fold (mul (add x, c1), c2) -> (add (mul x, c2), c1*c2)
fold (shl (add x, c1), c2) -> (add (shl x, c2), c1<<c2)
This allows us to compile CodeGen/PowerPC/addi-reassoc.ll into:
_test1:
slwi r2, r4, 4
add r2, r2, r3
lwz r3, 36(r2)
blr
_test2:
mulli r2, r4, 5
add r2, r2, r3
lbz r2, 11(r2)
extsb r3, r2
blr
instead of:
_test1:
addi r2, r4, 2
slwi r2, r2, 4
add r2, r3, r2
lwz r3, 4(r2)
blr
_test2:
addi r2, r4, 2
mulli r2, r2, 5
add r2, r3, r2
lbz r2, 1(r2)
extsb r3, r2
blr
llvm-svn: 26535
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 280c708..0cf6801 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -802,7 +802,13 @@
return DAG.getNode(ISD::SHL, VT, Mul, Sh.getOperand(1));
}
}
-
+ // fold (mul (add x, c1), c2) -> (add (mul x, c2), c1*c2)
+ if (N1C && N0.getOpcode() == ISD::ADD && N0.Val->hasOneUse() &&
+ isa<ConstantSDNode>(N0.getOperand(1))) {
+ return DAG.getNode(ISD::ADD, VT,
+ DAG.getNode(ISD::MUL, VT, N0.getOperand(0), N1),
+ DAG.getNode(ISD::MUL, VT, N0.getOperand(1), N1));
+ }
// reassociate mul
SDOperand RMUL = ReassociateOps(ISD::MUL, N0, N1);
@@ -1446,6 +1452,13 @@
if (N1C && N0.getOpcode() == ISD::SRA && N1 == N0.getOperand(1))
return DAG.getNode(ISD::AND, VT, N0.getOperand(0),
DAG.getConstant(~0ULL << N1C->getValue(), VT));
+ // fold (shl (add x, c1), c2) -> (add (shl x, c2), c1<<c2)
+ if (N1C && N0.getOpcode() == ISD::ADD && N0.Val->hasOneUse() &&
+ isa<ConstantSDNode>(N0.getOperand(1))) {
+ return DAG.getNode(ISD::ADD, VT,
+ DAG.getNode(ISD::SHL, VT, N0.getOperand(0), N1),
+ DAG.getNode(ISD::SHL, VT, N0.getOperand(1), N1));
+ }
return SDOperand();
}