[PATCH] D110924: [LoopUtils] Consider unreachable-terminated blocks as deoptimizing

[Dmitry Makogon via Phabricator via llvm-commits]

dmakogon updated this revision to Diff 377758.
dmakogon edited the summary of this revision.
dmakogon added a comment.
Herald added a subscriber: zzheng.

Added test and fixed `getExpectedExitLoopLatchBranch` annotation


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D110924/new/

https://reviews.llvm.org/D110924

Files:
  llvm/lib/Transforms/Utils/LoopUtils.cpp
  llvm/test/Transforms/LoopUnroll/peel-multiple-unreachable-exits.ll


Index: llvm/test/Transforms/LoopUnroll/peel-multiple-unreachable-exits.ll
===================================================================
--- llvm/test/Transforms/LoopUnroll/peel-multiple-unreachable-exits.ll
+++ llvm/test/Transforms/LoopUnroll/peel-multiple-unreachable-exits.ll
@@ -365,28 +365,55 @@
 define void @peel_exits_to_blocks_branch_to_unreachable_block_with_profile(i32* %ptr, i32 %N, i32 %x, i1 %c.1) !prof !0 {
 ; CHECK-LABEL: @peel_exits_to_blocks_branch_to_unreachable_block_with_profile(
 ; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[LOOP_HEADER_PEEL_BEGIN:%.*]]
+; CHECK:       loop.header.peel.begin:
+; CHECK-NEXT:    br label [[LOOP_HEADER_PEEL:%.*]]
+; CHECK:       loop.header.peel:
+; CHECK-NEXT:    [[C_PEEL:%.*]] = icmp ult i32 1, [[N:%.*]]
+; CHECK-NEXT:    br i1 [[C_PEEL]], label [[THEN_PEEL:%.*]], label [[ELSE_PEEL:%.*]], !prof [[PROF4:![0-9]+]]
+; CHECK:       else.peel:
+; CHECK-NEXT:    [[C_2_PEEL:%.*]] = icmp eq i32 1, [[X:%.*]]
+; CHECK-NEXT:    br i1 [[C_2_PEEL]], label [[EXIT_2:%.*]], label [[LOOP_LATCH_PEEL:%.*]]
+; CHECK:       then.peel:
+; CHECK-NEXT:    br i1 [[C_1:%.*]], label [[EXIT_1:%.*]], label [[LOOP_LATCH_PEEL]]
+; CHECK:       loop.latch.peel:
+; CHECK-NEXT:    [[M_PEEL:%.*]] = phi i32 [ 0, [[THEN_PEEL]] ], [ [[X]], [[ELSE_PEEL]] ]
+; CHECK-NEXT:    [[GEP_PEEL:%.*]] = getelementptr i32, i32* [[PTR:%.*]], i32 1
+; CHECK-NEXT:    store i32 [[M_PEEL]], i32* [[GEP_PEEL]], align 4
+; CHECK-NEXT:    [[IV_NEXT_PEEL:%.*]] = add nuw nsw i32 1, 1
+; CHECK-NEXT:    [[C_3_PEEL:%.*]] = icmp ult i32 [[IV_NEXT_PEEL]], [[N]]
+; CHECK-NEXT:    br i1 [[C_3_PEEL]], label [[LOOP_HEADER_PEEL_NEXT:%.*]], label [[EXIT:%.*]], !prof [[PROF4]]
+; CHECK:       loop.header.peel.next:
+; CHECK-NEXT:    br label [[LOOP_HEADER_PEEL_NEXT1:%.*]]
+; CHECK:       loop.header.peel.next1:
+; CHECK-NEXT:    br label [[ENTRY_PEEL_NEWPH:%.*]]
+; CHECK:       entry.peel.newph:
 ; CHECK-NEXT:    br label [[LOOP_HEADER:%.*]]
 ; CHECK:       loop.header:
-; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ 1, [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[LOOP_LATCH:%.*]] ]
-; CHECK-NEXT:    [[C:%.*]] = icmp ult i32 [[IV]], [[N:%.*]]
-; CHECK-NEXT:    br i1 [[C]], label [[THEN:%.*]], label [[ELSE:%.*]], !prof [[PROF3:![0-9]+]]
+; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ [[IV_NEXT_PEEL]], [[ENTRY_PEEL_NEWPH]] ], [ [[IV_NEXT:%.*]], [[LOOP_LATCH:%.*]] ]
