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Relax the "don't unroll loops containing calls" rule. Instead, when a loop contains a call, lower the
unrolling threshold to the optimize-for-size threshold. Basically, for loops containing calls, unrolling can still be profitable as long as the loop is REALLY small. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@113439 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -132,8 +132,10 @@ bool LoopUnroll::runOnLoop(Loop *L, LPPassManager &LPM) {
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unsigned LoopSize = ApproximateLoopSize(L, NumCalls);
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DEBUG(dbgs() << " Loop Size = " << LoopSize << "\n");
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if (NumCalls != 0) {
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DEBUG(dbgs() << " Not unrolling loop with function calls.\n");
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return false;
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// Even for a loop that contains calls, it can still be profitable to
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// unroll if the loop is really, REALLY small.
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DEBUG(dbgs() <<" Using lower threshold for loop with function calls.\n");
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CurrentThreshold = OptSizeUnrollThreshold;
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}
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uint64_t Size = (uint64_t)LoopSize*Count;
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if (TripCount != 1 && Size > CurrentThreshold) {
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51
test/Transforms/LoopUnroll/call.ll
Normal file
51
test/Transforms/LoopUnroll/call.ll
Normal file
@ -0,0 +1,51 @@
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; RUN: opt < %s -S -loop-unroll | FileCheck %s
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@id = internal global i32 0
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@val = internal global [4 x i32] zeroinitializer, align 16
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; CHECK: @test
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define i32 @test(i32 %k) nounwind ssp {
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; CHECK-NOT: call i32 @test(i32 %t.06)
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; CHECK: call i32 @test(i32 0)
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; CHECK-NOT: call i32 @test(i32 %t.06)
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; CHECK: call i32 @test(i32 1)
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; CHECK-NOT: call i32 @test(i32 %t.06)
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; CHECK: call i32 @test(i32 2)
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; CHECK-NOT: call i32 @test(i32 %t.06)
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; CHECK: call i32 @test(i32 3)
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; CHECK-NOT: call i32 @test(i32 %t.06)
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bb.nph:
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%0 = load i32* @id, align 4
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%1 = add nsw i32 %0, 1
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store i32 %1, i32* @id, align 4
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%2 = sext i32 %k to i64
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%3 = getelementptr inbounds [4 x i32]* @val, i64 0, i64 %2
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store i32 %1, i32* %3, align 4
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br label %bb
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bb: ; preds = %bb2, %bb.nph
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%indvar = phi i64 [ 0, %bb.nph ], [ %indvar.next, %bb2 ]
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%scevgep = getelementptr [4 x i32]* @val, i64 0, i64 %indvar
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%4 = load i32* %scevgep, align 4
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%5 = icmp eq i32 %4, 0
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br i1 %5, label %bb1, label %bb2
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bb1: ; preds = %bb
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%t.06 = trunc i64 %indvar to i32
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%6 = tail call i32 @test(i32 %t.06) nounwind
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br label %bb2
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bb2: ; preds = %bb1, %bb
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%indvar.next = add i64 %indvar, 1
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%exitcond = icmp eq i64 %indvar.next, 4
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br i1 %exitcond, label %bb4, label %bb
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bb4: ; preds = %bb2
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%.pre = load i32* @id, align 4
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%7 = add nsw i32 %.pre, -1
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store i32 %7, i32* @id, align 4
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store i32 0, i32* %3, align 4
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ret i32 undef
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; CHECK: }
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}
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