From 7c63aac7bd4e5ce3402f2ef7c1d5b66047230147 Mon Sep 17 00:00:00 2001 From: Philip Reames Date: Mon, 4 Jan 2021 09:50:47 -0800 Subject: [PATCH] Revert "[LoopDeletion] Break backedge of loops when known not taken" This reverts commit dd6bb367d19e3bf18353e40de54d35480999a930. Multi-stage builders are showing an assertion failure w/LCSSA not being preserved on entry to IndVars. Reason isn't clear, reverting while investigating. --- .../include/llvm/Transforms/Utils/LoopUtils.h | 6 - llvm/lib/Transforms/Scalar/LoopDeletion.cpp | 44 +-- llvm/lib/Transforms/Utils/LoopUtils.cpp | 31 -- .../Transforms/IndVarSimplify/X86/pr45360.ll | 6 +- .../IndVarSimplify/exit_value_test2.ll | 6 +- .../Transforms/LoopDeletion/update-scev.ll | 3 +- llvm/test/Transforms/LoopDeletion/zero-btc.ll | 335 ------------------ 7 files changed, 7 insertions(+), 424 deletions(-) delete mode 100644 llvm/test/Transforms/LoopDeletion/zero-btc.ll diff --git a/llvm/include/llvm/Transforms/Utils/LoopUtils.h b/llvm/include/llvm/Transforms/Utils/LoopUtils.h index 82c0d9e070d7..b29add4cba0e 100644 --- a/llvm/include/llvm/Transforms/Utils/LoopUtils.h +++ b/llvm/include/llvm/Transforms/Utils/LoopUtils.h @@ -179,12 +179,6 @@ bool hoistRegion(DomTreeNode *, AAResults *, LoopInfo *, DominatorTree *, void deleteDeadLoop(Loop *L, DominatorTree *DT, ScalarEvolution *SE, LoopInfo *LI, MemorySSA *MSSA = nullptr); -/// Remove the backedge of the specified loop. Handles loop nests and general -/// loop structures subject to the precondition that the loop has a single -/// latch block. Preserves all listed analyses. -void breakLoopBackedge(Loop *L, DominatorTree &DT, ScalarEvolution &SE, - LoopInfo &LI, MemorySSA *MSSA); - /// Try to promote memory values to scalars by sinking stores out of /// the loop and moving loads to before the loop. We do this by looping over /// the stores in the loop, looking for stores to Must pointers which are diff --git a/llvm/lib/Transforms/Scalar/LoopDeletion.cpp b/llvm/lib/Transforms/Scalar/LoopDeletion.cpp index 04120032f0f4..065db647561e 100644 --- a/llvm/lib/Transforms/Scalar/LoopDeletion.cpp +++ b/llvm/lib/Transforms/Scalar/LoopDeletion.cpp @@ -26,7 +26,6 @@ #include "llvm/Transforms/Scalar.h" #include "llvm/Transforms/Scalar/LoopPassManager.h" #include "llvm/Transforms/Utils/LoopUtils.h" - using namespace llvm; #define DEBUG_TYPE "loop-delete" @@ -39,14 +38,6 @@ enum class LoopDeletionResult { Deleted, }; -static LoopDeletionResult merge(LoopDeletionResult A, LoopDeletionResult B) { - if (A == LoopDeletionResult::Deleted || B == LoopDeletionResult::Deleted) - return LoopDeletionResult::Deleted; - if (A == LoopDeletionResult::Modified || B == LoopDeletionResult::Modified) - return LoopDeletionResult::Modified; - return LoopDeletionResult::Unmodified; -} - /// Determines if a loop is dead. /// /// This assumes that we've already checked for unique exit and exiting blocks, @@ -135,26 +126,6 @@ static bool isLoopNeverExecuted(Loop *L) { return true; } -/// If we can prove the backedge is untaken, remove it. This destroys the -/// loop, but leaves the (now trivially loop invariant) control