[IR] Remove the DIExpression field from DIGlobalVariable.

This patch implements PR31013 by introducing a
DIGlobalVariableExpression that holds a pair of DIGlobalVariable and
DIExpression.

Currently, DIGlobalVariables holds a DIExpression. This is not the
best way to model this:

(1) The DIGlobalVariable should describe the source level variable,
    not how to get to its location.

(2) It makes it unsafe/hard to update the expressions when we call
    replaceExpression on the DIGLobalVariable.

(3) It makes it impossible to represent a global variable that is in
    more than one location (e.g., a variable with multiple
    DW_OP_LLVM_fragment-s).  We also moved away from attaching the
    DIExpression to DILocalVariable for the same reasons.

<rdar://problem/29250149>
https://llvm.org/bugs/show_bug.cgi?id=31013
Differential Revision: https://reviews.llvm.org/D26769

llvm-svn: 289902

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/test/DebugInfo/COFF/virtual-method-kinds.ll b/llvm/test/DebugInfo/COFF/virtual-method-kinds.ll
index 12958bb5089..e91c6405da1 100644
--- a/llvm/test/DebugInfo/COFF/virtual-method-kinds.ll
+++ b/llvm/test/DebugInfo/COFF/virtual-method-kinds.ll
@@ -237,7 +237,7 @@ attributes #6 = { nounwind }
 !1 = !DIFile(filename: "t.cpp", directory: "D:\5Csrc\5Cllvm\5Cbuild")
 !2 = !{}
 !3 = !{!4}
-!4 = distinct !DIGlobalVariable(name: "p", linkageName: "\01?p@@3PEAUC@@EA", scope: !0, file: !1, line: 13, type: !5, isLocal: false, isDefinition: true)
+!4 = distinct !DIGlobalVariableExpression(var: !DIGlobalVariable(name: "p", linkageName: "\01?p@@3PEAUC@@EA", scope: !0, file: !1, line: 13, type: !5, isLocal: false, isDefinition: true))
 !5 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !6, size: 64, align: 64)
 !6 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "C", file: !1, line: 9, size: 64, align: 64, elements: !7, vtableHolder: !12, identifier: ".?AUC@@")
 !7 = !{!8, !30, !34}