Revert r106263, "Fold the ShrinkDemandedOps pass into the regular DAGCombiner pass,"... it was causing both 'file' (with clang) and 176.gcc (with llvm-gcc) to be miscompiled.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106634 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 8 insertions, 37 deletions

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index a72415f953..81a382b7e7 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -2030,7 +2030,7 @@ SDValue DAGCombiner::SimplifyBinOpWithSameOpcodeHands(SDNode *N) {
   // fold (OP (zext x), (zext y)) -> (zext (OP x, y))
   // fold (OP (sext x), (sext y)) -> (sext (OP x, y))
   // fold (OP (aext x), (aext y)) -> (aext (OP x, y))
-  // fold (OP (trunc x), (trunc y)) -> (trunc (OP x, y)) (if trunc isn't free)
+  // fold (OP (trunc x), (trunc y)) -> (trunc (OP x, y))
   //
   // do not sink logical op inside of a vector extend, since it may combine
   // into a vsetcc.
@@ -2040,10 +2040,7 @@ SDValue DAGCombiner::SimplifyBinOpWithSameOpcodeHands(SDNode *N) {
        // Avoid infinite looping with PromoteIntBinOp.
        (N0.getOpcode() == ISD::ANY_EXTEND &&
         (!LegalTypes || TLI.isTypeDesirableForOp(N->getOpcode(), Op0VT))) ||
-       (N0.getOpcode() == ISD::TRUNCATE &&
-        (!TLI.isZExtFree(VT, Op0VT) ||
-         !TLI.isTruncateFree(Op0VT, VT)) &&
-        TLI.isTypeLegal(Op0VT))) &&
+       (N0.getOpcode() == ISD::TRUNCATE && TLI.isTypeLegal(Op0VT))) &&
       !VT.isVector() &&
       Op0VT == N1.getOperand(0).getValueType() &&
       (!LegalOperations || TLI.isOperationLegal(N->getOpcode(), Op0VT))) {
@@ -2430,11 +2427,6 @@ SDValue DAGCombiner::visitOR(SDNode *N) {
   if (SDNode *Rot = MatchRotate(N0, N1, N->getDebugLoc()))
     return SDValue(Rot, 0);
 
-  // Simplify the operands using demanded-bits information.
-  if (!VT.isVector() &&
-      SimplifyDemandedBits(SDValue(N, 0)))
-    return SDValue(N, 0);
-
   return SDValue();
 }
 
@@ -3168,11 +3160,6 @@ SDValue DAGCombiner::visitSRL(SDNode *N) {
       return NewSRL;
   }
 
-  // Attempt to convert a srl of a load into a narrower zero-extending load.
-  SDValue NarrowLoad = ReduceLoadWidth(N);
-  if (NarrowLoad.getNode())
-    return NarrowLoad;
-
   // Here is a common situation. We want to optimize:
   //
   //   %a = ...
@@ -3650,7 +3637,10 @@ SDValue DAGCombiner::visitZERO_EXTEND(SDNode *N) {
 
   // fold (zext (truncate x)) -> (and x, mask)
   if (N0.getOpcode() == ISD::TRUNCATE &&
-      (!LegalOperations || TLI.isOperationLegal(ISD::AND, VT))) {
+      (!LegalOperations || TLI.isOperationLegal(ISD::AND, VT)) &&
+      (!TLI.isTruncateFree(N0.getOperand(0).getValueType(),
+                           N0.getValueType()) ||
+       !TLI.isZExtFree(N0.getValueType(), VT))) {
     SDValue Op = N0.getOperand(0);
     if (Op.getValueType().bitsLT(VT)) {
       Op = DAG.getNode(ISD::ANY_EXTEND, N->getDebugLoc(), VT, Op);
@@ -4036,7 +4026,6 @@ SDValue DAGCombiner::GetDemandedBits(SDValue V, const APInt &Mask) {
 /// extended, also fold the extension to form a extending load.
 SDValue DAGCombiner::ReduceLoadWidth(SDNode *N) {
   unsigned Opc = N->getOpcode();
-
   ISD::LoadExtType ExtType = ISD::NON_EXTLOAD;
   SDValue N0 = N->getOperand(0);
   EVT VT = N->getValueType(0);
@@ -4053,15 +4042,6 @@ SDValue DAGCombiner::ReduceLoadWidth(SDNode *N) {
     ExtVT = cast<VTSDNode>(N->getOperand(1))->getVT();
     if (LegalOperations && !TLI.isLoadExtLegal(ISD::SEXTLOAD, ExtVT))
       return SDValue();
-  } else if (Opc == ISD::SRL) {
-    // Annother special-case: SRL is basically zero-extending a narrower
-    // value.
-    ExtType = ISD::ZEXTLOAD;
-    N0 = SDValue(N, 0);
-    ConstantSDNode *N01 = dyn_cast<ConstantSDNode>(N0.getOperand(1));
-    if (!N01) return SDValue();
-    ExtVT = EVT::getIntegerVT(*DAG.getContext(),
-                              VT.getSizeInBits() - N01->getZExtValue());
   }
 
   unsigned EVTBits = ExtVT.getSizeInBits();
@@ -4265,17 +4245,8 @@ SDValue DAGCombiner::visitTRUNCATE(SDNode *N) {
 
   // fold (truncate (load x)) -> (smaller load x)
   // fold (truncate (srl (load x), c)) -> (smaller load (x+c/evtbits))
-  if (!LegalTypes || TLI.isTypeDesirableForOp(N0.getOpcode(), VT)) {
-    SDValue Reduced = ReduceLoadWidth(N);
-    if (Reduced.getNode())
-      return Reduced;
-  }
-
-  // Simplify the operands using demanded-bits information.
-  if (!VT.isVector() &&
-      SimplifyDemandedBits(SDValue(N, 0)))
-    return SDValue(N, 0);
-
+  if (!LegalTypes || TLI.isTypeDesirableForOp(N0.getOpcode(), VT))
+    return ReduceLoadWidth(N);
   return SDValue();
 }