From 794cd3418b0a3d92f968a28f3f1ae4fa1b7a7761 Mon Sep 17 00:00:00 2001
From: Hans Wennborg <hans@hanshq.net>
Date: Fri, 24 Apr 2015 16:53:55 +0000
Subject: [PATCH] Switch lowering: fix APInt overflow causing infinite loop /
 OOM

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235729 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../SelectionDAG/SelectionDAGBuilder.cpp      |  3 +-
 test/CodeGen/X86/switch.ll                    | 63 +++++++++++++++++++
 2 files changed, 65 insertions(+), 1 deletion(-)

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 14421834a55..01419cf8fa1 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -7236,7 +7236,8 @@ bool SelectionDAGBuilder::buildJumpTable(CaseClusterVector &Clusters,
       for (uint64_t J = 0; J < Gap; J++)
         Table.push_back(DefaultMBB);
     }
-    for (APInt X = Low; X.sle(High); ++X)
+    uint64_t ClusterSize = (High - Low).getLimitedValue() + 1;
+    for (uint64_t J = 0; J < ClusterSize; ++J)
       Table.push_back(Clusters[I].MBB);
     JTWeights[Clusters[I].MBB] += Clusters[I].Weight;
   }
diff --git a/test/CodeGen/X86/switch.ll b/test/CodeGen/X86/switch.ll
index de9f38fc874..9baee19a2a6 100644
--- a/test/CodeGen/X86/switch.ll
+++ b/test/CodeGen/X86/switch.ll
@@ -304,3 +304,66 @@ sw:
 ; NOOPT-NEXT: retq
 ; NOOPT: jmp .[[L]]
 }
+
+
+define void @int_max_table_cluster(i8 %x) {
+entry:
+  switch i8 %x, label %return [
+    i8 0, label %bb0 i8 1, label %bb0 i8 2, label %bb0 i8 3, label %bb0
+    i8 4, label %bb0 i8 5, label %bb0 i8 6, label %bb0 i8 7, label %bb0
+    i8 8, label %bb0 i8 9, label %bb0 i8 10, label %bb0 i8 11, label %bb0
+    i8 12, label %bb0 i8 13, label %bb0 i8 14, label %bb0 i8 15, label %bb0
+    i8 16, label %bb0 i8 17, label %bb0 i8 18, label %bb0 i8 19, label %bb0
+    i8 20, label %bb0 i8 21, label %bb0 i8 22, label %bb0 i8 23, label %bb0
+    i8 24, label %bb0 i8 25, label %bb0 i8 26, label %bb0 i8 27, label %bb0
+    i8 28, label %bb0 i8 29, label %bb0 i8 30, label %bb0 i8 31, label %bb0
+    i8 32, label %bb0 i8 33, label %bb0 i8 34, label %bb0 i8 35, label %bb0
+    i8 36, label %bb0 i8 37, label %bb0 i8 38, label %bb0 i8 39, label %bb0
+    i8 40, label %bb0 i8 41, label %bb0 i8 42, label %bb0 i8 43, label %bb0
+    i8 44, label %bb0 i8 45, label %bb0 i8 46, label %bb0 i8 47, label %bb0
+    i8 48, label %bb0 i8 49, label %bb0 i8 50, label %bb0 i8 51, label %bb0
+    i8 52, label %bb0 i8 53, label %bb0 i8 54, label %bb0 i8 55, label %bb0
+    i8 56, label %bb0 i8 57, label %bb0 i8 58, label %bb0 i8 59, label %bb0
+    i8 60, label %bb0 i8 61, label %bb0 i8 62, label %bb0 i8 63, label %bb0
+    i8 64, label %bb0 i8 65, label %bb0 i8 66, label %bb0 i8 67, label %bb0
+    i8 68, label %bb0 i8 69, label %bb0 i8 70, label %bb0 i8 71, label %bb0
+    i8 72, label %bb0 i8 73, label %bb0 i8 74, label %bb0 i8 75, label %bb0
+    i8 76, label %bb0 i8 77, label %bb0 i8 78, label %bb0 i8 79, label %bb0
+    i8 80, label %bb0 i8 81, label %bb0 i8 82, label %bb0 i8 83, label %bb0
+    i8 84, label %bb0 i8 85, label %bb0 i8 86, label %bb0 i8 87, label %bb0
+    i8 88, label %bb0 i8 89, label %bb0 i8 90, label %bb0 i8 91, label %bb0
+    i8 92, label %bb0 i8 93, label %bb0 i8 94, label %bb0 i8 95, label %bb0
+    i8 96, label %bb0 i8 97, label %bb0 i8 98, label %bb0 i8 99, label %bb0
+    i8 100, label %bb0 i8 101, label %bb0 i8 102, label %bb0 i8 103, label %bb0
+    i8 104, label %bb0 i8 105, label %bb0 i8 106, label %bb0 i8 107, label %bb0
+    i8 108, label %bb0 i8 109, label %bb0 i8 110, label %bb0 i8 111, label %bb0
+    i8 112, label %bb0 i8 113, label %bb0 i8 114, label %bb0 i8 115, label %bb0
+    i8 116, label %bb0 i8 117, label %bb0 i8 118, label %bb0 i8 119, label %bb0
+    i8 120, label %bb0 i8 121, label %bb0 i8 122, label %bb0 i8 123, label %bb0
+    i8 124, label %bb0 i8 125, label %bb0 i8 126, label %bb0 i8 127, label %bb0
+    i8 -64, label %bb1 i8 -63, label %bb1 i8 -62, label %bb1 i8 -61, label %bb1
+    i8 -60, label %bb1 i8 -59, label %bb1 i8 -58, label %bb1 i8 -57, label %bb1
+    i8 -56, label %bb1 i8 -55, label %bb1 i8 -54, label %bb1 i8 -53, label %bb1
+    i8 -52, label %bb1 i8 -51, label %bb1 i8 -50, label %bb1 i8 -49, label %bb1
+    i8 -48, label %bb1 i8 -47, label %bb1 i8 -46, label %bb1 i8 -45, label %bb1
+    i8 -44, label %bb1 i8 -43, label %bb1 i8 -42, label %bb1 i8 -41, label %bb1
+    i8 -40, label %bb1 i8 -39, label %bb1 i8 -38, label %bb1 i8 -37, label %bb1
+    i8 -36, label %bb1 i8 -35, label %bb1 i8 -34, label %bb1 i8 -33, label %bb1
+    i8 -32, label %bb2 i8 -31, label %bb2 i8 -30, label %bb2 i8 -29, label %bb2
+    i8 -28, label %bb2 i8 -27, label %bb2 i8 -26, label %bb2 i8 -25, label %bb2
+    i8 -24, label %bb2 i8 -23, label %bb2 i8 -22, label %bb2 i8 -21, label %bb2
+    i8 -20, label %bb2 i8 -19, label %bb2 i8 -18, label %bb2 i8 -17, label %bb2
+    i8 -16, label %bb3 i8 -15, label %bb3 i8 -14, label %bb3 i8 -13, label %bb3
+    i8 -12, label %bb3 i8 -11, label %bb3 i8 -10, label %bb3 i8 -9, label %bb3
+  ]
+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
+bb3: tail call void @g(i32 1) br label %return
+return: ret void
+
+; Don't infloop on jump tables where the upper bound is the max value of the
+; input type (in this case 127).
+; CHECK-LABEL: int_max_table_cluster
+; CHECK: jmpq *.LJTI
+}
-- 
2.34.1