[AMDGPU] Match udot8 pattern

Summary: D.u32 = S0.u4[0] * S1.u4[0] +

         S0.u4[1] * S1.u4[1] +
         S0.u4[2] * S1.u4[2] +
         S0.u4[3] * S1.u4[3] +
         S0.u4[4] * S1.u4[4] +
         S0.u4[5] * S1.u4[5] +
         S0.u4[6] * S1.u4[6] +
         S0.u4[7] * S1.u4[7] +
         S2.u32

Author: FarhanaAleen

Reviewed By: arsenm, nhaehnle

Differential Revision: https://reviews.llvm.org/D51947

llvm-svn: 342497

llvm/lib/Target/AMDGPU/VOP3PInstructions.td

@@ -168,34 +168,53 @@ defm : MadFmaMixPats<fma, V_FMA_MIX_F32, V_FMA_MIXLO_F16, V_FMA_MIXHI_F16>;
 class Srl<int N> : PatFrag<(ops node:$src),
                            (srl node:$src, (i32 N))>;
 
-foreach Bits = [8, 16, 24] in {
-  def srl#Bits : Srl<Bits>;
-}
+foreach Bits = 1-7 in
+  def srl#!shl(Bits, 2) : Srl<!shl(Bits, 2)>;
 
-def and_255 : PatFrag<
-  (ops node:$src0), (and node:$src0, (i32 255))
->;
-
-class Extract_U8<int FromBitIndex> : PatFrag<(
-  ops node:$src),
-  !if (!eq (FromBitIndex, 24), // last element
+class Extract_U<int FromBitIndex, int BitMask> : PatFrag<
+  (ops node:$src),
+  !if (!or (!and (!eq (BitMask, 255), !eq (FromBitIndex, 24)),
+            !and (!eq (BitMask, 15), !eq (FromBitIndex, 28))), // last element
        (!cast<Srl>("srl"#FromBitIndex) node:$src),
        !if (!eq (FromBitIndex, 0), // first element
-            (and_255 node:$src),
-            (and_255 (!cast<Srl>("srl"#FromBitIndex) node:$src))))>;
+            (and node:$src, (i32 BitMask)),
+            (and (!cast<Srl>("srl"#FromBitIndex) node:$src), (i32 BitMask))))>;
 
-// Defines patterns that extract each Index'ed 8bit from a 32bit scalar value;
-foreach Index = [1, 2, 3, 4] in {
-  def UElt#Index : Extract_U8<!shl(!add(Index, -1), 3)>;
-}
+foreach Index = 0-3 in {
+  // Defines patterns that extract each Index'ed 8bit from an unsigned
+  // 32bit scalar value;
+  def U#Index#"_8bit" : Extract_U<!shl(Index, 3),
+                                  255>;
 
-// Defines multiplication patterns where the multiplication is happening on each
-// Index'ed 8bit of a 32bit scalar value.
-foreach Index = [1, 2, 3, 4] in {
+  // Defines multiplication patterns where the multiplication is happening on each
+  // Index'ed 8bit of a 32bit scalar value.
   def MulU_Elt#Index : PatFrag<
     (ops node:$src0, node:$src1),
-    (AMDGPUmul_u24_oneuse (!cast<Extract_U8>("UElt"#Index) node:$src0),
-                          (!cast<Extract_U8>("UElt"#Index) node:$src1))>;
+    (AMDGPUmul_u24_oneuse (!cast<Extract_U>("U"#Index#"_8bit") node:$src0),
+                          (!cast<Extract_U>("U"#Index#"_8bit") node:$src1))>;
+}
+
+// Different variants of dot8 patterns cause a huge increase in the compile time.
+// Define non-associative/commutative add/mul to prevent permutation in the dot8
+// pattern.
+def NonACAdd        : SDNode<"ISD::ADD"       , SDTIntBinOp>;
+def NonACAdd_oneuse : HasOneUseBinOp<NonACAdd>;
+
+def NonACAMDGPUmul_u24        : SDNode<"AMDGPUISD::MUL_U24"       , SDTIntBinOp>;
+def NonACAMDGPUmul_u24_oneuse : HasOneUseBinOp<NonACAMDGPUmul_u24>;
+
+foreach Index = 0-7 in {
+  // Defines patterns that extract each Index'ed 4bit from an unsigned
+  // 32bit scalar value;
+  def U#Index#"_4bit" : Extract_U<!shl(Index, 2),
+                                  15>;
+
+  // Defines multiplication patterns where the multiplication is happening on each
+  // Index'ed 8bit of a 32bit scalar value.
+  def MulU#Index#"_4bit" : PatFrag<
+    (ops node:$src0, node:$src1),
+    (NonACAMDGPUmul_u24_oneuse (!cast<Extract_U>("U"#Index#"_4bit") node:$src0),
+                               (!cast<Extract_U>("U"#Index#"_4bit") node:$src1))>;
 }
 
 class UDot2Pat<Instruction Inst> : GCNPat <
@@ -246,11 +265,17 @@ def : UDot2Pat<V_DOT2_U32_U16>;
 def : SDot2Pat<V_DOT2_I32_I16>;
 
 def : GCNPat <
-  !cast<dag>(!foldl((i32 i32:$src2), [1, 2, 3, 4], lhs, y,
+  !cast<dag>(!foldl((i32 i32:$src2), [0, 1, 2, 3], lhs, y,
                     (add_oneuse lhs, (!cast<PatFrag>("MulU_Elt"#y) i32:$src0, i32:$src1)))),
   (V_DOT4_U32_U8 (i32 8), $src0, (i32 8), $src1, (i32 8), $src2, (i1 0))
 >;
 
+def : GCNPat <
+  !cast<dag>(!foldl((add_oneuse i32:$src2, (MulU0_4bit i32:$src0, i32:$src1)), [1, 2, 3, 4, 5, 6, 7], lhs, y,
+                    (NonACAdd_oneuse lhs, (!cast<PatFrag>("MulU"#y#"_4bit") i32:$src0, i32:$src1)))),
+  (V_DOT8_U32_U4 (i32 8), $src0, (i32 8), $src1, (i32 8), $src2, (i1 0))
+>;
+
 } // End SubtargetPredicate = HasDLInsts
 
 multiclass VOP3P_Real_vi<bits<10> op> {