Teach SimplifyCFG to turn

  (indirectbr (select cond, blockaddress(@fn, BlockA),
                            blockaddress(@fn, BlockB)))
into
  (br cond, BlockA, BlockB).

llvm-svn: 120943

1 files changed, 118 insertions, 0 deletions

diff --git a/llvm/test/Transforms/SimplifyCFG/indirectbr.ll b/llvm/test/Transforms/SimplifyCFG/indirectbr.ll
index de4f5b60755..7fb4def5b93 100644
--- a/llvm/test/Transforms/SimplifyCFG/indirectbr.ll
+++ b/llvm/test/Transforms/SimplifyCFG/indirectbr.ll
@@ -62,3 +62,121 @@ entry:
 BB0:
   ret void
 }
+
+
+; Make sure the blocks in the next few tests aren't trivially removable as
+; successors by taking their addresses.
+
+@anchor = constant [13 x i8*] [
+  i8* blockaddress(@indbrtest3, %L1), i8* blockaddress(@indbrtest3, %L2), i8* blockaddress(@indbrtest3, %L3),
+  i8* blockaddress(@indbrtest4, %L1), i8* blockaddress(@indbrtest4, %L2), i8* blockaddress(@indbrtest4, %L3),
+  i8* blockaddress(@indbrtest5, %L1), i8* blockaddress(@indbrtest5, %L2), i8* blockaddress(@indbrtest5, %L3), i8* blockaddress(@indbrtest5, %L4),
+  i8* blockaddress(@indbrtest6, %L1), i8* blockaddress(@indbrtest6, %L2), i8* blockaddress(@indbrtest6, %L3)
+]
+
+; SimplifyCFG should turn the indirectbr into a conditional branch on the
+; condition of the select.
+
+; CHECK: @indbrtest3
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br i1 %cond, label %L1, label %L2
+; CHECK-NOT: indirectbr
+; CHECK-NOT: br
+; CHECK-NOT: L3:
+define void @indbrtest3(i1 %cond, i8* %address) nounwind {
+entry:
+  %indirect.goto.dest = select i1 %cond, i8* blockaddress(@indbrtest3, %L1), i8* blockaddress(@indbrtest3, %L2)
+  indirectbr i8* %indirect.goto.dest, [label %L1, label %L2, label %L3]
+
+L1:
+  call void @A()
+  ret void
+L2:
+  call void @C()
+  ret void
+L3:
+  call void @foo()
+  ret void
+}
+
+; SimplifyCFG should turn the indirectbr into an unconditional branch to the
+; only possible destination.
+; As in @indbrtest1, it should really remove the branch entirely, but it doesn't
+; because it's in the entry block.
+
+; CHECK: @indbrtest4
+; CHECK-NEXT: entry:
+; CHECK-NEXT: br label %L1
+define void @indbrtest4(i1 %cond) nounwind {
+entry:
+  %indirect.goto.dest = select i1 %cond, i8* blockaddress(@indbrtest4, %L1), i8* blockaddress(@indbrtest4, %L1)
+  indirectbr i8* %indirect.goto.dest, [label %L1, label %L2, label %L3]
+
+L1:
+  call void @A()
+  ret void
+L2:
+  call void @C()
+  ret void
+L3:
+  call void @foo()
+  ret void
+}
+
+; SimplifyCFG should turn the indirectbr into an unreachable because neither
+; destination is listed as a successor.
+
+; CHECK: @indbrtest5
+; CHECK-NEXT: entry:
+; CHECK-NEXT: unreachable
+; CHECK-NEXT: }
+define void @indbrtest5(i1 %cond, i8* %anchor) nounwind {
+entry:
+  %indirect.goto.dest = select i1 %cond, i8* blockaddress(@indbrtest5, %L1), i8* blockaddress(@indbrtest5, %L2)
+; This needs to have more than one successor for this test, otherwise it gets
+; replaced with an unconditional branch to the single successor.
+  indirectbr i8* %indirect.goto.dest, [label %L3, label %L4]
+
+L1:
+  call void @A()
+  ret void
+L2:
+  call void @C()
+  ret void
+L3:
+  call void @foo()
+  ret void
+L4:
+  call void @foo()
+
+; This keeps blockaddresses not otherwise listed as successors from being zapped
+; before SimplifyCFG even looks at the indirectbr.
+  indirectbr i8* %anchor, [label %L1, label %L2]
+}
+
+; The same as above, except the selected addresses are equal.
+
+; CHECK: @indbrtest6
+; CHECK-NEXT: entry:
+; CHECK-NEXT: unreachable
+; CHECK-NEXT: }
+define void @indbrtest6(i1 %cond, i8* %anchor) nounwind {
+entry:
+  %indirect.goto.dest = select i1 %cond, i8* blockaddress(@indbrtest6, %L1), i8* blockaddress(@indbrtest6, %L1)
+; This needs to have more than one successor for this test, otherwise it gets
+; replaced with an unconditional branch to the single successor.
+  indirectbr i8* %indirect.goto.dest, [label %L2, label %L3]
+
+L1:
+  call void @A()
+  ret void
+L2:
+  call void @C()
+  ret void
+L3:
+  call void @foo()
+
+; This keeps blockaddresses not otherwise listed as successors from being zapped
+; before SimplifyCFG even looks at the indirectbr.
+  indirectbr i8* %anchor, [label %L1, label %L2]
+}