DAGCombiner: Turn divs of vector splats into vectorized multiplications.
Otherwise the legalizer would just scalarize everything. Support for
mulhi in the targets isn't that great yet so on most targets we get
exactly the same scalarized output. Add a test for x86 vector udiv.
I had to disable the mulhi nodes on ARM because there aren't any patterns
for it. As far as I know ARM has instructions for getting the high part of
a multiply so this should be fixed.
llvm-svn: 207315
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index a52dacf..7850bc2 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -2024,7 +2024,7 @@
// if integer divide is expensive and we satisfy the requirements, emit an
// alternate sequence.
- if (N1C && !N1C->isNullValue() && !TLI.isIntDivCheap()) {
+ if ((N1C || N1->getOpcode() == ISD::BUILD_VECTOR) && !TLI.isIntDivCheap()) {
SDValue Op = BuildSDIV(N);
if (Op.getNode()) return Op;
}
@@ -2076,7 +2076,7 @@
}
}
// fold (udiv x, c) -> alternate
- if (N1C && !N1C->isNullValue() && !TLI.isIntDivCheap()) {
+ if ((N1C || N1->getOpcode() == ISD::BUILD_VECTOR) && !TLI.isIntDivCheap()) {
SDValue Op = BuildUDIV(N);
if (Op.getNode()) return Op;
}
@@ -11191,8 +11191,24 @@
/// multiplying by a magic number. See:
/// <http://the.wall.riscom.net/books/proc/ppc/cwg/code2.html>
SDValue DAGCombiner::BuildSDIV(SDNode *N) {
+ const APInt *Divisor;
+ if (N->getValueType(0).isVector()) {
+ // Handle splat vectors.
+ BuildVectorSDNode *BV = cast<BuildVectorSDNode>(N->getOperand(1));
+ if (ConstantSDNode *C = BV->getConstantSplatValue())
+ Divisor = &C->getAPIntValue();
+ else
+ return SDValue();
+ } else {
+ Divisor = &cast<ConstantSDNode>(N->getOperand(1))->getAPIntValue();
+ }
+
+ // Avoid division by zero.
+ if (!*Divisor)
+ return SDValue();
+
std::vector<SDNode*> Built;
- SDValue S = TLI.BuildSDIV(N, DAG, LegalOperations, &Built);
+ SDValue S = TLI.BuildSDIV(N, *Divisor, DAG, LegalOperations, &Built);
for (std::vector<SDNode*>::iterator ii = Built.begin(), ee = Built.end();
ii != ee; ++ii)
@@ -11200,13 +11216,29 @@
return S;
}
-/// BuildUDIVSequence - Given an ISD::UDIV node expressing a divide by constant,
+/// BuildUDIV - Given an ISD::UDIV node expressing a divide by constant,
/// return a DAG expression to select that will generate the same value by
/// multiplying by a magic number. See:
/// <http://the.wall.riscom.net/books/proc/ppc/cwg/code2.html>
SDValue DAGCombiner::BuildUDIV(SDNode *N) {
+ const APInt *Divisor;
+ if (N->getValueType(0).isVector()) {
+ // Handle splat vectors.
+ BuildVectorSDNode *BV = cast<BuildVectorSDNode>(N->getOperand(1));
+ if (ConstantSDNode *C = BV->getConstantSplatValue())
+ Divisor = &C->getAPIntValue();
+ else
+ return SDValue();
+ } else {
+ Divisor = &cast<ConstantSDNode>(N->getOperand(1))->getAPIntValue();
+ }
+
+ // Avoid division by zero.
+ if (!*Divisor)
+ return SDValue();
+
std::vector<SDNode*> Built;
- SDValue S = TLI.BuildUDIV(N, DAG, LegalOperations, &Built);
+ SDValue S = TLI.BuildUDIV(N, *Divisor, DAG, LegalOperations, &Built);
for (std::vector<SDNode*>::iterator ii = Built.begin(), ee = Built.end();
ii != ee; ++ii)