+; CHECK-NEXT:    br i1 true, label [[THEN:%.*]], label [[ELSE:%.*]], !prof [[PROF4]]
 ; CHECK:       then:
-; CHECK-NEXT:    br i1 [[C_1:%.*]], label [[EXIT_1:%.*]], label [[LOOP_LATCH]]
+; CHECK-NEXT:    br i1 [[C_1]], label [[EXIT_1_LOOPEXIT:%.*]], label [[LOOP_LATCH]]
 ; CHECK:       else:
-; CHECK-NEXT:    [[C_2:%.*]] = icmp eq i32 [[IV]], [[X:%.*]]
-; CHECK-NEXT:    br i1 [[C_2]], label [[EXIT_2:%.*]], label [[LOOP_LATCH]]
+; CHECK-NEXT:    br i1 true, label [[EXIT_2_LOOPEXIT:%.*]], label [[LOOP_LATCH]]
 ; CHECK:       loop.latch:
 ; CHECK-NEXT:    [[M:%.*]] = phi i32 [ 0, [[THEN]] ], [ [[X]], [[ELSE]] ]
-; CHECK-NEXT:    [[GEP:%.*]] = getelementptr i32, i32* [[PTR:%.*]], i32 [[IV]]
+; CHECK-NEXT:    [[GEP:%.*]] = getelementptr i32, i32* [[PTR]], i32 [[IV]]
 ; CHECK-NEXT:    store i32 [[M]], i32* [[GEP]], align 4
 ; CHECK-NEXT:    [[IV_NEXT]] = add nuw nsw i32 [[IV]], 1
 ; CHECK-NEXT:    [[C_3:%.*]] = icmp ult i32 [[IV_NEXT]], [[N]]
-; CHECK-NEXT:    br i1 [[C_3]], label [[LOOP_HEADER]], label [[EXIT:%.*]], !prof [[PROF3]]
+; CHECK-NEXT:    br i1 [[C_3]], label [[LOOP_HEADER]], label [[EXIT_LOOPEXIT:%.*]], !prof [[PROF4]], !llvm.loop [[LOOP5:![0-9]+]]
+; CHECK:       exit.loopexit:
+; CHECK-NEXT:    br label [[EXIT]]
 ; CHECK:       exit:
 ; CHECK-NEXT:    ret void
+; CHECK:       exit.1.loopexit:
+; CHECK-NEXT:    br label [[EXIT_1]]
 ; CHECK:       exit.1:
 ; CHECK-NEXT:    call void @foo()
 ; CHECK-NEXT:    br label [[UNREACHABLE_TERM:%.*]]
+; CHECK:       exit.2.loopexit:
+; CHECK-NEXT:    br label [[EXIT_2]]
 ; CHECK:       exit.2:
 ; CHECK-NEXT:    call void @bar()
 ; CHECK-NEXT:    br label [[UNREACHABLE_TERM]]
Index: llvm/lib/Transforms/Utils/LoopUtils.cpp
===================================================================
--- llvm/lib/Transforms/Utils/LoopUtils.cpp
+++ llvm/lib/Transforms/Utils/LoopUtils.cpp
@@ -778,8 +778,12 @@
 
 
 /// Checks if \p L has single exit through latch block except possibly
-/// "deoptimizing" exits. Returns branch instruction terminating the loop
-/// latch if above check is successful, nullptr otherwise.
+/// "deoptimizing" (@llvm.experimental.deoptimize or unreachable-terminated)
+/// exits or such exits that all paths starting from them converge
+/// to a block that either has a @llvm.experimental.deoptimize call
+/// prior to its terminating return instruction or is terminated by unreachable.
+/// Returns branch instruction terminating the loop latch if above check is
+/// successful, nullptr otherwise.
 static BranchInst *getExpectedExitLoopLatchBranch(Loop *L) {
   BasicBlock *Latch = L->getLoopLatch();
   if (!Latch)
@@ -795,8 +799,9 @@
 
   SmallVector<BasicBlock *, 4> ExitBlocks;
   L->getUniqueNonLatchExitBlocks(ExitBlocks);
-  if (any_of(ExitBlocks, [](const BasicBlock *EB) {
-        return !EB->getTerminatingDeoptimizeCall();
+
+  if (any_of(ExitBlocks, [&](const BasicBlock *EB) {
+        return !IsBlockFollowedByDeoptOrUnreachable(EB);
       }))
     return nullptr;
 


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