[llvm] r230175 - [SDAG] Use correct alignments on expanded vector trunc-store/ext-loads

[Hal Finkel]

Author: hfinkel
Date: Sun Feb 22 09:58:04 2015
New Revision: 230175

URL: http://llvm.org/viewvc/llvm-project?rev=230175&view=rev
Log:
[SDAG] Use correct alignments on expanded vector trunc-store/ext-loads

When expanding a truncating store or extending load using vector extracts or
inserts and scalar stores and loads, we were giving each of these scalar stores
or loads the same alignment as the original vector operation. While this will
often be right (most vector operations, especially those produced by
autovectorization, have the alignment of the underlying scalar type), the
vector operation could certainly have a larger alignment.

No test case (yet); noticed by inspection.

Modified:
    llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp?rev=230175&r1=230174&r2=230175&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp Sun Feb 22 09:58:04 2015
@@ -512,7 +512,8 @@ SDValue VectorLegalizer::ExpandLoad(SDVa
         ScalarLoad = DAG.getLoad(WideVT, dl, Chain, BasePTR,
                                  LD->getPointerInfo().getWithOffset(Offset),
                                  LD->isVolatile(), LD->isNonTemporal(),
-                                 LD->isInvariant(), LD->getAlignment(),
+                                 LD->isInvariant(),
+                                 MinAlign(LD->getAlignment(), Offset),
                                  LD->getAAInfo());
       } else {
         EVT LoadVT = WideVT;
@@ -524,7 +525,8 @@ SDValue VectorLegalizer::ExpandLoad(SDVa
                                     LD->getPointerInfo().getWithOffset(Offset),
                                     LoadVT, LD->isVolatile(),
                                     LD->isNonTemporal(), LD->isInvariant(),
-                                    LD->getAlignment(), LD->getAAInfo());
+                                    MinAlign(LD->getAlignment(), Offset),
+                                    LD->getAAInfo());
       }
 
       RemainingBytes -= LoadBytes;
@@ -595,7 +597,7 @@ SDValue VectorLegalizer::ExpandLoad(SDVa
                 Chain, BasePTR, LD->getPointerInfo().getWithOffset(Idx * Stride),
                 SrcVT.getScalarType(),
                 LD->isVolatile(), LD->isNonTemporal(), LD->isInvariant(),
-                LD->getAlignment(), LD->getAAInfo());
+                MinAlign(LD->getAlignment(), Idx * Stride), LD->getAAInfo());
 
       BasePTR = DAG.getNode(ISD::ADD, dl, BasePTR.getValueType(), BasePTR,
                          DAG.getConstant(Stride, BasePTR.getValueType()));
@@ -654,7 +656,8 @@ SDValue VectorLegalizer::ExpandStore(SDV
     // This scalar TruncStore may be illegal, but we legalize it later.
     SDValue Store = DAG.getTruncStore(Chain, dl, Ex, BasePTR,
                ST->getPointerInfo().getWithOffset(Idx*Stride), MemSclVT,
-               isVolatile, isNonTemporal, Alignment, AAInfo);
+               isVolatile, isNonTemporal, MinAlign(Alignment, Idx*Stride),
+               AAInfo);
 
     BasePTR = DAG.getNode(ISD::ADD, dl, BasePTR.getValueType(), BasePTR,
                                DAG.getConstant(Stride, BasePTR.getValueType()));