commit 50284d81f863a6576582e1a171a22eb0f012ddf3
author Dan Gohman <gohman@apple.com> Tue Sep 16 22:05:41 2008 +0000
committer Dan Gohman <gohman@apple.com> Tue Sep 16 22:05:41 2008 +0000
tree 49bc73869e78253a52772428bdb8e1e8bdc23d0c
parent 056292fd738924f3f7703725d8f630983794b5a5

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!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@56253 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/SelectionDAG/LegalizeDAG.cpp

diff --git a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index ba78b81..0d27e66 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -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);

lib/CodeGen/SelectionDAG/SelectionDAG.cpp

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 793f5c9..a6851ee 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -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);