[RISCV] Add scheduling information for SiFive VCIX (#86093)

This adds `RISCVScheduleXSf.td` with `SchedWrite` definitions for all VCIX instructions and uses it in `RISCVSchedSiFive7.td` to set default latencies for these instructions, helping with issue #83391. Of course these default latencies cannot be accurate (since each coprocessor will have different latencies), but this seems to be enough to avoid some of the problematic behavior described in the bug. In any case, this seems to be enough to help with #83391 in our internal testing. A subsequent discussion is how to structure the code such that it's easier for downstream consumers of this to use `SiFive7` scheduling model with accurate VCIX latencies. But we can probably have a separate issue to discuss that.
llvm · Apr 16, 2024 · 6da1966 · 6da1966
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diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfoXSf.td b/llvm/lib/Target/RISCV/RISCVInstrInfoXSf.td
@@ -307,44 +307,68 @@ multiclass VPseudoVC_X<LMULInfo m, DAGOperand RS1Class,
                        Operand OpClass = payload2> {
   let VLMul = m.value in {
     let Defs = [VCIX_STATE], Uses = [VCIX_STATE] in {
-      def "PseudoVC_" # NAME # "_SE_" # m.MX : VPseudoVC_X<OpClass, RS1Class>;
-      def "PseudoVC_V_" # NAME # "_SE_" # m.MX : VPseudoVC_V_X<OpClass, m.vrclass, RS1Class>;
+      def "PseudoVC_" # NAME # "_SE_" # m.MX
+        : VPseudoVC_X<OpClass, RS1Class>,
+          Sched<[!cast<SchedWrite>("WriteVC_" # NAME # "_" # m.MX)]>;
+      def "PseudoVC_V_" # NAME # "_SE_" # m.MX
+        : VPseudoVC_V_X<OpClass, m.vrclass, RS1Class>,
+          Sched<[!cast<SchedWrite>("WriteVC_V_" # NAME # "_" # m.MX)]>;
     }
-    def "PseudoVC_V_" # NAME # "_" # m.MX : VPseudoVC_V_X<OpClass, m.vrclass, RS1Class>;
+    def "PseudoVC_V_" # NAME # "_" # m.MX
+      : VPseudoVC_V_X<OpClass, m.vrclass, RS1Class>,
+        Sched<[!cast<SchedWrite>("WriteVC_V_" # NAME # "_" # m.MX)]>;
   }
 }
 
 multiclass VPseudoVC_XV<LMULInfo m, DAGOperand RS1Class,
                         Operand OpClass = payload2> {
   let VLMul = m.value in {
     let Defs = [VCIX_STATE], Uses = [VCIX_STATE] in {
-      def "PseudoVC_" # NAME # "_SE_" # m.MX : VPseudoVC_XV<OpClass, m.vrclass, RS1Class>;
-      def "PseudoVC_V_" # NAME # "_SE_" # m.MX : VPseudoVC_V_XV<OpClass, m.vrclass, m.vrclass, RS1Class>;
+      def "PseudoVC_" # NAME # "_SE_" # m.MX
+        : VPseudoVC_XV<OpClass, m.vrclass, RS1Class>,
+          Sched<[!cast<SchedWrite>("WriteVC_" # NAME # "_" # m.MX)]>;
+      def "PseudoVC_V_" # NAME # "_SE_" # m.MX
+        : VPseudoVC_V_XV<OpClass, m.vrclass, m.vrclass, RS1Class>,
+          Sched<[!cast<SchedWrite>("WriteVC_V_" # NAME # "_" # m.MX)]>;
     }
-    def "PseudoVC_V_" # NAME # "_" # m.MX : VPseudoVC_V_XV<OpClass, m.vrclass, m.vrclass, RS1Class>;
+    def "PseudoVC_V_" # NAME # "_" # m.MX
+      : VPseudoVC_V_XV<OpClass, m.vrclass, m.vrclass, RS1Class>,
+        Sched<[!cast<SchedWrite>("WriteVC_V_" # NAME # "_" # m.MX)]>;
   }
 }
 
