[llvm] r316313 - [ARM] Allow unrolling of multi-block loops.
Sam Parker via llvm-commits
llvm-commits at lists.llvm.org
Mon Oct 23 01:05:14 PDT 2017
Author: sam_parker
Date: Mon Oct 23 01:05:14 2017
New Revision: 316313
URL: http://llvm.org/viewvc/llvm-project?rev=316313&view=rev
Log:
[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
Added:
llvm/trunk/test/Transforms/LoopUnroll/ARM/multi-blocks.ll
Modified:
llvm/trunk/lib/Target/ARM/ARMTargetTransformInfo.cpp
Modified: llvm/trunk/lib/Target/ARM/ARMTargetTransformInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMTargetTransformInfo.cpp?rev=316313&r1=316312&r2=316313&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMTargetTransformInfo.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMTargetTransformInfo.cpp Mon Oct 23 01:05:14 2017
@@ -586,34 +586,53 @@ void ARMTTIImpl::getUnrollingPreferences
if (!ST->isMClass())
return BasicTTIImplBase::getUnrollingPreferences(L, SE, UP);
- // Only enable on Thumb-2 targets for simple loops.
- if (!ST->isThumb2() || L->getNumBlocks() != 1)
- return;
-
// Disable loop unrolling for Oz and Os.
UP.OptSizeThreshold = 0;
UP.PartialOptSizeThreshold = 0;
- BasicBlock *BB = L->getLoopLatch();
- if (BB->getParent()->optForSize())
+ if (L->getHeader()->getParent()->optForSize())
+ return;
+
+ // Only enable on Thumb-2 targets.
+ if (!ST->isThumb2())
+ return;
+
+ SmallVector<BasicBlock*, 4> ExitingBlocks;
+ L->getExitingBlocks(ExitingBlocks);
+ DEBUG(dbgs() << "Loop has:\n"
+ << "Blocks: " << L->getNumBlocks() << "\n"
+ << "Exit blocks: " << ExitingBlocks.size() << "\n");
+
+ // Only allow another exit other than the latch. This acts as an early exit
+ // as it mirrors the profitability calculation of the runtime unroller.
+ if (ExitingBlocks.size() > 2)
+ return;
+
+ // Limit the CFG of the loop body for targets with a branch predictor.
+ // Allowing 4 blocks permits if-then-else diamonds in the body.
+ if (ST->hasBranchPredictor() && L->getNumBlocks() > 4)
return;
// Scan the loop: don't unroll loops with calls as this could prevent
// inlining.
unsigned Cost = 0;
- for (auto &I : *BB) {
- if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
- ImmutableCallSite CS(&I);
- if (const Function *F = CS.getCalledFunction()) {
- if (!isLoweredToCall(F))
- continue;
+ for (auto *BB : L->getBlocks()) {
+ for (auto &I : *BB) {
+ if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
+ ImmutableCallSite CS(&I);
+ if (const Function *F = CS.getCalledFunction()) {
+ if (!isLoweredToCall(F))
+ continue;
+ }
+ return;
}
- return;
+ SmallVector<const Value*, 4> Operands(I.value_op_begin(),
+ I.value_op_end());
+ Cost += getUserCost(&I, Operands);
}
