JumpTableReg, SwitchOp);
JT.Reg = JumpTableReg;
- // Emit the range check for the jump table, and branch to the default block
- // for the switch statement if the value being switched on exceeds the largest
- // case in the switch.
- SDValue CMP = DAG.getSetCC(
- dl, TLI.getSetCCResultType(DAG.getDataLayout(), *DAG.getContext(),
- Sub.getValueType()),
- Sub, DAG.getConstant(JTH.Last - JTH.First, dl, VT), ISD::SETUGT);
-
- SDValue BrCond = DAG.getNode(ISD::BRCOND, dl,
- MVT::Other, CopyTo, CMP,
- DAG.getBasicBlock(JT.Default));
-
- // Avoid emitting unnecessary branches to the next block.
- if (JT.MBB != NextBlock(SwitchBB))
- BrCond = DAG.getNode(ISD::BR, dl, MVT::Other, BrCond,
- DAG.getBasicBlock(JT.MBB));
-
- DAG.setRoot(BrCond);
+ if (!JTH.OmitRangeCheck) {
+ // Emit the range check for the jump table, and branch to the default block
+ // for the switch statement if the value being switched on exceeds the
+ // largest case in the switch.
+ SDValue CMP = DAG.getSetCC(
+ dl, TLI.getSetCCResultType(DAG.getDataLayout(), *DAG.getContext(),
+ Sub.getValueType()),
+ Sub, DAG.getConstant(JTH.Last - JTH.First, dl, VT), ISD::SETUGT);
+
+ SDValue BrCond = DAG.getNode(ISD::BRCOND, dl,
+ MVT::Other, CopyTo, CMP,
+ DAG.getBasicBlock(JT.Default));
+
+ // Avoid emitting unnecessary branches to the next block.
+ if (JT.MBB != NextBlock(SwitchBB))
+ BrCond = DAG.getNode(ISD::BR, dl, MVT::Other, BrCond,
+ DAG.getBasicBlock(JT.MBB));
+
+ DAG.setRoot(BrCond);
+ } else {
+ SDValue BrCond = DAG.getNode(ISD::BR, dl, MVT::Other, CopyTo,
+ DAG.getBasicBlock(JT.MBB));
+ DAG.setRoot(BrCond);
+ SwitchBB->removeSuccessor(JT.Default, true);
+ }
}
/// Create a LOAD_STACK_GUARD node, and let it carry the target specific global
->createJumpTableIndex(Table);
// Set up the jump table info.
+ bool UnreachableDefault =
+ isa<UnreachableInst>(SI->getDefaultDest()->getFirstNonPHIOrDbg());
+ bool OmitRangeCheck = UnreachableDefault;
JumpTable JT(-1U, JTI, JumpTableMBB, nullptr);
JumpTableHeader JTH(Clusters[First].Low->getValue(),
Clusters[Last].High->getValue(), SI->getCondition(),
- nullptr, false);
+ nullptr, false, OmitRangeCheck);
JTCases.emplace_back(std::move(JTH), std::move(JT));
JTCluster = CaseCluster::jumpTable(Clusters[First].Low, Clusters[Last].High,
// if there are many clusters.
sortAndRangeify(Clusters);
- if (TM.getOptLevel() != CodeGenOpt::None) {
- // Replace an unreachable default with the most popular destination.
- // FIXME: Exploit unreachable default more aggressively.
- bool UnreachableDefault =
- isa<UnreachableInst>(SI.getDefaultDest()->getFirstNonPHIOrDbg());
- if (UnreachableDefault && !Clusters.empty()) {
- DenseMap<const BasicBlock *, unsigned> Popularity;
- unsigned MaxPop = 0;
- const BasicBlock *MaxBB = nullptr;
- for (auto I : SI.cases()) {
- const BasicBlock *BB = I.getCaseSuccessor();
- if (++Popularity[BB] > MaxPop) {
- MaxPop = Popularity[BB];
- MaxBB = BB;
- }
- }
- // Set new default.
- assert(MaxPop > 0 && MaxBB);
- DefaultMBB = FuncInfo.MBBMap[MaxBB];
-
- // Remove cases that were pointing to the destination that is now the
- // default.
- CaseClusterVector New;
- New.reserve(Clusters.size());
- for (CaseCluster &CC : Clusters) {
- if (CC.MBB != DefaultMBB)
- New.push_back(CC);
- }
- Clusters = std::move(New);
- }
- }
-
// The branch probablity of the peeled case.
