Remove dead *extloads. This allows us to codegen vector.ll:test_extract_elt
to:
test_extract_elt:
alloc r3 = ar.pfs,0,1,0,0
adds r8 = 12, r32
;;
ldfs f8 = [r8]
mov ar.pfs = r3
br.ret.sptk.many rp
instead of:
test_extract_elt:
alloc r3 = ar.pfs,0,1,0,0
adds r8 = 28, r32
adds r9 = 24, r32
adds r10 = 20, r32
adds r11 = 16, r32
;;
ldfs f6 = [r8]
;;
ldfs f6 = [r9]
adds r8 = 12, r32
adds r9 = 8, r32
adds r14 = 4, r32
;;
ldfs f6 = [r10]
;;
ldfs f6 = [r11]
ldfs f8 = [r8]
;;
ldfs f6 = [r9]
;;
ldfs f6 = [r14]
;;
ldfs f6 = [r32]
mov ar.pfs = r3
br.ret.sptk.many rp
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@27297 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 4d1e393..7eeb100 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -208,6 +208,7 @@
SDOperand visitBRCOND(SDNode *N);
SDOperand visitBR_CC(SDNode *N);
SDOperand visitLOAD(SDNode *N);
+ SDOperand visitXEXTLOAD(SDNode *N);
SDOperand visitSTORE(SDNode *N);
SDOperand visitINSERT_VECTOR_ELT(SDNode *N);
SDOperand visitVINSERT_VECTOR_ELT(SDNode *N);
@@ -643,6 +644,9 @@
case ISD::BRCOND: return visitBRCOND(N);
case ISD::BR_CC: return visitBR_CC(N);
case ISD::LOAD: return visitLOAD(N);
+ case ISD::EXTLOAD:
+ case ISD::SEXTLOAD:
+ case ISD::ZEXTLOAD: return visitXEXTLOAD(N);
case ISD::STORE: return visitSTORE(N);
case ISD::INSERT_VECTOR_ELT: return visitINSERT_VECTOR_ELT(N);
case ISD::VINSERT_VECTOR_ELT: return visitVINSERT_VECTOR_ELT(N);
@@ -2278,6 +2282,21 @@
return SDOperand();
}
+/// visitXEXTLOAD - Handle EXTLOAD/ZEXTLOAD/SEXTLOAD.
+SDOperand DAGCombiner::visitXEXTLOAD(SDNode *N) {
+ SDOperand Chain = N->getOperand(0);
+ SDOperand Ptr = N->getOperand(1);
+ SDOperand SrcValue = N->getOperand(2);
+ SDOperand EVT = N->getOperand(3);
+
+ // If there are no uses of the loaded value, change uses of the chain value
+ // into uses of the chain input (i.e. delete the dead load).
+ if (N->hasNUsesOfValue(0, 0))
+ return CombineTo(N, DAG.getNode(ISD::UNDEF, N->getValueType(0)), Chain);
+
+ return SDOperand();
+}
+
SDOperand DAGCombiner::visitSTORE(SDNode *N) {
SDOperand Chain = N->getOperand(0);
SDOperand Value = N->getOperand(1);