[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 and a change
to the Bitcode record for DIGlobalVariable, that makes upgrading the
old format unambiguous also for variables without DIExpressions.

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

llvm-svn: 290153

1 files changed, 49 insertions, 32 deletions

diff --git a/llvm/unittests/IR/MetadataTest.cpp b/llvm/unittests/IR/MetadataTest.cpp
index ab6785c23d8..4ee931d4109 100644
--- a/llvm/unittests/IR/MetadataTest.cpp
+++ b/llvm/unittests/IR/MetadataTest.cpp
@@ -1828,16 +1828,13 @@ TEST_F(DIGlobalVariableTest, get) {
   DIType *Type = getDerivedType();
   bool IsLocalToUnit = false;
   bool IsDefinition = true;
-  auto *Expr = DIExpression::get(Context, {1, 2});
-  auto *Expr2 = DIExpression::get(Context, {1, 2, 3});
   DIDerivedType *StaticDataMemberDeclaration =
       cast<DIDerivedType>(getDerivedType());
   uint32_t AlignInBits = 8;
 
   auto *N = DIGlobalVariable::get(Context, Scope, Name, LinkageName, File, Line,
                                   Type, IsLocalToUnit, IsDefinition,
-                                  Expr, StaticDataMemberDeclaration,
-                                  AlignInBits);
+                                  StaticDataMemberDeclaration, AlignInBits);
   EXPECT_EQ(dwarf::DW_TAG_variable, N->getTag());
   EXPECT_EQ(Scope, N->getScope());
   EXPECT_EQ(Name, N->getName());
@@ -1847,68 +1844,88 @@ TEST_F(DIGlobalVariableTest, get) {
   EXPECT_EQ(Type, N->getType());
   EXPECT_EQ(IsLocalToUnit, N->isLocalToUnit());
   EXPECT_EQ(IsDefinition, N->isDefinition());
-  EXPECT_EQ(Expr, N->getExpr());
   EXPECT_EQ(StaticDataMemberDeclaration, N->getStaticDataMemberDeclaration());
   EXPECT_EQ(AlignInBits, N->getAlignInBits());
   EXPECT_EQ(N, DIGlobalVariable::get(Context, Scope, Name, LinkageName, File,
                                      Line, Type, IsLocalToUnit, IsDefinition,
-                                     Expr, StaticDataMemberDeclaration,
-                                     AlignInBits));
+                                     StaticDataMemberDeclaration, AlignInBits));
 
