[TableGen][GISel] Delete unused Src arguments (NFC) (#120445)

The last uses were removed in #120332 and #120426.

When emitting renderers, we shouldn't look at the source DAG at all. The
required information is provided by the destination DAG and by the
instructions referenced in that DAG. Sometimes, we do want to know if a
result was referenced in the source DAG; this can be checked by calling
`RuleMatcher::hasOperand`. Any other use of the source DAG when emitting
renderers is likely an error.

Pull Request: #120445

Author: s-barannikov

llvm/utils/TableGen/GlobalISelEmitter.cpp

@@ -393,28 +393,30 @@ class GlobalISelEmitter final : public GlobalISelMatchTableExecutorEmitter {
                            bool OperandIsAPointer, bool OperandIsImmArg,
                            unsigned OpIdx, unsigned &TempOpIdx);
 
-  Expected<BuildMIAction &> createAndImportInstructionRenderer(
-      RuleMatcher &M, InstructionMatcher &InsnMatcher,
-      const TreePatternNode &Src, const TreePatternNode &Dst);
+  Expected<BuildMIAction &>
+  createAndImportInstructionRenderer(RuleMatcher &M,
+                                     InstructionMatcher &InsnMatcher,
+                                     const TreePatternNode &Dst);
   Expected<action_iterator> createAndImportSubInstructionRenderer(
       action_iterator InsertPt, RuleMatcher &M, const TreePatternNode &Dst,
-      const TreePatternNode &Src, unsigned TempReg);
+      unsigned TempReg);
   Expected<action_iterator>
   createInstructionRenderer(action_iterator InsertPt, RuleMatcher &M,
                             const TreePatternNode &Dst);
 
   Expected<action_iterator>
   importExplicitDefRenderers(action_iterator InsertPt, RuleMatcher &M,
                              BuildMIAction &DstMIBuilder,
-                             const TreePatternNode &Src,
                              const TreePatternNode &Dst, unsigned Start = 0);
 
-  Expected<action_iterator> importExplicitUseRenderers(
-      action_iterator InsertPt, RuleMatcher &M, BuildMIAction &DstMIBuilder,
-      const llvm::TreePatternNode &Dst, const TreePatternNode &Src);
-  Expected<action_iterator> importExplicitUseRenderer(
-      action_iterator InsertPt, RuleMatcher &Rule, BuildMIAction &DstMIBuilder,
-      const TreePatternNode &DstChild, const TreePatternNode &Src);
+  Expected<action_iterator>
+  importExplicitUseRenderers(action_iterator InsertPt, RuleMatcher &M,
+                             BuildMIAction &DstMIBuilder,
+                             const TreePatternNode &Dst);
+  Expected<action_iterator>
+  importExplicitUseRenderer(action_iterator InsertPt, RuleMatcher &Rule,
+                            BuildMIAction &DstMIBuilder,
+                            const TreePatternNode &Dst);
   Error importDefaultOperandRenderers(action_iterator InsertPt, RuleMatcher &M,
                                       BuildMIAction &DstMIBuilder,
                                       const DAGDefaultOperand &DefaultOp) const;
@@ -1196,23 +1198,22 @@ Error GlobalISelEmitter::importChildMatcher(
 
 Expected<action_iterator> GlobalISelEmitter::importExplicitUseRenderer(
     action_iterator InsertPt, RuleMatcher &Rule, BuildMIAction &DstMIBuilder,
-    const TreePatternNode &DstChild, const TreePatternNode &Src) {
+    const TreePatternNode &Dst) {
 
-  const auto &SubOperand = Rule.getComplexSubOperand(DstChild.getName());
+  const auto &SubOperand = Rule.getComplexSubOperand(Dst.getName());
   if (SubOperand) {
     DstMIBuilder.addRenderer<RenderComplexPatternOperand>(
-        *std::get<0>(*SubOperand), DstChild.getName(), std::get<1>(*SubOperand),
+        *std::get<0>(*SubOperand), Dst.getName(), std::get<1>(*SubOperand),
         std::get<2>(*SubOperand));
     return InsertPt;
   }
 
-  if (!DstChild.isLeaf()) {
-    if (DstChild.getOperator()->isSubClassOf("SDNodeXForm")) {
-      auto &Child = DstChild.getChild(0);
-      auto I = SDNodeXFormEquivs.find(DstChild.getOperator());
+  if (!Dst.isLeaf()) {
+    if (Dst.getOperator()->isSubClassOf("SDNodeXForm")) {
+      auto &Child = Dst.getChild(0);
+      auto I = SDNodeXFormEquivs.find(Dst.getOperator());
       if (I != SDNodeXFormEquivs.end()) {
-        const Record *XFormOpc =
-            DstChild.getOperator()->getValueAsDef("Opcode");
+        const Record *XFormOpc = Dst.getOperator()->getValueAsDef("Opcode");
         if (XFormOpc->getName() == "timm") {
           // If this is a TargetConstant, there won't be a corresponding
           // instruction to transform. Instead, this will refer directly to an
@@ -1231,10 +1232,10 @@ Expected<action_iterator> GlobalISelEmitter::importExplicitUseRenderer(
 