BranchProbability PeeledCaseProb = BranchProbability::getZero();
MachineBasicBlock *PeeledSwitchMBB =
const Value *SValue;
MachineBasicBlock *HeaderBB;
bool Emitted;
+ bool OmitRangeCheck;
JumpTableHeader(APInt F, APInt L, const Value *SV, MachineBasicBlock *H,
- bool E = false)
+ bool E = false, bool ORC = false)
: First(std::move(F)), Last(std::move(L)), SValue(SV), HeaderBB(H),
- Emitted(E) {}
+ Emitted(E), OmitRangeCheck(ORC) {}
};
using JumpTableBlock = std::pair<JumpTableHeader, JumpTable>;
--- /dev/null
+; RUN: llc -O3 -o - %s | FileCheck %s
+
+; Test that the output in the presence of an unreachable default does not have
+; a compare and branch at the top of the switch to handle the default case.
+
+target triple = "aarch64-unknown-linux-gnu"
+
+; Function Attrs: nounwind
+define void @fn(i4) {
+ switch i4 %0, label %default [
+ i4 0, label %case_0
+ i4 1, label %case_1
+ i4 2, label %case_2
+ i4 3, label %case_3
+ i4 4, label %case_4
+ i4 5, label %case_5
+ ]
+
+; CHECK-LABEL: fn:
+; CHECK-NOT: sub
+; CHECK-NOT: cmp
+; CHECK-NOT: b.hi
+; CHECK: ldrb {{w[0-9]+}}, [{{x[0-9]+}}, {{x[0-9]+}}]
+; CHECK: add {{x[0-9]+}}, {{x[0-9]+}}, {{x[0-9]+}}, lsl #2
+; CHECK: br {{x[0-9]+}}
+
+default:
+ unreachable
+
+case_0:
+ tail call void @handle_case_00(i4 %0) #2
+ br label %return_label
+
+case_1:
+ tail call void @handle_case_01(i4 %0) #2
+ br label %return_label
+
+case_2:
+ tail call void @handle_case_02(i4 %0) #2
+ br label %return_label
+
+case_3:
+ tail call void @handle_case_03(i4 %0) #2
+ br label %return_label
+
+case_4:
+ tail call void @handle_case_04(i4 %0) #2
+ br label %return_label
+
+case_5:
+ tail call void @handle_case_05(i4 %0) #2
+ br label %return_label
+
+return_label:
+ ret void
+}
+
+declare void @handle_case_00(i4)
+declare void @handle_case_01(i4)
+declare void @handle_case_02(i4)
+declare void @handle_case_03(i4)
+declare void @handle_case_04(i4)
+declare void @handle_case_05(i4)
define void @pr38743() #1 align 2 {
; CHECK-LABEL: pr38743:
-; CHECK: # %bb.0: # %bb
-; CHECK-NEXT: cmpl $3, %eax
-; CHECK-NEXT: je .LBB0_4
-; CHECK-NEXT: # %bb.1: # %bb
-; CHECK-NEXT: cmpl $1, %eax
-; CHECK-NEXT: je .LBB0_2
-; CHECK-NEXT: # %bb.3: # %bb5
-; CHECK-NEXT: movzwl .str.17+{{.*}}(%rip), %eax
-; CHECK-NEXT: movw %ax, -{{[0-9]+}}(%rsp)
-; CHECK-NEXT: movq {{.*}}(%rip), %rax
-; CHECK-NEXT: jmp .LBB0_5
-; CHECK-NEXT: .LBB0_4: # %bb8
-; CHECK-NEXT: movq .str.18+{{.*}}(%rip), %rax
-; CHECK-NEXT: movq %rax, -{{[0-9]+}}(%rsp)
-; CHECK-NEXT: movq {{.*}}(%rip), %rax
-; CHECK-NEXT: jmp .LBB0_5
-; CHECK-NEXT: .LBB0_2: # %bb2
-; CHECK-NEXT: movq .str.16+{{.*}}(%rip), %rax
-; CHECK-NEXT: movq %rax, -{{[0-9]+}}(%rsp)
-; CHECK-NEXT: movq {{.*}}(%rip), %rax
-; CHECK-NEXT: .LBB0_5: # %bb12
-; CHECK-NEXT: movq %rax, -{{[0-9]+}}(%rsp)
-; CHECK-NEXT: movq -{{[0-9]+}}(%rsp), %rax
-; CHECK-NEXT: movq %rax, (%rax)
-; CHECK-NEXT: movb -{{[0-9]+}}(%rsp), %al
