Weak non-function symbols were being accessed directly, which is

incorrect, as the chosen representative of the weak symbol may not live
with the code in question. Always indirect the access through the TOC
instead.

Patch by Kyle Butt!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@253708 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/PowerPC/PPCAsmPrinter.cpp b/lib/Target/PowerPC/PPCAsmPrinter.cpp
index 79ece1733209fb8813c596a0c5943ae56dba3075..2b900009d77976d9f09f62a93d85a95beeb0584e 100644 (file)
--- a/lib/Target/PowerPC/PPCAsmPrinter.cpp
+++ b/lib/Target/PowerPC/PPCAsmPrinter.cpp
@@ -669,28 +669,22 @@ void PPCAsmPrinter::EmitInstruction(const MachineInstr *MI) {
             MO.isBlockAddress()) &&
            "Invalid operand for ADDIStocHA!");
     MCSymbol *MOSymbol = nullptr;
-    bool IsExternal = false;
-    bool IsNonLocalFunction = false;
-    bool IsCommon = false;
-    bool IsAvailExt = false;
+    bool GlobalToc = false;
 
     if (MO.isGlobal()) {
       const GlobalValue *GV = MO.getGlobal();
       MOSymbol = getSymbol(GV);
-      IsExternal = GV->isDeclaration();
-      IsCommon = GV->hasCommonLinkage();
-      IsNonLocalFunction = GV->getType()->getElementType()->isFunctionTy() &&
-        !GV->isStrongDefinitionForLinker();
-      IsAvailExt = GV->hasAvailableExternallyLinkage();
-    } else if (MO.isCPI())
+      unsigned char GVFlags = Subtarget->classifyGlobalReference(GV);
+      GlobalToc = (GVFlags & PPCII::MO_NLP_FLAG);
+    } else if (MO.isCPI()) {
       MOSymbol = GetCPISymbol(MO.getIndex());
-    else if (MO.isJTI())
+    } else if (MO.isJTI()) {
       MOSymbol = GetJTISymbol(MO.getIndex());
-    else if (MO.isBlockAddress())
+    } else if (MO.isBlockAddress()) {
       MOSymbol = GetBlockAddressSymbol(MO.getBlockAddress());
+    }
 
-    if (IsExternal || IsNonLocalFunction || IsCommon || IsAvailExt ||
-        MO.isJTI() || MO.isBlockAddress() ||
+    if (GlobalToc || MO.isJTI() || MO.isBlockAddress() ||
         TM.getCodeModel() == CodeModel::Large)
       MOSymbol = lookUpOrCreateTOCEntry(MOSymbol);
 
@@ -727,13 +721,14 @@ void PPCAsmPrinter::EmitInstruction(const MachineInstr *MI) {
         MOSymbol = lookUpOrCreateTOCEntry(MOSymbol);
     }
     else if (MO.isGlobal()) {
-      const GlobalValue *GValue = MO.getGlobal();
-      MOSymbol = getSymbol(GValue);
-      if (GValue->getType()->getElementType()->isFunctionTy() ||
-          GValue->isDeclaration() || GValue->hasCommonLinkage() ||
-          GValue->hasAvailableExternallyLinkage() ||
-          TM.getCodeModel() == CodeModel::Large)
-        MOSymbol = lookUpOrCreateTOCEntry(MOSymbol);
+      const GlobalValue *GV = MO.getGlobal();
+      MOSymbol = getSymbol(GV);
+      DEBUG(
+        unsigned char GVFlags = Subtarget->classifyGlobalReference(GV);
+        assert((GVFlags & PPCII::MO_NLP_FLAG) &&
+               "LDtocL used on symbol that could be accessed directly is "
+               "invalid. Must match ADDIStocHA."));
+      MOSymbol = lookUpOrCreateTOCEntry(MOSymbol);
     }
 
     const MCExpr *Exp =
@@ -754,21 +749,18 @@ void PPCAsmPrinter::EmitInstruction(const MachineInstr *MI) {
     const MachineOperand &MO = MI->getOperand(2);
     assert((MO.isGlobal() || MO.isCPI()) && "Invalid operand for ADDItocL");
     MCSymbol *MOSymbol = nullptr;
-    bool IsExternal = false;
-    bool IsNonLocalFunction = false;
 