 multiclass VPseudoVC_XVV<LMULInfo m, DAGOperand RS1Class,
                          Operand OpClass = payload2> {
   let VLMul = m.value in {
     let Defs = [VCIX_STATE], Uses = [VCIX_STATE] in {
-      def "PseudoVC_" # NAME # "_SE_" # m.MX : VPseudoVC_XVV<OpClass, m.vrclass, m.vrclass, RS1Class>;
-      def "PseudoVC_V_" # NAME # "_SE_" # m.MX : VPseudoVC_V_XVV<OpClass, m.vrclass, m.vrclass, RS1Class>;
+      def "PseudoVC_" # NAME # "_SE_" # m.MX
+        : VPseudoVC_XVV<OpClass, m.vrclass, m.vrclass, RS1Class>,
+          Sched<[!cast<SchedWrite>("WriteVC_" # NAME # "_" # m.MX)]>;
+      def "PseudoVC_V_" # NAME # "_SE_" # m.MX
+        : VPseudoVC_V_XVV<OpClass, m.vrclass, m.vrclass, RS1Class>,
+          Sched<[!cast<SchedWrite>("WriteVC_V_" # NAME # "_" # m.MX)]>;
     }
-    def "PseudoVC_V_" # NAME # "_" # m.MX : VPseudoVC_V_XVV<OpClass, m.vrclass, m.vrclass, RS1Class>;
+    def "PseudoVC_V_" # NAME # "_" # m.MX
+      : VPseudoVC_V_XVV<OpClass, m.vrclass, m.vrclass, RS1Class>,
+        Sched<[!cast<SchedWrite>("WriteVC_V_" # NAME # "_" # m.MX)]>;
   }
 }
 
 multiclass VPseudoVC_XVW<LMULInfo m, DAGOperand RS1Class,
                          Operand OpClass = payload2> {
   let VLMul = m.value in {
     let Defs = [VCIX_STATE], Uses = [VCIX_STATE] in
-    def "PseudoVC_" # NAME # "_SE_" # m.MX : VPseudoVC_XVV<OpClass, m.wvrclass, m.vrclass, RS1Class>;
+    def "PseudoVC_" # NAME # "_SE_" # m.MX
+      : VPseudoVC_XVV<OpClass, m.wvrclass, m.vrclass, RS1Class>,
+        Sched<[!cast<SchedWrite>("WriteVC_" # NAME # "_" # m.MX)]>;
     let Constraints = "@earlyclobber $rd, $rd = $rs3" in {
       let Defs = [VCIX_STATE], Uses = [VCIX_STATE] in
-      def "PseudoVC_V_" # NAME # "_SE_" # m.MX : VPseudoVC_V_XVV<OpClass, m.wvrclass, m.vrclass, RS1Class>;
-      def "PseudoVC_V_" # NAME # "_" # m.MX : VPseudoVC_V_XVV<OpClass, m.wvrclass, m.vrclass, RS1Class>;
+      def "PseudoVC_V_" # NAME # "_SE_" # m.MX
+        : VPseudoVC_V_XVV<OpClass, m.wvrclass, m.vrclass, RS1Class>,
+          Sched<[!cast<SchedWrite>("WriteVC_V_" # NAME # "_" # m.MX)]>;
+      def "PseudoVC_V_" # NAME # "_" # m.MX
+        : VPseudoVC_V_XVV<OpClass, m.wvrclass, m.vrclass, RS1Class>,
+          Sched<[!cast<SchedWrite>("WriteVC_V_" # NAME # "_" # m.MX)]>;
     }
   }
 }

diff --git a/llvm/lib/Target/RISCV/RISCVSchedRocket.td b/llvm/lib/Target/RISCV/RISCVSchedRocket.td
@@ -261,4 +261,5 @@ defm : UnsupportedSchedZbkx;
 defm : UnsupportedSchedZfa;
 defm : UnsupportedSchedZfh;
 defm : UnsupportedSchedSFB;
+defm : UnsupportedSchedXsfvcp;
 }
diff --git a/llvm/lib/Target/RISCV/RISCVSchedSiFive7.td b/llvm/lib/Target/RISCV/RISCVSchedSiFive7.td
@@ -962,6 +962,54 @@ let Latency = 3 in
 
 def : InstRW<[WriteIALU], (instrs COPY)>;
 
