[llvm] 3c9022c - Bail out jump threading on indirect branches (#103688)
via llvm-commits
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Tue Sep 10 22:39:05 PDT 2024
Author: AdityaK
Date: 2024-09-10T22:39:02-07:00
New Revision: 3c9022c965b85951f30af140da591f819acef8a0
URL: https://github.com/llvm/llvm-project/commit/3c9022c965b85951f30af140da591f819acef8a0
DIFF: https://github.com/llvm/llvm-project/commit/3c9022c965b85951f30af140da591f819acef8a0.diff
LOG: Bail out jump threading on indirect branches (#103688)
The bug was introduced by
https://github.com/llvm/llvm-project/pull/68473
Fixes: #102351
Added:
llvm/test/Transforms/SimplifyCFG/switch-branch-fold-indirectbr-102351.ll
Modified:
llvm/lib/Transforms/Utils/Local.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index d0669e44f821b3..c85c819263e2a1 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1028,7 +1028,14 @@ CanRedirectPredsOfEmptyBBToSucc(BasicBlock *BB, BasicBlock *Succ,
if (!BB->hasNPredecessorsOrMore(2))
return false;
- // Get single common predecessors of both BB and Succ
+ if (any_of(BBPreds, [](const BasicBlock *Pred) {
+ return isa<PHINode>(Pred->begin()) &&
+ isa<IndirectBrInst>(Pred->getTerminator());
+ }))
+ return false;
+
+ // Get the single common predecessor of both BB and Succ. Return false
+ // when there are more than one common predecessors.
for (BasicBlock *SuccPred : SuccPreds) {
if (BBPreds.count(SuccPred)) {
if (CommonPred)
@@ -1133,7 +1140,7 @@ bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB,
bool BBKillable = CanPropagatePredecessorsForPHIs(BB, Succ, BBPreds);
- // Even if we can not fold bB into Succ, we may be able to redirect the
+ // Even if we can not fold BB into Succ, we may be able to redirect the
// predecessors of BB to Succ.
bool BBPhisMergeable =
BBKillable ||
diff --git a/llvm/test/Transforms/SimplifyCFG/switch-branch-fold-indirectbr-102351.ll b/llvm/test/Transforms/SimplifyCFG/switch-branch-fold-indirectbr-102351.ll
new file mode 100644
index 00000000000000..03aee68fa4248c
--- /dev/null
+++ b/llvm/test/Transforms/SimplifyCFG/switch-branch-fold-indirectbr-102351.ll
@@ -0,0 +1,104 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt < %s -passes=simplifycfg -S | FileCheck %s
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define dso_local noundef i32 @main() {
+; CHECK-LABEL: define dso_local noundef i32 @main() {
+; CHECK-NEXT: [[BB:.*]]:
+; CHECK-NEXT: [[ALLOCA:%.*]] = alloca [2 x ptr], align 16
+; CHECK-NEXT: store ptr blockaddress(@main, %[[BB4:.*]]), ptr [[ALLOCA]], align 16, !tbaa [[TBAA0:![0-9]+]]
+; CHECK-NEXT: [[GETELEMENTPTR:%.*]] = getelementptr inbounds [2 x ptr], ptr [[ALLOCA]], i64 0, i64 1
+; CHECK-NEXT: store ptr blockaddress(@main, %[[BB10:.*]]), ptr [[GETELEMENTPTR]], align 8, !tbaa [[TBAA0]]
+; CHECK-NEXT: br label %[[BB1:.*]]
+; CHECK: [[BB1]]:
+; CHECK-NEXT: [[PHI:%.*]] = phi i32 [ 0, %[[BB]] ], [ [[PHI8:%.*]], %[[BB7:.*]] ]
+; CHECK-NEXT: [[PHI2:%.*]] = phi i32 [ 0, %[[BB]] ], [ [[PHI9:%.*]], %[[BB7]] ]
+; CHECK-NEXT: switch i32 [[PHI]], label %[[BB7]] [
+; CHECK-NEXT: i32 0, label %[[BB12:.*]]
