From a67899195f74afe6b2350328cb73a6772bf40b48 Mon Sep 17 00:00:00 2001
From: Evan Cheng <evan.cheng@apple.com>
Date: Sun, 26 Mar 2006 09:50:58 +0000
Subject: [PATCH] Add ISD::isBuildVectorAllZeros predicate

llvm-svn: 27147
---
 llvm/include/llvm/CodeGen/SelectionDAGNodes.h |  5 +++-
 .../lib/CodeGen/SelectionDAG/SelectionDAG.cpp | 24 +++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/llvm/include/llvm/CodeGen/SelectionDAGNodes.h b/llvm/include/llvm/CodeGen/SelectionDAGNodes.h
index df76524ca119..4863940de272 100644
--- a/llvm/include/llvm/CodeGen/SelectionDAGNodes.h
+++ b/llvm/include/llvm/CodeGen/SelectionDAGNodes.h
@@ -458,7 +458,10 @@ namespace ISD {
   /// isBuildVectorAllOnesInteger - Return true if the specified node is a
   /// BUILD_VECTOR where all of the elements are ~0 or undef.
   bool isBuildVectorAllOnesInteger(const SDNode *N);
-  
+
+  /// isBuildVectorAllZeros - Return true if the specified node is a
+  /// BUILD_VECTOR where all of the elements are 0 or undef.
+  bool isBuildVectorAllZeros(const SDNode *N);
   
   //===--------------------------------------------------------------------===//
   /// ISD::CondCode enum - These are ordered carefully to make the bitfields
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 18e2ebcb45ee..c0cd64670117 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -101,6 +101,30 @@ bool ISD::isBuildVectorAllOnesInteger(const SDNode *N) {
 }
 
 
+/// isBuildVectorAllZeros - Return true if the specified node is a
+/// BUILD_VECTOR where all of the elements are 0 or undef.
+bool ISD::isBuildVectorAllZeros(const SDNode *N) {
+  if (N->getOpcode() != ISD::BUILD_VECTOR) return false;
+
+  bool AllUndef = true;
+  for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
+    SDOperand Elt = N->getOperand(i);
+    if (Elt.getOpcode() != ISD::UNDEF) {
+      AllUndef = false;
+      if (isa<ConstantSDNode>(Elt)) {
+        if (!cast<ConstantSDNode>(Elt)->isNullValue())
+          return false;
+      } else if (isa<ConstantFPSDNode>(Elt)) {
+        if (!cast<ConstantFPSDNode>(Elt)->isExactlyValue(0.0))
+          return false;
+      } else
+        return false;
+    }
+  }
+
+  return !AllUndef;
+}
+
 /// getSetCCSwappedOperands - Return the operation corresponding to (Y op X)
 /// when given the operation for (X op Y).
 ISD::CondCode ISD::getSetCCSwappedOperands(ISD::CondCode Operation) {