ARM: track globals promoted to coalesced const pool entries

Globals that are promoted to an ARM constant pool may alias with another
existing constant pool entry. We need to keep a reference to all globals
that were promoted to each constant pool value so that we can emit a
distinct label for each promoted global. These labels are necessary so
that debug info can refer to the promoted global without an undefined
reference during linking.

Patch by Stephen Crane!

llvm-svn: 312692

1 files changed, 14 insertions, 3 deletions

diff --git a/llvm/lib/Target/ARM/ARMConstantPoolValue.cpp b/llvm/lib/Target/ARM/ARMConstantPoolValue.cpp
index 9705c8b718b..88b3683bd75 100644
--- a/llvm/lib/Target/ARM/ARMConstantPoolValue.cpp
+++ b/llvm/lib/Target/ARM/ARMConstantPoolValue.cpp
@@ -140,8 +140,9 @@ ARMConstantPoolConstant::ARMConstantPoolConstant(const Constant *C,
 ARMConstantPoolConstant::ARMConstantPoolConstant(const GlobalVariable *GV,
                                                  const Constant *C)
     : ARMConstantPoolValue((Type *)C->getType(), 0, ARMCP::CPPromotedGlobal, 0,
-                           ARMCP::no_modifier, false),
-      CVal(C), GVar(GV) {}
+                           ARMCP::no_modifier, false), CVal(C) {
+  GVars.insert(GV);
+}
 
 ARMConstantPoolConstant *
 ARMConstantPoolConstant::Create(const Constant *C, unsigned ID) {
@@ -189,7 +190,15 @@ const BlockAddress *ARMConstantPoolConstant::getBlockAddress() const {
 
 int ARMConstantPoolConstant::getExistingMachineCPValue(MachineConstantPool *CP,
                                                        unsigned Alignment) {
-  return getExistingMachineCPValueImpl<ARMConstantPoolConstant>(CP, Alignment);
+  int index =
+    getExistingMachineCPValueImpl<ARMConstantPoolConstant>(CP, Alignment);
+  if (index != -1) {
+    auto *CPV = static_cast<ARMConstantPoolValue*>(
+        CP->getConstants()[index].Val.MachineCPVal);
+    auto *Constant = cast<ARMConstantPoolConstant>(CPV);
+    Constant->GVars.insert(GVars.begin(), GVars.end());
+  }
+  return index;
 }
 
 bool ARMConstantPoolConstant::hasSameValue(ARMConstantPoolValue *ACPV) {
@@ -199,6 +208,8 @@ bool ARMConstantPoolConstant::hasSameValue(ARMConstantPoolValue *ACPV) {
 
 void ARMConstantPoolConstant::addSelectionDAGCSEId(FoldingSetNodeID &ID) {
   ID.AddPointer(CVal);
+  for (const auto *GV : GVars)
+    ID.AddPointer(GV);
   ARMConstantPoolValue::addSelectionDAGCSEId(ID);
 }