   EXPECT_NE(N,
             DIGlobalVariable::get(Context, getSubprogram(), Name, LinkageName,
                                   File, Line, Type, IsLocalToUnit, IsDefinition,
-                                  Expr, StaticDataMemberDeclaration,
-                                  AlignInBits));
+                                  StaticDataMemberDeclaration, AlignInBits));
   EXPECT_NE(N, DIGlobalVariable::get(Context, Scope, "other", LinkageName, File,
                                      Line, Type, IsLocalToUnit, IsDefinition,
-                                     Expr, StaticDataMemberDeclaration,
-                                     AlignInBits));
+                                     StaticDataMemberDeclaration, AlignInBits));
   EXPECT_NE(N, DIGlobalVariable::get(Context, Scope, Name, "other", File, Line,
-                                     Type, IsLocalToUnit, IsDefinition, Expr,
-                                     StaticDataMemberDeclaration,
-                                     AlignInBits));
+                                     Type, IsLocalToUnit, IsDefinition,
+                                     StaticDataMemberDeclaration, AlignInBits));
   EXPECT_NE(N,
             DIGlobalVariable::get(Context, Scope, Name, LinkageName, getFile(),
-                                  Line, Type, IsLocalToUnit, IsDefinition, Expr,
-                                  StaticDataMemberDeclaration,
-                                  AlignInBits));
+                                  Line, Type, IsLocalToUnit, IsDefinition,
+                                  StaticDataMemberDeclaration, AlignInBits));
   EXPECT_NE(N,
             DIGlobalVariable::get(Context, Scope, Name, LinkageName, File,
                                   Line + 1, Type, IsLocalToUnit, IsDefinition,
-                                  Expr, StaticDataMemberDeclaration,
-                                  AlignInBits));
+                                  StaticDataMemberDeclaration, AlignInBits));
   EXPECT_NE(N,
             DIGlobalVariable::get(Context, Scope, Name, LinkageName, File, Line,
                                   getDerivedType(), IsLocalToUnit, IsDefinition,
-                                  Expr, StaticDataMemberDeclaration,
-                                  AlignInBits));
+                                  StaticDataMemberDeclaration, AlignInBits));
   EXPECT_NE(N, DIGlobalVariable::get(Context, Scope, Name, LinkageName, File,
                                      Line, Type, !IsLocalToUnit, IsDefinition,
-                                     Expr, StaticDataMemberDeclaration,
-                                     AlignInBits));
+                                     StaticDataMemberDeclaration, AlignInBits));
   EXPECT_NE(N, DIGlobalVariable::get(Context, Scope, Name, LinkageName, File,
                                      Line, Type, IsLocalToUnit, !IsDefinition,
-                                     Expr, StaticDataMemberDeclaration,
-                                     AlignInBits));
+                                     StaticDataMemberDeclaration, AlignInBits));
   EXPECT_NE(N, DIGlobalVariable::get(Context, Scope, Name, LinkageName, File,
                                      Line, Type, IsLocalToUnit, IsDefinition,
-                                     Expr2, StaticDataMemberDeclaration,
+                                     cast<DIDerivedType>(getDerivedType()),
                                      AlignInBits));
-  EXPECT_NE(N,
-            DIGlobalVariable::get(Context, Scope, Name, LinkageName, File, Line,
-                                  Type, IsLocalToUnit, IsDefinition, Expr,
-                                  cast<DIDerivedType>(getDerivedType()),
-                                  AlignInBits));
   EXPECT_NE(N, DIGlobalVariable::get(Context, Scope, Name, LinkageName, File,
                                      Line, Type, IsLocalToUnit, IsDefinition,
-                                     Expr, StaticDataMemberDeclaration,
+                                     StaticDataMemberDeclaration,
                                      (AlignInBits << 1)));
 
   TempDIGlobalVariable Temp = N->clone();
   EXPECT_EQ(N, MDNode::replaceWithUniqued(std::move(Temp)));
 }
 
+typedef MetadataTest DIGlobalVariableExpressionTest;
+
+TEST_F(DIGlobalVariableExpressionTest, get) {
+  DIScope *Scope = getSubprogram();
+  StringRef Name = "name";
+  StringRef LinkageName = "linkage";
+  DIFile *File = getFile();
+  unsigned Line = 5;
+  DIType *Type = getDerivedType();
+  bool IsLocalToUnit = false;
+  bool IsDefinition = true;
+  auto *Expr = DIExpression::get(Context, {1, 2});
+  auto *Expr2 = DIExpression::get(Context, {1, 2, 3});
+  DIDerivedType *StaticDataMemberDeclaration =
+      cast<DIDerivedType>(getDerivedType());
+  uint32_t AlignInBits = 8;
+
+  auto *Var = DIGlobalVariable::get(Context, Scope, Name, LinkageName, File,
+                                    Line, Type, IsLocalToUnit, IsDefinition,
+                                    StaticDataMemberDeclaration, AlignInBits);
+  auto *Var2 = DIGlobalVariable::get(Context, Scope, "other", LinkageName, File,
+                                     Line, Type, IsLocalToUnit, IsDefinition,
+                                     StaticDataMemberDeclaration, AlignInBits);
+  auto *N = DIGlobalVariableExpression::get(Context, Var, Expr);
+
+  EXPECT_EQ(Var, N->getVariable());
+  EXPECT_EQ(Expr, N->getExpression());
+  EXPECT_EQ(N, DIGlobalVariableExpression::get(Context, Var, Expr));
+  EXPECT_NE(N, DIGlobalVariableExpression::get(Context, Var2, Expr));
+  EXPECT_NE(N, DIGlobalVariableExpression::get(Context, Var, Expr2));
+
+  TempDIGlobalVariableExpression Temp = N->clone();
+  EXPECT_EQ(N, MDNode::replaceWithUniqued(std::move(Temp)));
+}
+
 typedef MetadataTest DILocalVariableTest;
 
 TEST_F(DILocalVariableTest, get) {