4 files changed, 95 insertions, 2 deletions
diff --git a/llvm/include/llvm/IR/Attributes.td b/llvm/include/llvm/IR/Attributes.td
index a9bcda094b7..8b490ec4fc8 100644
--- a/llvm/include/llvm/IR/Attributes.td
+++ b/llvm/include/llvm/IR/Attributes.td
@@ -168,6 +168,7 @@ def LessPreciseFPMAD : StrBoolAttr<"less-precise-fpmad">;
 def NoInfsFPMath : StrBoolAttr<"no-infs-fp-math">;
 def NoNansFPMath : StrBoolAttr<"no-nans-fp-math">;
 def UnsafeFPMath : StrBoolAttr<"unsafe-fp-math">;
+def NoJumpTables : StrBoolAttr<"no-jump-tables">;
 
 class CompatRule<string F> {
   // The name of the function called to check the attribute of the caller and
@@ -197,4 +198,5 @@ def : MergeRule<"setAND<NoInfsFPMathAttr>">;
 def : MergeRule<"setAND<NoNansFPMathAttr>">;
 def : MergeRule<"setAND<UnsafeFPMathAttr>">;
 def : MergeRule<"setOR<NoImplicitFloatAttr>">;
+def : MergeRule<"setOR<NoJumpTablesAttr>">;
 def : MergeRule<"adjustCallerSSPLevel">;
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 0f610cee3b8..71c015df520 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -7961,7 +7961,12 @@ bool SelectionDAGBuilder::isDense(const CaseClusterVector &Clusters,
   return NumCases * 100 >= Range * Density;
 }
 
-static inline bool areJTsAllowed(const TargetLowering &TLI) {
+static inline bool areJTsAllowed(const TargetLowering &TLI,
+                                 const SwitchInst *SI) {
+  const Function *Fn = SI->getParent()->getParent();
+  if (Fn->getFnAttribute("no-jump-tables").getValueAsString() == "true")
+    return false;
+
   return TLI.isOperationLegalOrCustom(ISD::BR_JT, MVT::Other) ||
          TLI.isOperationLegalOrCustom(ISD::BRIND, MVT::Other);
 }
@@ -8055,7 +8060,7 @@ void SelectionDAGBuilder::findJumpTables(CaseClusterVector &Clusters,
 #endif
 
   const TargetLowering &TLI = DAG.getTargetLoweringInfo();
-  if (!areJTsAllowed(TLI))
+  if (!areJTsAllowed(TLI, SI))
     return;
 
   const int64_t N = Clusters.size();
diff --git a/llvm/test/CodeGen/X86/switch.ll b/llvm/test/CodeGen/X86/switch.ll
index 70da4a2abb7..5bba78d4490 100644
--- a/llvm/test/CodeGen/X86/switch.ll
+++ b/llvm/test/CodeGen/X86/switch.ll
@@ -30,6 +30,47 @@ return: ret void
 ; NOOPT: jmpq
 }
 
+; Should never be lowered as a jump table because of the attribute
+define void @basic_nojumptable(i32 %x) "no-jump-tables"="true" {
+entry:
+  switch i32 %x, label %return [
+    i32 3, label %bb0
+    i32 1, label %bb1
+    i32 4, label %bb1
+    i32 5, label %bb2
+  ]
+bb0: tail call void @g(i32 0) br label %return
+bb1: tail call void @g(i32 1) br label %return
+bb2: tail call void @g(i32 1) br label %return
+return: ret void
+
+; Lowered as a jump table, both with and without optimization.
+; CHECK-LABEL: basic_nojumptable
+; CHECK-NOT: jmpq *.LJTI
+}
+
+; Should be lowered as a jump table because of the attribute
+define void @basic_nojumptable_false(i32 %x) "no-jump-tables"="false" {
+entry:
+  switch i32 %x, label %return [
+    i32 3, label %bb0
+    i32 1, label %bb1
+    i32 4, label %bb1
+    i32 5, label %bb2
+  ]
+bb0: tail call void @g(i32 0) br label %return
+bb1: tail call void @g(i32 1) br label %return
+bb2: tail call void @g(i32 1) br label %return
+return: ret void
+
+; Lowered as a jump table, both with and without optimization.
+; CHECK-LABEL: basic_nojumptable_false
+; CHECK: decl
+; CHECK: cmpl $4
+; CHECK: ja
+; CHECK: jmpq *.LJTI
+}
+
 
