Allow register classes to match a containing class in InstAliases.

If the register class in the source alias is a subclass of the register class
of the actual instruction, the alias can still match OK since the constraints
are strictly a subset of what the instruction can actually handle.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143200 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 9 insertions, 0 deletions

diff --git a/utils/TableGen/CodeGenInstruction.cpp b/utils/TableGen/CodeGenInstruction.cpp
index 53d499f395..9822de819d 100644
--- a/utils/TableGen/CodeGenInstruction.cpp
+++ b/utils/TableGen/CodeGenInstruction.cpp
@@ -423,6 +423,15 @@ bool CodeGenInstAlias::tryAliasOpMatch(DagInit *Result, unsigned AliasOpNo,
     return true;
   }
 
+  // For register operands, the source register class can be a subclass
+  // of the instruction register class, not just an exact match.
+  if (ADI && ADI->getDef()->isSubClassOf("RegisterClass")) {
+    if (!InstOpRec->isSubClassOf("RegisterClass"))
+      return false;
+    return T.getRegisterClass(InstOpRec)
+              .hasSubClass(&T.getRegisterClass(ADI->getDef()));
+  }
+
   // Handle explicit registers.
   if (ADI && ADI->getDef()->isSubClassOf("Register")) {
     if (InstOpRec->isSubClassOf("OptionalDefOperand")) {