flow and -/// side effects (if any) in place. -static LoopDeletionResult -breakBackedgeIfNotTaken(Loop *L, DominatorTree &DT, ScalarEvolution &SE, - LoopInfo &LI, MemorySSA *MSSA, - OptimizationRemarkEmitter &ORE) { - assert(L->isLCSSAForm(DT) && "Expected LCSSA!"); - - if (!L->getLoopLatch()) - return LoopDeletionResult::Unmodified; - - auto *BTC = SE.getBackedgeTakenCount(L); - if (!BTC->isZero()) - return LoopDeletionResult::Unmodified; - - breakLoopBackedge(L, DT, SE, LI, MSSA); - return LoopDeletionResult::Deleted; -} - /// Remove a loop if it is dead. /// /// A loop is considered dead if it does not impact the observable behavior of @@ -191,6 +162,7 @@ static LoopDeletionResult deleteLoopIfDead(Loop *L, DominatorTree &DT, return LoopDeletionResult::Unmodified; } + BasicBlock *ExitBlock = L->getUniqueExitBlock(); if (ExitBlock && isLoopNeverExecuted(L)) { @@ -268,14 +240,6 @@ PreservedAnalyses LoopDeletionPass::run(Loop &L, LoopAnalysisManager &AM, // but ORE cannot be preserved (see comment before the pass definition). OptimizationRemarkEmitter ORE(L.getHeader()->getParent()); auto Result = deleteLoopIfDead(&L, AR.DT, AR.SE, AR.LI, AR.MSSA, ORE); - - // If we can prove the backedge isn't taken, just break it and be done. This - // leaves the loop structure in place which means it can handle dispatching - // to the right exit based on whatever loop invariant structure remains. - if (Result != LoopDeletionResult::Deleted) - Result = merge(Result, breakBackedgeIfNotTaken(&L, AR.DT, AR.SE, AR.LI, - AR.MSSA, ORE)); - if (Result == LoopDeletionResult::Unmodified) return PreservedAnalyses::all(); @@ -335,12 +299,6 @@ bool LoopDeletionLegacyPass::runOnLoop(Loop *L, LPPassManager &LPM) { LoopDeletionResult Result = deleteLoopIfDead(L, DT, SE, LI, MSSA, ORE); - // If we can prove the backedge isn't taken, just break it and be done. This - // leaves the loop structure in place which means it can handle dispatching - // to the right exit based on whatever loop invariant structure remains. - if (Result != LoopDeletionResult::Deleted) - Result = merge(Result, breakBackedgeIfNotTaken(L, DT, SE, LI, MSSA, ORE)); - if (Result == LoopDeletionResult::Deleted) LPM.markLoopAsDeleted(*L); diff --git a/llvm/lib/Transforms/Utils/LoopUtils.cpp b/llvm/lib/Transforms/Utils/LoopUtils.cpp index 4f9899547c26..96f1d4219bac 100644 --- a/llvm/lib/Transforms/Utils/LoopUtils.cpp +++ b/llvm/lib/Transforms/Utils/LoopUtils.cpp @@ -756,37 +756,6 @@ void llvm::deleteDeadLoop(Loop *L, DominatorTree *DT, ScalarEvolution *SE, } } -void llvm::breakLoopBackedge(Loop *L, DominatorTree &DT, ScalarEvolution &SE, - LoopInfo &LI, MemorySSA *MSSA) { - - auto *Latch = L->getLoopLatch(); - assert(Latch); - auto *Header = L->getHeader(); - - SE.forgetLoop(L); - - // Note: By splitting the backedge, and then explicitly making it unreachable - // we gracefully handle corner cases such as non-bottom tested loops and the - // like. We also have the benefit of being able to reuse existing well tested - // code. It might be worth special casing the common bottom tested case at - // some point to avoid code