[PPC] Use alias symbols in address computation.

This seems to match what gcc does for ppc and what every other llvm
backend does.

This is a fixed version of r209638. The difference is to avoid any change
in behavior for functions. The logic for using constant pools for function
addresseses is spread over a few places and we have to keep them in sync.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209821 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 48 insertions, 34 deletions

diff --git a/lib/Target/PowerPC/PPCAsmPrinter.cpp b/lib/Target/PowerPC/PPCAsmPrinter.cpp
index 2174b18715..ee5e406c6f 100644
--- a/lib/Target/PowerPC/PPCAsmPrinter.cpp
+++ b/lib/Target/PowerPC/PPCAsmPrinter.cpp
@@ -380,15 +380,12 @@ void PPCAsmPrinter::EmitInstruction(const MachineInstr *MI) {
     bool IsAvailExt = false;
 
     if (MO.isGlobal()) {
-      const GlobalValue *GValue = MO.getGlobal();
-      const GlobalAlias *GAlias = dyn_cast<GlobalAlias>(GValue);
-      const GlobalValue *RealGValue = GAlias ? GAlias->getAliasee() : GValue;
-      MOSymbol = getSymbol(RealGValue);
-      const GlobalVariable *GVar = dyn_cast<GlobalVariable>(RealGValue);
-      IsExternal = GVar && !GVar->hasInitializer();
-      IsCommon = GVar && RealGValue->hasCommonLinkage();
-      IsFunction = !GVar;
-      IsAvailExt = GVar && RealGValue->hasAvailableExternallyLinkage();
+      const GlobalValue *GV = MO.getGlobal();
+      MOSymbol = getSymbol(GV);
+      IsExternal = GV->isDeclaration();
+      IsCommon = GV->hasCommonLinkage();
+      IsFunction = GV->getType()->getElementType()->isFunctionTy();
+      IsAvailExt = GV->hasAvailableExternallyLinkage();
     } else if (MO.isCPI())
       MOSymbol = GetCPISymbol(MO.getIndex());
     else if (MO.isJTI())
@@ -427,13 +424,10 @@ void PPCAsmPrinter::EmitInstruction(const MachineInstr *MI) {
     }
     else if (MO.isGlobal()) {
       const GlobalValue *GValue = MO.getGlobal();
-      const GlobalAlias *GAlias = dyn_cast<GlobalAlias>(GValue);
-      const GlobalValue *RealGValue = GAlias ? GAlias->getAliasee() : GValue;
-      MOSymbol = getSymbol(RealGValue);
-      const GlobalVariable *GVar = dyn_cast<GlobalVariable>(RealGValue);
-    
-      if (!GVar || !GVar->hasInitializer() || RealGValue->hasCommonLinkage() ||
-          RealGValue->hasAvailableExternallyLinkage() ||
+      MOSymbol = getSymbol(GValue);
+      if (GValue->getType()->getElementType()->isFunctionTy() ||
+          GValue->isDeclaration() || GValue->hasCommonLinkage() ||
+          GValue->hasAvailableExternallyLinkage() ||
           TM.getCodeModel() == CodeModel::Large)
         MOSymbol = lookUpOrCreateTOCEntry(MOSymbol);
     }
@@ -460,13 +454,10 @@ void PPCAsmPrinter::EmitInstruction(const MachineInstr *MI) {
     bool IsFunction = false;
 
     if (MO.isGlobal()) {
-      const GlobalValue *GValue = MO.getGlobal();
-      const GlobalAlias *GAlias = dyn_cast<GlobalAlias>(GValue);
-      const GlobalValue *RealGValue = GAlias ? GAlias->getAliasee() : GValue;
-      MOSymbol = getSymbol(RealGValue);
-      const GlobalVariable *GVar = dyn_cast<GlobalVariable>(RealGValue);
-      IsExternal = GVar && !GVar->hasInitializer();
-      IsFunction = !GVar;
+      const GlobalValue *GV = MO.getGlobal();
+      MOSymbol = getSymbol(GV);
+      IsExternal = GV->isDeclaration();
+      IsFunction = GV->getType()->getElementType()->isFunctionTy();
     } else if (MO.isCPI())
       MOSymbol = GetCPISymbol(MO.getIndex());
 
diff --git a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
index f6e075d271..b8f5957002 100644
--- a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
+++ b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
@@ -1472,17 +1472,9 @@ SDNode *PPCDAGToDAGISel::Select(SDNode *N) {
 
     if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(GA)) {
       const GlobalValue *GValue = G->getGlobal();
-      const GlobalAlias *GAlias = dyn_cast<GlobalAlias>(GValue);
-      const GlobalValue *RealGValue = GAlias ? GAlias->getAliasee() : GValue;
-      const GlobalVariable *GVar = dyn_cast<GlobalVariable>(RealGValue);
-      assert((GVar || isa<Function>(RealGValue)) &&
-             "Unexpected global value subclass!");
-
-      // An external variable is one without an initializer.  For these,
-      // for variables with common linkage, and for Functions, generate
-      // the LDtocL form.
-      if (!GVar || !GVar->hasInitializer() || RealGValue->hasCommonLinkage() ||
-          RealGValue->hasAvailableExternallyLinkage())
+      if (GValue->getType()->getElementType()->isFunctionTy() ||
+          GValue->isDeclaration() || GValue->hasCommonLinkage() ||
+          GValue->hasAvailableExternallyLinkage())
         return CurDAG->getMachineNode(PPC::LDtocL, dl, MVT::i64, GA,
                                       SDValue(Tmp, 0));
     }
diff --git a/test/CodeGen/PowerPC/alias.ll b/test/CodeGen/PowerPC/alias.ll
new file mode 100644
index 0000000000..86e41148a0
--- /dev/null
+++ b/test/CodeGen/PowerPC/alias.ll
@@ -0,0 +1,31 @@
+; RUN: llc < %s -mtriple=powerpc64-unknown-linux-gnu -code-model=medium| FileCheck --check-prefix=CHECK --check-prefix=MEDIUM %s
+; RUN: llc < %s -mtriple=powerpc64-unknown-linux-gnu -code-model=large | FileCheck --check-prefix=CHECK --check-prefix=LARGE %s
+
+@foo = global i32 42
+@fooa = alias i32* @foo
+
+@foo2 = global i64 42
+@foo2a = alias i64* @foo2
+
+; CHECK-LABEL: bar:
+define i32 @bar() {
+; MEDIUM: addis 3, 2, fooa@toc@ha
+; LARGE: addis 3, 2, .LC1@toc@ha
+  %a = load i32* @fooa
+  ret i32 %a
+}
+
+; CHECK-LABEL: bar2:
+define i64 @bar2() {
+; MEDIUM: addis 3, 2, foo2a@toc@ha
+; MEDIUM: addi 3, 3, foo2a@toc@l
+; LARGE: addis 3, 2, .LC3@toc@ha
+  %a = load i64* @foo2a
+  ret i64 %a
+}
+
+; LARGE: .LC1:
+; LARGE-NEXT: .tc fooa[TC],fooa
+
+; LARGE: .LC3:
+; LARGE-NEXT: .tc foo2a[TC],foo2a