LSR: Fold redundant bitcasts on-the-fly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146597 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Analysis/ScalarEvolutionExpander.cpp b/lib/Analysis/ScalarEvolutionExpander.cpp
index 59901aaa8390f2a9719b3b0b0d4560f3dd0db6e9..f3cf5494551576818656dab599bc7ed823c8aa36 100644 (file)
--- a/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -73,9 +73,14 @@ Value *SCEVExpander::InsertNoopCastOfTo(Value *V, Type *Ty) {
          "InsertNoopCastOfTo cannot change sizes!");
 
   // Short-circuit unnecessary bitcasts.
-  if (Op == Instruction::BitCast && V->getType() == Ty)
-    return V;
-
+  if (Op == Instruction::BitCast) {
+    if (V->getType() == Ty)
+      return V;
+    if (CastInst *CI = dyn_cast<CastInst>(V)) {
+      if (CI->getOperand(0)->getType() == Ty)
+        return CI->getOperand(0);
+    }
+  }
   // Short-circuit unnecessary inttoptr<->ptrtoint casts.
   if ((Op == Instruction::PtrToInt || Op == Instruction::IntToPtr) &&
       SE.getTypeSizeInBits(Ty) == SE.getTypeSizeInBits(V->getType())) {

diff --git a/test/Transforms/LoopStrengthReduce/post-inc-icmpzero.ll b/test/Transforms/LoopStrengthReduce/post-inc-icmpzero.ll
index 27609157ec8c5cc871e3fbc40e6cdc7848559642..76aa08c26e85008453fe651e9b7ff9400ff76d99 100644 (file)
--- a/test/Transforms/LoopStrengthReduce/post-inc-icmpzero.ll
+++ b/test/Transforms/LoopStrengthReduce/post-inc-icmpzero.ll
@@ -4,12 +4,12 @@
 ; LSR should property handle the post-inc offset when folding the
 ; non-IV operand of an icmp into the IV.
 
-; CHECK:   %5 = sub i64 %sub.ptr.lhs.cast, %sub.ptr.rhs.cast
-; CHECK:   %6 = lshr i64 %5, 1
-; CHECK:   %7 = mul i64 %6, 2
+; CHECK:   %4 = sub i64 %sub.ptr.lhs.cast, %sub.ptr.rhs.cast
+; CHECK:   %5 = lshr i64 %4, 1
+; CHECK:   %6 = mul i64 %5, 2
 ; CHECK:   br label %for.body
 ; CHECK: for.body:
-; CHECK:   %lsr.iv2 = phi i64 [ %lsr.iv.next, %for.body ], [ %7, %for.body.lr.ph ]
+; CHECK:   %lsr.iv2 = phi i64 [ %lsr.iv.next, %for.body ], [ %6, %for.body.lr.ph ]
 ; CHECK:   %lsr.iv.next = add i64 %lsr.iv2, -2
 ; CHECK:   %lsr.iv.next3 = inttoptr i64 %lsr.iv.next to i16*
 ; CHECK:   %cmp27 = icmp eq i16* %lsr.iv.next3, null