[TableGen] ShouldIgnore Pattern bit to disable DAG pattern imports during GISel (#88382)

Added GISelShouldIgnore property to class Pattern in TargetSelectionDAG.td; it's similar to FastISelShouldIgnore. This bit can be put on a record to avoid its pattern import within GlobalISelEmitter. This allows one to avoid the record's GISel .td implementation, .inc generation, and any skipped pattern warnings from -warn-on-skipped-patterns.

Author: jofrn

llvm/include/llvm/Target/TargetSelectionDAG.td

@@ -1979,6 +1979,7 @@ class Pattern<dag patternToMatch, list<dag> resultInstrs> {
   list<dag>       ResultInstrs    = resultInstrs;
   list<Predicate> Predicates      = [];  // See class Instruction in Target.td.
   int             AddedComplexity = 0;   // See class Instruction in Target.td.
+  bit           GISelShouldIgnore = 0;
 }
 
 // Pat - A simple (but common) form of a pattern, which produces a simple result

llvm/test/TableGen/GlobalISelEmitterSkippedPatterns.td

@@ -1,4 +1,6 @@
 // RUN: llvm-tblgen -warn-on-skipped-patterns -gen-global-isel -I %p/../../include %s -I %p/Common -o /dev/null 2>&1 | FileCheck %s
+// RUN: llvm-tblgen -warn-on-skipped-patterns -gen-global-isel -I %p/../../include %s -I %p/Common -o /dev/null -DIGNORE 2>&1 | FileCheck --allow-empty --check-prefix=IGNORED %s
+
 include "llvm/Target/Target.td"
 include "GlobalISelEmitterCommon.td"
 
@@ -23,6 +25,10 @@ def INSN : I<(outs GPR32:$dst), (ins GPR32:$src1, complex:$src2), []>;
 
 //===- Bail out when we define a variable twice wrt complex suboperands. -===//
 
+#ifdef IGNORE
+let GISelShouldIgnore = 1 in
+#endif
+// IGNORED-NOT: warning: Skipped pattern: Error: {{.*}}
 // CHECK: warning: Skipped pattern: Error: Complex suboperand x referenced by different operands: complex_rr:x:y and complex_rr:x:z.
 def : Pat<(add (complex_rr GPR32:$x, GPR32:$y),
                (complex_rr GPR32:$x, GPR32:$z)),

llvm/test/TableGen/simplify-patfrag.td

@@ -1,4 +1,5 @@
 // RUN: llvm-tblgen -gen-dag-isel -I %p/../../include %s 2>&1 | FileCheck %s
+// RUN: llvm-tblgen -gen-dag-isel -I %p/../../include -DIGNORE %s 2>&1 | FileCheck %s
 
 include "llvm/Target/Target.td"
 
@@ -29,6 +30,10 @@ def anyconvert : PatFrags<(ops node:$src),
                           [(bitconvert node:$src),
                            (specialconvert node:$src)]>;
 
+#ifdef IGNORE
+// Ensure ShouldIgnore does not disable records in dag isel emitter
+let GISelShouldIgnore = 1 in
+#endif
 // And a rule that matches that PatFrag and turns it into i2f
 def : Pat<(f32 (anyconvert (i32 GPR:$val))), (i2f GPR:$val)>;
 

llvm/utils/TableGen/Common/CodeGenDAGPatterns.cpp

@@ -4246,7 +4246,7 @@ static TreePatternNodePtr PromoteXForms(TreePatternNodePtr N) {
 
 void CodeGenDAGPatterns::ParseOnePattern(
     Record *TheDef, TreePattern &Pattern, TreePattern &Result,
-    const std::vector<Record *> &InstImpResults) {
+    const std::vector<Record *> &InstImpResults, bool ShouldIgnore) {
 
   // Inline pattern fragments and expand multiple alternatives.
   Pattern.InlinePatternFragments();
@@ -4332,7 +4332,7 @@ void CodeGenDAGPatterns::ParseOnePattern(
         AddPatternToMatch(&Pattern,
                           PatternToMatch(TheDef, Preds, T, Temp.getOnlyTree(),
                                          InstImpResults, Complexity,
-                                         TheDef->getID()));
+                                         TheDef->getID(), ShouldIgnore));
     }
   } else {
     // Show a message about a dropped pattern with some info to make it
@@ -4378,7 +4378,8 @@ void CodeGenDAGPatterns::ParsePatterns() {
       FindPatternInputsAndOutputs(Pattern, Pattern.getTree(j), InstInputs,
                                   InstResults, InstImpResults);
 