- SmallVector<const Value*, 4> Operands(I.value_op_begin(),
- I.value_op_end());
- Cost += getUserCost(&I, Operands);
}
+ DEBUG(dbgs() << "Cost of loop: " << Cost << "\n");
+
UP.Partial = true;
UP.Runtime = true;
UP.UnrollRemainder = true;
Added: llvm/trunk/test/Transforms/LoopUnroll/ARM/multi-blocks.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/ARM/multi-blocks.ll?rev=316313&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LoopUnroll/ARM/multi-blocks.ll (added)
+++ llvm/trunk/test/Transforms/LoopUnroll/ARM/multi-blocks.ll Mon Oct 23 01:05:14 2017
@@ -0,0 +1,316 @@
+; RUN: opt -mtriple=thumbv8m.main -mcpu=cortex-m33 -loop-unroll -S < %s -o - | FileCheck %s
+; RUN: opt -mtriple=thumbv7em -mcpu=cortex-m7 -loop-unroll -S < %s -o - | FileCheck %s
+
+;CHECK-LABEL: test_three_blocks
+;CHECK: for.body.epil:
+;CHECK: if.then.epil:
+;CHECK: for.inc.epil:
+;CHECK: for.body:
+;CHECK: if.then:
+;CHECK: for.inc:
+;CHECK: for.body.epil.1:
+;CHECK: if.then.epil.1:
+;CHECK: for.inc.epil.1:
+;CHECK: for.body.epil.2:
+;CHECK: if.then.epil.2:
+;CHECK: for.inc.epil.2:
+;CHECK: if.then.1:
+;CHECK: for.inc.1:
+;CHECK: if.then.2:
+;CHECK: for.inc.2:
+;CHECK: if.then.3:
+;CHECK: for.inc.3:
+define void @test_three_blocks(i32* nocapture %Output,
+ i32* nocapture readonly %Condition,
+ i32* nocapture readonly %Input,
+ i32 %MaxJ) {
+entry:
+ %cmp8 = icmp eq i32 %MaxJ, 0
+ br i1 %cmp8, label %for.cond.cleanup, label %for.body.preheader
+
+for.body.preheader: ; preds = %entry
+ br label %for.body
+
+for.cond.cleanup: ; preds = %for.inc, %entry
+ %temp.0.lcssa = phi i32 [ 0, %entry ], [ %temp.1, %for.inc ]
+ store i32 %temp.0.lcssa, i32* %Output, align 4
+ ret void
+
+for.body: ; preds = %for.body.preheader, %for.inc
+ %j.010 = phi i32 [ %inc, %for.inc ], [ 0, %for.body.preheader ]
+ %temp.09 = phi i32 [ %temp.1, %for.inc ], [ 0, %for.body.preheader ]
+ %arrayidx = getelementptr inbounds i32, i32* %Condition, i32 %j.010
+ %0 = load i32, i32* %arrayidx, align 4
+ %tobool = icmp eq i32 %0, 0
+ br i1 %tobool, label %for.inc, label %if.then
+
+if.then: ; preds = %for.body
+ %arrayidx1 = getelementptr inbounds i32, i32* %Input, i32 %j.010
+ %1 = load i32, i32* %arrayidx1, align 4
+ %add = add i32 %1, %temp.09
+ br label %for.inc
+
+for.inc: ; preds = %for.body, %if.then
+ %temp.1 = phi i32 [ %add, %if.then ], [ %temp.09, %for.body ]
+ %inc = add nuw i32 %j.010, 1
+ %exitcond = icmp eq i32 %inc, %MaxJ
+ br i1 %exitcond, label %for.cond.cleanup, label %for.body
+}
+
+;CHECK-LABEL: test_two_exits
+;CHECK: for.body:
+;CHECK: if.end:
+;CHECK: cleanup.loopexit:
+;CHECK: cleanup:
+;CHECK: for.body.1:
+;CHECK: if.end.1:
+;CHECK: for.body.2:
+;CHECK: if.end.2:
+;CHECK: for.body.3:
+;CHECK: if.end.3:
