forked from OSchip/llvm-project
[ARM] Allow unrolling of multi-block loops.
Before, loop unrolling was only enabled for loops with a single block. This restriction has been removed and replaced by: - allow a maximum of two exiting blocks, - a four basic block limit for cores with a branch predictor. Differential Revision: https://reviews.llvm.org/D38952 llvm-svn: 316313
This commit is contained in:
Sam Parker
parent
01e3bf8afd
commit
487ab86942
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@ -586,34 +586,53 @@ void ARMTTIImpl::getUnrollingPreferences(Loop *L, ScalarEvolution &SE,
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if (!ST->isMClass())
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return BasicTTIImplBase::getUnrollingPreferences(L, SE, UP);
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// Only enable on Thumb-2 targets for simple loops.
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if (!ST->isThumb2() || L->getNumBlocks() != 1)
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return;
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// Disable loop unrolling for Oz and Os.
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UP.OptSizeThreshold = 0;
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UP.PartialOptSizeThreshold = 0;
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BasicBlock *BB = L->getLoopLatch();
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if (BB->getParent()->optForSize())
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if (L->getHeader()->getParent()->optForSize())
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return;
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// Only enable on Thumb-2 targets.
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if (!ST->isThumb2())
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return;
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SmallVector<BasicBlock*, 4> ExitingBlocks;
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L->getExitingBlocks(ExitingBlocks);
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DEBUG(dbgs() << "Loop has:\n"
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<< "Blocks: " << L->getNumBlocks() << "\n"
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<< "Exit blocks: " << ExitingBlocks.size() << "\n");
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// Only allow another exit other than the latch. This acts as an early exit
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// as it mirrors the profitability calculation of the runtime unroller.
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if (ExitingBlocks.size() > 2)
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return;
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// Limit the CFG of the loop body for targets with a branch predictor.
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// Allowing 4 blocks permits if-then-else diamonds in the body.
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if (ST->hasBranchPredictor() && L->getNumBlocks() > 4)
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return;
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// Scan the loop: don't unroll loops with calls as this could prevent
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// inlining.
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unsigned Cost = 0;
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for (auto &I : *BB) {
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if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
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ImmutableCallSite CS(&I);
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if (const Function *F = CS.getCalledFunction()) {
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if (!isLoweredToCall(F))
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continue;
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for (auto *BB : L->getBlocks()) {
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for (auto &I : *BB) {
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if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
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ImmutableCallSite CS(&I);
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if (const Function *F = CS.getCalledFunction()) {
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if (!isLoweredToCall(F))
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continue;
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}
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return;
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}
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return;
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SmallVector<const Value*, 4> Operands(I.value_op_begin(),
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I.value_op_end());
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Cost += getUserCost(&I, Operands);
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}
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SmallVector<const Value*, 4> Operands(I.value_op_begin(),
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I.value_op_end());
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Cost += getUserCost(&I, Operands);
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}
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DEBUG(dbgs() << "Cost of loop: " << Cost << "\n");
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UP.Partial = true;
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UP.Runtime = true;
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UP.UnrollRemainder = true;
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@ -0,0 +1,316 @@
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; RUN: opt -mtriple=thumbv8m.main -mcpu=cortex-m33 -loop-unroll -S < %s -o - | FileCheck %s
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; RUN: opt -mtriple=thumbv7em -mcpu=cortex-m7 -loop-unroll -S < %s -o - | FileCheck %s
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;CHECK-LABEL: test_three_blocks
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;CHECK: for.body.epil:
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;CHECK: if.then.epil:
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;CHECK: for.inc.epil:
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;CHECK: for.body:
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;CHECK: if.then:
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;CHECK: for.inc:
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;CHECK: for.body.epil.1:
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;CHECK: if.then.epil.1:
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;CHECK: for.inc.epil.1:
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;CHECK: for.body.epil.2:
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;CHECK: if.then.epil.2:
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;CHECK: for.inc.epil.2:
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;CHECK: if.then.1:
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;CHECK: for.inc.1:
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;CHECK: if.then.2:
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;CHECK: for.inc.2:
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;CHECK: if.then.3:
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;CHECK: for.inc.3:
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define void @test_three_blocks(i32* nocapture %Output,
