2016-08-04 02:17:35 +08:00
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; RUN: llc -verify-machineinstrs < %s | FileCheck %s
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[PowerPC] Fix LoopPreIncPrep not to depend on SCEV constant simplifications
Under most circumstances, if SCEV can simplify X-Y to a constant, then it can
also simplify Y-X to a constant. However, there is no guarantee that this is
always true, and concensus is not to consider that a correctness bug in SCEV
(although it is undesirable).
PPCLoopPreIncPrep gathers pointers used to access memory (via loads, stores and
prefetches) into buckets, where in each bucket the relative pointer offsets are
constant. We used to keep each bucket as a multimap, where SCEV's subtraction
operation was used to define the ordering predicate. Instead, use a fixed SCEV
base expression for each bucket, record the constant offsets from that base
expression, and adjust it later, if desirable, once all pointers have been
collected.
Doing it this way should be more compile-time efficient than the previous
scheme (in addition to making the implementation less sensitive to SCEV
simplification quirks).
Fixes PR25170.
llvm-svn: 252417
2015-11-08 16:04:40 +08:00
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target datalayout = "e-p:64:64-i64:64-n32:64"
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target triple = "powerpc64le-linux"
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%struct.BSS1.0.9.28.39.43.46.47.54.56.57.64.65.69.71.144 = type <{ [220 x i8] }>
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@.BSS1 = external unnamed_addr global %struct.BSS1.0.9.28.39.43.46.47.54.56.57.64.65.69.71.144, align 32
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; Function Attrs: noinline nounwind
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define void @ety2_() #0 {
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; This test case used to crash because the preinc prep pass would assume that
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; if X-Y could be simplified to a constant, than so could Y-X. While not
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; desirable, we cannot actually make this guarantee.
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; CHECK-LABEL: @ety2_
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L.entry:
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%0 = load i32, i32* undef, align 4
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%1 = sext i32 %0 to i64
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%2 = shl nsw i64 %1, 3
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%3 = add nsw i64 %2, 8
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br label %L.LB1_425
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L.LB1_425: ; preds = %L.LB1_427, %L.entry
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%4 = phi i64 [ %21, %L.LB1_427 ], [ undef, %L.entry ]
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br i1 undef, label %L.LB1_427, label %L.LB1_816
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L.LB1_816: ; preds = %L.LB1_425
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switch i32 undef, label %L.LB1_432 [
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i32 30, label %L.LB1_805
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i32 10, label %L.LB1_451
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i32 20, label %L.LB1_451
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]
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L.LB1_451: ; preds = %L.LB1_816, %L.LB1_816
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unreachable
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L.LB1_432: ; preds = %L.LB1_816
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%.in.31 = lshr i64 %4, 32
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%5 = trunc i64 %.in.31 to i32
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br i1 undef, label %L.LB1_769, label %L.LB1_455
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L.LB1_455: ; preds = %L.LB1_432
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unreachable
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L.LB1_769: ; preds = %L.LB1_432
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%6 = sext i32 %5 to i64
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%7 = add nsw i64 %6, 2
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%8 = add nsw i64 %6, -1
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%9 = mul i64 %8, %1
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%10 = add i64 %9, %7
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%11 = shl i64 %10, 3
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%12 = getelementptr i8, i8* undef, i64 %11
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%13 = mul nsw i64 %6, %1
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%14 = add i64 %7, %13
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%15 = shl i64 %14, 3
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%16 = getelementptr i8, i8* undef, i64 %15
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br i1 undef, label %L.LB1_662, label %L.LB1_662.prol
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L.LB1_662.prol: ; preds = %L.LB1_662.prol, %L.LB1_769
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%indvars.iv.next20.prol = add nuw nsw i64 undef, 1
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br i1 undef, label %L.LB1_662, label %L.LB1_662.prol
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L.LB1_662: ; preds = %L.LB1_437.2, %L.LB1_662.prol, %L.LB1_769
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%indvars.iv19 = phi i64 [ %indvars.iv.next20.3, %L.LB1_437.2 ], [ 0, %L.LB1_769 ], [ %indvars.iv.next20.prol, %L.LB1_662.prol ]
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%indvars.iv.next20 = add nuw nsw i64 %indvars.iv19, 1
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%17 = mul i64 %indvars.iv.next20, %3
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%18 = getelementptr i8, i8* %16, i64 %17
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%19 = bitcast i8* %18 to double*
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store double 0.000000e+00, double* %19, align 8
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%indvars.iv.next20.1 = add nsw i64 %indvars.iv19, 2
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%20 = mul i64 %indvars.iv.next20.1, %3
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br i1 undef, label %L.LB1_437.2, label %L.LB1_824.2
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L.LB1_427: ; preds = %L.LB1_425
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%21 = load i64, i64* bitcast (i8* getelementptr inbounds (%struct.BSS1.0.9.28.39.43.46.47.54.56.57.64.65.69.71.144, %struct.BSS1.0.9.28.39.43.46.47.54.56.57.64.65.69.71.144* @.BSS1, i64 0, i32 0, i64 8) to i64*), align 8
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br label %L.LB1_425
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L.LB1_805: ; preds = %L.LB1_816
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ret void
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L.LB1_824.2: ; preds = %L.LB1_662
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%22 = getelementptr i8, i8* %12, i64 %20
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%23 = bitcast i8* %22 to double*
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store double 0.000000e+00, double* %23, align 8
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br label %L.LB1_437.2
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L.LB1_437.2: ; preds = %L.LB1_824.2, %L.LB1_662
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%indvars.iv.next20.3 = add nsw i64 %indvars.iv19, 4
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br label %L.LB1_662
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}
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attributes #0 = { noinline nounwind }
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