     // We accept 'bb' here. It's an operator because BasicBlockSDNode isn't
     // inline, but in MI it's just another operand.
-    if (DstChild.getOperator()->isSubClassOf("SDNode")) {
-      auto &ChildSDNI = CGP.getSDNodeInfo(DstChild.getOperator());
+    if (Dst.getOperator()->isSubClassOf("SDNode")) {
+      auto &ChildSDNI = CGP.getSDNodeInfo(Dst.getOperator());
       if (ChildSDNI.getSDClassName() == "BasicBlockSDNode") {
-        DstMIBuilder.addRenderer<CopyRenderer>(DstChild.getName());
+        DstMIBuilder.addRenderer<CopyRenderer>(Dst.getName());
         return InsertPt;
       }
     }
@@ -1243,26 +1244,25 @@ Expected<action_iterator> GlobalISelEmitter::importExplicitUseRenderer(
     // rendered as operands.
     // FIXME: The target should be able to choose sign-extended when appropriate
     //        (e.g. on Mips).
-    if (DstChild.getOperator()->getName() == "timm") {
-      DstMIBuilder.addRenderer<CopyRenderer>(DstChild.getName());
+    if (Dst.getOperator()->getName() == "timm") {
+      DstMIBuilder.addRenderer<CopyRenderer>(Dst.getName());
       return InsertPt;
     }
-    if (DstChild.getOperator()->getName() == "tframeindex") {
-      DstMIBuilder.addRenderer<CopyRenderer>(DstChild.getName());
+    if (Dst.getOperator()->getName() == "tframeindex") {
+      DstMIBuilder.addRenderer<CopyRenderer>(Dst.getName());
       return InsertPt;
     }
-    if (DstChild.getOperator()->getName() == "imm") {
-      DstMIBuilder.addRenderer<CopyConstantAsImmRenderer>(DstChild.getName());
+    if (Dst.getOperator()->getName() == "imm") {
+      DstMIBuilder.addRenderer<CopyConstantAsImmRenderer>(Dst.getName());
       return InsertPt;
     }
-    if (DstChild.getOperator()->getName() == "fpimm") {
-      DstMIBuilder.addRenderer<CopyFConstantAsFPImmRenderer>(
-          DstChild.getName());
+    if (Dst.getOperator()->getName() == "fpimm") {
+      DstMIBuilder.addRenderer<CopyFConstantAsFPImmRenderer>(Dst.getName());
       return InsertPt;
     }
 
-    if (DstChild.getOperator()->isSubClassOf("Instruction")) {
-      auto OpTy = getInstResultType(DstChild, Target);
+    if (Dst.getOperator()->isSubClassOf("Instruction")) {
+      auto OpTy = getInstResultType(Dst, Target);
       if (!OpTy)
         return OpTy.takeError();
 
@@ -1272,29 +1272,28 @@ Expected<action_iterator> GlobalISelEmitter::importExplicitUseRenderer(
       DstMIBuilder.addRenderer<TempRegRenderer>(TempRegID);
 
       auto InsertPtOrError = createAndImportSubInstructionRenderer(
-          ++InsertPt, Rule, DstChild, Src, TempRegID);
+          ++InsertPt, Rule, Dst, TempRegID);
       if (auto Error = InsertPtOrError.takeError())
         return std::move(Error);
       return InsertPtOrError.get();
     }
 
     return failedImport("Dst pattern child isn't a leaf node or an MBB" +
-                        llvm::to_string(DstChild));
+                        llvm::to_string(Dst));
   }
 
   // It could be a specific immediate in which case we should just check for
   // that immediate.
-  if (const IntInit *ChildIntInit =
-          dyn_cast<IntInit>(DstChild.getLeafValue())) {
+  if (const IntInit *ChildIntInit = dyn_cast<IntInit>(Dst.getLeafValue())) {
     DstMIBuilder.addRenderer<ImmRenderer>(ChildIntInit->getValue());
     return InsertPt;
   }
 