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i32* nocapture readonly %Condition,
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i32* nocapture readonly %Input,
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i32 %MaxJ) {
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entry:
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%cmp8 = icmp eq i32 %MaxJ, 0
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br i1 %cmp8, label %for.cond.cleanup, label %for.body.preheader
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for.body.preheader: ; preds = %entry
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br label %for.body
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for.cond.cleanup: ; preds = %for.inc, %entry
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%temp.0.lcssa = phi i32 [ 0, %entry ], [ %temp.1, %for.inc ]
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store i32 %temp.0.lcssa, i32* %Output, align 4
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ret void
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for.body: ; preds = %for.body.preheader, %for.inc
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%j.010 = phi i32 [ %inc, %for.inc ], [ 0, %for.body.preheader ]
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%temp.09 = phi i32 [ %temp.1, %for.inc ], [ 0, %for.body.preheader ]
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%arrayidx = getelementptr inbounds i32, i32* %Condition, i32 %j.010
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%0 = load i32, i32* %arrayidx, align 4
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%tobool = icmp eq i32 %0, 0
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br i1 %tobool, label %for.inc, label %if.then
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if.then: ; preds = %for.body
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%arrayidx1 = getelementptr inbounds i32, i32* %Input, i32 %j.010
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%1 = load i32, i32* %arrayidx1, align 4
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%add = add i32 %1, %temp.09
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br label %for.inc
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for.inc: ; preds = %for.body, %if.then
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%temp.1 = phi i32 [ %add, %if.then ], [ %temp.09, %for.body ]
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%inc = add nuw i32 %j.010, 1
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%exitcond = icmp eq i32 %inc, %MaxJ
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br i1 %exitcond, label %for.cond.cleanup, label %for.body
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}
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;CHECK-LABEL: test_two_exits
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;CHECK: for.body:
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;CHECK: if.end:
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;CHECK: cleanup.loopexit:
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;CHECK: cleanup:
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;CHECK: for.body.1:
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;CHECK: if.end.1:
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;CHECK: for.body.2:
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;CHECK: if.end.2:
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;CHECK: for.body.3:
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;CHECK: if.end.3:
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define void @test_two_exits(i32* nocapture %Output,
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i32* nocapture readonly %Condition,
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i32* nocapture readonly %Input,
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i32 %MaxJ) {
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entry:
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%cmp14 = icmp eq i32 %MaxJ, 0
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br i1 %cmp14, label %cleanup, label %for.body.preheader
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for.body.preheader: ; preds = %entry
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br label %for.body
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for.body: ; preds = %for.body.preheader, %if.end
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%j.016 = phi i32 [ %inc, %if.end ], [ 0, %for.body.preheader ]
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%temp.015 = phi i32 [ %temp.0.add, %if.end ], [ 0, %for.body.preheader ]
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%arrayidx = getelementptr inbounds i32, i32* %Input, i32 %j.016
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%0 = load i32, i32* %arrayidx, align 4
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%cmp1 = icmp ugt i32 %0, 65535
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br i1 %cmp1, label %cleanup, label %if.end
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if.end: ; preds = %for.body
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%arrayidx2 = getelementptr inbounds i32, i32* %Condition, i32 %j.016
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%1 = load i32, i32* %arrayidx2, align 4
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%tobool = icmp eq i32 %1, 0
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%add = select i1 %tobool, i32 0, i32 %0
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%temp.0.add = add i32 %add, %temp.015
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%inc = add nuw i32 %j.016, 1
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%cmp = icmp ult i32 %inc, %MaxJ
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br i1 %cmp, label %for.body, label %cleanup
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cleanup: ; preds = %if.end, %for.body, %entry
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%temp.0.lcssa = phi i32 [ 0, %entry ], [ %temp.015, %for.body ], [ %temp.0.add, %if.end ]
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store i32 %temp.0.lcssa, i32* %Output, align 4
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ret void
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}
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;CHECK-LABEL: test_three_exits
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;CHECK-NOT: for.body.epil
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;CHECK-NOT: if.end.epil
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;CHECK-LABEL: for.body
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;CHECK-LABEL: if.end
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;CHECK-LABEL: if.end5
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define void @test_three_exits(i32* nocapture %Output,
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i32* nocapture readonly %Condition,
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i32* nocapture readonly %Input,
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i32 %MaxJ) {
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entry:
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%cmp20 = icmp eq i32 %MaxJ, 0
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br i1 %cmp20, label %cleanup, label %for.body.preheader
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for.body.preheader: ; preds = %entry
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br label %for.body
