[LLVM-C] Add Accessors For Global Variable Metadata Properties

[CodaFi]

Summary

Metadata for a global variable is really a (GlobalVariable, Expression) tuple. Allow access to these, then allow retrieving the file, scope, and line for a DIVariable, whether global or local. This should be the last of the accessors required for uniform access to location and file information metadata.

[CodaFi]

@jberdine This patch handles the global variable side of things. You should be able to replace those accessors in Core with a call to LLVMGlobalCopyAllMetadata. You can filter for !dbg and dig out the global variable expression. From there, you locate from global variable expression to global variable with LLVMDIGlobalVariableExpressionGetVariable and from global variable to line with LLVMDIVariableGetLine.

In general, it isn't safe to assume that the first metadata attachment you find on a global variable is !dbg, so the existing bindings in Core will fail to retrieve information in some odd cases.

[jberdine]

Thanks! These are working for me, though I needed to expose one more function, see D60795 (and feel free to incorporate it into this one).

One build-breaking typo noted inline.

llvm/lib/IR/DebugInfo.cpp

1257

s/getExpresssion/getExpression/

[CodaFi]

llvm/lib/IR/DebugInfo.cpp

1257

Ugh, this New MacBook keyboard of mine... Thanks.

[CodaFi]

@whitequark Could I get your stamp of approval as well?

[whitequark]

LGTM

llvm/include/llvm-c/DebugInfo.h

  * \param AlignInBits Variable alignment(or 0 if no alignment attr was
  *                    specified)
  */
 LLVMMetadataRef LLVMDIBuilderCreateGlobalVariableExpression(
     LLVMDIBuilderRef Builder, LLVMMetadataRef Scope, const char *Name,
     size_t NameLen, const char *Linkage, size_t LinkLen, LLVMMetadataRef File,
     unsigned LineNo, LLVMMetadataRef Ty, LLVMBool LocalToUnit,
     LLVMMetadataRef Expr, LLVMMetadataRef Decl, uint32_t AlignInBits);
+
+/**
+ * Retrieves the \c DIVariable associated with this global variable expression.
+ * \param GVE    The global variable expression.
+ *
+ * @see llvm::DIGlobalVariableExpression::getVariable()
+ */
+LLVMMetadataRef LLVMDIGlobalVariableExpressionGetVariable(LLVMMetadataRef GVE);
+
+/**
+ * Retrieves the \c DIExpression associated with this global variable expression.
+ * \param GVE    The global variable expression.
+ *
+ * @see llvm::DIGlobalVariableExpression::getExpression()
+ */
+LLVMMetadataRef LLVMDIGlobalVariableExpressionGetExpression(
+    LLVMMetadataRef GVE);
+
+/**
+ * Get the metadata of the file associated with a given variable.
+ * \param Var     The variable object.
+ *
+ * @see DIVariable::getFile()
+ */
+LLVMMetadataRef LLVMDIVariableGetFile(LLVMMetadataRef Var);
+
+/**
+ * Get the metadata of the scope associated with a given variable.
+ * \param Var     The variable object.
+ *
+ * @see DIVariable::getScope()
+ */
+LLVMMetadataRef LLVMDIVariableGetScope(LLVMMetadataRef Var);
+
+/**
+ * Get the source line where this \c DIVariable is declared.
+ * \param Var     The DIVariable.
+ *
+ * @see DIVariable::getLine()
+ */
+unsigned LLVMDIVariableGetLine(LLVMMetadataRef Var);
+
 /**
  * Create a new temporary \c MDNode.  Suitable for use in constructing cyclic
  * \c MDNode structures. A temporary \c MDNode is not uniqued, may be RAUW'd,
  * and must be manually deleted with \c LLVMDisposeTemporaryMDNode.
  * \param Ctx            The context in which to construct the temporary node.
  * \param Data           The metadata elements.
  * \param NumElements    Number of metadata elements.
  */

llvm/lib/IR/DebugInfo.cpp

LLVMMetadataRef LLVMDIBuilderCreateGlobalVariableExpression(
     LLVMMetadataRef Expr, LLVMMetadataRef Decl, uint32_t AlignInBits) {
   return wrap(unwrap(Builder)->createGlobalVariableExpression(
       unwrapDI<DIScope>(Scope), {Name, NameLen}, {Linkage, LinkLen},
       unwrapDI<DIFile>(File), LineNo, unwrapDI<DIType>(Ty), LocalToUnit,
       unwrap<DIExpression>(Expr), unwrapDI<MDNode>(Decl),
       nullptr, AlignInBits));
 }
 
+LLVMMetadataRef LLVMDIGlobalVariableExpressionGetVariable(LLVMMetadataRef GVE) {
+  return wrap(unwrapDI<DIGlobalVariableExpression>(GVE)->getVariable());
+}
+
+LLVMMetadataRef LLVMDIGlobalVariableExpressionGetExpression(
+    LLVMMetadataRef GVE) {
+  return wrap(unwrapDI<DIGlobalVariableExpression>(GVE)->getExpresssion());
+}
+
+LLVMMetadataRef LLVMDIVariableGetFile(LLVMMetadataRef Var) {
+  return wrap(unwrapDI<DIVariable>(Var)->getFile());
+}
+
+LLVMMetadataRef LLVMDIVariableGetScope(LLVMMetadataRef Var) {
+  return wrap(unwrapDI<DIVariable>(Var)->getScope());
+}
+
+unsigned LLVMDIVariableGetLine(LLVMMetadataRef Var) {
+  return unwrapDI<DIVariable>(Var)->getLine();
+}
+
 LLVMMetadataRef LLVMTemporaryMDNode(LLVMContextRef Ctx, LLVMMetadataRef *Data,
                                     size_t Count) {
   return wrap(
       MDTuple::getTemporary(*unwrap(Ctx), {unwrap(Data), Count}).release());
 }
 
 void LLVMDisposeTemporaryMDNode(LLVMMetadataRef TempNode) {
   MDNode::deleteTemporary(unwrapDI<MDNode>(TempNode));