[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.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223059 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Ahmed Bougacha 2014-12-01 18:43:53 +00:00
parent e8f8c64e35
commit eb1f2e8eb0
2 changed files with 83 additions and 1 deletions

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@ -592,7 +592,11 @@ MachineVerifier::visitMachineBasicBlockBefore(const MachineBasicBlock *MBB) {
}
} else if (TBB && !FBB && Cond.empty()) {
// Block unconditionally branches somewhere.
if (MBB->succ_size() != 1+LandingPadSuccs.size()) {
// If the block has exactly one successor, that happens to be a
// landingpad, accept it as valid control flow.
if (MBB->succ_size() != 1+LandingPadSuccs.size() &&
(MBB->succ_size() != 1 || LandingPadSuccs.size() != 1 ||
*MBB->succ_begin() != *LandingPadSuccs.begin())) {
report("MBB exits via unconditional branch but doesn't have "
"exactly one CFG successor!", MBB);
} else if (!MBB->isSuccessor(TBB)) {

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@ -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, ...)