-    ParseOnePattern(CurPattern, Pattern, Result, InstImpResults);
+    ParseOnePattern(CurPattern, Pattern, Result, InstImpResults,
+                    CurPattern->getValueAsBit("GISelShouldIgnore"));
   }
 }
 
@@ -4407,10 +4408,10 @@ void CodeGenDAGPatterns::ExpandHwModeBasedTypes() {
       return;
     }
 
-    PatternsToMatch.emplace_back(P.getSrcRecord(), P.getPredicates(),
-                                 std::move(NewSrc), std::move(NewDst),
-                                 P.getDstRegs(), P.getAddedComplexity(),
-                                 Record::getNewUID(Records), Check);
+    PatternsToMatch.emplace_back(
+        P.getSrcRecord(), P.getPredicates(), std::move(NewSrc),
+        std::move(NewDst), P.getDstRegs(), P.getAddedComplexity(),
+        Record::getNewUID(Records), P.getGISelShouldIgnore(), Check);
   };
 
   for (PatternToMatch &P : Copy) {
@@ -4781,6 +4782,7 @@ void CodeGenDAGPatterns::GenerateVariants() {
           Variant, PatternsToMatch[i].getDstPatternShared(),
           PatternsToMatch[i].getDstRegs(),
           PatternsToMatch[i].getAddedComplexity(), Record::getNewUID(Records),
+          PatternsToMatch[i].getGISelShouldIgnore(),
           PatternsToMatch[i].getHwModeFeatures());
     }
 

llvm/utils/TableGen/Common/CodeGenDAGPatterns.h

@@ -1057,17 +1057,19 @@ class PatternToMatch {
   TreePatternNodePtr DstPattern; // Resulting pattern.
   std::vector<Record *> Dstregs; // Physical register defs being matched.
   std::string HwModeFeatures;
-  int AddedComplexity; // Add to matching pattern complexity.
-  unsigned ID;         // Unique ID for the record.
+  int AddedComplexity;    // Add to matching pattern complexity.
+  bool GISelShouldIgnore; // Should GlobalISel ignore importing this pattern.
+  unsigned ID;            // Unique ID for the record.
 
 public:
   PatternToMatch(Record *srcrecord, ListInit *preds, TreePatternNodePtr src,
                  TreePatternNodePtr dst, std::vector<Record *> dstregs,
-                 int complexity, unsigned uid, const Twine &hwmodefeatures = "")
+                 int complexity, unsigned uid, bool ignore,
+                 const Twine &hwmodefeatures = "")
       : SrcRecord(srcrecord), Predicates(preds), SrcPattern(src),
         DstPattern(dst), Dstregs(std::move(dstregs)),
         HwModeFeatures(hwmodefeatures.str()), AddedComplexity(complexity),
-        ID(uid) {}
+        GISelShouldIgnore(ignore), ID(uid) {}
 
   Record *getSrcRecord() const { return SrcRecord; }
   ListInit *getPredicates() const { return Predicates; }
@@ -1078,6 +1080,7 @@ class PatternToMatch {
   const std::vector<Record *> &getDstRegs() const { return Dstregs; }
   StringRef getHwModeFeatures() const { return HwModeFeatures; }
   int getAddedComplexity() const { return AddedComplexity; }
+  bool getGISelShouldIgnore() const { return GISelShouldIgnore; }
   unsigned getID() const { return ID; }
 
   std::string getPredicateCheck() const;
@@ -1240,7 +1243,8 @@ class CodeGenDAGPatterns {
 
   void ParseOnePattern(Record *TheDef, TreePattern &Pattern,
                        TreePattern &Result,
-                       const std::vector<Record *> &InstImpResults);
+                       const std::vector<Record *> &InstImpResults,
+                       bool ShouldIgnore = false);
   void AddPatternToMatch(TreePattern *Pattern, PatternToMatch &&PTM);
   void FindPatternInputsAndOutputs(
       TreePattern &I, TreePatternNodePtr Pat,

llvm/utils/TableGen/GlobalISelEmitter.cpp

@@ -2411,6 +2411,8 @@ void GlobalISelEmitter::run(raw_ostream &OS) {
   for (const PatternToMatch &Pat : CGP.ptms()) {
     ++NumPatternTotal;
 
+    if (Pat.getGISelShouldIgnore())
+      continue; // skip without warning
     auto MatcherOrErr = runOnPattern(Pat);
 
     // The pattern analysis can fail, indicating an unsupported pattern.