+// VCIX
+//
+// In principle we don't know the latency of any VCIX instructions. But instead
+// of taking the default of 1, which can lead to issues [1], we assume that they
+// have a fairly high latency.
+//
+// [1] https://github.com/llvm/llvm-project/issues/83391
+foreach mx = SchedMxList in {
+  defvar Cycles = SiFive7GetCyclesDefault<mx>.c;
+  defvar IsWorstCase = SiFive7IsWorstCaseMX<mx, SchedMxList>.c;
+  let Latency = !mul(Cycles, 10),
+      AcquireAtCycles = [0, 1],
+      ReleaseAtCycles = [1, !add(1, Cycles)] in {
+    defm "" : LMULWriteResMX<"WriteVC_V_I",   [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    defm "" : LMULWriteResMX<"WriteVC_V_X",   [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    defm "" : LMULWriteResMX<"WriteVC_V_IV",  [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    defm "" : LMULWriteResMX<"WriteVC_V_VV",  [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    defm "" : LMULWriteResMX<"WriteVC_V_XV",  [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    defm "" : LMULWriteResMX<"WriteVC_V_IVV", [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    defm "" : LMULWriteResMX<"WriteVC_V_IVW", [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    defm "" : LMULWriteResMX<"WriteVC_V_VVV", [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    defm "" : LMULWriteResMX<"WriteVC_V_VVW", [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    defm "" : LMULWriteResMX<"WriteVC_V_XVV", [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    defm "" : LMULWriteResMX<"WriteVC_V_XVW", [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    foreach f = ["FPR16", "FPR32", "FPR64"] in {
+      defm "" : LMULWriteResMX<"WriteVC_V_" # f # "V",  [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+      defm "" : LMULWriteResMX<"WriteVC_V_" # f # "VV", [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+      defm "" : LMULWriteResMX<"WriteVC_V_" # f # "VW", [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    }
+    defm "" : LMULWriteResMX<"WriteVC_I",   [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    defm "" : LMULWriteResMX<"WriteVC_X",   [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    defm "" : LMULWriteResMX<"WriteVC_IV",  [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    defm "" : LMULWriteResMX<"WriteVC_VV",  [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    defm "" : LMULWriteResMX<"WriteVC_XV",  [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    defm "" : LMULWriteResMX<"WriteVC_IVV", [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    defm "" : LMULWriteResMX<"WriteVC_IVW", [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    defm "" : LMULWriteResMX<"WriteVC_VVV", [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    defm "" : LMULWriteResMX<"WriteVC_VVW", [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    defm "" : LMULWriteResMX<"WriteVC_XVV", [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    defm "" : LMULWriteResMX<"WriteVC_XVW", [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    foreach f = ["FPR16", "FPR32", "FPR64"] in {
+      defm "" : LMULWriteResMX<"WriteVC_" # f # "V",  [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+      defm "" : LMULWriteResMX<"WriteVC_" # f # "VV", [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+      defm "" : LMULWriteResMX<"WriteVC_" # f # "VW", [SiFive7VCQ, SiFive7VA], mx, IsWorstCase>;
+    }
+  }
+}
+
 //===----------------------------------------------------------------------===//
 