+; CHECK-NEXT: i32 1, label %[[BB4]]
+; CHECK-NEXT: i32 2, label %[[BB6:.*]]
+; CHECK-NEXT: ]
+; CHECK: [[BB4]]:
+; CHECK-NEXT: [[PHI5:%.*]] = phi i32 [ [[PHI13:%.*]], %[[BB12]] ], [ [[PHI2]], %[[BB1]] ]
+; CHECK-NEXT: br label %[[BB7]]
+; CHECK: [[BB6]]:
+; CHECK-NEXT: [[CALL:%.*]] = call i32 @foo(i32 noundef [[PHI2]])
+; CHECK-NEXT: [[ADD:%.*]] = add nsw i32 [[PHI2]], 1
+; CHECK-NEXT: br label %[[BB12]]
+; CHECK: [[BB7]]:
+; CHECK-NEXT: [[PHI8]] = phi i32 [ [[PHI]], %[[BB1]] ], [ 2, %[[BB4]] ]
+; CHECK-NEXT: [[PHI9]] = phi i32 [ [[PHI2]], %[[BB1]] ], [ [[PHI5]], %[[BB4]] ]
+; CHECK-NEXT: br label %[[BB1]], !llvm.loop [[LOOP4:![0-9]+]]
+; CHECK: [[BB10]]:
+; CHECK-NEXT: [[CALL11:%.*]] = call i32 @foo(i32 noundef [[PHI13]])
+; CHECK-NEXT: ret i32 0
+; CHECK: [[BB12]]:
+; CHECK-NEXT: [[PHI13]] = phi i32 [ [[ADD]], %[[BB6]] ], [ [[PHI2]], %[[BB1]] ]
+; CHECK-NEXT: [[SEXT:%.*]] = sext i32 [[PHI13]] to i64
+; CHECK-NEXT: [[GETELEMENTPTR14:%.*]] = getelementptr inbounds [2 x ptr], ptr [[ALLOCA]], i64 0, i64 [[SEXT]]
+; CHECK-NEXT: [[LOAD:%.*]] = load ptr, ptr [[GETELEMENTPTR14]], align 8, !tbaa [[TBAA0]]
+; CHECK-NEXT: indirectbr ptr [[LOAD]], [label %[[BB4]], label %bb10]
+;
+bb:
+ %alloca = alloca [2 x ptr], align 16
+ store ptr blockaddress(@main, %bb4), ptr %alloca, align 16, !tbaa !0
+ %getelementptr = getelementptr inbounds [2 x ptr], ptr %alloca, i64 0, i64 1
+ store ptr blockaddress(@main, %bb10), ptr %getelementptr, align 8, !tbaa !0
+ br label %bb1
+
+bb1: ; preds = %bb7, %bb
+ %phi = phi i32 [ 0, %bb ], [ %phi8, %bb7 ]
+ %phi2 = phi i32 [ 0, %bb ], [ %phi9, %bb7 ]
+ switch i32 %phi, label %bb7 [
+ i32 0, label %bb3
+ i32 1, label %bb4
+ i32 2, label %bb6
+ ]
+
+bb3: ; preds = %bb1
+ br label %bb12
+
+bb4: ; preds = %bb12, %bb1
+ %phi5 = phi i32 [ %phi13, %bb12 ], [ %phi2, %bb1 ]
+ br label %bb7
+
+bb6: ; preds = %bb1
+ %call = call i32 @foo(i32 noundef %phi2)
+ %add = add nsw i32 %phi2, 1
+ br label %bb12
+
+bb7: ; preds = %bb4, %bb1
+ %phi8 = phi i32 [ %phi, %bb1 ], [ 2, %bb4 ]
+ %phi9 = phi i32 [ %phi2, %bb1 ], [ %phi5, %bb4 ]
+ br label %bb1, !llvm.loop !4
+
+bb10: ; preds = %bb12
+ %call11 = call i32 @foo(i32 noundef %phi13)
+ ret i32 0
+
+bb12: ; preds = %bb6, %bb3
+ %phi13 = phi i32 [ %add, %bb6 ], [ %phi2, %bb3 ]
+ %sext = sext i32 %phi13 to i64
+ %getelementptr14 = getelementptr inbounds [2 x ptr], ptr %alloca, i64 0, i64 %sext
+ %load = load ptr, ptr %getelementptr14, align 8, !tbaa !0
+ indirectbr ptr %load, [label %bb4, label %bb10]
+}
+
+declare i32 @foo(i32)
+
+!0 = !{!1, !1, i64 0}
+!1 = !{!"any pointer", !2, i64 0}
+!2 = !{!"omnipotent char", !3, i64 0}
+!3 = !{!"Simple C++ TBAA"}
+!4 = !{!5, !5, i64 0}
+!5 = !{!"int", !2, i64 0}
+;.
+; CHECK: [[TBAA0]] = !{[[META1:![0-9]+]], [[META1]], i64 0}
+; CHECK: [[META1]] = !{!"any pointer", [[META2:![0-9]+]], i64 0}
+; CHECK: [[META2]] = !{!"omnipotent char", [[META3:![0-9]+]], i64 0}
+; CHECK: [[META3]] = !{!"Simple C++ TBAA"}
+; CHECK: [[LOOP4]] = !{[[META5:![0-9]+]], [[META5]], i64 0}
+; CHECK: [[META5]] = !{!"int", [[META2]], i64 0}
+;.
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