b9808e5660
Loop unrolling tends to produce chains of `%x1 = add %x0, 1; %x2 = add %x1, 1; ...` with one add per unrolled iteration. This patch simplifies these adds to `%xN = add %x0, N` directly during unrolling, rather than waiting for InstCombine to do so. The motivation for this is that having a single add (rather than an add chain) on the induction variable makes it a simple recurrence, which we specially recognize in a number of places. This allows InstCombine to directly perform folds with that knowledge, instead of first folding the add chains, and then doing other folds in another InstCombine iteration. Due to the reduced number of InstCombine iterations, this also results in a small compile-time improvement. Differential Revision: https://reviews.llvm.org/D153540
208 lines
5.8 KiB
LLVM
208 lines
5.8 KiB
LLVM
; RUN: opt < %s -S -passes=loop-unroll -unroll-count=4 | FileCheck -check-prefix=CHECK_COUNT4 %s
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; RUN: opt < %s -S -passes=loop-unroll | FileCheck -check-prefix=CHECK_NOCOUNT %s
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; RUN: opt < %s -S -passes='require<profile-summary>,function(loop-unroll)' -pgso | FileCheck -check-prefix=PGSO %s
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; RUN: opt < %s -S -passes='require<profile-summary>,function(loop-unroll)' -pgso=false | FileCheck -check-prefix=NPGSO %s
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;///////////////////// TEST 1 //////////////////////////////
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; This test shows that the loop is unrolled according to the specified
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; unroll factor.
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define void @Test1() nounwind {
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entry:
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br label %loop
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loop:
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%iv = phi i32 [ 0, %entry ], [ %inc, %loop ]
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%inc = add i32 %iv, 1
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%exitcnd = icmp uge i32 %inc, 1024
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br i1 %exitcnd, label %exit, label %loop
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exit:
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ret void
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}
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; CHECK_COUNT4-LABEL: @Test1
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; CHECK_COUNT4: phi
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; CHECK_COUNT4-NEXT: add{{.*}}, 4
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; CHECK_COUNT4-NEXT: icmp
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;///////////////////// TEST 2 //////////////////////////////
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; This test shows that with optnone attribute, the loop is not unrolled
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; even if an unroll factor was specified.
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define void @Test2() nounwind optnone noinline {
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entry:
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br label %loop
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loop:
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%iv = phi i32 [ 0, %entry ], [ %inc, %loop ]
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%inc = add i32 %iv, 1
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%exitcnd = icmp uge i32 %inc, 1024
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br i1 %exitcnd, label %exit, label %loop
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exit:
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ret void
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}
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; CHECK_COUNT4-LABEL: @Test2
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; CHECK_COUNT4: phi
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; CHECK_COUNT4-NEXT: add
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; CHECK_COUNT4-NEXT: icmp
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;///////////////////// TEST 3 //////////////////////////////
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; This test shows that this loop is fully unrolled by default.
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@tab = common global [24 x i32] zeroinitializer, align 4
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define i32 @Test3() {
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entry:
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br label %for.body
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for.body: ; preds = %for.body, %entry
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%i.05 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
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%arrayidx = getelementptr inbounds [24 x i32], ptr @tab, i32 0, i32 %i.05
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store i32 %i.05, ptr %arrayidx, align 4
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%inc = add nuw nsw i32 %i.05, 1
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%exitcond = icmp eq i32 %inc, 24
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br i1 %exitcond, label %for.end, label %for.body
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for.end: ; preds = %for.body
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ret i32 42
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}
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; CHECK_NOCOUNT-LABEL: @Test3
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; CHECK_NOCOUNT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: store
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; CHECK_NOCOUNT-NEXT: ret
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;///////////////////// TEST 4 //////////////////////////////
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; This test shows that with optsize attribute, this loop is not unrolled.
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define i32 @Test4() optsize {
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entry:
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br label %for.body
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for.body: ; preds = %for.body, %entry
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%i.05 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
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%arrayidx = getelementptr inbounds [24 x i32], ptr @tab, i32 0, i32 %i.05
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store i32 %i.05, ptr %arrayidx, align 4
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%inc = add nuw nsw i32 %i.05, 1
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%exitcond = icmp eq i32 %inc, 24
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br i1 %exitcond, label %for.end, label %for.body
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for.end: ; preds = %for.body
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ret i32 42
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}
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; CHECK_NOCOUNT-LABEL: @Test4
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; CHECK_NOCOUNT: phi
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; CHECK_NOCOUNT: icmp
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;///////////////////// TEST 5 //////////////////////////////
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; This test shows that with PGO, this loop is cold and not unrolled.
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define i32 @Test5() !prof !14 {
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entry:
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br label %for.body
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for.body: ; preds = %for.body, %entry
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%i.05 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
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%arrayidx = getelementptr inbounds [24 x i32], ptr @tab, i32 0, i32 %i.05
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store i32 %i.05, ptr %arrayidx, align 4
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%inc = add nuw nsw i32 %i.05, 1
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%exitcond = icmp eq i32 %inc, 24
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br i1 %exitcond, label %for.end, label %for.body
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for.end: ; preds = %for.body
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ret i32 42
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}
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; PGSO-LABEL: @Test5
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; PGSO: phi
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; PGSO: icmp
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; NPGSO-LABEL: @Test5
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; NPGSO-NOT: phi
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; NPGSO-NOT: icmp
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;///////////////////// TEST 6 //////////////////////////////
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; This test tests that unroll hints take precedence over PGSO and that this loop
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; gets unrolled even though it's cold.
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define i32 @Test6() !prof !14 {
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entry:
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br label %for.body
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for.body: ; preds = %for.body, %entry
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%i.05 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
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%arrayidx = getelementptr inbounds [24 x i32], ptr @tab, i32 0, i32 %i.05
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store i32 %i.05, ptr %arrayidx, align 4
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%inc = add nuw nsw i32 %i.05, 1
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%exitcond = icmp eq i32 %inc, 24
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br i1 %exitcond, label %for.end, label %for.body, !llvm.loop !15
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for.end: ; preds = %for.body
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ret i32 42
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}
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; PGSO-LABEL: @Test6
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; PGSO: store
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; PGSO: store
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; PGSO: store
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; PGSO: store
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; NPGSO-LABEL: @Test6
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; NPGSO: store
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; NPGSO: store
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; NPGSO: store
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; NPGSO: store
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!llvm.module.flags = !{!0}
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!0 = !{i32 1, !"ProfileSummary", !1}
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!1 = !{!2, !3, !4, !5, !6, !7, !8, !9}
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!2 = !{!"ProfileFormat", !"InstrProf"}
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!3 = !{!"TotalCount", i64 10000}
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!4 = !{!"MaxCount", i64 10}
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!5 = !{!"MaxInternalCount", i64 1}
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!6 = !{!"MaxFunctionCount", i64 1000}
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!7 = !{!"NumCounts", i64 3}
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!8 = !{!"NumFunctions", i64 3}
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!9 = !{!"DetailedSummary", !10}
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!10 = !{!11, !12, !13}
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!11 = !{i32 10000, i64 100, i32 1}
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!12 = !{i32 999000, i64 100, i32 1}
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!13 = !{i32 999999, i64 1, i32 2}
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!14 = !{!"function_entry_count", i64 0}
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!15 = !{!15, !16}
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!16 = !{!"llvm.loop.unroll.count", i32 4}
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