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clang-p2996/llvm/test/Analysis/ScalarEvolution/incorrect-exit-count.ll
Nikita Popov 3cd4571405 [SCEV] Make use of non-null pointers for range calculation 
We know that certain pointers (e.g. non-extern-weak globals or
allocas in default address space) are not null, in which case the
lowest address they can be allocated at is their alignment.

This allows us to calculate better exit counts for loops that have
an additional null check in the guarding condition
(see alloca_icmp_null_exit_count).

Differential Revision: https://reviews.llvm.org/D153624
2023-06-29 09:09:17 +02:00

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; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py
; RUN: opt -passes='print<scalar-evolution>' < %s -disable-output 2>&1 | FileCheck %s
@b = dso_local global i32 5, align 4
@__const.f.g = private unnamed_addr constant [1 x [4 x i16]] [[4 x i16] [i16 1, i16 0, i16 0, i16 0]], align 2
@a = common dso_local global i32 0, align 4
@c = common dso_local global i32 0, align 4
@d = common dso_local global i32 0, align 4
@e = common dso_local global i32 0, align 4
; When inner.loop is taken as an exiting block of outer.loop, we cannot use the
; addrec of %storemerge1921.3, which is {3, +, -1}<inner.loop>, to calculate the
; exit count because it doesn't belong to outer.loop.
define dso_local i32 @f() {
; CHECK-LABEL: 'f'
; CHECK-NEXT: Classifying expressions for: @f
; CHECK-NEXT: %storemerge23 = phi i32 [ 3, %entry ], [ %dec16, %for.inc13.3 ]
; CHECK-NEXT: --> {3,+,-1}<nsw><%outer.loop> U: [1,4) S: [1,4) Exits: <<Unknown>> LoopDispositions: { %outer.loop: Computable, %for.cond6: Invariant, %inner.loop: Invariant }
; CHECK-NEXT: %storemerge1921 = phi i32 [ 3, %outer.loop ], [ %dec, %for.end ]
; CHECK-NEXT: --> {3,+,-1}<nsw><%for.cond6> U: [3,4) S: [3,4) Exits: <<Unknown>> LoopDispositions: { %for.cond6: Computable, %outer.loop: Variant }
; CHECK-NEXT: %idxprom20 = zext i32 %storemerge1921 to i64
; CHECK-NEXT: --> (zext i32 {3,+,-1}<nsw><%for.cond6> to i64) U: [3,4) S: [3,4) Exits: <<Unknown>> LoopDispositions: { %for.cond6: Computable, %outer.loop: Variant }
; CHECK-NEXT: %arrayidx7 = getelementptr inbounds [1 x [4 x i16]], ptr @__const.f.g, i64 0, i64 0, i64 %idxprom20
; CHECK-NEXT: --> ((2 * (zext i32 {3,+,-1}<nsw><%for.cond6> to i64))<nuw><nsw> + @__const.f.g)<nuw> U: [8,-3) S: [-9223372036854775808,9223372036854775807) Exits: <<Unknown>> LoopDispositions: { %for.cond6: Computable, %outer.loop: Variant }
; CHECK-NEXT: %i = load i16, ptr %arrayidx7, align 2
; CHECK-NEXT: --> %i U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %for.cond6: Variant, %outer.loop: Variant }
; CHECK-NEXT: %storemerge1822.lcssa.ph = phi i32 [ 0, %for.cond6 ]
; CHECK-NEXT: --> 0 U: [0,1) S: [0,1)
; CHECK-NEXT: %storemerge1822.lcssa.ph32 = phi i32 [ 3, %inner.loop ]
; CHECK-NEXT: --> 3 U: [3,4) S: [3,4)
; CHECK-NEXT: %storemerge1822.lcssa = phi i32 [ %storemerge1822.lcssa.ph, %if.end.loopexit ], [ %storemerge1822.lcssa.ph32, %if.end.loopexit31 ]
; CHECK-NEXT: --> %storemerge1822.lcssa U: [0,4) S: [0,4)
