[llvm] r360232 - [SCCP] Fix crash when trying to constant-fold terminators multiple times.
Florian Hahn via llvm-commits
llvm-commits at lists.llvm.org
Wed May 8 02:09:54 PDT 2019
Author: fhahn
Date: Wed May 8 02:09:54 2019
New Revision: 360232
URL: http://llvm.org/viewvc/llvm-project?rev=360232&view=rev
Log:
[SCCP] Fix crash when trying to constant-fold terminators multiple times.
If we fold a branch/switch to an unconditional branch to another dead block we
replace the branch with unreachable, to avoid attempting to fold the
unconditional branch.
Reviewers: davide, efriedma, mssimpso, jdoerfert
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D61300
Added:
llvm/trunk/test/Transforms/SCCP/switch-constantfold-crash.ll
Modified:
llvm/trunk/lib/Transforms/Scalar/SCCP.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/SCCP.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SCCP.cpp?rev=360232&r1=360231&r2=360232&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/SCCP.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/SCCP.cpp Wed May 8 02:09:54 2019
@@ -2083,12 +2083,22 @@ bool llvm::runIPSCCP(
// If we have forced an edge for an indeterminate value, then force the
// terminator to fold to that edge.
forceIndeterminateEdge(I, Solver);
- bool Folded = ConstantFoldTerminator(I->getParent(),
+ BasicBlock *InstBB = I->getParent();
+ bool Folded = ConstantFoldTerminator(InstBB,
/*DeleteDeadConditions=*/false,
/*TLI=*/nullptr, &DTU);
assert(Folded &&
"Expect TermInst on constantint or blockaddress to be folded");
(void) Folded;
+ // If we folded the terminator to an unconditional branch to another
+ // dead block, replace it with Unreachable, to avoid trying to fold that
+ // branch again.
+ BranchInst *BI = cast<BranchInst>(InstBB->getTerminator());
+ if (BI && BI->isUnconditional() &&
+ !Solver.isBlockExecutable(BI->getSuccessor(0))) {
+ InstBB->getTerminator()->eraseFromParent();
+ new UnreachableInst(InstBB->getContext(), InstBB);
+ }
}
// Mark dead BB for deletion.
DTU.deleteBB(DeadBB);
Added: llvm/trunk/test/Transforms/SCCP/switch-constantfold-crash.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SCCP/switch-constantfold-crash.ll?rev=360232&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/SCCP/switch-constantfold-crash.ll (added)
+++ llvm/trunk/test/Transforms/SCCP/switch-constantfold-crash.ll Wed May 8 02:09:54 2019
@@ -0,0 +1,92 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -ipsccp < %s -S | FileCheck %s
+; RUN: opt -passes=ipsccp < %s -S | FileCheck %s
+
+define void @barney() {
+; CHECK-LABEL: @barney(
+; CHECK-NEXT: bb:
+; CHECK-NEXT: br label %bb9
+; CHECK: bb6:
+; CHECK-NEXT: unreachable
+; CHECK: bb9:
+; CHECK-NEXT: unreachable
+;
+bb:
+ br label %bb9
+
+bb6: ; preds = %bb9
+ unreachable
+
+bb7: ; preds = %bb9
+ unreachable
+
+bb9: ; preds = %bb
+ switch i16 0, label %bb6 [
+ i16 61, label %bb7
+ ]
+}
+
+define void @blam() {
+; CHECK-LABEL: @blam(
+; CHECK-NEXT: bb:
+; CHECK-NEXT: br label %bb16
+; CHECK: bb16:
+; CHECK-NEXT: br label %bb38
+; CHECK: bb38:
+; CHECK-NEXT: unreachable
+;
+bb:
+ br label %bb16
+
+bb16: ; preds = %bb
+ switch i32 0, label %bb38 [
+ i32 66, label %bb17
+ i32 63, label %bb18
+ i32 86, label %bb19
+ ]
+
+bb17: ; preds = %bb16
+ unreachable
+
+bb18: ; preds = %bb16
+ unreachable
+
+bb19: ; preds = %bb16
+ unreachable
+
+bb38: ; preds = %bb16
+ unreachable
+}
+
+
+define void @hoge() {
+; CHECK-LABEL: @hoge(
+; CHECK-NEXT: bb:
+; CHECK-NEXT: br label %bb2
+; CHECK: bb2:
+; CHECK-NEXT: unreachable
+; CHECK: bb3:
+; CHECK-NEXT: unreachable
+;
+bb:
+ switch i16 undef, label %bb1 [
+ i16 135, label %bb2
+ i16 66, label %bb2
+ ]
+
+bb1: ; preds = %bb
+ ret void
+
+bb2: ; preds = %bb, %bb
+ switch i16 0, label %bb3 [
+ i16 61, label %bb4
+ i16 54, label %bb4
+ i16 49, label %bb4
+ ]
+
+bb3: ; preds = %bb2
+ unreachable
+
+bb4: ; preds = %bb2, %bb2, %bb2
+ unreachable
+}
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