SimplifyCFG: Don't crash when forming a switch bitmap with an undef default value.

Fixes PR13985.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164934 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index a5e4d44b85ee73312cf808447eb5603cd906b40b..6da791bb1cb55f90c850fef2cc22091d9f743d44 100644 (file)
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -3351,8 +3351,11 @@ SwitchLookupTable::SwitchLookupTable(Module &M,
     APInt TableInt(TableSize * IT->getBitWidth(), 0);
     for (uint64_t I = TableSize; I > 0; --I) {
       TableInt <<= IT->getBitWidth();
-      ConstantInt *Val = cast<ConstantInt>(TableContents[I - 1]);
-      TableInt |= Val->getValue().zext(TableInt.getBitWidth());
+      // Insert values into the bitmap. Undef values are set to zero.
+      if (!isa<UndefValue>(TableContents[I - 1])) {
+        ConstantInt *Val = cast<ConstantInt>(TableContents[I - 1]);
+        TableInt |= Val->getValue().zext(TableInt.getBitWidth());
+      }
     }
     BitMap = ConstantInt::get(M.getContext(), TableInt);
     BitMapElementTy = IT;

diff --git a/test/Transforms/SimplifyCFG/switch_to_lookup_table.ll b/test/Transforms/SimplifyCFG/switch_to_lookup_table.ll
index 134ac4eeb1440b0f20a07f192a51c03fcaf0fad3..aa48ec6481f5d80c5e471682788807f2f3247c8f 100644 (file)
--- a/test/Transforms/SimplifyCFG/switch_to_lookup_table.ll
+++ b/test/Transforms/SimplifyCFG/switch_to_lookup_table.ll
@@ -269,3 +269,27 @@ if.end:
 ; CHECK: switch
 ; CHECK: phi
 }
+
+; PR13985
+define i1 @undef(i32 %tmp) uwtable ssp {
+bb:
+  switch i32 %tmp, label %bb3 [
+    i32 0, label %bb1
+    i32 1, label %bb1
+    i32 7, label %bb2
+    i32 8, label %bb2
+  ]
+
+bb1:                                              ; preds = %bb, %bb
+  br label %bb3
+
+bb2:                                              ; preds = %bb, %bb
+  br label %bb3
+
+bb3:                                              ; preds = %bb2, %bb1, %bb
+  %tmp4 = phi i1 [ undef, %bb ], [ false, %bb2 ], [ true, %bb1 ]
+  ret i1 %tmp4
+; CHECK: define i1 @undef
+; CHECK: %switch.cast = trunc i32 %switch.tableidx to i9
+; CHECK: %switch.downshift = lshr i9 3, %switch.shiftamt
+}