; CHECK-NEXT: %i1 = load i32, ptr @e, align 4
; CHECK-NEXT: --> %i1 U: full-set S: full-set
; CHECK-NEXT: %i2 = load volatile i32, ptr @b, align 4
; CHECK-NEXT: --> %i2 U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %for.cond6: Variant, %outer.loop: Variant }
; CHECK-NEXT: %dec = add nsw i32 %storemerge1921, -1
; CHECK-NEXT: --> {2,+,-1}<nsw><%for.cond6> U: [2,3) S: [2,3) Exits: <<Unknown>> LoopDispositions: { %for.cond6: Computable, %outer.loop: Variant }
; CHECK-NEXT: %inc.lcssa.lcssa = phi i32 [ 4, %for.inc13.3 ]
; CHECK-NEXT: --> 4 U: [4,5) S: [4,5)
; CHECK-NEXT: %retval.0 = phi i32 [ %i1, %if.end ], [ 0, %cleanup.loopexit ]
; CHECK-NEXT: --> %retval.0 U: full-set S: full-set
; CHECK-NEXT: %storemerge1921.3 = phi i32 [ 3, %for.end ], [ %dec.3, %for.end.3 ]
; CHECK-NEXT: --> {3,+,-1}<nsw><%inner.loop> U: [3,4) S: [3,4) Exits: <<Unknown>> LoopDispositions: { %inner.loop: Computable, %outer.loop: Variant }
; CHECK-NEXT: %idxprom20.3 = zext i32 %storemerge1921.3 to i64
; CHECK-NEXT: --> (zext i32 {3,+,-1}<nsw><%inner.loop> to i64) U: [3,4) S: [3,4) Exits: <<Unknown>> LoopDispositions: { %inner.loop: Computable, %outer.loop: Variant }
; CHECK-NEXT: %arrayidx7.3 = getelementptr inbounds [1 x [4 x i16]], ptr @__const.f.g, i64 0, i64 0, i64 %idxprom20.3
; CHECK-NEXT: --> ((2 * (zext i32 {3,+,-1}<nsw><%inner.loop> to i64))<nuw><nsw> + @__const.f.g)<nuw> U: [8,-3) S: [-9223372036854775808,9223372036854775807) Exits: <<Unknown>> LoopDispositions: { %inner.loop: Computable, %outer.loop: Variant }
; CHECK-NEXT: %i7 = load i16, ptr %arrayidx7.3, align 2
; CHECK-NEXT: --> %i7 U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %inner.loop: Variant, %outer.loop: Variant }
; CHECK-NEXT: %i8 = load volatile i32, ptr @b, align 4
; CHECK-NEXT: --> %i8 U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %inner.loop: Variant, %outer.loop: Variant }
; CHECK-NEXT: %dec.3 = add nsw i32 %storemerge1921.3, -1
; CHECK-NEXT: --> {2,+,-1}<nsw><%inner.loop> U: [2,3) S: [2,3) Exits: <<Unknown>> LoopDispositions: { %inner.loop: Computable, %outer.loop: Variant }
; CHECK-NEXT: %storemerge1921.lcssa25.3 = phi i32 [ %storemerge1921.3, %for.end.3 ]
; CHECK-NEXT: --> {3,+,-1}<nsw><%inner.loop> U: [3,4) S: [3,4) Exits: <<Unknown>> LoopDispositions: { %outer.loop: Variant, %for.cond6: Variant, %inner.loop: Computable }
; CHECK-NEXT: %dec16 = add nsw i32 %storemerge23, -1
; CHECK-NEXT: --> {2,+,-1}<nsw><%outer.loop> U: [0,3) S: [0,3) Exits: <<Unknown>> LoopDispositions: { %outer.loop: Computable, %for.cond6: Invariant, %inner.loop: Invariant }
; CHECK-NEXT: Determining loop execution counts for: @f
; CHECK-NEXT: Loop %for.cond6: <multiple exits> Unpredictable backedge-taken count.
; CHECK-NEXT: exit count for for.cond6: 0
; CHECK-NEXT: exit count for for.end: ***COULDNOTCOMPUTE***
; CHECK-NEXT: Loop %for.cond6: constant max backedge-taken count is 0
; CHECK-NEXT: Loop %for.cond6: symbolic max backedge-taken count is 0
; CHECK-NEXT: symbolic max exit count for for.cond6: 0
; CHECK-NEXT: symbolic max exit count for for.end: ***COULDNOTCOMPUTE***
; CHECK-NEXT: Loop %for.cond6: Unpredictable predicated backedge-taken count.
