[APInt] Add APInt::insertBits() method to insert an APInt into a larger APInt

We currently have to insert bits via a temporary variable of the same size as the target with various shift/mask stages, resulting in further temporary variables, all of which require the allocation of memory for large APInts (MaskSizeInBits > 64).

This is another of the compile time issues identified in PR32037 (see also D30265).

This patch adds the APInt::insertBits() helper method which avoids the temporary memory allocation and masks/inserts the raw bits directly into the target.

Differential Revision: https://reviews.llvm.org/D30780

llvm-svn: 297458

1 files changed, 4 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index d7e97e95e91..c64cc68d177 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -7523,11 +7523,11 @@ bool BuildVectorSDNode::isConstantSplat(APInt &SplatValue,
     if (OpVal.isUndef())
       SplatUndef.setBits(BitPos, BitPos + EltBitSize);
     else if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(OpVal))
-      SplatValue |= CN->getAPIntValue().zextOrTrunc(EltBitSize).
-                    zextOrTrunc(sz) << BitPos;
+      SplatValue.insertBits(CN->getAPIntValue().zextOrTrunc(EltBitSize),
+                            BitPos);
     else if (ConstantFPSDNode *CN = dyn_cast<ConstantFPSDNode>(OpVal))
-      SplatValue |= CN->getValueAPF().bitcastToAPInt().zextOrTrunc(sz) <<BitPos;
-     else
+      SplatValue.insertBits(CN->getValueAPF().bitcastToAPInt(), BitPos);
+    else
       return false;
   }