[llvm-commits] [llvm] r56253 - in /llvm/trunk/lib/CodeGen/SelectionDAG: LegalizeDAG.cpp SelectionDAG.cpp

[Dan Gohman]

Author: djg
Date: Tue Sep 16 17:05:41 2008
New Revision: 56253

URL: http://llvm.org/viewvc/llvm-project?rev=56253&view=rev
Log:
Change SelectionDAG::getConstantPool to always set the alignment of the
ConstantPoolSDNode, using the target's preferred alignment for the
constant type.

In LegalizeDAG, when performing loads from the constant pool, the
ConstantPoolSDNode's alignment is used in the calls to getLoad and
getExtLoad.

This change prevents SelectionDAG::getLoad/getExtLoad from incorrectly
choosing the ABI alignment for constant pool loads when Alignment == 0.
The incorrect alignment is only a performance issue when ABI alignment
does not equal preferred alignment (i.e., on x86 it was generating
MOVUPS instead of MOVAPS for v4f32 constant loads when the default ABI
alignment for 128bit vectors is forced to 1 byte.)

Patch by Paul Redmond!

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

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp?rev=56253&r1=56252&r2=56253&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp Tue Sep 16 17:05:41 2008
@@ -467,12 +467,13 @@
   }
 
   SDValue CPIdx = DAG.getConstantPool(LLVMC, TLI.getPointerTy());
+  unsigned Alignment = 1 << cast<ConstantPoolSDNode>(CPIdx)->getAlignment();
   if (Extend)
     return DAG.getExtLoad(ISD::EXTLOAD, OrigVT, DAG.getEntryNode(),
                           CPIdx, PseudoSourceValue::getConstantPool(),
-                          0, VT);
+                          0, VT, false, Alignment);
   return DAG.getLoad(OrigVT, DAG.getEntryNode(), CPIdx,
-                     PseudoSourceValue::getConstantPool(), 0);
+                     PseudoSourceValue::getConstantPool(), 0, false, Alignment);
 }
 
 
@@ -4997,8 +4998,10 @@
     }
     Constant *CP = ConstantVector::get(CV);
     SDValue CPIdx = DAG.getConstantPool(CP, TLI.getPointerTy());
+    unsigned Alignment = 1 << cast<ConstantPoolSDNode>(CPIdx)->getAlignment();
     return DAG.getLoad(VT, DAG.getEntryNode(), CPIdx,
-                       PseudoSourceValue::getConstantPool(), 0);
+                       PseudoSourceValue::getConstantPool(), 0,
+                       false, Alignment);
   }
   
   if (SplatValue.getNode()) {   // Splat of one value?
@@ -5433,17 +5436,19 @@
     static Constant *FudgeFactor = ConstantInt::get(Type::Int64Ty, FF);
 
     SDValue CPIdx = DAG.getConstantPool(FudgeFactor, TLI.getPointerTy());
+    unsigned Alignment = 1 << cast<ConstantPoolSDNode>(CPIdx)->getAlignment();
     CPIdx = DAG.getNode(ISD::ADD, TLI.getPointerTy(), CPIdx, CstOffset);
     SDValue FudgeInReg;
     if (DestTy == MVT::f32)
       FudgeInReg = DAG.getLoad(MVT::f32, DAG.getEntryNode(), CPIdx,
-                               PseudoSourceValue::getConstantPool(), 0);
+                               PseudoSourceValue::getConstantPool(), 0,
+                               false, Alignment);
     else if (DestTy.bitsGT(MVT::f32))
       // FIXME: Avoid the extend by construction the right constantpool?
       FudgeInReg = DAG.getExtLoad(ISD::EXTLOAD, DestTy, DAG.getEntryNode(),
                                   CPIdx,
                                   PseudoSourceValue::getConstantPool(), 0,
-                                  MVT::f32);
+                                  MVT::f32, false, Alignment);
     else 
       assert(0 && "Unexpected conversion");
 
@@ -5582,17 +5587,19 @@
   static Constant *FudgeFactor = ConstantInt::get(Type::Int64Ty, FF);
 
   SDValue CPIdx = DAG.getConstantPool(FudgeFactor, TLI.getPointerTy());
+  unsigned Alignment = 1 << cast<ConstantPoolSDNode>(CPIdx)->getAlignment();
   CPIdx = DAG.getNode(ISD::ADD, TLI.getPointerTy(), CPIdx, CstOffset);
   SDValue FudgeInReg;
   if (DestVT == MVT::f32)
     FudgeInReg = DAG.getLoad(MVT::f32, DAG.getEntryNode(), CPIdx,
-                             PseudoSourceValue::getConstantPool(), 0);
+                             PseudoSourceValue::getConstantPool(), 0,
+                             false, Alignment);
   else {
     FudgeInReg =
       LegalizeOp(DAG.getExtLoad(ISD::EXTLOAD, DestVT,
                                 DAG.getEntryNode(), CPIdx,
                                 PseudoSourceValue::getConstantPool(), 0,
-                                MVT::f32));
+                                MVT::f32, false, Alignment));
   }
 
   return DAG.getNode(ISD::FADD, DestVT, Tmp1, FudgeInReg);

Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp?rev=56253&r1=56252&r2=56253&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAG.cpp Tue Sep 16 17:05:41 2008
@@ -1019,6 +1019,9 @@
 SDValue SelectionDAG::getConstantPool(Constant *C, MVT VT,
                                       unsigned Alignment, int Offset,
                                       bool isTarget) {
+  if (Alignment == 0)
+    Alignment =
+      TLI.getTargetData()->getPreferredTypeAlignmentShift(C->getType());
   unsigned Opc = isTarget ? ISD::TargetConstantPool : ISD::ConstantPool;
   FoldingSetNodeID ID;
   AddNodeIDNode(ID, Opc, getVTList(VT), 0, 0);
@@ -1039,6 +1042,9 @@
 SDValue SelectionDAG::getConstantPool(MachineConstantPoolValue *C, MVT VT,
                                       unsigned Alignment, int Offset,
                                       bool isTarget) {
+  if (Alignment == 0)
+    Alignment =
+      TLI.getTargetData()->getPreferredTypeAlignmentShift(C->getType());
   unsigned Opc = isTarget ? ISD::TargetConstantPool : ISD::ConstantPool;
   FoldingSetNodeID ID;
   AddNodeIDNode(ID, Opc, getVTList(VT), 0, 0);