[llvm] 1b18064 - [TableGen] Print message about dropped patterns with -debug

[Krzysztof Parzyszek via llvm-commits]

Author: Krzysztof Parzyszek
Date: 2023-05-10T14:51:57-07:00
New Revision: 1b1806406908c185202bd62b7315f1627bfb5aa7

URL: https://github.com/llvm/llvm-project/commit/1b1806406908c185202bd62b7315f1627bfb5aa7
DIFF: https://github.com/llvm/llvm-project/commit/1b1806406908c185202bd62b7315f1627bfb5aa7.diff

LOG: [TableGen] Print message about dropped patterns with -debug

A selection pattern can be silently dropped if type inference fails to
deduce some types. Print a message when that happens, and -debug was
applied.

Added: 
    

Modified: 
    llvm/utils/TableGen/CodeGenDAGPatterns.cpp

Removed: 
    


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diff  --git a/llvm/utils/TableGen/CodeGenDAGPatterns.cpp b/llvm/utils/TableGen/CodeGenDAGPatterns.cpp
index ed2eda8f9792..1ce735c82415 100644
--- a/llvm/utils/TableGen/CodeGenDAGPatterns.cpp
+++ b/llvm/utils/TableGen/CodeGenDAGPatterns.cpp
@@ -4333,13 +4333,24 @@ void CodeGenDAGPatterns::ParseOnePattern(Record *TheDef,
   // that register class does not accept that type, the type inference
   // will lead to a contradiction, which is not an error however, but
   // a sign that this pattern will simply never match.
-  if (Temp.getOnlyTree()->hasPossibleType())
-    for (const auto &T : Pattern.getTrees())
+  if (Temp.getOnlyTree()->hasPossibleType()) {
+    for (const auto &T : Pattern.getTrees()) {
       if (T->hasPossibleType())
         AddPatternToMatch(&Pattern,
                           PatternToMatch(TheDef, Preds, T, Temp.getOnlyTree(),
                                          InstImpResults, Complexity,
                                          TheDef->getID()));
+    }
+  } else {
+    // Show a message about a dropped pattern with some info to make it
+    // easier to identify it in the .td files.
+    LLVM_DEBUG({
+      dbgs() << "Dropping: ";
+      Pattern.dump();
+      Temp.getOnlyTree()->dump();
+      dbgs() << "\n";
+    });
+  }
 }
 
 void CodeGenDAGPatterns::ParsePatterns() {