[llvm] r271816 - [SimplifyCFG] Don't kill empty cleanuppads with multiple uses
David Majnemer via llvm-commits
llvm-commits at lists.llvm.org
Sat Jun 4 16:50:04 PDT 2016
Author: majnemer
Date: Sat Jun 4 18:50:03 2016
New Revision: 271816
URL: http://llvm.org/viewvc/llvm-project?rev=271816&view=rev
Log:
[SimplifyCFG] Don't kill empty cleanuppads with multiple uses
A basic block could contain:
%cp = cleanuppad []
cleanupret from %cp unwind to caller
This basic block is empty and is thus a candidate for removal. However,
there can be other uses of %cp outside of this basic block. This is
only possible in unreachable blocks.
Make our transform more correct by checking that the pad has a single
user before removing the BB.
This fixes PR28005.
Modified:
llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
llvm/trunk/test/Transforms/SimplifyCFG/empty-cleanuppad.ll
Modified: llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp?rev=271816&r1=271815&r2=271816&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp Sat Jun 4 18:50:03 2016
@@ -3424,6 +3424,11 @@ static bool removeEmptyCleanup(CleanupRe
// This isn't an empty cleanup.
return false;
+ // We cannot kill the pad if it has multiple uses. This typically arises
+ // from unreachable basic blocks.
+ if (!CPInst->hasOneUse())
+ return false;
+
// Check that there are no other instructions except for benign intrinsics.
BasicBlock::iterator I = CPInst->getIterator(), E = RI->getIterator();
while (++I != E) {
Modified: llvm/trunk/test/Transforms/SimplifyCFG/empty-cleanuppad.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/empty-cleanuppad.ll?rev=271816&r1=271815&r2=271816&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/SimplifyCFG/empty-cleanuppad.ll (original)
+++ llvm/trunk/test/Transforms/SimplifyCFG/empty-cleanuppad.ll Sat Jun 4 18:50:03 2016
@@ -434,6 +434,30 @@ try.cont:
ret i32 0
}
+; CHECK-LABEL: define void @f10(
+define void @f10(i32 %V) personality i32 (...)* @__CxxFrameHandler3 {
+entry:
+ invoke void @g()
+ to label %unreachable unwind label %cleanup
+; CHECK: call void @g()
+; CHECK-NEXT: unreachable
+
+unreachable:
+ unreachable
+
+cleanup:
+ %cp = cleanuppad within none []
+ switch i32 %V, label %cleanupret1 [
+ i32 0, label %cleanupret2
+ ]
+
+cleanupret1:
+ cleanupret from %cp unwind to caller
+
+cleanupret2:
+ cleanupret from %cp unwind to caller
+}
+
%struct.S = type { i8 }
%struct.S2 = type { i8 }
declare void @"\01??1S2@@QEAA at XZ"(%struct.S2*)
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