 define void @simple_ranges(i32 %x) {
 entry:
@@ -47,6 +88,8 @@ bb0: tail call void @g(i32 0) br label %return
 bb1: tail call void @g(i32 1) br label %return
 return: ret void
 
+
+
 ; Should be lowered to two range checks.
 ; CHECK-LABEL: simple_ranges
 ; CHECK: leal -100
diff --git a/llvm/test/Transforms/Inline/attributes.ll b/llvm/test/Transforms/Inline/attributes.ll
index 0458fa23f79..62b10fb3beb 100644
--- a/llvm/test/Transforms/Inline/attributes.ll
+++ b/llvm/test/Transforms/Inline/attributes.ll
@@ -241,6 +241,49 @@ define i32 @test_no-implicit-float3(i32 %i) noimplicitfloat {
 ; CHECK-NEXT: ret i32
 }
 
+; Check that no-jump-tables flag propagates from inlined callee to caller 
+
+define i32 @no-use-jump-tables_callee0(i32 %i) {
+  ret i32 %i
+; CHECK: @no-use-jump-tables_callee0(i32 %i) {
+; CHECK-NEXT: ret i32
+}
+
+define i32 @no-use-jump-tables_callee1(i32 %i) "no-jump-tables"="true" {
+  ret i32 %i
+; CHECK: @no-use-jump-tables_callee1(i32 %i) [[NOUSEJUMPTABLES:#[0-9]+]] {
+; CHECK-NEXT: ret i32
+}
+
+define i32 @test_no-use-jump-tables0(i32 %i) {
+  %1 = call i32 @no-use-jump-tables_callee0(i32 %i)
+  ret i32 %1
+; CHECK: @test_no-use-jump-tables0(i32 %i) {
+; CHECK-NEXT: ret i32
+}
+
+define i32 @test_no-use-jump-tables1(i32 %i) {
+  %1 = call i32 @no-use-jump-tables_callee1(i32 %i)
+  ret i32 %1
+; CHECK: @test_no-use-jump-tables1(i32 %i) [[NOUSEJUMPTABLES]] {
+; CHECK-NEXT: ret i32
+}
+
+define i32 @test_no-use-jump-tables2(i32 %i) "no-jump-tables"="true" {
+  %1 = call i32 @no-use-jump-tables_callee0(i32 %i)
+  ret i32 %1
+; CHECK: @test_no-use-jump-tables2(i32 %i) [[NOUSEJUMPTABLES]] {
+; CHECK-NEXT: ret i32
+}
+
+define i32 @test_no-use-jump-tables3(i32 %i) "no-jump-tables"="true" {
+  %1 = call i32 @no-use-jump-tables_callee1(i32 %i)
+  ret i32 %1
+; CHECK: @test_no-use-jump-tables3(i32 %i) [[NOUSEJUMPTABLES]] {
+; CHECK-NEXT: ret i32
+}
+
 ; CHECK: attributes [[FPMAD_FALSE]] = { "less-precise-fpmad"="false" }
 ; CHECK: attributes [[FPMAD_TRUE]] = { "less-precise-fpmad"="true" }
 ; CHECK: attributes [[NOIMPLICITFLOAT]] = { noimplicitfloat }
+; CHECK: attributes [[NOUSEJUMPTABLES]] = { "no-jump-tables"="true" }
+\ No newline at end of file