+define void @test_two_exits(i32* nocapture %Output,
+ i32* nocapture readonly %Condition,
+ i32* nocapture readonly %Input,
+ i32 %MaxJ) {
+entry:
+ %cmp14 = icmp eq i32 %MaxJ, 0
+ br i1 %cmp14, label %cleanup, label %for.body.preheader
+
+for.body.preheader: ; preds = %entry
+ br label %for.body
+
+for.body: ; preds = %for.body.preheader, %if.end
+ %j.016 = phi i32 [ %inc, %if.end ], [ 0, %for.body.preheader ]
+ %temp.015 = phi i32 [ %temp.0.add, %if.end ], [ 0, %for.body.preheader ]
+ %arrayidx = getelementptr inbounds i32, i32* %Input, i32 %j.016
+ %0 = load i32, i32* %arrayidx, align 4
+ %cmp1 = icmp ugt i32 %0, 65535
+ br i1 %cmp1, label %cleanup, label %if.end
+
+if.end: ; preds = %for.body
+ %arrayidx2 = getelementptr inbounds i32, i32* %Condition, i32 %j.016
+ %1 = load i32, i32* %arrayidx2, align 4
+ %tobool = icmp eq i32 %1, 0
+ %add = select i1 %tobool, i32 0, i32 %0
+ %temp.0.add = add i32 %add, %temp.015
+ %inc = add nuw i32 %j.016, 1
+ %cmp = icmp ult i32 %inc, %MaxJ
+ br i1 %cmp, label %for.body, label %cleanup
+
+cleanup: ; preds = %if.end, %for.body, %entry
+ %temp.0.lcssa = phi i32 [ 0, %entry ], [ %temp.015, %for.body ], [ %temp.0.add, %if.end ]
+ store i32 %temp.0.lcssa, i32* %Output, align 4
+ ret void
+}
+
+;CHECK-LABEL: test_three_exits
+;CHECK-NOT: for.body.epil
+;CHECK-NOT: if.end.epil
+;CHECK-LABEL: for.body
+;CHECK-LABEL: if.end
+;CHECK-LABEL: if.end5
+define void @test_three_exits(i32* nocapture %Output,
+ i32* nocapture readonly %Condition,
+ i32* nocapture readonly %Input,
+ i32 %MaxJ) {
+entry:
+ %cmp20 = icmp eq i32 %MaxJ, 0
+ br i1 %cmp20, label %cleanup, label %for.body.preheader
+
+for.body.preheader: ; preds = %entry
+ br label %for.body
+
+for.body: ; preds = %for.body.preheader, %if.end5
+ %j.022 = phi i32 [ %inc, %if.end5 ], [ 0, %for.body.preheader ]
+ %temp.021 = phi i32 [ %temp.0.add, %if.end5 ], [ 0, %for.body.preheader ]
+ %arrayidx = getelementptr inbounds i32, i32* %Condition, i32 %j.022
+ %0 = load i32, i32* %arrayidx, align 4
+ %cmp1 = icmp ugt i32 %0, 65535
+ br i1 %cmp1, label %cleanup, label %if.end
+
+if.end: ; preds = %for.body
+ %arrayidx2 = getelementptr inbounds i32, i32* %Input, i32 %j.022
+ %1 = load i32, i32* %arrayidx2, align 4
+ %cmp3 = icmp ugt i32 %1, 65535
+ br i1 %cmp3, label %cleanup, label %if.end5
+
+if.end5: ; preds = %if.end
+ %tobool = icmp eq i32 %0, 0
+ %add = select i1 %tobool, i32 0, i32 %1
+ %temp.0.add = add i32 %add, %temp.021
+ %inc = add nuw i32 %j.022, 1
+ %cmp = icmp ult i32 %inc, %MaxJ
+ br i1 %cmp, label %for.body, label %cleanup
+
+cleanup: ; preds = %if.end5, %for.body, %if.end, %entry
+ %temp.0.lcssa = phi i32 [ 0, %entry ], [ %temp.021, %if.end ], [ %temp.021, %for.body ], [ %temp.0.add, %if.end5 ]