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for.body: ; preds = %for.body.preheader, %if.end5
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%j.022 = phi i32 [ %inc, %if.end5 ], [ 0, %for.body.preheader ]
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%temp.021 = phi i32 [ %temp.0.add, %if.end5 ], [ 0, %for.body.preheader ]
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%arrayidx = getelementptr inbounds i32, i32* %Condition, i32 %j.022
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%0 = load i32, i32* %arrayidx, align 4
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%cmp1 = icmp ugt i32 %0, 65535
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br i1 %cmp1, label %cleanup, label %if.end
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if.end: ; preds = %for.body
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%arrayidx2 = getelementptr inbounds i32, i32* %Input, i32 %j.022
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%1 = load i32, i32* %arrayidx2, align 4
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%cmp3 = icmp ugt i32 %1, 65535
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br i1 %cmp3, label %cleanup, label %if.end5
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if.end5: ; preds = %if.end
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%tobool = icmp eq i32 %0, 0
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%add = select i1 %tobool, i32 0, i32 %1
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%temp.0.add = add i32 %add, %temp.021
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%inc = add nuw i32 %j.022, 1
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%cmp = icmp ult i32 %inc, %MaxJ
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br i1 %cmp, label %for.body, label %cleanup
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cleanup: ; preds = %if.end5, %for.body, %if.end, %entry
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%temp.0.lcssa = phi i32 [ 0, %entry ], [ %temp.021, %if.end ], [ %temp.021, %for.body ], [ %temp.0.add, %if.end5 ]
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store i32 %temp.0.lcssa, i32* %Output, align 4
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ret void
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}
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;CHECK-LABEL: test_four_blocks
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;CHECK: for.body.epil:
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;CHECK: if.else.epil:
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;CHECK: if.then.epil:
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;CHECK: for.cond.cleanup:
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;CHECK: for.body:
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;CHECK: if.then:
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;CHECK: for.inc:
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;CHECK: for.body.epil.1:
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;CHECK: if.else.epil.1:
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;CHECK: if.then.epil.1:
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;CHECK: for.inc.epil.1:
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;CHECK: for.body.epil.2:
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;CHECK: if.else.epil.2:
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;CHECK: if.then.epil.2:
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;CHECK: for.inc.epil.2:
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;CHECK: if.else.1:
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;CHECK: if.then.1:
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;CHECK: for.inc.1:
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;CHECK: if.else.2:
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;CHECK: if.then.2:
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;CHECK: for.inc.2:
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;CHECK: if.else.3:
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;CHECK: if.then.3:
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;CHECK: for.inc.3:
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define void @test_four_blocks(i32* nocapture %Output,
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i32* nocapture readonly %Condition,
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i32* nocapture readonly %Input,
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i32 %MaxJ) {
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entry:
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%cmp25 = icmp ugt i32 %MaxJ, 1
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br i1 %cmp25, label %for.body.lr.ph, label %for.cond.cleanup
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for.body.lr.ph: ; preds = %entry
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%.pre = load i32, i32* %Input, align 4
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br label %for.body
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for.cond.cleanup: ; preds = %for.inc, %entry
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%temp.0.lcssa = phi i32 [ 0, %entry ], [ %temp.1, %for.inc ]
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store i32 %temp.0.lcssa, i32* %Output, align 4
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ret void
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for.body: ; preds = %for.inc, %for.body.lr.ph
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%0 = phi i32 [ %.pre, %for.body.lr.ph ], [ %2, %for.inc ]
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%j.027 = phi i32 [ 1, %for.body.lr.ph ], [ %inc, %for.inc ]
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%temp.026 = phi i32 [ 0, %for.body.lr.ph ], [ %temp.1, %for.inc ]
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%arrayidx = getelementptr inbounds i32, i32* %Condition, i32 %j.027
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%1 = load i32, i32* %arrayidx, align 4
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%cmp1 = icmp ugt i32 %1, 65535
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%arrayidx2 = getelementptr inbounds i32, i32* %Input, i32 %j.027
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%2 = load i32, i32* %arrayidx2, align 4
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%cmp4 = icmp ugt i32 %2, %0
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br i1 %cmp1, label %if.then, label %if.else
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if.then: ; preds = %for.body
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%cond = zext i1 %cmp4 to i32
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%add = add i32 %temp.026, %cond
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br label %for.inc
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if.else: ; preds = %for.body
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%not.cmp4 = xor i1 %cmp4, true
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%sub = sext i1 %not.cmp4 to i32
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%sub10.sink = add i32 %j.027, %sub
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%arrayidx11 = getelementptr inbounds i32, i32* %Input, i32 %sub10.sink
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%3 = load i32, i32* %arrayidx11, align 4
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%sub13 = sub i32 %temp.026, %3
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br label %for.inc