     if (MO.isGlobal()) {
       const GlobalValue *GV = MO.getGlobal();
+      DEBUG(
+        unsigned char GVFlags = Subtarget->classifyGlobalReference(GV);
+        assert (
+            !(GVFlags & PPCII::MO_NLP_FLAG) &&
+            "Interposable definitions must use indirect access."));
       MOSymbol = getSymbol(GV);
-      IsExternal = GV->isDeclaration();
-      IsNonLocalFunction = GV->getType()->getElementType()->isFunctionTy() &&
-        !GV->isStrongDefinitionForLinker();
-    } else if (MO.isCPI())
+    } else if (MO.isCPI()) {
       MOSymbol = GetCPISymbol(MO.getIndex());
-
-    if (IsNonLocalFunction || IsExternal ||
-        TM.getCodeModel() == CodeModel::Large)
-      MOSymbol = lookUpOrCreateTOCEntry(MOSymbol);
+    }
 
     const MCExpr *Exp =
       MCSymbolRefExpr::create(MOSymbol, MCSymbolRefExpr::VK_PPC_TOC_LO,

diff --git a/lib/Target/PowerPC/PPCFastISel.cpp b/lib/Target/PowerPC/PPCFastISel.cpp
index 38477018ea005988d9a3eef2d504bc23b67664a8..5b9451c2bd7ba0b6127c610001c9af4883afc9bd 100644 (file)
--- a/lib/Target/PowerPC/PPCFastISel.cpp
+++ b/lib/Target/PowerPC/PPCFastISel.cpp
@@ -1972,19 +1972,15 @@ unsigned PPCFastISel::PPCMaterializeGV(const GlobalValue *GV, MVT VT) {
     BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(PPC::ADDIStocHA),
             HighPartReg).addReg(PPC::X2).addGlobalAddress(GV);
 
-    // If/when switches are implemented, jump tables should be handled
-    // on the "if" path here.
-    if (CModel == CodeModel::Large ||
-        (GV->getType()->getElementType()->isFunctionTy() &&
-         !GV->isStrongDefinitionForLinker()) ||
-        GV->isDeclaration() || GV->hasCommonLinkage() ||
-        GV->hasAvailableExternallyLinkage())
+    unsigned char GVFlags = PPCSubTarget->classifyGlobalReference(GV);
+    if (GVFlags & PPCII::MO_NLP_FLAG) {
       BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(PPC::LDtocL),
               DestReg).addGlobalAddress(GV).addReg(HighPartReg);
-    else
+    } else {
       // Otherwise generate the ADDItocL.
       BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(PPC::ADDItocL),
               DestReg).addReg(HighPartReg).addGlobalAddress(GV);
+    }
   }
 
   return DestReg;

diff --git a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
index e9b54af79a864e72d6717ffeb13714d015289d8a..438a2980f2ce6750a0da2f866c837eaccafc1393 100644 (file)
--- a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
+++ b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
@@ -2902,9 +2902,7 @@ SDNode *PPCDAGToDAGISel::Select(SDNode *N) {
       break;
 
     // The first source operand is a TargetGlobalAddress or a TargetJumpTable.
-    // If it is an externally defined symbol, a symbol with common linkage,
-    // a non-local function address, or a jump table address, or if we are
-    // generating code for large code model, we generate:
+    // If it must be toc-referenced according to PPCSubTarget, we generate:
     //   LDtocL(<ga:@sym>, ADDIStocHA(%X2, <ga:@sym>))
     // Otherwise we generate:
     //   ADDItocL(ADDIStocHA(%X2, <ga:@sym>), <ga:@sym>)
@@ -2919,13 +2917,12 @@ SDNode *PPCDAGToDAGISel::Select(SDNode *N) {
                                       MVT::i64, GA, SDValue(Tmp, 0)));
 
