Allow InstAlias's to use immediate matcher patterns that xform the value.

For example,

On ARM, "mov r3, #-3" is an alias for "mvn r3, #2", so we want to use a
matcher pattern that handles the bitwise negation when mapping to t2MVNi.

llvm-svn: 143233

1 files changed, 19 insertions, 2 deletions

diff --git a/llvm/utils/TableGen/CodeGenInstruction.cpp b/llvm/utils/TableGen/CodeGenInstruction.cpp
index 9822de819db..d6515cade27 100644
--- a/llvm/utils/TableGen/CodeGenInstruction.cpp
+++ b/llvm/utils/TableGen/CodeGenInstruction.cpp
@@ -428,8 +428,11 @@ bool CodeGenInstAlias::tryAliasOpMatch(DagInit *Result, unsigned AliasOpNo,
   if (ADI && ADI->getDef()->isSubClassOf("RegisterClass")) {
     if (!InstOpRec->isSubClassOf("RegisterClass"))
       return false;
-    return T.getRegisterClass(InstOpRec)
-              .hasSubClass(&T.getRegisterClass(ADI->getDef()));
+    if (!T.getRegisterClass(InstOpRec)
+              .hasSubClass(&T.getRegisterClass(ADI->getDef())))
+      return false;
+    ResOp = ResultOperand(Result->getArgName(AliasOpNo), ADI->getDef());
+    return true;
   }
 
   // Handle explicit registers.
@@ -473,6 +476,7 @@ bool CodeGenInstAlias::tryAliasOpMatch(DagInit *Result, unsigned AliasOpNo,
     return true;
   }
 
+  // Literal integers.
   if (IntInit *II = dynamic_cast<IntInit*>(Arg)) {
     if (hasSubOps || !InstOpRec->isSubClassOf("Operand"))
       return false;
@@ -484,6 +488,19 @@ bool CodeGenInstAlias::tryAliasOpMatch(DagInit *Result, unsigned AliasOpNo,
     return true;
   }
 
+  // If both are Operands with the same MVT, allow the conversion. It's
+  // up to the user to make sure the values are appropriate, just like
+  // for isel Pat's.
+  if (InstOpRec->isSubClassOf("Operand") &&
+      ADI->getDef()->isSubClassOf("Operand")) {
+    // FIXME: What other attributes should we check here? Identical
+    // MIOperandInfo perhaps?
+    if (InstOpRec->getValueInit("Type") != ADI->getDef()->getValueInit("Type"))
+      return false;
+    ResOp = ResultOperand(Result->getArgName(AliasOpNo), ADI->getDef());
+    return true;
+  }
+
   return false;
 }