Speculatively disable Dan's commits 143177 and 143179 to see if

it fixes the dragonegg self-host (it looks like gcc is miscompiled).
Original commit messages:
Eliminate LegalizeOps' LegalizedNodes map and have it just call RAUW
on every node as it legalizes them. This makes it easier to use
hasOneUse() heuristics, since unneeded nodes can be removed from the
DAG earlier.

Make LegalizeOps visit the DAG in an operands-last order. It previously
used operands-first, because LegalizeTypes has to go operands-first, and
LegalizeTypes used to be part of LegalizeOps, but they're now split.
The operands-last order is more natural for several legalization tasks.
For example, it allows lowering code for nodes with floating-point or
vector constants to see those constants directly instead of seeing the
lowered form (often constant-pool loads). This makes some things
somewhat more complicated today, though it ought to allow things to be
simpler in the future. It also fixes some bugs exposed by Legalizing
using RAUW aggressively.

Remove the part of LegalizeOps that attempted to patch up invalid chain
operands on libcalls generated by LegalizeTypes, since it doesn't work
with the new LegalizeOps traversal order. Instead, define what
LegalizeTypes is doing to be correct, and transfer the responsibility
of keeping calls from having overlapping calling sequences into the
scheduler.

Teach the scheduler to model callseq_begin/end pairs as having a
physical register definition/use to prevent calls from having
overlapping calling sequences. This is also somewhat complicated, though
there are ways it might be simplified in the future.

This addresses rdar://9816668, rdar://10043614, rdar://8434668, and others.
Please direct high-level questions about this patch to management.

Delete #if 0 code accidentally left in.

llvm-svn: 143188

1 files changed, 3 insertions, 16 deletions

diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index bfc1690df9f..31e522d4d70 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -1353,10 +1353,12 @@ ARMTargetLowering::LowerCall(SDValue Chain, SDValue Callee,
       SDValue Src = DAG.getNode(ISD::ADD, dl, getPointerTy(), Arg, SrcOffset);
       SDValue SizeNode = DAG.getConstant(Flags.getByValSize() - 4*offset,
                                          MVT::i32);
+      // TODO: Disable AlwaysInline when it becomes possible
+      //       to emit a nested call sequence.
       MemOpChains.push_back(DAG.getMemcpy(Chain, dl, Dst, Src, SizeNode,
                                           Flags.getByValAlign(),
                                           /*isVolatile=*/false,
-                                          /*AlwaysInline=*/false,
+                                          /*AlwaysInline=*/true,
                                           MachinePointerInfo(0),
                                           MachinePointerInfo(0)));
 
@@ -4348,24 +4350,9 @@ static SDValue LowerVECTOR_SHUFFLE(SDValue Op, SelectionDAG &DAG) {
       // If this is undef splat, generate it via "just" vdup, if possible.
       if (Lane == -1) Lane = 0;
 
-      // Test if V1 is a SCALAR_TO_VECTOR.
       if (Lane == 0 && V1.getOpcode() == ISD::SCALAR_TO_VECTOR) {
         return DAG.getNode(ARMISD::VDUP, dl, VT, V1.getOperand(0));
       }
-      // Test if V1 is a BUILD_VECTOR which is equivalent to a SCALAR_TO_VECTOR
-      // (and probably will turn into a SCALAR_TO_VECTOR once legalization
-      // reaches it).
-      if (Lane == 0 && V1.getOpcode() == ISD::BUILD_VECTOR &&
-          !isa<ConstantSDNode>(V1.getOperand(0))) {
-        bool IsScalarToVector = true;
-        for (unsigned i = 1, e = V1.getNumOperands(); i != e; ++i)
-          if (V1.getOperand(i).getOpcode() != ISD::UNDEF) {
-            IsScalarToVector = false;
-            break;
-          }
-        if (IsScalarToVector)
-          return DAG.getNode(ARMISD::VDUP, dl, VT, V1.getOperand(0));
-      }
       return DAG.getNode(ARMISD::VDUPLANE, dl, VT, V1,
                          DAG.getConstant(Lane, MVT::i32));
     }