[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, 2 insertions, 2 deletions

diff --git a/llvm/test/Transforms/Inline/alloca-dbgdeclare.ll b/llvm/test/Transforms/Inline/alloca-dbgdeclare.ll
index 78b888fd652..aeb7e055e99 100644
--- a/llvm/test/Transforms/Inline/alloca-dbgdeclare.ll
+++ b/llvm/test/Transforms/Inline/alloca-dbgdeclare.ll
@@ -107,8 +107,8 @@ attributes #3 = { noreturn nounwind }
 !23 = !{null}
 !24 = distinct !DISubprogram(name: "fn5", linkageName: "_Z3fn5v", line: 13, isLocal: false, isDefinition: true, flags: DIFlagPrototyped, isOptimized: true, unit: !0, scopeLine: 13, file: !5, scope: !16, type: !22, variables: !2)
 !25 = !{!26, !27}
-!26 = !DIGlobalVariable(name: "a", line: 4, isLocal: false, isDefinition: true, scope: null, file: !16, type: !4)
-!27 = !DIGlobalVariable(name: "b", line: 4, isLocal: false, isDefinition: true, scope: null, file: !16, type: !4)
+!26 = !DIGlobalVariableExpression(var: !DIGlobalVariable(name: "a", line: 4, isLocal: false, isDefinition: true, scope: null, file: !16, type: !4))
+!27 = !DIGlobalVariableExpression(var: !DIGlobalVariable(name: "b", line: 4, isLocal: false, isDefinition: true, scope: null, file: !16, type: !4))
 !28 = !{i32 2, !"Dwarf Version", i32 4}
 !29 = !{i32 2, !"Debug Info Version", i32 3}
 !30 = !{!"clang version 3.7.0 (trunk 227480) (llvm/trunk 227517)"}