[MachineVerifier] Accept a MBB with a single landing pad successor.

The MachineVerifier used to check that there was always exactly one
unconditional branch to a non-landingpad (normal) successor.
If that normal successor to an invoke BB is unreachable, it seems
reasonable to only have one successor, the landing pad.
On targets other than AArch64 (and on AArch64 with a different testcase),
the branch folder turns the branch to the landing pad into a fallthrough.
The MachineVerifier, which relies on AnalyzeBranch, is unable to check
the condition, and doesn't complain. However, it does in this specific
testcase, where the branch to the landing pad remained.
Make the MachineVerifier accept it.

llvm-svn: 223059

1 files changed, 78 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/AArch64/br-to-eh-lpad.ll b/llvm/test/CodeGen/AArch64/br-to-eh-lpad.ll
new file mode 100644
index 00000000000..20bffd9e412
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/br-to-eh-lpad.ll
@@ -0,0 +1,78 @@
+; RUN: llc < %s -mtriple=aarch64-apple-ios -verify-machineinstrs
+
+; This function tests that the machine verifier accepts an unconditional
+; branch from an invoke basic block, to its EH landing pad basic block.
+; The test is brittle and isn't ideally reduced, because in most cases the
+; branch would be removed (for instance, turned into a fallthrough), and in
+; that case, the machine verifier, which relies on analyzing branches for this
+; kind of verification, is unable to check anything, so accepts the CFG.
+
+define void @test_branch_to_landingpad() {
+entry:
+  br i1 undef, label %if.end50.thread, label %if.then6
+
+lpad:
+  %0 = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @__objc_personality_v0 to i8*)
+          catch %struct._objc_typeinfo.12.129.194.285.350.493.519.532.571.597.623.765* @"OBJC_EHTYPE_$_NSString"
+          catch %struct._objc_typeinfo.12.129.194.285.350.493.519.532.571.597.623.765* @OBJC_EHTYPE_id
+          catch i8* null
+  br i1 undef, label %invoke.cont33, label %catch.fallthrough
+
+catch.fallthrough:
+  %matches31 = icmp eq i32 undef, 0
+  br i1 %matches31, label %invoke.cont41, label %finally.catchall
+
+if.then6:
+  invoke void @objc_exception_throw()
+          to label %invoke.cont7 unwind label %lpad
+
+invoke.cont7:
+  unreachable
+
+if.end50.thread:
+  tail call void (i8*, ...)* @printf(i8* getelementptr inbounds ([17 x i8]* @.str1, i64 0, i64 0), i32 125)
+  tail call void (i8*, ...)* @printf(i8* getelementptr inbounds ([17 x i8]* @.str1, i64 0, i64 0), i32 128)
+  unreachable
+
+invoke.cont33:
+  tail call void (i8*, ...)* @printf(i8* getelementptr inbounds ([17 x i8]* @.str1, i64 0, i64 0), i32 119)
+  unreachable
+
+invoke.cont41:
+  invoke void @objc_exception_rethrow()
+          to label %invoke.cont43 unwind label %lpad40
+
+invoke.cont43:
+  unreachable
+
+lpad40:
+  %1 = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @__objc_personality_v0 to i8*)
+          catch i8* null
+  br label %finally.catchall
+
+finally.catchall:
+  tail call void (i8*, ...)* @printf(i8* getelementptr inbounds ([17 x i8]* @.str1, i64 0, i64 0), i32 125)
+  unreachable
+}
+
+%struct._objc_typeinfo.12.129.194.285.350.493.519.532.571.597.623.765 = type { i8**, i8*, %struct._class_t.10.127.192.283.348.491.517.530.569.595.621.764* }
+%struct._class_t.10.127.192.283.348.491.517.530.569.595.621.764 = type { %struct._class_t.10.127.192.283.348.491.517.530.569.595.621.764*, %struct._class_t.10.127.192.283.348.491.517.530.569.595.621.764*, %struct._objc_cache.0.117.182.273.338.481.507.520.559.585.611.754*, i8* (i8*, i8*)**, %struct._class_ro_t.9.126.191.282.347.490.516.529.568.594.620.763* }
+%struct._objc_cache.0.117.182.273.338.481.507.520.559.585.611.754 = type opaque
+%struct._class_ro_t.9.126.191.282.347.490.516.529.568.594.620.763 = type { i32, i32, i32, i8*, i8*, %struct.__method_list_t.2.119.184.275.340.483.509.522.561.587.613.756*, %struct._objc_protocol_list.6.123.188.279.344.487.513.526.565.591.617.760*, %struct._ivar_list_t.8.125.190.281.346.489.515.528.567.593.619.762*, i8*, %struct._prop_list_t.4.121.186.277.342.485.511.524.563.589.615.758* }
+%struct.__method_list_t.2.119.184.275.340.483.509.522.561.587.613.756 = type { i32, i32, [0 x %struct._objc_method.1.118.183.274.339.482.508.521.560.586.612.755] }
+%struct._objc_method.1.118.183.274.339.482.508.521.560.586.612.755 = type { i8*, i8*, i8* }
+%struct._objc_protocol_list.6.123.188.279.344.487.513.526.565.591.617.760 = type { i64, [0 x %struct._protocol_t.5.122.187.278.343.486.512.525.564.590.616.759*] }
+%struct._protocol_t.5.122.187.278.343.486.512.525.564.590.616.759 = type { i8*, i8*, %struct._objc_protocol_list.6.123.188.279.344.487.513.526.565.591.617.760*, %struct.__method_list_t.2.119.184.275.340.483.509.522.561.587.613.756*, %struct.__method_list_t.2.119.184.275.340.483.509.522.561.587.613.756*, %struct.__method_list_t.2.119.184.275.340.483.509.522.561.587.613.756*, %struct.__method_list_t.2.119.184.275.340.483.509.522.561.587.613.756*, %struct._prop_list_t.4.121.186.277.342.485.511.524.563.589.615.758*, i32, i32, i8** }
+%struct._ivar_list_t.8.125.190.281.346.489.515.528.567.593.619.762 = type { i32, i32, [0 x %struct._ivar_t.7.124.189.280.345.488.514.527.566.592.618.761] }
+%struct._ivar_t.7.124.189.280.345.488.514.527.566.592.618.761 = type { i32*, i8*, i8*, i32, i32 }
+%struct._prop_list_t.4.121.186.277.342.485.511.524.563.589.615.758 = type { i32, i32, [0 x %struct._prop_t.3.120.185.276.341.484.510.523.562.588.614.757] }
+%struct._prop_t.3.120.185.276.341.484.510.523.562.588.614.757 = type { i8*, i8* }
+
+@.str1 = external unnamed_addr constant [17 x i8], align 1
+@OBJC_EHTYPE_id = external global %struct._objc_typeinfo.12.129.194.285.350.493.519.532.571.597.623.765
+@"OBJC_EHTYPE_$_NSString" = external global %struct._objc_typeinfo.12.129.194.285.350.493.519.532.571.597.623.765, section "__DATA,__datacoal_nt,coalesced", align 8
+
+declare void @objc_exception_throw()
+declare void @objc_exception_rethrow()
+declare i32 @__objc_personality_v0(...)
+declare void @printf(i8* nocapture readonly, ...)