churn. - - std::unique_ptr MSSAU; - if (MSSA) - MSSAU = std::make_unique(MSSA); - - auto *BackedgeBB = SplitEdge(Latch, Header, &DT, &LI, MSSAU.get()); - - DomTreeUpdater DTU(&DT, DomTreeUpdater::UpdateStrategy::Eager); - (void)changeToUnreachable(BackedgeBB->getTerminator(), /*UseTrap*/false, - /*PreserveLCSSA*/true, &DTU, MSSAU.get()); - - // Erase (and destroy) this loop instance. Handles relinking sub-loops - // and blocks within the loop as needed. - LI.erase(L); -} - - /// 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. diff --git a/llvm/test/Transforms/IndVarSimplify/X86/pr45360.ll b/llvm/test/Transforms/IndVarSimplify/X86/pr45360.ll index 397c23cfd3ea..d0857fa707b1 100644 --- a/llvm/test/Transforms/IndVarSimplify/X86/pr45360.ll +++ b/llvm/test/Transforms/IndVarSimplify/X86/pr45360.ll @@ -23,8 +23,8 @@ define dso_local i32 @main() { ; CHECK-NEXT: [[I6:%.*]] = load i32, i32* @a, align 4 ; CHECK-NEXT: [[I24:%.*]] = load i32, i32* @b, align 4 ; CHECK-NEXT: [[D_PROMOTED9:%.*]] = load i32, i32* @d, align 4 -; CHECK-NEXT: br label [[BB13_PREHEADER:%.*]] -; CHECK: bb13.preheader: +; CHECK-NEXT: br label [[BB1:%.*]] +; CHECK: bb1: ; CHECK-NEXT: [[I8_LCSSA10:%.*]] = phi i32 [ [[D_PROMOTED9]], [[BB:%.*]] ], [ [[I8:%.*]], [[BB19_PREHEADER:%.*]] ] ; CHECK-NEXT: [[I8]] = and i32 [[I8_LCSSA10]], [[I6]] ; CHECK-NEXT: [[I21:%.*]] = icmp eq i32 [[I8]], 0 @@ -33,7 +33,7 @@ define dso_local i32 @main() { ; CHECK-NEXT: [[I26:%.*]] = urem i32 [[I24]], [[I8]] ; CHECK-NEXT: store i32 [[I26]], i32* @e, align 4 ; CHECK-NEXT: [[I30_NOT:%.*]] = icmp eq i32 [[I26]], 0 -; CHECK-NEXT: br i1 [[I30_NOT]], label [[BB32_LOOPEXIT:%.*]], label [[BB13_PREHEADER]] +; CHECK-NEXT: br i1 [[I30_NOT]], label [[BB32_LOOPEXIT:%.*]], label [[BB1]] ; CHECK: bb13.preheader.bb27.thread.split_crit_edge: ; CHECK-NEXT: store i32 -1, i32* @f, align 4 ; CHECK-NEXT: store i32 0, i32* @d, align 4 diff --git a/llvm/test/Transforms/IndVarSimplify/exit_value_test2.ll b/llvm/test/Transforms/IndVarSimplify/exit_value_test2.ll index 674003910373..93cced597cac 100644 --- a/llvm/test/Transforms/IndVarSimplify/exit_value_test2.ll +++ b/llvm/test/Transforms/IndVarSimplify/exit_value_test2.ll @@ -89,10 +89,8 @@ define i32 @zero_backedge_count_test(i32 %unknown_init, i32* %unknown_mem) { ; CHECK-NEXT: entry: ; CHECK-NEXT: br label [[LOOP:%.*]] ; CHECK: loop: -; CHECK-NEXT: [[UNKNOWN_NEXT:%.*]] = load volatile i32, i32* [[UNKNOWN_MEM:%.*]], align 4 -; CHECK-NEXT: br i1 false, label [[LOOP_LOOP_CRIT_EDGE:%.*]], label [[LEAVE:%.*]] -; CHECK: loop.loop_crit_edge: -; CHECK-NEXT: unreachable +; CHECK-NEXT: [[UNKNOWN_NEXT:%.*]] = load volatile i32, i32* [[UNKNOWN_MEM:%.*]] +; CHECK-NEXT: br i1 false, label [[LOOP]], label [[LEAVE:%.*]] ; CHECK: leave: ; CHECK-NEXT: ret i32 [[UNKNOWN_INIT:%.