Similarly, analyze truncate through multiply.

llvm-svn: 123842

1 files changed, 14 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 7258feca6c7..424f74427be 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -833,6 +833,20 @@ const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op,
       return getAddExpr(Operands, false, false);
   }
 
+  // trunc(x1*x2*...*xN) --> trunc(x1)*trunc(x2)*...*trunc(xN) if we can
+  // eliminate all the truncates.
+  if (const SCEVMulExpr *SM = dyn_cast<SCEVMulExpr>(Op)) {
+    SmallVector<const SCEV *, 4> Operands;
+    bool hasTrunc = false;
+    for (unsigned i = 0, e = SM->getNumOperands(); i != e && !hasTrunc; ++i) {
+      const SCEV *S = getTruncateExpr(SM->getOperand(i), Ty);
+      hasTrunc = isa<SCEVTruncateExpr>(S);
+      Operands.push_back(S);
+    }
+    if (!hasTrunc)
+      return getMulExpr(Operands, false, false);
+  }
+
   // If the input value is a chrec scev, truncate the chrec's operands.
   if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
     SmallVector<const SCEV *, 4> Operands;