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Invoke SimplifyIndVar when we partially unroll a loop. Fixes PR10534.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@137203 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -79,6 +79,7 @@ namespace {
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AU.addPreservedID(LoopSimplifyID);
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AU.addRequiredID(LCSSAID);
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AU.addPreservedID(LCSSAID);
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AU.addRequired<ScalarEvolution>();
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AU.addPreserved<ScalarEvolution>();
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// FIXME: Loop unroll requires LCSSA. And LCSSA requires dom info.
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// If loop unroll does not preserve dom info then LCSSA pass on next
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@ -187,12 +188,8 @@ bool LoopUnroll::runOnLoop(Loop *L, LPPassManager &LPM) {
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}
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// Unroll the loop.
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Function *F = L->getHeader()->getParent();
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if (!UnrollLoop(L, Count, TripCount, TripMultiple, LI, &LPM))
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return false;
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// FIXME: Reconstruct dom info, because it is not preserved properly.
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if (DominatorTree *DT = getAnalysisIfAvailable<DominatorTree>())
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DT->runOnFunction(*F);
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return true;
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}
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@ -29,6 +29,7 @@
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Utils/Cloning.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include "llvm/Transforms/Utils/SimplifyIndVar.h"
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using namespace llvm;
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// TODO: Should these be here or in LoopUnroll?
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@ -130,6 +131,9 @@ static BasicBlock *FoldBlockIntoPredecessor(BasicBlock *BB, LoopInfo* LI,
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///
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/// If a LoopPassManager is passed in, and the loop is fully removed, it will be
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/// removed from the LoopPassManager as well. LPM can also be NULL.
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///
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/// This utility preserves LoopInfo. If DominatorTree or ScalarEvolution are
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/// available it must also preseve those analyses.
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bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount,
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unsigned TripMultiple, LoopInfo *LI, LPPassManager *LPM) {
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BasicBlock *Preheader = L->getLoopPreheader();
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@ -163,7 +167,8 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount,
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// Notify ScalarEvolution that the loop will be substantially changed,
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// if not outright eliminated.
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if (ScalarEvolution *SE = LPM->getAnalysisIfAvailable<ScalarEvolution>())
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ScalarEvolution *SE = LPM->getAnalysisIfAvailable<ScalarEvolution>();
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if (SE)
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SE->forgetLoop(L);
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if (TripCount != 0)
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@ -374,6 +379,24 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount,
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}
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}
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// FIXME: Reconstruct dom info, because it is not preserved properly.
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// Incrementally updating domtree after loop unrolling woud be easy.
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if (DominatorTree *DT = LPM->getAnalysisIfAvailable<DominatorTree>())
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DT->runOnFunction(*L->getHeader()->getParent());
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// Simplify any new induction variables in the partially unrolled loop.
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if (SE && !CompletelyUnroll) {
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SmallVector<WeakVH, 16> DeadInsts;
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simplifyLoopIVs(L, SE, LPM, DeadInsts);
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// Aggressively clean up dead instructions that simplifyLoopIVs already
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// identified. Any remaining should be cleaned up below.
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while (!DeadInsts.empty())
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if (Instruction *Inst =
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dyn_cast_or_null<Instruction>(&*DeadInsts.pop_back_val()))
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RecursivelyDeleteTriviallyDeadInstructions(Inst);
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}
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// At this point, the code is well formed. We now do a quick sweep over the
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// inserted code, doing constant propagation and dead code elimination as we
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// go.
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39
test/Transforms/LoopUnroll/2011-08-09-IVSimplify.ll
Normal file
39
test/Transforms/LoopUnroll/2011-08-09-IVSimplify.ll
Normal file
@ -0,0 +1,39 @@
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; RUN: opt -S < %s -loop-unroll -unroll-count=4 -disable-iv-rewrite | FileCheck %s
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;
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; Test induction variable simplify after loop unrolling. It should
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; expose nice opportunities for GVN.
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target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-f80:128:128-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32"
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; PR10534: LoopUnroll not keeping canonical induction variable...
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; CHECK: while.body.1:
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; CHECK: %shr.1 = lshr i32 %bit_addr.addr.01, 5
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; CHECK: %arrayidx.1 = getelementptr inbounds i32* %bitmap, i32 %shr.1
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; CHECK: while.body.2:
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; CHECK: %shr.2 = lshr i32 %bit_addr.addr.01, 5
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; CHECK: %arrayidx.2 = getelementptr inbounds i32* %bitmap, i32 %shr.2
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; CHECK: while.body.3:
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; CHECK: %shr.3 = lshr i32 %bit_addr.addr.01, 5
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; CHECK: %arrayidx.3 = getelementptr inbounds i32* %bitmap, i32 %shr.3
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define void @FlipBit(i32* nocapture %bitmap, i32 %bit_addr, i32 %nbits) nounwind {
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entry:
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br label %while.body
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while.body:
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%nbits.addr.02 = phi i32 [ 128, %entry ], [ %dec, %while.body ]
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%bit_addr.addr.01 = phi i32 [ 0, %entry ], [ %inc, %while.body ]
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%dec = add i32 %nbits.addr.02, -1
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%shr = lshr i32 %bit_addr.addr.01, 5
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%rem = and i32 %bit_addr.addr.01, 31
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%shl = shl i32 1, %rem
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%arrayidx = getelementptr inbounds i32* %bitmap, i32 %shr
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%tmp6 = load i32* %arrayidx, align 4
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%xor = xor i32 %tmp6, %shl
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store i32 %xor, i32* %arrayidx, align 4
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%inc = add i32 %bit_addr.addr.01, 1
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%tobool = icmp eq i32 %dec, 0
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br i1 %tobool, label %while.end, label %while.body
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while.end:
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ret void
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}
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