*]] ; diff --git a/llvm/test/Transforms/LoopDeletion/update-scev.ll b/llvm/test/Transforms/LoopDeletion/update-scev.ll index f156af538049..44d23aa4060d 100644 --- a/llvm/test/Transforms/LoopDeletion/update-scev.ll +++ b/llvm/test/Transforms/LoopDeletion/update-scev.ll @@ -44,8 +44,7 @@ for.body6: ; preds = %for.body6, %for.bod %conv10 = zext i1 %cmp9 to i32 %and = and i32 %conv10, %g.138 %inc = add i32 %h.039, 1 - %exit = icmp eq i32 %inc, 20000 - br i1 %exit, label %for.inc11, label %for.body6 + br i1 undef, label %for.inc11, label %for.body6 for.inc11: ; preds = %for.body6 %and.lcssa = phi i32 [ %and, %for.body6 ] diff --git a/llvm/test/Transforms/LoopDeletion/zero-btc.ll b/llvm/test/Transforms/LoopDeletion/zero-btc.ll deleted file mode 100644 index ab0423f3e036..000000000000 --- a/llvm/test/Transforms/LoopDeletion/zero-btc.ll +++ /dev/null @@ -1,335 +0,0 @@ -; NOTE: Assertions have been autogenerated by utils/update_test_checks.py -; RUN: opt < %s -loop-deletion -S | FileCheck %s - -@G = external global i32 - -define void @test_trivial() { -; CHECK-LABEL: @test_trivial( -; CHECK-NEXT: entry: -; CHECK-NEXT: br label [[LOOP:%.*]] -; CHECK: loop: -; CHECK-NEXT: store i32 0, i32* @G, align 4 -; CHECK-NEXT: br i1 false, label [[LOOP_LOOP_CRIT_EDGE:%.*]], label [[EXIT:%.*]] -; CHECK: loop.loop_crit_edge: -; CHECK-NEXT: unreachable -; CHECK: exit: -; CHECK-NEXT: ret void -; -entry: - br label %loop - -loop: - store i32 0, i32* @G - br i1 false, label %loop, label %exit - -exit: - ret void -} - - -define void @test_bottom_tested() { -; CHECK-LABEL: @test_bottom_tested( -; CHECK-NEXT: entry: -; CHECK-NEXT: br label [[LOOP:%.*]] -; CHECK: loop: -; CHECK-NEXT: [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ] -; CHECK-NEXT: store i32 0, i32* @G, align 4 -; CHECK-NEXT: [[IV_INC:%.*]] = add i32 [[IV]], 1 -; CHECK-NEXT: [[BE_TAKEN:%.*]] = icmp ne i32 [[IV_INC]], 1 -; CHECK-NEXT: br i1 [[BE_TAKEN]], label [[LOOP_LOOP_CRIT_EDGE:%.*]], label [[EXIT:%.*]] -; CHECK: loop.loop_crit_edge: -; CHECK-NEXT: unreachable -; CHECK: exit: -; CHECK-NEXT: ret void -; -entry: - br label %loop - -loop: - %iv = phi i32 [ 0, %entry], [ %iv.inc, %loop ] - store i32 0, i32* @G - %iv.inc = add i32 %iv, 1 - %be_taken = icmp ne i32 %iv.inc, 1 - br i1 %be_taken, label %loop, label %exit - -exit: - ret void -} - -define void @test_early_exit() { -; CHECK-LABEL: @test_early_exit( -; CHECK-NEXT: entry: -; CHECK-NEXT: br label [[LOOP:%.*]] -; CHECK: loop: -; CHECK-NEXT: [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ] -; CHECK-NEXT: store i32 0, i32* @G, align 4 -; CHECK-NEXT: [[IV_INC:%.*]] = add i32 [[IV]], 1 -; CHECK-NEXT: [[BE_TAKEN:%.*]] = icmp ne i32 [[IV_INC]], 1 -; CHECK-NEXT: br i1 [[BE_TAKEN]], label [[LATCH:%.*]], label [[EXIT:%.*]] -; CHECK: latch: -; CHECK-NEXT: br label [[LATCH_SPLIT:%.*]] -; CHECK: latch.split: -; CHECK-NEXT: unreachable -; CHECK: exit: -; CHECK-NEXT: ret void -; -entry: - br label %loop - -loop: - %iv = phi i32 [ 0, %entry], [ %iv.inc, %latch ] - store i32 0, i32* @G - %iv.inc = add i32 %iv, 1 - %be_taken = icmp ne i32 %iv.inc, 1 - br i1 %be_taken, label %latch, label %exit -latch: - br label %loop - -exit: - ret void -} - -define void @test_multi_exit1() { -; CHECK-LABEL: @test_multi_exit1( -; CHECK-NEXT: entry: -; CHECK-NEXT: br label [[LOOP:%.*]] -; CHECK: loop: -; CHECK-NEXT: [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ] -; CHECK-NEXT: store i32 0, i32* @G, align 4 -; CHECK-NEXT: [[IV_INC:%.