   // Otherwise, we're looking for a bog-standard RegisterClass operand.
-  if (auto *ChildDefInit = dyn_cast<DefInit>(DstChild.getLeafValue())) {
+  if (auto *ChildDefInit = dyn_cast<DefInit>(Dst.getLeafValue())) {
     auto *ChildRec = ChildDefInit->getDef();
 
-    ArrayRef<TypeSetByHwMode> ChildTypes = DstChild.getExtTypes();
+    ArrayRef<TypeSetByHwMode> ChildTypes = Dst.getExtTypes();
     if (ChildTypes.size() != 1)
       return failedImport("Dst pattern child has multiple results");
 
@@ -1315,11 +1314,11 @@ Expected<action_iterator> GlobalISelEmitter::importExplicitUseRenderer(
       if (ChildRec->isSubClassOf("RegisterOperand") &&
           !ChildRec->isValueUnset("GIZeroRegister")) {
         DstMIBuilder.addRenderer<CopyOrAddZeroRegRenderer>(
-            DstChild.getName(), ChildRec->getValueAsDef("GIZeroRegister"));
+            Dst.getName(), ChildRec->getValueAsDef("GIZeroRegister"));
         return InsertPt;
       }
 
-      DstMIBuilder.addRenderer<CopyRenderer>(DstChild.getName());
+      DstMIBuilder.addRenderer<CopyRenderer>(Dst.getName());
       return InsertPt;
     }
 
@@ -1335,9 +1334,9 @@ Expected<action_iterator> GlobalISelEmitter::importExplicitUseRenderer(
         return failedImport(
             "SelectionDAG ComplexPattern not mapped to GlobalISel");
 
-      const OperandMatcher &OM = Rule.getOperandMatcher(DstChild.getName());
+      const OperandMatcher &OM = Rule.getOperandMatcher(Dst.getName());
       DstMIBuilder.addRenderer<RenderComplexPatternOperand>(
-          *ComplexPattern->second, DstChild.getName(),
+          *ComplexPattern->second, Dst.getName(),
           OM.getAllocatedTemporariesBaseID());
       return InsertPt;
     }
@@ -1348,16 +1347,19 @@ Expected<action_iterator> GlobalISelEmitter::importExplicitUseRenderer(
 
   // Handle the case where the MVT/register class is omitted in the dest pattern
   // but MVT exists in the source pattern.
-  if (isa<UnsetInit>(DstChild.getLeafValue()) &&
-      Rule.hasOperand(DstChild.getName())) {
-    DstMIBuilder.addRenderer<CopyRenderer>(DstChild.getName());
+  if (isa<UnsetInit>(Dst.getLeafValue()) && Rule.hasOperand(Dst.getName())) {
+    DstMIBuilder.addRenderer<CopyRenderer>(Dst.getName());
     return InsertPt;
   }
   return failedImport("Dst pattern child is an unsupported kind");
 }
 
+/// Generates code that builds the resulting instruction(s) from the destination
+/// DAG. Note that to do this we do not and should not need the source DAG.
+/// We do need to know whether a generated instruction defines a result of the
+/// source DAG; this information is available via RuleMatcher::hasOperand.
 Expected<BuildMIAction &> GlobalISelEmitter::createAndImportInstructionRenderer(
-    RuleMatcher &M, InstructionMatcher &InsnMatcher, const TreePatternNode &Src,
+    RuleMatcher &M, InstructionMatcher &InsnMatcher,
     const TreePatternNode &Dst) {
   auto InsertPtOrError = createInstructionRenderer(M.actions_end(), M, Dst);
   if (auto Error = InsertPtOrError.takeError())
@@ -1377,23 +1379,21 @@ Expected<BuildMIAction &> GlobalISelEmitter::createAndImportInstructionRenderer(
     CopyToPhysRegMIBuilder.addRenderer<CopyPhysRegRenderer>(PhysInput.first);
   }
 
-  if (auto Error =
-          importExplicitDefRenderers(InsertPt, M, DstMIBuilder, Src, Dst)
-              .takeError())
+  if (auto Error = importExplicitDefRenderers(InsertPt, M, DstMIBuilder, Dst)
+                       .takeError())
     return std::move(Error);
 
-  if (auto Error =
-          importExplicitUseRenderers(InsertPt, M, DstMIBuilder, Dst, Src)
-              .takeError())
+  if (auto Error = importExplicitUseRenderers(InsertPt, M, DstMIBuilder, Dst)
+                       .takeError())
     return std::move(Error);
 
   return DstMIBuilder;
 }
 
 Expected<action_iterator>
 GlobalISelEmitter::createAndImportSubInstructionRenderer(
-    const action_iterator InsertPt, RuleMatcher &M, const TreePatternNode &Dst,
-    const TreePatternNode &Src, unsigned TempRegID) {
+    action_iterator InsertPt, RuleMatcher &M, const TreePatternNode &Dst,
+    unsigned TempRegID) {
   auto InsertPtOrError = createInstructionRenderer(InsertPt, M, Dst);
 
