Legalizer optimize a pair of div / mod to a call to divrem libcall if they are
not legal. However, it should use a div instruction + mul + sub if divide is
legal. The rem legalization code was missing a check and incorrectly uses a
divrem libcall even when div is legal.
rdar://12481395
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165778 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index bb4f365..2ec129f 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -3153,6 +3153,8 @@
Tmp3 = Node->getOperand(1);
if (TLI.isOperationLegalOrCustom(DivRemOpc, VT) ||
(isDivRemLibcallAvailable(Node, isSigned, TLI) &&
+ // If div is legal, it's better to do the normal expansion
+ !TLI.isOperationLegalOrCustom(DivOpc, Node->getValueType(0)) &&
useDivRem(Node, isSigned, false))) {
Tmp1 = DAG.getNode(DivRemOpc, dl, VTs, Tmp2, Tmp3).getValue(1);
} else if (TLI.isOperationLegalOrCustom(DivOpc, VT)) {