commit 0fe7776da5d5c3f63c03d6bf5a01d293da5f73d3
author Chris Lattner <sabre@nondot.org> Sun Jan 16 00:17:20 2005 +0000
committer Chris Lattner <sabre@nondot.org> Sun Jan 16 00:17:20 2005 +0000
tree 9d208458573bddf0986272ac3a3b0896cd332ba9
parent 4d97864e927a2cf9fadbb78503507a74ed72d03a

Eliminate unneeded extensions.

llvm-svn: 19577

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 89c53e8..d3d44a8 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -855,6 +855,15 @@
            "Cannot *_EXTEND_INREG FP types");
     if (EVT == VT) return N1;  // Not actually extending
     assert(EVT < VT && "Not extending!");
+
+    // If we are sign extending an extension, use the original source.
+    if (N1.getOpcode() == ISD::ZERO_EXTEND_INREG ||
+        N1.getOpcode() == ISD::SIGN_EXTEND_INREG) {
+      if (N1.getOpcode() == Opcode &&
+          cast<MVTSDNode>(N1)->getExtraValueType() <= EVT)
+        return N1;
+    }
+
     break;
   }