 // Bypass and advance

diff --git a/llvm/lib/Target/RISCV/RISCVSchedSiFiveP400.td b/llvm/lib/Target/RISCV/RISCVSchedSiFiveP400.td
@@ -366,4 +366,5 @@ defm : UnsupportedSchedZbkx;
 defm : UnsupportedSchedSFB;
 defm : UnsupportedSchedZfa;
 defm : UnsupportedSchedV;
+defm : UnsupportedSchedXsfvcp;
 }
diff --git a/llvm/lib/Target/RISCV/RISCVSchedSiFiveP600.td b/llvm/lib/Target/RISCV/RISCVSchedSiFiveP600.td
@@ -1040,4 +1040,5 @@ defm : UnsupportedSchedZbkb;
 defm : UnsupportedSchedZbkx;
 defm : UnsupportedSchedSFB;
 defm : UnsupportedSchedZfa;
+defm : UnsupportedSchedXsfvcp;
 }
diff --git a/llvm/lib/Target/RISCV/RISCVSchedSyntacoreSCR1.td b/llvm/lib/Target/RISCV/RISCVSchedSyntacoreSCR1.td
@@ -212,4 +212,5 @@ defm : UnsupportedSchedZbkb;
 defm : UnsupportedSchedZbkx;
 defm : UnsupportedSchedZfa;
 defm : UnsupportedSchedZfh;
+defm : UnsupportedSchedXsfvcp;
 }
diff --git a/llvm/lib/Target/RISCV/RISCVSchedXiangShanNanHu.td b/llvm/lib/Target/RISCV/RISCVSchedXiangShanNanHu.td
@@ -311,4 +311,5 @@ defm : UnsupportedSchedZfa;
 defm : UnsupportedSchedZfh;
 defm : UnsupportedSchedSFB;
 defm : UnsupportedSchedZabha;
+defm : UnsupportedSchedXsfvcp;
 }
diff --git a/llvm/lib/Target/RISCV/RISCVSchedule.td b/llvm/lib/Target/RISCV/RISCVSchedule.td
@@ -296,3 +296,4 @@ def : ReadAdvance<ReadAtomicHD, 0>;
 // Include the scheduler resources for other instruction extensions.
 include "RISCVScheduleZb.td"
 include "RISCVScheduleV.td"
+include "RISCVScheduleXSf.td"
diff --git a/llvm/lib/Target/RISCV/RISCVScheduleXSf.td b/llvm/lib/Target/RISCV/RISCVScheduleXSf.td
@@ -0,0 +1,59 @@
+//===-- RISCVScheduleXSf.td - Scheduling Definitions XSf ---*- tablegen -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file describes the scheduling information for SiFive extensions.
+//
+//===----------------------------------------------------------------------===//
+
+multiclass LMULSchedWritesVCIX<string id>{
+defm "" : LMULSchedWrites<"WriteVC_" # id>;
+defm "" : LMULSchedWrites<"WriteVC_V_" # id>;
+}
+
+defm "" : LMULSchedWritesVCIX<"I">;
+defm "" : LMULSchedWritesVCIX<"X">;
+defm "" : LMULSchedWritesVCIX<"IV">;
+defm "" : LMULSchedWritesVCIX<"VV">;
+defm "" : LMULSchedWritesVCIX<"XV">;
+defm "" : LMULSchedWritesVCIX<"IVV">;
+defm "" : LMULSchedWritesVCIX<"IVW">;
+defm "" : LMULSchedWritesVCIX<"VVV">;
+defm "" : LMULSchedWritesVCIX<"VVW">;
+defm "" : LMULSchedWritesVCIX<"XVV">;
+defm "" : LMULSchedWritesVCIX<"XVW">;
+foreach f = ["FPR16", "FPR32", "FPR64"] in {
+  defm "" : LMULSchedWritesVCIX<f # "V">;
+  defm "" : LMULSchedWritesVCIX<f # "VV">;
+  defm "" : LMULSchedWritesVCIX<f # "VW">;
+}
+
+multiclass LMULWriteResVCIX<string id, list<ProcResourceKind> resources>{
+defm : LMULWriteRes<"WriteVC_" # id, resources>;
+defm : LMULWriteRes<"WriteVC_V_" # id, resources>;
+}
+
+multiclass UnsupportedSchedXsfvcp {
+let Unsupported = true in {
+defm : LMULWriteResVCIX<"I", []>;
+defm : LMULWriteResVCIX<"X", []>;
+defm : LMULWriteResVCIX<"IV", []>;
+defm : LMULWriteResVCIX<"VV", []>;
+defm : LMULWriteResVCIX<"XV", []>;
+defm : LMULWriteResVCIX<"IVV", []>;
+defm : LMULWriteResVCIX<"IVW", []>;
+defm : LMULWriteResVCIX<"VVV", []>;
+defm : LMULWriteResVCIX<"VVW", []>;
+defm : LMULWriteResVCIX<"XVV", []>;
+defm : LMULWriteResVCIX<"XVW", []>;
+foreach f = ["FPR16", "FPR32", "FPR64"] in {
+  defm : LMULWriteResVCIX<f # "V", []>;
+  defm : LMULWriteResVCIX<f # "VV", []>;
+  defm : LMULWriteResVCIX<f # "VW", []>;
+}
+}
+}