[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, 19 insertions, 7 deletions

diff --git a/llvm/lib/IR/LLVMContextImpl.h b/llvm/lib/IR/LLVMContextImpl.h
index f1cc12a2902..55443c598f9 100644
--- a/llvm/lib/IR/LLVMContextImpl.h
+++ b/llvm/lib/IR/LLVMContextImpl.h
@@ -763,18 +763,16 @@ template <> struct MDNodeKeyImpl<DIGlobalVariable> {
   Metadata *Type;
   bool IsLocalToUnit;
   bool IsDefinition;
-  Metadata *Expr;
   Metadata *StaticDataMemberDeclaration;
   uint32_t AlignInBits;
 
   MDNodeKeyImpl(Metadata *Scope, MDString *Name, MDString *LinkageName,
                 Metadata *File, unsigned Line, Metadata *Type,
                 bool IsLocalToUnit, bool IsDefinition,
-                Metadata *Expr, Metadata *StaticDataMemberDeclaration,
-                uint32_t AlignInBits)
+                Metadata *StaticDataMemberDeclaration, uint32_t AlignInBits)
       : Scope(Scope), Name(Name), LinkageName(LinkageName), File(File),
         Line(Line), Type(Type), IsLocalToUnit(IsLocalToUnit),
-        IsDefinition(IsDefinition), Expr(Expr),
+        IsDefinition(IsDefinition),
         StaticDataMemberDeclaration(StaticDataMemberDeclaration),
         AlignInBits(AlignInBits) {}
   MDNodeKeyImpl(const DIGlobalVariable *N)
@@ -782,7 +780,6 @@ template <> struct MDNodeKeyImpl<DIGlobalVariable> {
         LinkageName(N->getRawLinkageName()), File(N->getRawFile()),
         Line(N->getLine()), Type(N->getRawType()),
         IsLocalToUnit(N->isLocalToUnit()), IsDefinition(N->isDefinition()),
-        Expr(N->getRawExpr()),
         StaticDataMemberDeclaration(N->getRawStaticDataMemberDeclaration()),
         AlignInBits(N->getAlignInBits()) {}
 
@@ -792,7 +789,6 @@ template <> struct MDNodeKeyImpl<DIGlobalVariable> {
            File == RHS->getRawFile() && Line == RHS->getLine() &&
            Type == RHS->getRawType() && IsLocalToUnit == RHS->isLocalToUnit() &&
            IsDefinition == RHS->isDefinition() &&
-           Expr == RHS->getRawExpr() &&
            StaticDataMemberDeclaration ==
                RHS->getRawStaticDataMemberDeclaration() &&
            AlignInBits == RHS->getAlignInBits();
@@ -806,7 +802,7 @@ template <> struct MDNodeKeyImpl<DIGlobalVariable> {
     // generated IR is random for each run and test fails with Align included.
     // TODO: make hashing work fine with such situations
     return hash_combine(Scope, Name, LinkageName, File, Line, Type,
-                        IsLocalToUnit, IsDefinition, /* AlignInBits, */ Expr,
+                        IsLocalToUnit, IsDefinition, /* AlignInBits, */
                         StaticDataMemberDeclaration);
   }
 };
@@ -863,6 +859,22 @@ template <> struct MDNodeKeyImpl<DIExpression> {
   }
 };
 
+template <> struct MDNodeKeyImpl<DIGlobalVariableExpression> {
+  Metadata *Variable;
+  Metadata *Expression;
+
+  MDNodeKeyImpl(Metadata *Variable, Metadata *Expression)
+      : Variable(Variable), Expression(Expression) {}
+  MDNodeKeyImpl(const DIGlobalVariableExpression *N)
+      : Variable(N->getRawVariable()), Expression(N->getRawExpression()) {}
+
+  bool isKeyOf(const DIGlobalVariableExpression *RHS) const {
+    return Variable == RHS->getRawVariable() &&
+           Expression == RHS->getRawExpression();
+  }
+  unsigned getHashValue() const { return hash_combine(Variable, Expression); }
+};
+
 template <> struct MDNodeKeyImpl<DIObjCProperty> {
   MDString *Name;
   Metadata *File;