[PATCH] D127712: Prevent crash when TurnSwitchRangeIntoICmp recieves default null dest
Samuel Eubanks via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Mon Jun 13 21:17:59 PDT 2022
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TurnSwitchRangeIntoICmp crashes when given a switch with a default destination of undef
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D127712
Files:
llvm/lib/Transforms/Utils/SimplifyCFG.cpp
llvm/test/Transforms/SimplifyCFG/switch-default-undef.ll
Index: llvm/test/Transforms/SimplifyCFG/switch-default-undef.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/SimplifyCFG/switch-default-undef.ll
@@ -0,0 +1,45 @@
+; RUN: opt -passes=simplifycfg"<switch-range-to-icmp>" -S %s | FileCheck %s
+
+; CHECK: define void @0(i8 %sw, i32* %p0) {
+; CHECK: group2:
+; CHECK: call void @bar(i32* %p0)
+; CHECK: ret void
+; CHECK: }
+define void @0(i8 %sw, i32* %p0) {
+ switch i8 %sw, label %group3 [
+ i8 0, label %group1
+ i8 1, label %group1
+ i8 2, label %group1
+ i8 3, label %group1
+ i8 11, label %group1
+ i8 12, label %group1
+ i8 13, label %group1
+ i8 7, label %group1
+ i8 17, label %group1
+ i8 14, label %group1
+ i8 15, label %group1
+ i8 4, label %group2
+ i8 5, label %group2
+ i8 6, label %group2
+ i8 8, label %group2
+ i8 9, label %group2
+ i8 10, label %group2
+ ]
+
+group1:
+ br label %exit
+
+group2:
+ br label %exit
+
+group3:
+ br label %exit
+
+exit:
+ %phi = phi i32* [ null, %group3 ], [ %p0, %group2 ], [ null, %group1 ]
+ call void @bar(i32* %phi)
+ ret void
+}
+
+; CHECK: declare void @bar(i32* nonnull dereferenceable(4))
+declare void @bar(i32* nonnull dereferenceable(4))
\ No newline at end of file
Index: llvm/lib/Transforms/Utils/SimplifyCFG.cpp
===================================================================
--- llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -5185,8 +5185,9 @@
}
}
-/// Turn a switch with two reachable destinations into an integer range
-/// comparison and branch.
+/// Turn a switch into an integer range comparison and branch.
+/// Switches with more than 2 destinations are ignored.
+/// Switches with 1 destation are also ignored.
bool SimplifyCFGOpt::TurnSwitchRangeIntoICmp(SwitchInst *SI,
IRBuilder<> &Builder) {
assert(SI->getNumCases() > 1 && "Degenerate switch?");
@@ -5218,6 +5219,10 @@
}
return false; // More than two destinations.
}
+ // All destinations are the same and the default is undef
+ if (!DestB) {
+ return false;
+ }
assert(DestA && DestB &&
"Single-destination switch should have been folded.");
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