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for.inc: ; preds = %if.then, %if.else
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%temp.1 = phi i32 [ %add, %if.then ], [ %sub13, %if.else ]
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%inc = add nuw i32 %j.027, 1
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%exitcond = icmp eq i32 %inc, %MaxJ
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br i1 %exitcond, label %for.cond.cleanup, label %for.body
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}
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;CHECK-LABEL: test_five_blocks
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;CHECK-NOT: for.body.epil:
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;CHECK: for.body:
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;CHECK: if.end:
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;CHECK: if.else:
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;CHECK: for.inc:
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;CHECK-NOT: for.inc.1:
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define void @test_five_blocks(i32* nocapture %Output,
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i32* nocapture readonly %Condition,
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i32* nocapture readonly %Input,
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i32 %MaxJ) {
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entry:
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%cmp24 = icmp ugt i32 %MaxJ, 1
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br i1 %cmp24, label %for.body.preheader, label %cleanup
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for.body.preheader: ; preds = %entry
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br label %for.body
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for.body: ; preds = %for.body.preheader, %for.inc
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%j.026 = phi i32 [ %inc, %for.inc ], [ 1, %for.body.preheader ]
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%temp.025 = phi i32 [ %temp.1, %for.inc ], [ 0, %for.body.preheader ]
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%arrayidx = getelementptr inbounds i32, i32* %Input, i32 %j.026
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%0 = load i32, i32* %arrayidx, align 4
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%add = add i32 %0, %temp.025
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%cmp1 = icmp ugt i32 %add, 16777215
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br i1 %cmp1, label %cleanup, label %if.end
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if.end: ; preds = %for.body
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%arrayidx2 = getelementptr inbounds i32, i32* %Condition, i32 %j.026
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%1 = load i32, i32* %arrayidx2, align 4
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%cmp3 = icmp ugt i32 %1, 65535
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br i1 %cmp3, label %if.then4, label %if.else
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if.then4: ; preds = %if.end
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%sub = add i32 %j.026, -1
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%arrayidx6 = getelementptr inbounds i32, i32* %Input, i32 %sub
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%2 = load i32, i32* %arrayidx6, align 4
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%cmp7 = icmp ugt i32 %0, %2
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%cond = zext i1 %cmp7 to i32
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%add8 = add i32 %add, %cond
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br label %for.inc
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if.else: ; preds = %if.end
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%and = and i32 %add, %0
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br label %for.inc
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for.inc: ; preds = %if.then4, %if.else
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%temp.1 = phi i32 [ %add8, %if.then4 ], [ %and, %if.else ]
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%inc = add nuw i32 %j.026, 1
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%cmp = icmp ult i32 %inc, %MaxJ
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br i1 %cmp, label %for.body, label %cleanup
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cleanup: ; preds = %for.inc, %for.body, %entry
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%temp.2 = phi i32 [ 0, %entry ], [ %add, %for.body ], [ %temp.1, %for.inc ]
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store i32 %temp.2, i32* %Output, align 4
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ret void
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}
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;CHECK-LABEL: iterate_inc
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;CHECK: while.body:
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;CHECK: while.end:
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;CHECK: while.body.1:
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;CHECK: while.body.2:
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;CHECK: while.body.3:
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%struct.Node = type { %struct.Node*, i32 }
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define void @iterate_inc(%struct.Node* %n, i32 %limit) {
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entry:
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%tobool5 = icmp eq %struct.Node* %n, null
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br i1 %tobool5, label %while.end, label %land.rhs.preheader
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land.rhs.preheader: ; preds = %entry
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br label %land.rhs
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land.rhs: ; preds = %land.rhs.preheader, %while.body
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%list.addr.06 = phi %struct.Node* [ %2, %while.body ], [ %n, %land.rhs.preheader ]
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%val = getelementptr inbounds %struct.Node, %struct.Node* %list.addr.06, i32 0, i32 1
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%0 = load i32, i32* %val, align 4
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%cmp = icmp slt i32 %0, %limit
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br i1 %cmp, label %while.body, label %while.end
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while.body: ; preds = %land.rhs
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%inc = add nsw i32 %0, 1
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store i32 %inc, i32* %val, align 4
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%1 = bitcast %struct.Node* %list.addr.06 to %struct.Node**
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%2 = load %struct.Node*, %struct.Node** %1, align 4
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%tobool = icmp eq %struct.Node* %2, null
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br i1 %tobool, label %while.end, label %land.rhs
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|
||||
while.end: ; preds = %land.rhs, %while.body, %entry
|
||||
ret void
|
||||
}
|
||||
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Reference in New Issue