+ store i32 %temp.0.lcssa, i32* %Output, align 4
+ ret void
+}
+
+;CHECK-LABEL: test_four_blocks
+;CHECK: for.body.epil:
+;CHECK: if.else.epil:
+;CHECK: if.then.epil:
+;CHECK: for.cond.cleanup:
+;CHECK: for.body:
+;CHECK: if.then:
+;CHECK: for.inc:
+;CHECK: for.body.epil.1:
+;CHECK: if.else.epil.1:
+;CHECK: if.then.epil.1:
+;CHECK: for.inc.epil.1:
+;CHECK: for.body.epil.2:
+;CHECK: if.else.epil.2:
+;CHECK: if.then.epil.2:
+;CHECK: for.inc.epil.2:
+;CHECK: if.else.1:
+;CHECK: if.then.1:
+;CHECK: for.inc.1:
+;CHECK: if.else.2:
+;CHECK: if.then.2:
+;CHECK: for.inc.2:
+;CHECK: if.else.3:
+;CHECK: if.then.3:
+;CHECK: for.inc.3:
+define void @test_four_blocks(i32* nocapture %Output,
+ i32* nocapture readonly %Condition,
+ i32* nocapture readonly %Input,
+ i32 %MaxJ) {
+entry:
+ %cmp25 = icmp ugt i32 %MaxJ, 1
+ br i1 %cmp25, label %for.body.lr.ph, label %for.cond.cleanup
+
+for.body.lr.ph: ; preds = %entry
+ %.pre = load i32, i32* %Input, align 4
+ br label %for.body
+
+for.cond.cleanup: ; preds = %for.inc, %entry
+ %temp.0.lcssa = phi i32 [ 0, %entry ], [ %temp.1, %for.inc ]
+ store i32 %temp.0.lcssa, i32* %Output, align 4
+ ret void
+
+for.body: ; preds = %for.inc, %for.body.lr.ph
+ %0 = phi i32 [ %.pre, %for.body.lr.ph ], [ %2, %for.inc ]
+ %j.027 = phi i32 [ 1, %for.body.lr.ph ], [ %inc, %for.inc ]
+ %temp.026 = phi i32 [ 0, %for.body.lr.ph ], [ %temp.1, %for.inc ]
+ %arrayidx = getelementptr inbounds i32, i32* %Condition, i32 %j.027
+ %1 = load i32, i32* %arrayidx, align 4
+ %cmp1 = icmp ugt i32 %1, 65535
+ %arrayidx2 = getelementptr inbounds i32, i32* %Input, i32 %j.027
+ %2 = load i32, i32* %arrayidx2, align 4
+ %cmp4 = icmp ugt i32 %2, %0
+ br i1 %cmp1, label %if.then, label %if.else
+
+if.then: ; preds = %for.body
+ %cond = zext i1 %cmp4 to i32
+ %add = add i32 %temp.026, %cond
+ br label %for.inc
+
+if.else: ; preds = %for.body
+ %not.cmp4 = xor i1 %cmp4, true
+ %sub = sext i1 %not.cmp4 to i32
+ %sub10.sink = add i32 %j.027, %sub
+ %arrayidx11 = getelementptr inbounds i32, i32* %Input, i32 %sub10.sink
+ %3 = load i32, i32* %arrayidx11, align 4
+ %sub13 = sub i32 %temp.026, %3
+ br label %for.inc
+
+for.inc: ; preds = %if.then, %if.else
+ %temp.1 = phi i32 [ %add, %if.then ], [ %sub13, %if.else ]
+ %inc = add nuw i32 %j.027, 1
+ %exitcond = icmp eq i32 %inc, %MaxJ
+ br i1 %exitcond, label %for.cond.cleanup, label %for.body
+}
+
+;CHECK-LABEL: test_five_blocks
+;CHECK-NOT: for.body.epil:
+;CHECK: for.body:
+;CHECK: if.end:
+;CHECK: if.else:
+;CHECK: for.inc:
+;CHECK-NOT: for.inc.1:
+define void @test_five_blocks(i32* nocapture %Output,
+ i32* nocapture readonly %Condition,
+ i32* nocapture readonly %Input,
+ i32 %MaxJ) {
+entry:
+ %cmp24 = icmp ugt i32 %MaxJ, 1
