[PPC] Implement vmrgew and vmrgow instructions
This patch adds support for the vector merge even word and vector merge odd word
instructions introduced in POWER8.
Phabricator review: http://reviews.llvm.org/D10704
llvm-svn: 240650
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 2600ee5..af493c0 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -1279,6 +1279,99 @@
}
}
+/**
+ * \brief Common function used to match vmrgew and vmrgow shuffles
+ *
+ * The indexOffset determines whether to look for even or odd words in
+ * the shuffle mask. This is based on the of the endianness of the target
+ * machine.
+ * - Little Endian:
+ * - Use offset of 0 to check for odd elements
+ * - Use offset of 4 to check for even elements
+ * - Big Endian:
+ * - Use offset of 0 to check for even elements
+ * - Use offset of 4 to check for odd elements
+ * A detailed description of the vector element ordering for little endian and
+ * big endian can be found at <a
+ * href="http://www.ibm.com/developerworks/library/l-ibm-xl-c-cpp-compiler/index.html">
+ * Targeting your applications - what little endian and big endian IBM XL C/C++
+ * compiler differences mean to you </a>
+ *
+ * The mask to the shuffle vector instruction specifies the indices of the
+ * elements from the two input vectors to place in the result. The elements are
+ * numbered in array-access order, starting with the first vector. These vectors
+ * are always of type v16i8, thus each vector will contain 16 elements of size
+ * 8. More info on the shuffle vector can be found in the <a
+ * href="http://llvm.org/docs/LangRef.html#shufflevector-instruction">Language
+ * Reference</a>.
+ *
+ * The RHSStartValue indicates whether the same input vectors are used (unary)
+ * or two different input vectors are used, based on the following:
+ * - If the instruction uses the same vector for both inputs, the range of the
+ * indices will be 0 to 15. In this case, the RHSStart value passed should
+ * be 0.
+ * - If the instruction has two different vectors then the range of the
+ * indices will be 0 to 31. In this case, the RHSStart value passed should
+ * be 16 (indices 0-15 specify elements in the first vector while indices 16
+ * to 31 specify elements in the second vector).
+ *
+ * \param[in] N The shuffle vector SD Node to analyze
+ * \param[in] IndexOffset Specifies whether to look for even or odd elements
+ * \param[in] RHSStartValue Specifies the starting index for the righthand input
+ * vector to the shuffle_vector instruction
+ * \return true iff this shuffle vector represents an even or odd word merge
+ */
+static bool isVMerge(ShuffleVectorSDNode *N, unsigned IndexOffset,
+ unsigned RHSStartValue) {
+ if (N->getValueType(0) != MVT::v16i8)
+ return false;
+
+ for (unsigned i = 0; i < 2; ++i)
+ for (unsigned j = 0; j < 4; ++j)
+ if (!isConstantOrUndef(N->getMaskElt(i*4+j),
+ i*RHSStartValue+j+IndexOffset) ||
+ !isConstantOrUndef(N->getMaskElt(i*4+j+8),
+ i*RHSStartValue+j+IndexOffset+8))
+ return false;
+ return true;
+}
+
+/**
+ * \brief Determine if the specified shuffle mask is suitable for the vmrgew or
+ * vmrgow instructions.
+ *
+ * \param[in] N The shuffle vector SD Node to analyze
+ * \param[in] CheckEven Check for an even merge (true) or an odd merge (false)
+ * \param[in] ShuffleKind Identify the type of merge:
+ * - 0 = big-endian merge with two different inputs;
+ * - 1 = either-endian merge with two identical inputs;
+ * - 2 = little-endian merge with two different inputs (inputs are swapped for
+ * little-endian merges).
+ * \param[in] DAG The current SelectionDAG
+ * \return true iff this shuffle mask
+ */
+bool PPC::isVMRGEOShuffleMask(ShuffleVectorSDNode *N, bool CheckEven,
+ unsigned ShuffleKind, SelectionDAG &DAG) {
+ if (DAG.getTarget().getDataLayout()->isLittleEndian()) {
+ unsigned indexOffset = CheckEven ? 4 : 0;
+ if (ShuffleKind == 1) // Unary
+ return isVMerge(N, indexOffset, 0);
+ else if (ShuffleKind == 2) // swapped
+ return isVMerge(N, indexOffset, 16);
+ else
+ return false;
+ }
+ else {
+ unsigned indexOffset = CheckEven ? 0 : 4;
+ if (ShuffleKind == 1) // Unary
+ return isVMerge(N, indexOffset, 0);
+ else if (ShuffleKind == 0) // Normal
+ return isVMerge(N, indexOffset, 16);
+ else
+ return false;
+ }
+ return false;
+}
/// isVSLDOIShuffleMask - If this is a vsldoi shuffle mask, return the shift
/// amount, otherwise return -1.
@@ -7046,7 +7139,9 @@
PPC::isVMRGLShuffleMask(SVOp, 4, 1, DAG) ||
PPC::isVMRGHShuffleMask(SVOp, 1, 1, DAG) ||
PPC::isVMRGHShuffleMask(SVOp, 2, 1, DAG) ||
- PPC::isVMRGHShuffleMask(SVOp, 4, 1, DAG)) {
+ PPC::isVMRGHShuffleMask(SVOp, 4, 1, DAG) ||
+ PPC::isVMRGEOShuffleMask(SVOp, true, 1, DAG) ||
+ PPC::isVMRGEOShuffleMask(SVOp, false, 1, DAG)) {
return Op;
}
}
@@ -7064,7 +7159,9 @@
PPC::isVMRGLShuffleMask(SVOp, 4, ShuffleKind, DAG) ||
PPC::isVMRGHShuffleMask(SVOp, 1, ShuffleKind, DAG) ||
PPC::isVMRGHShuffleMask(SVOp, 2, ShuffleKind, DAG) ||
- PPC::isVMRGHShuffleMask(SVOp, 4, ShuffleKind, DAG))
+ PPC::isVMRGHShuffleMask(SVOp, 4, ShuffleKind, DAG) ||
+ PPC::isVMRGEOShuffleMask(SVOp, true, ShuffleKind, DAG) ||
+ PPC::isVMRGEOShuffleMask(SVOp, false, ShuffleKind, DAG))
return Op;
// Check to see if this is a shuffle of 4-byte values. If so, we can use our