Remove SCEVAllocSizeExpr and SCEVFieldOffsetExpr, and in their place

use plain SCEVUnknowns with ConstantExpr::getSizeOf and
ConstantExpr::getOffsetOf constants. This eliminates a bunch of
special-case code.

Also add code for pattern-matching these expressions, for clients that
want to recognize them.

Move ScalarEvolution's logic for expanding array and vector sizeof
expressions into an element count times the element size, to expose
the multiplication to subsequent folding, into the regular constant
folder.

llvm-svn: 94737

1 files changed, 9 insertions, 17 deletions

diff --git a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
index a72f58f64fa..9e2e712cdd0 100644
--- a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -427,22 +427,22 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *const *op_begin,
             }
           }
       } else {
-        // Without TargetData, just check for a SCEVFieldOffsetExpr of the
+        // Without TargetData, just check for an offsetof expression of the
         // appropriate struct type.
         for (unsigned i = 0, e = Ops.size(); i != e; ++i)
-          if (const SCEVFieldOffsetExpr *FO =
-                dyn_cast<SCEVFieldOffsetExpr>(Ops[i]))
-            if (FO->getStructType() == STy) {
-              unsigned FieldNo = FO->getFieldNo();
-              GepIndices.push_back(
-                  ConstantInt::get(Type::getInt32Ty(Ty->getContext()),
-                                   FieldNo));
-              ElTy = STy->getTypeAtIndex(FieldNo);
+          if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Ops[i])) {
+            const StructType *StructTy;
+            Constant *FieldNo;
+            if (U->isOffsetOf(StructTy, FieldNo) && StructTy == STy) {
+              GepIndices.push_back(FieldNo);
+              ElTy =
+                STy->getTypeAtIndex(cast<ConstantInt>(FieldNo)->getZExtValue());
               Ops[i] = SE.getConstant(Ty, 0);
               AnyNonZeroIndices = true;
               FoundFieldNo = true;
               break;
             }
+          }
       }
       // If no struct field offsets were found, tentatively assume that
       // field zero was selected (since the zero offset would obviously
@@ -1001,14 +1001,6 @@ Value *SCEVExpander::visitUMaxExpr(const SCEVUMaxExpr *S) {
   return LHS;
 }
 
-Value *SCEVExpander::visitFieldOffsetExpr(const SCEVFieldOffsetExpr *S) {
-  return ConstantExpr::getOffsetOf(S->getStructType(), S->getFieldNo());
-}
-
-Value *SCEVExpander::visitAllocSizeExpr(const SCEVAllocSizeExpr *S) {
-  return ConstantExpr::getSizeOf(S->getAllocType());
-}
-
 Value *SCEVExpander::expandCodeFor(const SCEV *SH, const Type *Ty) {
   // Expand the code for this SCEV.
   Value *V = expand(SH);