From 111ec25a8e40a320ec25ea332a65ca3ee327be37 Mon Sep 17 00:00:00 2001
From: Simon Dardis <simon.dardis@imgtec.com>
Date: Fri, 24 Jun 2016 08:43:27 +0000
Subject: [PATCH] Revert "Revert "[misched] Extend scheduler to handle
 unsupported features""

This reverts commit r273565.

This was an over-eager revert.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@273658 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Target/TargetSchedule.td | 16 ++++++++++++++
 utils/TableGen/CodeGenSchedule.cpp    | 30 ++++++++++++++++++++++++++-
 utils/TableGen/CodeGenSchedule.h      |  8 +++++++
 3 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/include/llvm/Target/TargetSchedule.td b/include/llvm/Target/TargetSchedule.td
index 7f92e8b6556..74b98ac5f6c 100644
--- a/include/llvm/Target/TargetSchedule.td
+++ b/include/llvm/Target/TargetSchedule.td
@@ -55,6 +55,8 @@ include "llvm/Target/TargetItinerary.td"
 
 class Instruction; // Forward def
 
+class Predicate; // Forward def
+
 // DAG operator that interprets the DAG args as Instruction defs.
 def instrs;
 
@@ -97,6 +99,20 @@ class SchedMachineModel {
   // resulting from changes to the instruction definitions.
   bit CompleteModel = 1;
 
+  // A processor may only implement part of published ISA, due to either new ISA
+  // extensions, (e.g. Pentium 4 doesn't have AVX) or implementation
+  // (ARM/MIPS/PowerPC/SPARC soft float cores).
+  //
+  // For a processor which doesn't support some feature(s), the schedule model
+  // can use:
+  //
+  // let<Predicate> UnsupportedFeatures = [HaveA,..,HaveY];
+  //
+  // to skip the checks for scheduling information when building LLVM for
+  // instructions which have any of the listed predicates in their Predicates
+  // field.
+  list<Predicate> UnsupportedFeatures = [];
+
   bit NoModel = 0; // Special tag to indicate missing machine model.
 }
 
diff --git a/utils/TableGen/CodeGenSchedule.cpp b/utils/TableGen/CodeGenSchedule.cpp
index 57a426bffb3..d1b141e3160 100644
--- a/utils/TableGen/CodeGenSchedule.cpp
+++ b/utils/TableGen/CodeGenSchedule.cpp
@@ -120,6 +120,10 @@ CodeGenSchedModels::CodeGenSchedModels(RecordKeeper &RK,
   // (For per-operand resources mapped to itinerary classes).
   collectProcItinRW();
 
+  // Find UnsupportedFeatures records for each processor.
+  // (For per-operand resources mapped to itinerary classes).
+  collectProcUnsupportedFeatures();
+
   // Infer new SchedClasses from SchedVariant.
   inferSchedClasses();
 
@@ -829,6 +833,15 @@ void CodeGenSchedModels::collectProcItinRW() {
   }
 }
 
+// Gather the unsupported features for processor models.
+void CodeGenSchedModels::collectProcUnsupportedFeatures() {
+  for (CodeGenProcModel &ProcModel : ProcModels) {
+    for (Record *Pred : ProcModel.ModelDef->getValueAsListOfDefs("UnsupportedFeatures")) {
+       ProcModel.UnsupportedFeaturesDefs.push_back(Pred);
+    }
+  }
+}
+
 /// Infer new classes from existing classes. In the process, this may create new
 /// SchedWrites from sequences of existing SchedWrites.
 void CodeGenSchedModels::inferSchedClasses() {
@@ -1540,6 +1553,8 @@ void CodeGenSchedModels::checkCompleteness() {
     for (const CodeGenInstruction *Inst : Target.getInstructionsByEnumValue()) {
       if (Inst->hasNoSchedulingInfo)
         continue;
+      if (ProcModel.isUnsupported(*Inst))
+        continue;
       unsigned SCIdx = getSchedClassIdx(*Inst);
       if (!SCIdx) {
         if (Inst->TheDef->isValueUnset("SchedRW") && !HadCompleteModel) {
@@ -1575,7 +1590,10 @@ void CodeGenSchedModels::checkCompleteness() {
       << "- Consider setting 'CompleteModel = 0' while developing new models.\n"
       << "- Pseudo instructions can be marked with 'hasNoSchedulingInfo = 1'.\n"
       << "- Instructions should usually have Sched<[...]> as a superclass, "
-         "you may temporarily use an empty list.\n\n";
+         "you may temporarily use an empty list.\n"
+      << "- Instructions related to unsupported features can be excluded with "
+         "list<Predicate> UnsupportedFeatures = [HasA,..,HasY]; in the "
+         "processor model.\n\n";
     PrintFatalError("Incomplete schedule model");
   }
 }
@@ -1756,6 +1774,16 @@ unsigned CodeGenProcModel::getProcResourceIdx(Record *PRDef) const {
   return 1 + (PRPos - ProcResourceDefs.begin());
 }
 
+bool CodeGenProcModel::isUnsupported(const CodeGenInstruction &Inst) const {
+  for (const Record *TheDef : UnsupportedFeaturesDefs) {
+    for (const Record *PredDef : Inst.TheDef->getValueAsListOfDefs("Predicates")) {
+      if (TheDef->getName() == PredDef->getName())
+        return true;
+    }
+  }
+  return false;
+}
+
 #ifndef NDEBUG
 void CodeGenProcModel::dump() const {
   dbgs() << Index << ": " << ModelName << " "
diff --git a/utils/TableGen/CodeGenSchedule.h b/utils/TableGen/CodeGenSchedule.h
index 7a236ad0dd8..755ffd25b0c 100644
--- a/utils/TableGen/CodeGenSchedule.h
+++ b/utils/TableGen/CodeGenSchedule.h
@@ -189,6 +189,10 @@ struct CodeGenProcModel {
   // This list is empty if no ItinRW refers to this Processor.
   RecVec ItinRWDefs;
 
+  // List of unsupported feature.
+  // This list is empty if the Processor has no UnsupportedFeatures.
+  RecVec UnsupportedFeaturesDefs;
+
   // All read/write resources associated with this processor.
   RecVec WriteResDefs;
   RecVec ReadAdvanceDefs;
@@ -211,6 +215,8 @@ struct CodeGenProcModel {
 
   unsigned getProcResourceIdx(Record *PRDef) const;
 
+  bool isUnsupported(const CodeGenInstruction &Inst) const;
+
 #ifndef NDEBUG
   void dump() const;
 #endif
@@ -402,6 +408,8 @@ private:
 
   void collectProcItinRW();
 
+  void collectProcUnsupportedFeatures();
+
   void inferSchedClasses();
 
   void checkCompleteness();