-; CHECK-NEXT: movq -{{[0-9]+}}(%rsp), %rcx
-; CHECK-NEXT: movzwl -{{[0-9]+}}(%rsp), %edx
-; CHECK-NEXT: movl -{{[0-9]+}}(%rsp), %esi
-; CHECK-NEXT: movb -{{[0-9]+}}(%rsp), %dil
-; CHECK-NEXT: movb %al, (%rax)
-; CHECK-NEXT: movq %rcx, 1(%rax)
-; CHECK-NEXT: movw %dx, 9(%rax)
-; CHECK-NEXT: movl %esi, 11(%rax)
-; CHECK-NEXT: movb %dil, 15(%rax)
-; CHECK-NEXT: retq
+; CHECK: # %bb.0: # %bb
+; CHECK-NEXT: xorl %eax, %eax
+; CHECK-NEXT: jmpq *.LJTI0_0(,%rax,8)
+; CHECK-NEXT: .[[LABEL1:[A-Z_0-9]+]]: # %bb5
+; CHECK-NEXT: movzwl .str.17+{{.*}}(%rip), %eax
+; CHECK-NEXT: movw %ax, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT: movq .str.17(%rip), %rax
+; CHECK-NEXT: jmp .[[LABEL4:[A-Z_0-9]+]]
+; CHECK-NEXT: .[[LABEL2:[A-Z_0-9]+]]: # %bb2
+; CHECK-NEXT: movq .str.16+{{.*}}(%rip), %rax
+; CHECK-NEXT: movq %rax, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT: movq .str.16(%rip), %rax
+; CHECK-NEXT: jmp .[[LABEL4]]
+; CHECK-NEXT: .[[LABEL3:[A-Z_0-9]+]]: # %bb8
+; CHECK-NEXT: movq .str.18+{{.*}}(%rip), %rax
+; CHECK-NEXT: movq %rax, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT: movq .str.18(%rip), %rax
+; CHECK-NEXT: .[[LABEL4]]: # %bb12
+; CHECK-NEXT: movq %rax, -{{[0-9]+}}(%rsp)
+; CHECK-NEXT: movq -{{[0-9]+}}(%rsp), %rax
+; CHECK-NEXT: movq %rax, (%rax)
+; CHECK-NEXT: movb -{{[0-9]+}}(%rsp), %al
+; CHECK-NEXT: movq -{{[0-9]+}}(%rsp), %rcx
+; CHECK-NEXT: movzwl -{{[0-9]+}}(%rsp), %edx
+; CHECK-NEXT: movl -{{[0-9]+}}(%rsp), %esi
+; CHECK-NEXT: movb -{{[0-9]+}}(%rsp), %dil
+; CHECK-NEXT: movb %al, (%rax)
+; CHECK-NEXT: movq %rcx, {{[0-9]+}}(%rax)
+; CHECK-NEXT: movw %dx, {{[0-9]+}}(%rax)
+; CHECK-NEXT: movl %esi, {{[0-9]+}}(%rax)
+; CHECK-NEXT: movb %dil, {{[0-9]+}}(%rax)
+; CHECK-NEXT: retq
+; CHECK-LABEL: .LJTI0_0:
+; CHECK: .quad .[[LABEL2]]
+; CHECK-NEXT: .quad .[[LABEL1]]
+; CHECK-NEXT: .quad .[[LABEL3]]
+; CHECK-NEXT: .quad .[[LABEL1]]
bb:
%tmp = alloca %0, align 16
%tmp1 = bitcast %0* %tmp to i8*
; RUN: llc -mtriple=i686-pc-gnu-linux -print-machineinstrs=expand-isel-pseudos %s -o /dev/null 2>&1 | FileCheck %s -check-prefix=CHECK-JT-PROB
-; An unreachable default destination is replaced with the most popular case label.
+; An unreachable default destination is ignored and no compare and branch
+; is generated for the default values.
define void @foo(i32 %x, i32* %to) {
; CHECK-LABEL: foo:
; CHECK: movl 4(%esp), [[REG:%e[a-z]{2}]]
-; CHECK: cmpl $3, [[REG]]
-; CHECK: ja .LBB0_6
-; CHECK-NEXT: # %bb.1:
; CHECK-NEXT: jmpl *.LJTI0_0(,[[REG]],4)
; CHECK: movl $4
; CHECK: retl
; The jump table has four entries.
; CHECK-LABEL: .LJTI0_0:
+; CHECK-NEXT: .long .LBB0_1
; CHECK-NEXT: .long .LBB0_2
; CHECK-NEXT: .long .LBB0_3
; CHECK-NEXT: .long .LBB0_4
; CHECK-NEXT: .long .LBB0_5
+; CHECK-NEXT: .long .LBB0_5
}
; Check if branch probabilities are correctly assigned to the jump table.
projects / llvm / commitdiff