*]] = add i32 [[IV]], 1 -; CHECK-NEXT: [[BE_TAKEN:%.*]] = icmp ne i32 [[IV_INC]], 1 -; CHECK-NEXT: br i1 [[BE_TAKEN]], label [[LATCH:%.*]], label [[EXIT:%.*]] -; CHECK: latch: -; CHECK-NEXT: store i32 1, i32* @G, align 4 -; CHECK-NEXT: [[COND2:%.*]] = icmp ult i32 [[IV_INC]], 30 -; CHECK-NEXT: br i1 [[COND2]], label [[LATCH_LOOP_CRIT_EDGE:%.*]], label [[EXIT]] -; CHECK: latch.loop_crit_edge: -; CHECK-NEXT: unreachable -; CHECK: exit: -; CHECK-NEXT: ret void -; -entry: - br label %loop - -loop: - %iv = phi i32 [ 0, %entry], [ %iv.inc, %latch ] - store i32 0, i32* @G - %iv.inc = add i32 %iv, 1 - %be_taken = icmp ne i32 %iv.inc, 1 - br i1 %be_taken, label %latch, label %exit -latch: - store i32 1, i32* @G - %cond2 = icmp ult i32 %iv.inc, 30 - br i1 %cond2, label %loop, label %exit - -exit: - ret void -} - -define void @test_multi_exit2() { -; CHECK-LABEL: @test_multi_exit2( -; CHECK-NEXT: entry: -; CHECK-NEXT: br label [[LOOP:%.*]] -; CHECK: loop: -; CHECK-NEXT: store i32 0, i32* @G, align 4 -; CHECK-NEXT: br i1 true, label [[LATCH:%.*]], label [[EXIT:%.*]] -; CHECK: latch: -; CHECK-NEXT: store i32 1, i32* @G, align 4 -; CHECK-NEXT: br i1 false, label [[LATCH_LOOP_CRIT_EDGE:%.*]], label [[EXIT]] -; CHECK: latch.loop_crit_edge: -; CHECK-NEXT: unreachable -; CHECK: exit: -; CHECK-NEXT: ret void -; -entry: - br label %loop - -loop: - store i32 0, i32* @G - br i1 true, label %latch, label %exit -latch: - store i32 1, i32* @G - br i1 false, label %loop, label %exit - -exit: - ret void -} - -; TODO: SCEV seems not to recognize this as a zero btc loop -define void @test_multi_exit3(i1 %cond1) { -; CHECK-LABEL: @test_multi_exit3( -; CHECK-NEXT: entry: -; CHECK-NEXT: br label [[LOOP:%.*]] -; CHECK: loop: -; CHECK-NEXT: [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[IV_INC:%.*]], [[LATCH:%.*]] ] -; CHECK-NEXT: store i32 0, i32* @G, align 4 -; CHECK-NEXT: br i1 [[COND1:%.*]], label [[LATCH]], label [[EXIT:%.*]] -; CHECK: latch: -; CHECK-NEXT: store i32 1, i32* @G, align 4 -; CHECK-NEXT: [[IV_INC]] = add i32 [[IV]], 1 -; CHECK-NEXT: [[BE_TAKEN:%.*]] = icmp ne i32 [[IV_INC]], 1 -; CHECK-NEXT: br i1 [[BE_TAKEN]], label [[LOOP]], label [[EXIT]] -; CHECK: exit: -; CHECK-NEXT: ret void -; -entry: - br label %loop - -loop: - %iv = phi i32 [ 0, %entry], [ %iv.inc, %latch ] - store i32 0, i32* @G - br i1 %cond1, label %latch, label %exit -latch: - store i32 1, i32* @G - %iv.inc = add i32 %iv, 1 - %be_taken = icmp ne i32 %iv.inc, 1 - br i1 %be_taken, label %loop, label %exit - -exit: - ret void -} - -; Subtle - This is either zero btc, or infinite, thus, can't break -; backedge -define void @test_multi_exit4(i1 %cond1, i1 %cond2) { -; CHECK-LABEL: @test_multi_exit4( -; CHECK-NEXT: entry: -; CHECK-NEXT: br label [[LOOP:%.*]] -; CHECK: loop: -; CHECK-NEXT: store i32 0, i32* @G, align 4 -; CHECK-NEXT: br i1 [[COND1:%.*]], label [[LATCH:%.*]], label [[EXIT:%.*]] -; CHECK: latch: -; CHECK-NEXT: store i32 1, i32* @G, align 4 -; CHECK-NEXT: br i1 [[COND2:%.