   // TODO: Assert there's exactly one result.
@@ -1408,13 +1408,13 @@ GlobalISelEmitter::createAndImportSubInstructionRenderer(
   DstMIBuilder.addRenderer<TempRegRenderer>(TempRegID, true);
 
   // Handle additional (ignored) results.
-  InsertPtOrError = importExplicitDefRenderers(
-      std::prev(*InsertPtOrError), M, DstMIBuilder, Src, Dst, /*Start=*/1);
+  InsertPtOrError = importExplicitDefRenderers(std::prev(*InsertPtOrError), M,
+                                               DstMIBuilder, Dst, /*Start=*/1);
   if (auto Error = InsertPtOrError.takeError())
     return std::move(Error);
 
-  InsertPtOrError = importExplicitUseRenderers(InsertPtOrError.get(), M,
-                                               DstMIBuilder, Dst, Src);
+  InsertPtOrError =
+      importExplicitUseRenderers(InsertPtOrError.get(), M, DstMIBuilder, Dst);
   if (auto Error = InsertPtOrError.takeError())
     return std::move(Error);
 
@@ -1448,7 +1448,7 @@ Expected<action_iterator> GlobalISelEmitter::createInstructionRenderer(
 
 Expected<action_iterator> GlobalISelEmitter::importExplicitDefRenderers(
     action_iterator InsertPt, RuleMatcher &M, BuildMIAction &DstMIBuilder,
-    const TreePatternNode &Src, const TreePatternNode &Dst, unsigned Start) {
+    const TreePatternNode &Dst, unsigned Start) {
   const CodeGenInstruction *DstI = DstMIBuilder.getCGI();
 
   // Some instructions have multiple defs, but are missing a type entry
@@ -1497,7 +1497,7 @@ Expected<action_iterator> GlobalISelEmitter::importExplicitDefRenderers(
 
 Expected<action_iterator> GlobalISelEmitter::importExplicitUseRenderers(
     action_iterator InsertPt, RuleMatcher &M, BuildMIAction &DstMIBuilder,
-    const llvm::TreePatternNode &Dst, const llvm::TreePatternNode &Src) {
+    const TreePatternNode &Dst) {
   const CodeGenInstruction *DstI = DstMIBuilder.getCGI();
   CodeGenInstruction *OrigDstI = &Target.getInstruction(Dst.getOperator());
 
@@ -1527,7 +1527,7 @@ Expected<action_iterator> GlobalISelEmitter::importExplicitUseRenderers(
                                                         TempRegID);
 
       auto InsertPtOrError = createAndImportSubInstructionRenderer(
-          ++InsertPt, M, ValChild, Src, TempRegID);
+          ++InsertPt, M, ValChild, TempRegID);
       if (auto Error = InsertPtOrError.takeError())
         return std::move(Error);
 
@@ -1585,7 +1585,7 @@ Expected<action_iterator> GlobalISelEmitter::importExplicitUseRenderers(
         CodeGenSubRegIndex *SubIdx = CGRegs.getSubRegIdx(SubRegInit->getDef());
 
         auto InsertPtOrError =
-            importExplicitUseRenderer(InsertPt, M, DstMIBuilder, ValChild, Src);
+            importExplicitUseRenderer(InsertPt, M, DstMIBuilder, ValChild);
         if (auto Error = InsertPtOrError.takeError())
           return std::move(Error);
         InsertPt = InsertPtOrError.get();
@@ -1654,7 +1654,7 @@ Expected<action_iterator> GlobalISelEmitter::importExplicitUseRenderers(
     }
 
     auto InsertPtOrError = importExplicitUseRenderer(InsertPt, M, DstMIBuilder,
-                                                     Dst.getChild(Child), Src);
+                                                     Dst.getChild(Child));
     if (auto Error = InsertPtOrError.takeError())
       return std::move(Error);
     InsertPt = InsertPtOrError.get();
@@ -2135,7 +2135,7 @@ Expected<RuleMatcher> GlobalISelEmitter::runOnPattern(const PatternToMatch &P) {
   }
 
   auto DstMIBuilderOrError =
-      createAndImportInstructionRenderer(M, InsnMatcher, Src, Dst);
+      createAndImportInstructionRenderer(M, InsnMatcher, Dst);
   if (auto Error = DstMIBuilderOrError.takeError())
     return std::move(Error);
   BuildMIAction &DstMIBuilder = DstMIBuilderOrError.get();