Enable rematerialization of constants using AliasAnalysis::pointsToConstantMemory,

and knowledge of PseudoSourceValues. This unfortunately isn't sufficient to allow
constants to be rematerialized in PIC mode -- the extra indirection is a
complication.

llvm-svn: 54000

1 files changed, 20 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/PseudoSourceValue.cpp b/llvm/lib/CodeGen/PseudoSourceValue.cpp
index 27995547c60..bcf4ea8fb75 100644
--- a/llvm/lib/CodeGen/PseudoSourceValue.cpp
+++ b/llvm/lib/CodeGen/PseudoSourceValue.cpp
@@ -11,6 +11,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/PseudoSourceValue.h"
 #include "llvm/DerivedTypes.h"
 #include "llvm/Support/Compiler.h"
@@ -51,6 +52,9 @@ namespace llvm {
     const int FI;
   public:
     explicit FixedStackPseudoSourceValue(int fi) : FI(fi) {}
+
+    virtual bool isConstant(const MachineFrameInfo *MFI) const;
+
     virtual void print(std::ostream &OS) const {
       OS << "FixedStack" << FI;
     }
@@ -64,4 +68,20 @@ namespace llvm {
       V = new FixedStackPseudoSourceValue(FI);
     return V;
   }
+
+  bool PseudoSourceValue::isConstant(const MachineFrameInfo *) const {
+    if (this == getStack())
+      return false;
+    if (this == getGOT() ||
+        this == getConstantPool() ||
+        this == getJumpTable())
+      return true;
+    assert(0 && "Unknown PseudoSourceValue!");
+    return false;
+  }
+
+  bool
+  FixedStackPseudoSourceValue::isConstant(const MachineFrameInfo *MFI) const {
+    return MFI && MFI->isImmutableObjectIndex(FI);
+  }
 }