This patch addresses bug 14678 by fixing two problems in medium code model

code generation.  Variables addressed through a GlobalAlias were not being
handled, and variables with available_externally linkage were treated
incorrectly.  The patch contains two new tests to verify the correct code
generation for these cases.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171778 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 80 insertions, 12 deletions

diff --git a/lib/Target/PowerPC/PPCAsmPrinter.cpp b/lib/Target/PowerPC/PPCAsmPrinter.cpp
index 85f00dd..adb673b 100644
--- a/lib/Target/PowerPC/PPCAsmPrinter.cpp
+++ b/lib/Target/PowerPC/PPCAsmPrinter.cpp
@@ -426,20 +426,25 @@ void PPCAsmPrinter::EmitInstruction(const MachineInstr *MI) {
     bool IsExternal = false;
     bool IsFunction = false;
     bool IsCommon = false;
+    bool IsAvailExt = false;
 
     if (MO.isGlobal()) {
       const GlobalValue *GValue = MO.getGlobal();
-      MOSymbol = Mang->getSymbol(GValue);
-      const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GValue);
+      const GlobalAlias *GAlias = dyn_cast<GlobalAlias>(GValue);
+      const GlobalValue *RealGValue = GAlias ?
+        GAlias->resolveAliasedGlobal(false) : GValue;
+      MOSymbol = Mang->getSymbol(RealGValue);
+      const GlobalVariable *GVar = dyn_cast<GlobalVariable>(RealGValue);
       IsExternal = GVar && !GVar->hasInitializer();
-      IsCommon = GVar && GValue->hasCommonLinkage();
+      IsCommon = GVar && RealGValue->hasCommonLinkage();
       IsFunction = !GVar;
+      IsAvailExt = GVar && RealGValue->hasAvailableExternallyLinkage();
     } else if (MO.isCPI())
       MOSymbol = GetCPISymbol(MO.getIndex());
     else if (MO.isJTI())
       MOSymbol = GetJTISymbol(MO.getIndex());
 
-    if (IsExternal || IsFunction || IsCommon || MO.isJTI())
+    if (IsExternal || IsFunction || IsCommon || IsAvailExt || MO.isJTI())
       MOSymbol = lookUpOrCreateTOCEntry(MOSymbol);
 
     const MCExpr *Exp =
@@ -466,10 +471,14 @@ void PPCAsmPrinter::EmitInstruction(const MachineInstr *MI) {
       MOSymbol = lookUpOrCreateTOCEntry(GetJTISymbol(MO.getIndex()));
     else {
       const GlobalValue *GValue = MO.getGlobal();
-      MOSymbol = Mang->getSymbol(GValue);
-      const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GValue);
+      const GlobalAlias *GAlias = dyn_cast<GlobalAlias>(GValue);
+      const GlobalValue *RealGValue = GAlias ?
+        GAlias->resolveAliasedGlobal(false) : GValue;
+      MOSymbol = Mang->getSymbol(RealGValue);
+      const GlobalVariable *GVar = dyn_cast<GlobalVariable>(RealGValue);
     
-      if (!GVar || !GVar->hasInitializer() || GValue->hasCommonLinkage())
+      if (!GVar || !GVar->hasInitializer() || RealGValue->hasCommonLinkage() ||
+          RealGValue->hasAvailableExternallyLinkage())
         MOSymbol = lookUpOrCreateTOCEntry(MOSymbol);
     }
 
@@ -496,8 +505,11 @@ void PPCAsmPrinter::EmitInstruction(const MachineInstr *MI) {
 
     if (MO.isGlobal()) {
       const GlobalValue *GValue = MO.getGlobal();
-      MOSymbol = Mang->getSymbol(GValue);
-      const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GValue);
+      const GlobalAlias *GAlias = dyn_cast<GlobalAlias>(GValue);
+      const GlobalValue *RealGValue = GAlias ?
+        GAlias->resolveAliasedGlobal(false) : GValue;
+      MOSymbol = Mang->getSymbol(RealGValue);
+      const GlobalVariable *GVar = dyn_cast<GlobalVariable>(RealGValue);
       IsExternal = GVar && !GVar->hasInitializer();
       IsFunction = !GVar;
     } else if (MO.isCPI())
diff --git a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
index 9ac0a27..762b346 100644
--- a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
+++ b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
@@ -25,6 +25,7 @@
 #include "llvm/IR/Function.h"
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/IR/GlobalVariable.h"
+#include "llvm/IR/GlobalAlias.h"
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
@@ -1296,14 +1297,18 @@ SDNode *PPCDAGToDAGISel::Select(SDNode *N) {
 
