[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.

This reapplies r289902 with additional testcase upgrades.

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

llvm-svn: 289920

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/test/Transforms/StripSymbols/2010-08-25-crash.ll b/llvm/test/Transforms/StripSymbols/2010-08-25-crash.ll
index 4e454ba2c8b..69e4f261633 100644
--- a/llvm/test/Transforms/StripSymbols/2010-08-25-crash.ll
+++ b/llvm/test/Transforms/StripSymbols/2010-08-25-crash.ll
@@ -13,7 +13,7 @@ entry:
 !3 = !DISubroutineType(types: !4)
 !4 = !{!5}
 !5 = !DIBasicType(tag: DW_TAG_base_type, name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
-!6 = !DIGlobalVariable(name: "i", linkageName: "i", line: 2, isLocal: true, isDefinition: true, scope: !1, file: !1, type: !7)
+!6 = !DIGlobalVariableExpression(var: !DIGlobalVariable(name: "i", linkageName: "i", line: 2, isLocal: true, isDefinition: true, scope: !1, file: !1, type: !7))
 !7 = !DIDerivedType(tag: DW_TAG_const_type, file: !10, scope: !1, baseType: !5)
 !8 = !DILocation(line: 3, column: 13, scope: !9)
 !9 = distinct !DILexicalBlock(line: 3, column: 11, file: !10, scope: !0)