InstCombine: Don't miscompile (x lshr C1) udiv C2

[oota-llvm.git] / lib / Support / APInt.cpp

diff --git a/lib/Support/APInt.cpp b/lib/Support/APInt.cpp
index 02778b2fc7c799510001d477db1d9d8fbd4615fe..c20eeb269484e7afe2f2eef807258ba097f061ae 100644 (file)
--- a/lib/Support/APInt.cpp
+++ b/lib/Support/APInt.cpp
@@ -2064,19 +2064,29 @@ APInt APInt::umul_ov(const APInt &RHS, bool &Overflow) const {
   return Res;
 }
 
-APInt APInt::sshl_ov(unsigned ShAmt, bool &Overflow) const {
-  Overflow = ShAmt >= getBitWidth();
+APInt APInt::sshl_ov(const APInt &ShAmt, bool &Overflow) const {
+  Overflow = ShAmt.uge(getBitWidth());
   if (Overflow)
-    ShAmt = getBitWidth()-1;
+    return APInt(BitWidth, 0);
 
   if (isNonNegative()) // Don't allow sign change.
-    Overflow = ShAmt >= countLeadingZeros();
+    Overflow = ShAmt.uge(countLeadingZeros());
   else
-    Overflow = ShAmt >= countLeadingOnes();
+    Overflow = ShAmt.uge(countLeadingOnes());
   
   return *this << ShAmt;
 }
 
+APInt APInt::ushl_ov(const APInt &ShAmt, bool &Overflow) const {
+  Overflow = ShAmt.uge(getBitWidth());
+  if (Overflow)
+    return APInt(BitWidth, 0);
+
+  Overflow = ShAmt.ugt(countLeadingZeros());
+
+  return *this << ShAmt;
+}
+