[llvm] r301064 - LowerSwitch: Fix producing invalid IR on unreachable code
Matt Arsenault via llvm-commits
llvm-commits at lists.llvm.org
Fri Apr 21 16:54:13 PDT 2017
Author: arsenm
Date: Fri Apr 21 18:54:12 2017
New Revision: 301064
URL: http://llvm.org/viewvc/llvm-project?rev=301064&view=rev
Log:
LowerSwitch: Fix producing invalid IR on unreachable code
If a switch was in an unreachable block that branched
to a block with a phi, it would leave phis with missing
predecessors.
Added:
llvm/trunk/test/Transforms/LowerSwitch/phi-in-dead-block.ll
Modified:
llvm/trunk/lib/Transforms/Utils/LowerSwitch.cpp
Modified: llvm/trunk/lib/Transforms/Utils/LowerSwitch.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LowerSwitch.cpp?rev=301064&r1=301063&r2=301064&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/LowerSwitch.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/LowerSwitch.cpp Fri Apr 21 18:54:12 2017
@@ -403,6 +403,14 @@ void LowerSwitch::processSwitchInst(Swit
Value *Val = SI->getCondition(); // The value we are switching on...
BasicBlock* Default = SI->getDefaultDest();
+ // Don't handle unreachable blocks. If there are successors with phis, this
+ // would leave them behind with missing predecessors.
+ if ((CurBlock != &F->getEntryBlock() && pred_empty(CurBlock)) ||
+ CurBlock->getSinglePredecessor() == CurBlock) {
+ DeleteList.insert(CurBlock);
+ return;
+ }
+
// If there is only the default destination, just branch.
if (!SI->getNumCases()) {
BranchInst::Create(Default, CurBlock);
Added: llvm/trunk/test/Transforms/LowerSwitch/phi-in-dead-block.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LowerSwitch/phi-in-dead-block.ll?rev=301064&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LowerSwitch/phi-in-dead-block.ll (added)
+++ llvm/trunk/test/Transforms/LowerSwitch/phi-in-dead-block.ll Fri Apr 21 18:54:12 2017
@@ -0,0 +1,40 @@
+; RUN: opt -S -lowerswitch %s | FileCheck %s
+
+; CHECK-LABEL: @phi_in_dead_block(
+; CHECK-NOT: switch
+define void @phi_in_dead_block() {
+bb:
+ br i1 undef, label %bb2, label %bb3
+
+bb1: ; No predecessors!
+ switch i32 undef, label %bb2 [
+ i32 9, label %bb3
+ ]
+
+bb2: ; preds = %bb1, %bb
+ %tmp = phi i64 [ undef, %bb1 ], [ undef, %bb ]
+ unreachable
+
+bb3: ; preds = %bb1, %bb
+ unreachable
+}
+
+; CHECK-LABEL: @phi_in_dead_block_br_to_self(
+; CHECK-NOT: switch
+define void @phi_in_dead_block_br_to_self() {
+bb:
+ br i1 undef, label %bb2, label %bb3
+
+bb1: ; No predecessors!
+ switch i32 undef, label %bb2 [
+ i32 9, label %bb3
+ i32 10, label %bb1
+ ]
+
+bb2: ; preds = %bb1, %bb
+ %tmp = phi i64 [ undef, %bb1 ], [ undef, %bb ]
+ unreachable
+
+bb3: ; preds = %bb1, %bb
+ unreachable
+}
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