Teach DAGCombine to fold constant offsets into GlobalAddress nodes,

and add a TargetLowering hook for it to use to determine when this
is legal (i.e. not in PIC mode, etc.)

This allows instruction selection to emit folded constant offsets
in more cases, such as the included testcase, eliminating the need
for explicit arithmetic instructions.

This eliminates the need for the C++ code in X86ISelDAGToDAG.cpp
that attempted to achieve the same effect, but wasn't as effective.

Also, fix handling of offsets in GlobalAddressSDNodes in several
places, including changing GlobalAddressSDNode's offset from
int to int64_t.

The Mips, Alpha, Sparc, and CellSPU targets appear to be
unaware of GlobalAddress offsets currently, so set the hook to
false on those targets.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@57748 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 5 insertions, 5 deletions

diff --git a/include/llvm/CodeGen/MachineOperand.h b/include/llvm/CodeGen/MachineOperand.h
index f9d80c7fcc..e3cc814011 100644
--- a/include/llvm/CodeGen/MachineOperand.h
+++ b/include/llvm/CodeGen/MachineOperand.h
@@ -101,7 +101,7 @@ private:
         const char *SymbolName;   // For MO_ExternalSymbol.
         GlobalValue *GV;          // For MO_GlobalAddress.
       } Val;
-      int Offset;   // An offset from the object.
+      int64_t Offset;   // An offset from the object.
     } OffsetedInfo;
   } Contents;
   
@@ -273,7 +273,7 @@ public:
     return Contents.OffsetedInfo.Val.GV;
   }
   
-  int getOffset() const {
+  int64_t getOffset() const {
     assert((isGlobal() || isSymbol() || isCPI()) &&
            "Wrong MachineOperand accessor");
     return Contents.OffsetedInfo.Offset;
@@ -293,7 +293,7 @@ public:
     Contents.ImmVal = immVal;
   }
 
-  void setOffset(int Offset) {
+  void setOffset(int64_t Offset) {
     assert((isGlobal() || isSymbol() || isCPI()) &&
         "Wrong MachineOperand accessor");
     Contents.OffsetedInfo.Offset = Offset;
@@ -382,13 +382,13 @@ public:
     Op.setIndex(Idx);
     return Op;
   }
-  static MachineOperand CreateGA(GlobalValue *GV, int Offset) {
+  static MachineOperand CreateGA(GlobalValue *GV, int64_t Offset) {
     MachineOperand Op(MachineOperand::MO_GlobalAddress);
     Op.Contents.OffsetedInfo.Val.GV = GV;
     Op.setOffset(Offset);
     return Op;
   }
-  static MachineOperand CreateES(const char *SymName, int Offset = 0) {
+  static MachineOperand CreateES(const char *SymName, int64_t Offset = 0) {
     MachineOperand Op(MachineOperand::MO_ExternalSymbol);
     Op.Contents.OffsetedInfo.Val.SymbolName = SymName;
     Op.setOffset(Offset);