Switch lowering: fix assert in buildBitTests (PR23738)

[oota-llvm.git] / lib / CodeGen / SelectionDAG / SelectionDAGBuilder.cpp

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 85303d27dcf8f88199c008b94007fd00ea3ab254..a07a024557cbcef06a07af271845c0da2b80aa42 100644 (file)
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -2282,7 +2282,11 @@ void SelectionDAGBuilder::visitSelect(const User &I) {
     while (TLI.getTypeAction(Ctx, VT) == TargetLoweringBase::TypeSplitVector)
       VT = TLI.getTypeToTransformTo(Ctx, VT);
 
-    if (Opc != ISD::DELETED_NODE && TLI.isOperationLegalOrCustom(Opc, VT)) {
+    if (Opc != ISD::DELETED_NODE && TLI.isOperationLegalOrCustom(Opc, VT) &&
+        // If the underlying comparison instruction is used by any other instruction,
+        // the consumed instructions won't be destroyed, so it is not profitable
+        // to convert to a min/max.
+        cast<SelectInst>(&I)->getCondition()->hasOneUse()) {
       OpCode = Opc;
       LHSVal = getValue(LHS);
       RHSVal = getValue(RHS);
@@ -2848,7 +2852,17 @@ void SelectionDAGBuilder::visitLoad(const LoadInst &I) {
 
   bool isVolatile = I.isVolatile();
   bool isNonTemporal = I.getMetadata(LLVMContext::MD_nontemporal) != nullptr;
-  bool isInvariant = I.getMetadata(LLVMContext::MD_invariant_load) != nullptr;
+
+  // The IR notion of invariant_load only guarantees that all *non-faulting*
+  // invariant loads result in the same value.  The MI notion of invariant load
+  // guarantees that the load can be legally moved to any location within its
+  // containing function.  The MI notion of invariant_load is stronger than the
+  // IR notion of invariant_load -- an MI invariant_load is an IR invariant_load
+  // with a guarantee that the location being loaded from is dereferenceable
+  // throughout the function's lifetime.
+
+  bool isInvariant = I.getMetadata(LLVMContext::MD_invariant_load) != nullptr &&
+    isDereferenceablePointer(SV, *DAG.getTarget().getDataLayout());
   unsigned Alignment = I.getAlignment();
 
   AAMDNodes AAInfo;
@@ -7437,7 +7451,7 @@ bool SelectionDAGBuilder::buildJumpTable(CaseClusterVector &Clusters,
   JumpTableHeader JTH(Clusters[First].Low->getValue(),
                       Clusters[Last].High->getValue(), SI->getCondition(),
                       nullptr, false);
-  JTCases.push_back(JumpTableBlock(JTH, JT));
+  JTCases.emplace_back(std::move(JTH), std::move(JT));
 
   JTCluster = CaseCluster::jumpTable(Clusters[First].Low, Clusters[Last].High,
                                      JTCases.size() - 1, Weight);
@@ -7600,7 +7614,8 @@ bool SelectionDAGBuilder::buildBitTests(CaseClusterVector &Clusters,
 
   const int BitWidth =
       DAG.getTargetLoweringInfo().getPointerTy().getSizeInBits();
-  assert((High - Low + 1).sle(BitWidth) && "Case range must fit in bit mask!");
+  uint64_t Range = (High - Low).getLimitedValue(UINT64_MAX - 1) + 1;
+  assert(Range <= (uint64_t)BitWidth && "Case range must fit in bit mask!");
 
   if (Low.isNonNegative() && High.slt(BitWidth)) {
     // Optimize the case where all the case values fit in a
@@ -7650,9 +7665,9 @@ bool SelectionDAGBuilder::buildBitTests(CaseClusterVector &Clusters,
         FuncInfo.MF->CreateMachineBasicBlock(SI->getParent());
     BTI.push_back(BitTestCase(CB.Mask, BitTestBB, CB.BB, CB.ExtraWeight));
   }
-  BitTestCases.push_back(BitTestBlock(LowBound, CmpRange, SI->getCondition(),
-                                      -1U, MVT::Other, false, nullptr,
-                                      nullptr, std::move(BTI)));
+  BitTestCases.emplace_back(std::move(LowBound), std::move(CmpRange),
+                            SI->getCondition(), -1U, MVT::Other, false, nullptr,
+                            nullptr, std::move(BTI));
 
   BTCluster = CaseCluster::bitTests(Clusters[First].Low, Clusters[Last].High,
                                     BitTestCases.size() - 1, TotalWeight);