      BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
+              TII.get(TargetOpcode::DBG_VALUE))
+        .addOperand(*Op).addImm(0)
+        .addMetadata(DI->getVariable());
+    } else {
       // We can't yet handle anything else here because it would require
       // generating code, thus altering codegen because of debug info.
       DEBUG(dbgs() << "Dropping debug info for " << *DI << "\n");
+    }
     return true;
   }
   case Intrinsic::dbg_value: {

test/DebugInfo/X86/op_deref.ll

@@ -10,7 +10,8 @@
 ; right now, so we check the asm output:
 ; RUN: llc -O0 -mtriple=x86_64-apple-darwin %s -o - -filetype=asm | FileCheck %s -check-prefix=ASM-CHECK
 ; vla should have a register-indirect address at one point.
-; ASM-CHECK: DEBUG_VALUE: vla <- [RCX+0]
+; ASM-CHECK: DEBUG_VALUE: vla <- RCX
+; ASM-CHECK: DW_OP_breg2
 
 define void @testVLAwithSize(i32 %s) nounwind uwtable ssp {
 entry:
@@ -77,7 +78,7 @@ declare void @llvm.stackrestore(i8*) nounwind
 !11 = metadata !{i32 1, i32 26, metadata !5, null}
 !12 = metadata !{i32 3, i32 13, metadata !13, null}
 !13 = metadata !{i32 786443, metadata !28, metadata !5, i32 2, i32 1, i32 0} ; [ DW_TAG_lexical_block ]
-!14 = metadata !{i32 786688, metadata !13, metadata !"vla", metadata !6, i32 3, metadata !15, i32 0, i32 0, i64 2} ; [ DW_TAG_auto_variable ]
+!14 = metadata !{i32 786688, metadata !13, metadata !"vla", metadata !6, i32 3, metadata !15, i32 8192, i32 0, i64 2} ; [ DW_TAG_auto_variable ]
 !15 = metadata !{i32 786433, null, null, metadata !"", i32 0, i64 0, i64 32, i32 0, i32 0, metadata !9, metadata !16, i32 0, null, null, null} ; [ DW_TAG_array_type ] [line 0, size 0, align 32, offset 0] [from int]
 !16 = metadata !{metadata !17}
 !17 = metadata !{i32 786465, i64 0, i64 -1}        ; [ DW_TAG_subrange_type ]

test/DebugInfo/X86/vla.ll

@@ -1,6 +1,7 @@
 ; RUN: llc -O0 -mtriple=x86_64-apple-darwin -filetype=asm %s -o - | FileCheck %s
-; Ensure that we generate a breg+0 location for the variable length array a.
-; CHECK: ##DEBUG_VALUE: vla:a <- [RDX+0]
+; Ensure that we generate an indirect location for the variable length array a.
+; CHECK: ##DEBUG_VALUE: vla:a <- RDX
+; CHECK: DW_OP_breg1
 ; rdar://problem/13658587
 ;
 ; generated from:
@@ -91,7 +92,7 @@ entry:
 !15 = metadata !{i32 786689, metadata !4, metadata !"n", metadata !5, i32 16777217, metadata !8, i32 0, i32 0} ; [ DW_TAG_arg_variable ] [n] [line 1]
 !16 = metadata !{i32 1, i32 0, metadata !4, null}
 !17 = metadata !{i32 2, i32 0, metadata !4, null}
-!18 = metadata !{i32 786688, metadata !4, metadata !"a", metadata !5, i32 2, metadata !19, i32 0, i32 0} ; [ DW_TAG_auto_variable ] [a] [line 2]
+!18 = metadata !{i32 786688, metadata !4, metadata !"a", metadata !5, i32 2, metadata !19, i32 8192, i32 0} ; [ DW_TAG_auto_variable ] [a] [line 2]
 !19 = metadata !{i32 786433, null, null, metadata !"", i32 0, i64 0, i64 32, i32 0, i32 0, metadata !8, metadata !20, i32 0, null, null, null} ; [ DW_TAG_array_type ] [line 0, size 0, align 32, offset 0] [from int]
 !20 = metadata !{metadata !21}
 !21 = metadata !{i32 786465, i64 0, i64 -1}       ; [ DW_TAG_subrange_type ] [unbounded]