[PATCH] D61705: Tablegen type comparison LE should be LT or equal.

[Pete Couperus via Phabricator via llvm-commits]

petecoup created this revision.
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petecoup added a reviewer: kparzysz.

This fixes case where one could have LE(A, B) AND LE(B, A) for different sized
vector types A,B.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D61705

Files:
  llvm/utils/TableGen/CodeGenDAGPatterns.cpp


Index: llvm/utils/TableGen/CodeGenDAGPatterns.cpp
===================================================================
--- llvm/utils/TableGen/CodeGenDAGPatterns.cpp
+++ llvm/utils/TableGen/CodeGenDAGPatterns.cpp
@@ -507,22 +507,14 @@
            (A.getScalarSizeInBits() == B.getScalarSizeInBits() &&
             A.getSizeInBits() < B.getSizeInBits());
   };
-  auto LE = [](MVT A, MVT B) -> bool {
+  auto LE = [&LT](MVT A, MVT B) -> bool {
     // This function is used when removing elements: when a vector is compared
     // to a non-vector, it should return false (to avoid removal).
     if (A.isVector() != B.isVector())
       return false;
 
-    // Note on the < comparison below:
-    // X86 has patterns like
-    //   (set VR128X:$dst, (v16i8 (X86vtrunc (v4i32 VR128X:$src1)))),
-    // where the truncated vector is given a type v16i8, while the source
-    // vector has type v4i32. They both have the same size in bits.
-    // The minimal type in the result is obviously v16i8, and when we remove
-    // all types from the source that are smaller-or-equal than v8i16, the
-    // only source type would also be removed (since it's equal in size).
-    return A.getScalarSizeInBits() <= B.getScalarSizeInBits() ||
-           A.getSizeInBits() < B.getSizeInBits();
+    return LT(A, B) || (A.getScalarSizeInBits() == B.getScalarSizeInBits() &&
+                        A.getSizeInBits() == B.getSizeInBits());
   };
 
   for (unsigned M : Modes) {


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