+ br i1 %cmp24, label %for.body.preheader, label %cleanup
+
+for.body.preheader: ; preds = %entry
+ br label %for.body
+
+for.body: ; preds = %for.body.preheader, %for.inc
+ %j.026 = phi i32 [ %inc, %for.inc ], [ 1, %for.body.preheader ]
+ %temp.025 = phi i32 [ %temp.1, %for.inc ], [ 0, %for.body.preheader ]
+ %arrayidx = getelementptr inbounds i32, i32* %Input, i32 %j.026
+ %0 = load i32, i32* %arrayidx, align 4
+ %add = add i32 %0, %temp.025
+ %cmp1 = icmp ugt i32 %add, 16777215
+ br i1 %cmp1, label %cleanup, label %if.end
+
+if.end: ; preds = %for.body
+ %arrayidx2 = getelementptr inbounds i32, i32* %Condition, i32 %j.026
+ %1 = load i32, i32* %arrayidx2, align 4
+ %cmp3 = icmp ugt i32 %1, 65535
+ br i1 %cmp3, label %if.then4, label %if.else
+
+if.then4: ; preds = %if.end
+ %sub = add i32 %j.026, -1
+ %arrayidx6 = getelementptr inbounds i32, i32* %Input, i32 %sub
+ %2 = load i32, i32* %arrayidx6, align 4
+ %cmp7 = icmp ugt i32 %0, %2
+ %cond = zext i1 %cmp7 to i32
+ %add8 = add i32 %add, %cond
+ br label %for.inc
+
+if.else: ; preds = %if.end
+ %and = and i32 %add, %0
+ br label %for.inc
+
+for.inc: ; preds = %if.then4, %if.else
+ %temp.1 = phi i32 [ %add8, %if.then4 ], [ %and, %if.else ]
+ %inc = add nuw i32 %j.026, 1
+ %cmp = icmp ult i32 %inc, %MaxJ
+ br i1 %cmp, label %for.body, label %cleanup
+
+cleanup: ; preds = %for.inc, %for.body, %entry
+ %temp.2 = phi i32 [ 0, %entry ], [ %add, %for.body ], [ %temp.1, %for.inc ]
+ store i32 %temp.2, i32* %Output, align 4
+ ret void
+}
+
+;CHECK-LABEL: iterate_inc
+;CHECK: while.body:
+;CHECK: while.end:
+;CHECK: while.body.1:
+;CHECK: while.body.2:
+;CHECK: while.body.3:
+%struct.Node = type { %struct.Node*, i32 }
+define void @iterate_inc(%struct.Node* %n, i32 %limit) {
+entry:
+ %tobool5 = icmp eq %struct.Node* %n, null
+ br i1 %tobool5, label %while.end, label %land.rhs.preheader
+
+land.rhs.preheader: ; preds = %entry
+ br label %land.rhs
+
+land.rhs: ; preds = %land.rhs.preheader, %while.body
+ %list.addr.06 = phi %struct.Node* [ %2, %while.body ], [ %n, %land.rhs.preheader ]
+ %val = getelementptr inbounds %struct.Node, %struct.Node* %list.addr.06, i32 0, i32 1
+ %0 = load i32, i32* %val, align 4
+ %cmp = icmp slt i32 %0, %limit
+ br i1 %cmp, label %while.body, label %while.end
+
+while.body: ; preds = %land.rhs
+ %inc = add nsw i32 %0, 1
+ store i32 %inc, i32* %val, align 4
+ %1 = bitcast %struct.Node* %list.addr.06 to %struct.Node**
+ %2 = load %struct.Node*, %struct.Node** %1, align 4
+ %tobool = icmp eq %struct.Node* %2, null
+ br i1 %tobool, label %while.end, label %land.rhs
+
+while.end: ; preds = %land.rhs, %while.body, %entry
+ ret void
+}
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