     if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(GA)) {
       const GlobalValue *GValue = G->getGlobal();
-      const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GValue);
-      assert((GVar || isa<Function>(GValue)) &&
+      const GlobalAlias *GAlias = dyn_cast<GlobalAlias>(GValue);
+      const GlobalValue *RealGValue = GAlias ?
+        GAlias->resolveAliasedGlobal(false) : 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() || GValue->hasCommonLinkage())
+      if (!GVar || !GVar->hasInitializer() || RealGValue->hasCommonLinkage() ||
+          RealGValue->hasAvailableExternallyLinkage())
         return CurDAG->getMachineNode(PPC::LDtocL, dl, MVT::i64, GA,
                                       SDValue(Tmp, 0));
     }
diff --git a/test/CodeGen/PowerPC/mcm-8.ll b/test/CodeGen/PowerPC/mcm-8.ll
new file mode 100644
index 0000000..9381a97
--- /dev/null
+++ b/test/CodeGen/PowerPC/mcm-8.ll
@@ -0,0 +1,24 @@
+; RUN: llc -mcpu=pwr7 -O0 -code-model=medium < %s | FileCheck %s
+
+; Test correct code generation for medium code model (32-bit TOC offsets)
+; for loading a variable with available-externally linkage.
+
+target datalayout = "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-f128:128:128-v128:128:128-n32:64"
+target triple = "powerpc64-unknown-linux-gnu"
+
+@x = available_externally constant [13 x i8] c"St9bad_alloc\00"
+
+define signext i8 @test_avext() nounwind {
+entry:
+  %0 = getelementptr inbounds [13 x i8]* @x, i32 0, i32 0
+  %1 = load i8* %0, align 1
+  ret i8 %1
+}
+
+; CHECK: test_avext:
+; CHECK: addis [[REG1:[0-9]+]], 2, .LC[[TOCNUM:[0-9]+]]@toc@ha
+; CHECK: ld [[REG2:[0-9]+]], .LC[[TOCNUM]]@toc@l([[REG1]])
+; CHECK: lbz {{[0-9]+}}, 0([[REG2]])
+; CHECK: .section .toc
+; CHECK: .LC[[TOCNUM]]:
+; CHECK: .tc {{[a-z0-9A-Z_.]+}}[TC],{{[a-z0-9A-Z_.]+}}
diff --git a/test/CodeGen/PowerPC/mcm-9.ll b/test/CodeGen/PowerPC/mcm-9.ll
new file mode 100644
index 0000000..422607c
--- /dev/null
+++ b/test/CodeGen/PowerPC/mcm-9.ll
@@ -0,0 +1,27 @@
+; RUN: llc -mcpu=pwr7 -O0 -code-model=medium <%s | FileCheck %s
+
+; Test correct code generation for medium code model (32-bit TOC offsets)
+; for loading and storing an aliased external variable.
+
+target datalayout = "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-f128:128:128-v128:128:128-n32:64"
+target triple = "powerpc64-unknown-linux-gnu"
+
+@ei = external global i32
+@a = alias i32* @ei
+
+define signext i32 @test_external() nounwind {
+entry:
+  %0 = load i32* @a, align 4
+  %inc = add nsw i32 %0, 1
+  store i32 %inc, i32* @a, align 4
+  ret i32 %0
+}
+
+; CHECK: test_external:
+; CHECK: addis [[REG1:[0-9]+]], 2, .LC[[TOCNUM:[0-9]+]]@toc@ha
+; CHECK: ld [[REG2:[0-9]+]], .LC[[TOCNUM]]@toc@l([[REG1]])
+; CHECK: lwz {{[0-9]+}}, 0([[REG2]])
+; CHECK: stw {{[0-9]+}}, 0([[REG2]])
+; CHECK: .section .toc
+; CHECK: .LC[[TOCNUM]]:
+; CHECK: .tc {{[a-z0-9A-Z_.]+}}[TC],{{[a-z0-9A-Z_.]+}}