diff options
Diffstat (limited to 'llvm/lib/Target/R600/R600ISelLowering.cpp')
| -rw-r--r-- | llvm/lib/Target/R600/R600ISelLowering.cpp | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/llvm/lib/Target/R600/R600ISelLowering.cpp b/llvm/lib/Target/R600/R600ISelLowering.cpp index 81a28be104a..3c2e3888e08 100644 --- a/llvm/lib/Target/R600/R600ISelLowering.cpp +++ b/llvm/lib/Target/R600/R600ISelLowering.cpp @@ -1379,6 +1379,11 @@ CompactSwizzlableVector(SelectionDAG &DAG, SDValue VectorEntry, }; for (unsigned i = 0; i < 4; i++) { + if (NewBldVec[i].getOpcode() == ISD::UNDEF) + // We mask write here to teach later passes that the ith element of this + // vector is undef. Thus we can use it to reduce 128 bits reg usage, + // break false dependencies and additionnaly make assembly easier to read. + RemapSwizzle[i] = 7; // SEL_MASK_WRITE if (ConstantFPSDNode *C = dyn_cast<ConstantFPSDNode>(NewBldVec[i])) { if (C->isZero()) { RemapSwizzle[i] = 4; // SEL_0 |