*]], label [[LOOP]], label [[EXIT]] -; CHECK: exit: -; CHECK-NEXT: ret void -; -entry: - br label %loop - -loop: - store i32 0, i32* @G - br i1 %cond1, label %latch, label %exit -latch: - store i32 1, i32* @G - br i1 %cond2, label %loop, label %exit - -exit: - ret void -} - -; A simple case with multiple exit blocks -define void @test_multi_exit5() { -; CHECK-LABEL: @test_multi_exit5( -; CHECK-NEXT: entry: -; CHECK-NEXT: br label [[LOOP:%.*]] -; CHECK: loop: -; CHECK-NEXT: store i32 0, i32* @G, align 4 -; CHECK-NEXT: br i1 true, label [[LATCH:%.*]], label [[EXIT1:%.*]] -; CHECK: latch: -; CHECK-NEXT: store i32 1, i32* @G, align 4 -; CHECK-NEXT: br i1 false, label [[LATCH_LOOP_CRIT_EDGE:%.*]], label [[EXIT2:%.*]] -; CHECK: latch.loop_crit_edge: -; CHECK-NEXT: unreachable -; CHECK: exit1: -; CHECK-NEXT: ret void -; CHECK: exit2: -; CHECK-NEXT: ret void -; -entry: - br label %loop - -loop: - store i32 0, i32* @G - br i1 true, label %latch, label %exit1 -latch: - store i32 1, i32* @G - br i1 false, label %loop, label %exit2 - -exit1: - ret void -exit2: - ret void -} - -define void @test_live_inner() { -; CHECK-LABEL: @test_live_inner( -; CHECK-NEXT: entry: -; CHECK-NEXT: br label [[LOOP:%.*]] -; CHECK: loop: -; CHECK-NEXT: store i32 0, i32* @G, align 4 -; CHECK-NEXT: br label [[INNER:%.*]] -; CHECK: inner: -; CHECK-NEXT: [[IV:%.*]] = phi i32 [ 0, [[LOOP]] ], [ [[IV_INC:%.*]], [[INNER]] ] -; CHECK-NEXT: store i32 [[IV]], i32* @G, align 4 -; CHECK-NEXT: [[IV_INC]] = add i32 [[IV]], 1 -; CHECK-NEXT: [[CND:%.*]] = icmp ult i32 [[IV_INC]], 200 -; CHECK-NEXT: br i1 [[CND]], label [[INNER]], label [[LATCH:%.*]] -; CHECK: latch: -; CHECK-NEXT: br i1 false, label [[LATCH_LOOP_CRIT_EDGE:%.*]], label [[EXIT:%.*]] -; CHECK: latch.loop_crit_edge: -; CHECK-NEXT: unreachable -; CHECK: exit: -; CHECK-NEXT: ret void -; -entry: - br label %loop - -loop: - store i32 0, i32* @G - br label %inner - -inner: - %iv = phi i32 [0, %loop], [%iv.inc, %inner] - store i32 %iv, i32* @G - %iv.inc = add i32 %iv, 1 - %cnd = icmp ult i32 %iv.inc, 200 - br i1 %cnd, label %inner, label %latch - -latch: - br i1 false, label %loop, label %exit - -exit: - ret void -} - -define void @test_live_outer() { -; CHECK-LABEL: @test_live_outer( -; CHECK-NEXT: entry: -; CHECK-NEXT: br label [[LOOP:%.*]] -; CHECK: loop: -; CHECK-NEXT: [[IV:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[IV_INC:%.*]], [[LATCH:%.*]] ] -; CHECK-NEXT: br label [[INNER:%.*]] -; CHECK: inner: -; CHECK-NEXT: store i32 0, i32* @G, align 4 -; CHECK-NEXT: br i1 false, label [[INNER_INNER_CRIT_EDGE:%.*]], label [[LATCH]] -; CHECK: inner.inner_crit_edge: -; CHECK-NEXT: unreachable -; CHECK: latch: -; CHECK-NEXT: store i32 [[IV]], i32* @G, align 4 -; CHECK-NEXT: [[IV_INC]] = add i32 [[IV]], 1 -; CHECK-NEXT: [[CND:%.*]] = icmp ult i32 [[IV_INC]], 200 -; CHECK-NEXT: br i1 [[CND]], label [[LOOP]], label [[EXIT:%.*]] -; CHECK: exit: -; CHECK-NEXT: ret void -; -entry: - br label %loop - -loop: - %iv = phi i32 [0, %entry], [%iv.inc, %latch] - br label %inner - -inner: - store i32 0, i32* @G - br i1 false, label %inner, label %latch - -latch: - store i32 %iv, i32* @G - %iv.inc = add i32 %iv, 1 - %cnd = icmp ult i32 %iv.inc, 200 - br i1 %cnd, label %loop, label %exit - -exit: - ret void -}