Expand GEPs in ScalarEvolution expressions. SCEV expressions can now

have pointer types, though in contrast to C pointer types, SCEV
addition is never implicitly scaled. This not only eliminates the
need for special code like IndVars' EliminatePointerRecurrence
and LSR's own GEP expansion code, it also does a better job because
it lets the normal optimizations handle pointer expressions just
like integer expressions.

Also, since LLVM IR GEPs can't directly index into multi-dimensional
VLAs, moving the GEP analysis out of client code and into the SCEV
framework makes it easier for clients to handle multi-dimensional
VLAs the same way as other arrays.

Some existing regression tests show improved optimization.
test/CodeGen/ARM/2007-03-13-InstrSched.ll in particular improved to
the point where if-conversion started kicking in; I turned it off
for this test to preserve the intent of the test.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@69258 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 12 insertions, 7 deletions

diff --git a/include/llvm/Analysis/ScalarEvolution.h b/include/llvm/Analysis/ScalarEvolution.h
index 0b148da..e923ae5 100644
--- a/include/llvm/Analysis/ScalarEvolution.h
+++ b/include/llvm/Analysis/ScalarEvolution.h
@@ -32,6 +32,7 @@ namespace llvm {
   class Type;
   class SCEVHandle;
   class ScalarEvolution;
+  class TargetData;
 
   /// SCEV - This class represent an analyzed expression in the program.  These
   /// are reference counted opaque objects that the client is not allowed to
@@ -71,10 +72,6 @@ namespace llvm {
     ///
     virtual const Type *getType() const = 0;
 
-    /// getBitWidth - Get the bit width of the type, if it has one, 0 otherwise.
-    /// 
-    uint32_t getBitWidth() const;
-
     /// isZero - Return true if the expression is a constant zero.
     ///
     bool isZero() const;
@@ -199,6 +196,10 @@ namespace llvm {
     static char ID; // Pass identification, replacement for typeid
     ScalarEvolution() : FunctionPass(&ID), Impl(0) {}
 
+    // getTargetData - Return the TargetData object contained in this
+    // ScalarEvolution.
+    const TargetData &getTargetData() const;
+
     /// getSCEV - Return a SCEV expression handle for the full generality of the
     /// specified expression.
     SCEVHandle getSCEV(Value *V) const;
diff --git a/include/llvm/Analysis/ScalarEvolutionExpander.h b/include/llvm/Analysis/ScalarEvolutionExpander.h
index cd075ef..8126a58 100644
--- a/include/llvm/Analysis/ScalarEvolutionExpander.h
+++ b/include/llvm/Analysis/ScalarEvolutionExpander.h
@@ -20,6 +20,8 @@
 #include "llvm/Analysis/ScalarEvolutionExpressions.h"
 
 namespace llvm {
+  class TargetData;
+
   /// SCEVExpander - This class uses information about analyze scalars to
   /// rewrite expressions in canonical form.
   ///
@@ -29,6 +31,7 @@ namespace llvm {
   struct SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> {
     ScalarEvolution &SE;
     LoopInfo &LI;
+    const TargetData &TD;
     std::map<SCEVHandle, Value*> InsertedExpressions;
     std::set<Instruction*> InsertedInstructions;
 
@@ -36,7 +39,8 @@ namespace llvm {
 
     friend struct SCEVVisitor<SCEVExpander, Value*>;
   public:
-    SCEVExpander(ScalarEvolution &se, LoopInfo &li) : SE(se), LI(li) {}
+    SCEVExpander(ScalarEvolution &se, LoopInfo &li, const TargetData &td)
+      : SE(se), LI(li), TD(td) {}
 
     LoopInfo &getLoopInfo() const { return LI; }
 
@@ -75,7 +79,7 @@ namespace llvm {
     /// expandCodeFor - Insert code to directly compute the specified SCEV
     /// expression into the program.  The inserted code is inserted into the
     /// specified block.
-    Value *expandCodeFor(SCEVHandle SH, Instruction *IP);
+    Value *expandCodeFor(SCEVHandle SH, const Type *Ty, Instruction *IP);
 
     /// InsertCastOfTo - Insert a cast of V to the specified type, doing what
     /// we can to share the casts.
@@ -87,7 +91,7 @@ namespace llvm {
                               Value *RHS, Instruction *InsertPt);
   protected:
     Value *expand(SCEV *S);
-    
+
     Value *visitConstant(SCEVConstant *S) {
       return S->getValue();
     }