Combine PPC's GetConstantBuildVectorBits and isConstantSplat functions to a new
method in a BuildVectorSDNode "pseudo-class".
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65747 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 171ddbd..9dfd6be 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -5554,3 +5554,94 @@
return Val.MachineCPVal->getType();
return Val.ConstVal->getType();
}
+
+// If this is a splat (repetition) of a value across the whole vector, return
+// the smallest size that splats it. For example, "0x01010101010101..." is a
+// splat of 0x01, 0x0101, and 0x01010101. We return SplatBits = 0x01 and
+// SplatSize = 1 byte.
+bool BuildVectorSDNode::isConstantSplat(unsigned &SplatBits,
+ unsigned &SplatUndef,
+ unsigned &SplatSize,
+ bool &HasAnyUndefs) {
+ uint64_t Bits128[2];
+ uint64_t Undef128[2];
+
+ // If this is a vector of constants or undefs, get the bits. A bit in
+ // UndefBits is set if the corresponding element of the vector is an
+ // ISD::UNDEF value. For undefs, the corresponding VectorBits values are
+ // zero.
+
+ // Start with zero'd results.
+ Bits128[0] = Bits128[1] = Undef128[0] = Undef128[1] = 0;
+
+ unsigned EltBitSize = getOperand(0).getValueType().getSizeInBits();
+ for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
+ SDValue OpVal = getOperand(i);
+
+ unsigned PartNo = i >= e/2; // In the upper 128 bits?
+ unsigned SlotNo = e/2 - (i & (e/2-1))-1; // Which subpiece of the uint64_t.
+
+ uint64_t EltBits = 0;
+ if (OpVal.getOpcode() == ISD::UNDEF) {
+ uint64_t EltUndefBits = ~0U >> (32-EltBitSize);
+ Undef128[PartNo] |= EltUndefBits << (SlotNo*EltBitSize);
+ continue;
+ } else if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(OpVal)) {
+ EltBits = CN->getZExtValue() & (~0U >> (32-EltBitSize));
+ } else if (ConstantFPSDNode *CN = dyn_cast<ConstantFPSDNode>(OpVal)) {
+ assert(CN->getValueType(0) == MVT::f32 &&
+ "Only one legal FP vector type!");
+ EltBits = FloatToBits(CN->getValueAPF().convertToFloat());
+ } else {
+ // Nonconstant element.
+ return false;
+ }
+
+ Bits128[PartNo] |= EltBits << (SlotNo*EltBitSize);
+ }
+
+ // Don't let undefs prevent splats from matching. See if the top 64-bits are
+ // the same as the lower 64-bits, ignoring undefs.
+ if ((Bits128[0] & ~Undef128[1]) != (Bits128[1] & ~Undef128[0]))
+ return false; // Can't be a splat if two pieces don't match.
+
+ uint64_t Bits64 = Bits128[0] | Bits128[1];
+ uint64_t Undef64 = Undef128[0] & Undef128[1];
+
+ // Check that the top 32-bits are the same as the lower 32-bits, ignoring
+ // undefs.
+ if ((Bits64 & (~Undef64 >> 32)) != ((Bits64 >> 32) & ~Undef64))
+ return false; // Can't be a splat if two pieces don't match.
+
+ HasAnyUndefs = (Undef128[0] | Undef128[1]) != 0;
+
+ uint32_t Bits32 = uint32_t(Bits64) | uint32_t(Bits64 >> 32);
+ uint32_t Undef32 = uint32_t(Undef64) & uint32_t(Undef64 >> 32);
+
+ // If the top 16-bits are different than the lower 16-bits, ignoring
+ // undefs, we have an i32 splat.
+ if ((Bits32 & (~Undef32 >> 16)) != ((Bits32 >> 16) & ~Undef32)) {
+ SplatBits = Bits32;
+ SplatUndef = Undef32;
+ SplatSize = 4;
+ return true;
+ }
+
+ uint16_t Bits16 = uint16_t(Bits32) | uint16_t(Bits32 >> 16);
+ uint16_t Undef16 = uint16_t(Undef32) & uint16_t(Undef32 >> 16);
+
+ // If the top 8-bits are different than the lower 8-bits, ignoring
+ // undefs, we have an i16 splat.
+ if ((Bits16 & (uint16_t(~Undef16) >> 8)) != ((Bits16 >> 8) & ~Undef16)) {
+ SplatBits = Bits16;
+ SplatUndef = Undef16;
+ SplatSize = 2;
+ return true;
+ }
+
+ // Otherwise, we have an 8-bit splat.
+ SplatBits = uint8_t(Bits16) | uint8_t(Bits16 >> 8);
+ SplatUndef = uint8_t(Undef16) & uint8_t(Undef16 >> 8);
+ SplatSize = 1;
+ return true;
+}