     if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(GA)) {
-      const GlobalValue *GValue = G->getGlobal();
-      if ((GValue->getType()->getElementType()->isFunctionTy() &&
-           !GValue->isStrongDefinitionForLinker()) ||
-          GValue->isDeclaration() || GValue->hasCommonLinkage() ||
-          GValue->hasAvailableExternallyLinkage())
+      const GlobalValue *GV = G->getGlobal();
+      unsigned char GVFlags = PPCSubTarget->classifyGlobalReference(GV);
+      if (GVFlags & PPCII::MO_NLP_FLAG) {
         return transferMemOperands(N, CurDAG->getMachineNode(PPC::LDtocL, dl,
                                         MVT::i64, GA, SDValue(Tmp, 0)));
+      }
     }
 
     return CurDAG->getMachineNode(PPC::ADDItocL, dl, MVT::i64,

diff --git a/lib/Target/PowerPC/PPCSubtarget.cpp b/lib/Target/PowerPC/PPCSubtarget.cpp
index 58daccae90f2f2a85f41783dd04432569af8dcc6..9a9bdfdad00fa1c9754fd64ad5748a118ec01303 100644 (file)
--- a/lib/Target/PowerPC/PPCSubtarget.cpp
+++ b/lib/Target/PowerPC/PPCSubtarget.cpp
@@ -210,5 +210,33 @@ bool PPCSubtarget::enableSubRegLiveness() const {
   return UseSubRegLiveness;
 }
 
+unsigned char PPCSubtarget::classifyGlobalReference(
+    const GlobalValue *GV) const {
+  // Note that currently we don't generate non-pic references.
+  // If a caller wants that, this will have to be updated.
+
+  // Large code model always uses the TOC even for local symbols.
+  if (TM.getCodeModel() == CodeModel::Large)
+    return PPCII::MO_PIC_FLAG | PPCII::MO_NLP_FLAG;
+
+  unsigned char flags = PPCII::MO_PIC_FLAG;
+
+  // Only if the relocation mode is PIC do we have to worry about
+  // interposition. In all other cases we can use a slightly looser standard to
+  // decide how to access the symbol.
+  if (TM.getRelocationModel() == Reloc::PIC_) {
+    // If it's local, or it's non-default, it can't be interposed.
+    if (!GV->hasLocalLinkage() &&
+        GV->hasDefaultVisibility()) {
+      flags |= PPCII::MO_NLP_FLAG;
+    }
+    return flags;
+  }
+
+  if (GV->isStrongDefinitionForLinker())
+    return flags;
+  return flags | PPCII::MO_NLP_FLAG;
+}
+
 bool PPCSubtarget::isELFv2ABI() const { return TM.isELFv2ABI(); }
 bool PPCSubtarget::isPPC64() const { return TM.isPPC64(); }

diff --git a/lib/Target/PowerPC/PPCSubtarget.h b/lib/Target/PowerPC/PPCSubtarget.h
index 0616c1f65604252f3827e11c2e07289026d4e72c..b21931b1b2dddd0090242323677a2636a71401f6 100644 (file)
--- a/lib/Target/PowerPC/PPCSubtarget.h
+++ b/lib/Target/PowerPC/PPCSubtarget.h
@@ -285,6 +285,10 @@ public:
   bool useAA() const override;
 
   bool enableSubRegLiveness() const override;
+
+  /// classifyGlobalReference - Classify a global variable reference for the
+  /// current subtarget accourding to how we should reference it.
+  unsigned char classifyGlobalReference(const GlobalValue *GV) const;
 };
 } // End llvm namespace
 

diff --git a/test/CodeGen/PowerPC/mcm-13.ll b/test/CodeGen/PowerPC/mcm-13.ll
new file mode 100644 (file)
index 0000000..ba371c5
--- /dev/null
+++ b/test/CodeGen/PowerPC/mcm-13.ll
@@ -0,0 +1,27 @@
+; RUN: llc -mcpu=pwr7 -O0 -code-model=medium <%s | FileCheck %s
+; RUN: llc -mcpu=pwr7 -O0 -code-model=large <%s | FileCheck %s
+
+; Test correct code generation for medium and large code model
+; for loading and storing a weak 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"
+
+@wi = weak global i32 0, align 4
+
+define signext i32 @test_weak() nounwind {
+entry:
+  %0 = load i32, i32* @wi, align 4
+  %inc = add nsw i32 %0, 1
+  store i32 %inc, i32* @wi, align 4
+  ret i32 %0
+}
+
+; CHECK-LABEL: test_weak:
+; 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_.]+}}