Allow alias to point to an arbitrary ConstantExpr.

This  patch changes GlobalAlias to point to an arbitrary ConstantExpr and it is
up to MC (or the system assembler) to decide if that expression is valid or not.

This reduces our ability to diagnose invalid uses and how early we can spot
them, but it also lets us do things like

@test5 = alias inttoptr(i32 sub (i32 ptrtoint (i32* @test2 to i32),
                                 i32 ptrtoint (i32* @bar to i32)) to i32*)

An important implication of this patch is that the notion of aliased global
doesn't exist any more. The alias has to encode the information needed to
access it in its metadata (linkage, visibility, type, etc).

Another consequence to notice is that getSection has to return a "const char *".
It could return a NullTerminatedStringRef if there was such a thing, but when
that was proposed the decision was to just uses "const char*" for that.

llvm-svn: 210062

1 files changed, 10 insertions, 12 deletions

diff --git a/llvm/lib/Target/XCore/XCoreISelLowering.cpp b/llvm/lib/Target/XCore/XCoreISelLowering.cpp
index 9d785864952..e9db2a8fa46 100644
--- a/llvm/lib/Target/XCore/XCoreISelLowering.cpp
+++ b/llvm/lib/Target/XCore/XCoreISelLowering.cpp
@@ -273,18 +273,16 @@ SDValue XCoreTargetLowering::getGlobalAddressWrapper(SDValue GA,
                                                      SelectionDAG &DAG) const {
   // FIXME there is no actual debug info here
   SDLoc dl(GA);
-  const GlobalValue *UnderlyingGV = GV;
-  // If GV is an alias then use the aliasee to determine the wrapper type
-  if (const GlobalAlias *GA = dyn_cast<GlobalAlias>(GV))
-    UnderlyingGV = GA->getAliasee();
-  if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(UnderlyingGV)) {
-    if ((GVar->isConstant() && GV->hasLocalLinkage()) ||
-        (GVar->hasSection() &&
-         StringRef(GVar->getSection()).startswith(".cp.")))
-      return DAG.getNode(XCoreISD::CPRelativeWrapper, dl, MVT::i32, GA);
-    return DAG.getNode(XCoreISD::DPRelativeWrapper, dl, MVT::i32, GA);
-  }
-  return DAG.getNode(XCoreISD::PCRelativeWrapper, dl, MVT::i32, GA);
+
+  if (GV->getType()->getElementType()->isFunctionTy())
+    return DAG.getNode(XCoreISD::PCRelativeWrapper, dl, MVT::i32, GA);
+
+  const auto *GVar = dyn_cast<GlobalVariable>(GV);
+  if ((GV->hasSection() && StringRef(GV->getSection()).startswith(".cp.")) ||
+      (GVar && GVar->isConstant() && GV->hasLocalLinkage()))
+    return DAG.getNode(XCoreISD::CPRelativeWrapper, dl, MVT::i32, GA);
+
+  return DAG.getNode(XCoreISD::DPRelativeWrapper, dl, MVT::i32, GA);
 }
 
 static bool IsSmallObject(const GlobalValue *GV, const XCoreTargetLowering &XTL) {