[llvm] r346504 - [SystemZ] Avoid inserting same value after replication

[Jonas Paulsson via llvm-commits]

Author: jonpa
Date: Fri Nov  9 07:44:28 2018
New Revision: 346504

URL: http://llvm.org/viewvc/llvm-project?rev=346504&view=rev
Log:
[SystemZ] Avoid inserting same value after replication

A minor improvement of buildVector() that skips creating an
INSERT_VECTOR_ELT for a Value which has already been used for the
REPLICATE.

Review: Ulrich Weigand
https://reviews.llvm.org/D54315

Added:
    llvm/trunk/test/CodeGen/SystemZ/vec-move-19.ll
Modified:
    llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp

Modified: llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp?rev=346504&r1=346503&r2=346504&view=diff
==============================================================================
--- llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/SystemZ/SystemZISelLowering.cpp Fri Nov  9 07:44:28 2018
@@ -4479,6 +4479,7 @@ static SDValue buildVector(SelectionDAG
   // Constants with undefs to get a full vector constant and use that
   // as the starting point.
   SDValue Result;
+  SDValue ReplicatedVal;
   if (NumConstants > 0) {
     for (unsigned I = 0; I < NumElements; ++I)
       if (!Constants[I].getNode())
@@ -4500,6 +4501,7 @@ static SDValue buildVector(SelectionDAG
     if (LoadElIdx != UINT_MAX) {
       Result = DAG.getNode(SystemZISD::REPLICATE, DL, VT, Elems[LoadElIdx]);
       Done[LoadElIdx] = true;
+      ReplicatedVal = Elems[LoadElIdx];
     } else {
       // Try to use VLVGP.
       unsigned I1 = NumElements / 2 - 1;
@@ -4520,7 +4522,7 @@ static SDValue buildVector(SelectionDAG
 
   // Use VLVGx to insert the other elements.
   for (unsigned I = 0; I < NumElements; ++I)
-    if (!Done[I] && !Elems[I].isUndef())
+    if (!Done[I] && !Elems[I].isUndef() && Elems[I] != ReplicatedVal)
       Result = DAG.getNode(ISD::INSERT_VECTOR_ELT, DL, VT, Result, Elems[I],
                            DAG.getConstant(I, DL, MVT::i32));
   return Result;

Added: llvm/trunk/test/CodeGen/SystemZ/vec-move-19.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/SystemZ/vec-move-19.ll?rev=346504&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/SystemZ/vec-move-19.ll (added)
+++ llvm/trunk/test/CodeGen/SystemZ/vec-move-19.ll Fri Nov  9 07:44:28 2018
@@ -0,0 +1,20 @@
+; RUN: llc < %s -mtriple=s390x-linux-gnu -mcpu=z13 | FileCheck %s
+
+; Test that a loaded value which is replicated is not inserted also in any
+; elements.
+
+; CHECK:      vlvgp   %v0, %r0, %r0
+; CHECK-NEXT: vrepf   %v24, %v0, 1
+; CHECK-NOT:  vlvgf   %v24, %r0, 1
+; CHECK-NOT:  vlvgf   %v24, %r0, 2
+
+define <4 x i32> @fun(i32 %arg, i32* %dst) {
+  %tmp = load i32, i32* undef
+  %tmp8 = insertelement <4 x i32> undef, i32 %tmp, i32 0
+  %tmp9 = insertelement <4 x i32> %tmp8, i32 %tmp, i32 1
+  %tmp10 = insertelement <4 x i32> %tmp9, i32 %tmp, i32 2
+  %tmp11 = insertelement <4 x i32> %tmp10, i32 %arg, i32 3
+  store i32 %tmp, i32* %dst
+  ret <4 x i32> %tmp11
+}
+