diff options
| -rw-r--r-- | llvm/lib/Analysis/MustExecute.cpp | 9 | ||||
| -rw-r--r-- | llvm/test/Analysis/MustExecute/loop-header.ll | 8 |
2 files changed, 11 insertions, 6 deletions
diff --git a/llvm/lib/Analysis/MustExecute.cpp b/llvm/lib/Analysis/MustExecute.cpp index e22831cd6a9..b616cd6f762 100644 --- a/llvm/lib/Analysis/MustExecute.cpp +++ b/llvm/lib/Analysis/MustExecute.cpp @@ -193,7 +193,8 @@ bool LoopSafetyInfo::allLoopPathsLeadToBlock(const Loop *CurLoop, SmallPtrSet<const BasicBlock *, 4> Predecessors; collectTransitivePredecessors(CurLoop, BB, Predecessors); - // Make sure that all successors of all predecessors of BB are either: + // Make sure that all successors of, all predecessors of BB which are not + // dominated by BB, are either: // 1) BB, // 2) Also predecessors of BB, // 3) Exit blocks which are not taken on 1st iteration. @@ -203,6 +204,12 @@ bool LoopSafetyInfo::allLoopPathsLeadToBlock(const Loop *CurLoop, // Predecessor block may throw, so it has a side exit. if (blockMayThrow(Pred)) return false; + + // BB dominates Pred, so if Pred runs, BB must run. + // This is true when Pred is a loop latch. + if (DT->dominates(BB, Pred)) + continue; + for (auto *Succ : successors(Pred)) if (CheckedSuccessors.insert(Succ).second && Succ != BB && !Predecessors.count(Succ)) diff --git a/llvm/test/Analysis/MustExecute/loop-header.ll b/llvm/test/Analysis/MustExecute/loop-header.ll index d0ec5fa6872..bc75ed683cb 100644 --- a/llvm/test/Analysis/MustExecute/loop-header.ll +++ b/llvm/test/Analysis/MustExecute/loop-header.ll @@ -83,17 +83,15 @@ exit: ret i1 false } -; FIXME: everything in inner loop header should be must execute -; for outer as well define i1 @nested_no_throw(i32* noalias %p, i32 %high) { ; CHECK-LABEL: @nested_no_throw ; CHECK-LABEL: loop: ; preds = %next ; CHECK: %iv = phi i32 [ 0, %entry ], [ %iv.next, %next ] ; (mustexec in: loop) ; CHECK: br label %inner_loop ; (mustexec in: loop) ; CHECK-LABEL: inner_loop: -; CHECK: %v = load i32, i32* %p ; (mustexec in: inner_loop) -; CHECK: %inner.test = icmp eq i32 %v, 0 ; (mustexec in: inner_loop) -; CHECK: br i1 %inner.test, label %inner_loop, label %next ; (mustexec in: inner_loop) +; CHECK: %v = load i32, i32* %p ; (mustexec in 2 loops: inner_loop, loop) +; CHECK: %inner.test = icmp eq i32 %v, 0 ; (mustexec in 2 loops: inner_loop, loop) +; CHECK: br i1 %inner.test, label %inner_loop, label %next ; (mustexec in 2 loops: inner_loop, loop) ; CHECK-LABEL: next: ; CHECK: %iv.next = add nuw nsw i32 %iv, 1 ; (mustexec in: loop) ; CHECK: %exit.test = icmp slt i32 %iv, %high ; (mustexec in: loop) |