; CHECK-NEXT: Loop %inner.loop: <multiple exits> Unpredictable backedge-taken count.
; CHECK-NEXT: exit count for inner.loop: 0
; CHECK-NEXT: exit count for for.end.3: ***COULDNOTCOMPUTE***
; CHECK-NEXT: Loop %inner.loop: constant max backedge-taken count is 0
; CHECK-NEXT: Loop %inner.loop: symbolic max backedge-taken count is 0
; CHECK-NEXT: symbolic max exit count for inner.loop: 0
; CHECK-NEXT: symbolic max exit count for for.end.3: ***COULDNOTCOMPUTE***
; CHECK-NEXT: Loop %inner.loop: Unpredictable predicated backedge-taken count.
; CHECK-NEXT: Loop %outer.loop: <multiple exits> Unpredictable backedge-taken count.
; CHECK-NEXT: exit count for for.cond6: ***COULDNOTCOMPUTE***
; CHECK-NEXT: exit count for inner.loop: ***COULDNOTCOMPUTE***
; CHECK-NEXT: exit count for for.inc13.3: 2
; CHECK-NEXT: Loop %outer.loop: constant max backedge-taken count is 2
; CHECK-NEXT: Loop %outer.loop: symbolic max backedge-taken count is 2
; CHECK-NEXT: symbolic max exit count for for.cond6: ***COULDNOTCOMPUTE***
; CHECK-NEXT: symbolic max exit count for inner.loop: ***COULDNOTCOMPUTE***
; CHECK-NEXT: symbolic max exit count for for.inc13.3: 2
; CHECK-NEXT: Loop %outer.loop: Unpredictable predicated backedge-taken count.
;
entry:
store i32 3, ptr @a, align 4
br label %outer.loop
outer.loop: ; preds = %for.inc13.3, %entry
%storemerge23 = phi i32 [ 3, %entry ], [ %dec16, %for.inc13.3 ]
br label %for.cond6
for.cond6: ; preds = %for.end, %outer.loop
%storemerge1921 = phi i32 [ 3, %outer.loop ], [ %dec, %for.end ]
%idxprom20 = zext i32 %storemerge1921 to i64
%arrayidx7 = getelementptr inbounds [1 x [4 x i16]], ptr @__const.f.g, i64 0, i64 0, i64 %idxprom20
%i = load i16, ptr %arrayidx7, align 2
%tobool8 = icmp eq i16 %i, 0
br i1 %tobool8, label %if.end.loopexit, label %for.end
if.end.loopexit: ; preds = %for.cond6
%storemerge1822.lcssa.ph = phi i32 [ 0, %for.cond6 ]
br label %if.end
if.end.loopexit31: ; preds = %inner.loop
%storemerge1822.lcssa.ph32 = phi i32 [ 3, %inner.loop ]
br label %if.end
if.end: ; preds = %if.end.loopexit31, %if.end.loopexit
%storemerge1822.lcssa = phi i32 [ %storemerge1822.lcssa.ph, %if.end.loopexit ], [ %storemerge1822.lcssa.ph32, %if.end.loopexit31 ]
store i32 %storemerge1822.lcssa, ptr @c, align 4
store i32 2, ptr @d, align 4
%i1 = load i32, ptr @e, align 4
br label %cleanup
for.end: ; preds = %for.cond6
%i2 = load volatile i32, ptr @b, align 4
%tobool9 = icmp eq i32 %i2, 0
%dec = add nsw i32 %storemerge1921, -1
br i1 %tobool9, label %for.cond6, label %inner.loop
cleanup.loopexit: ; preds = %for.inc13.3
%inc.lcssa.lcssa = phi i32 [ 4, %for.inc13.3 ]
store i32 %inc.lcssa.lcssa, ptr @c, align 4
br label %cleanup
cleanup: ; preds = %cleanup.loopexit, %if.end
%retval.0 = phi i32 [ %i1, %if.end ], [ 0, %cleanup.loopexit ]
ret i32 %retval.0
inner.loop: ; preds = %for.end.3, %for.end
%storemerge1921.3 = phi i32 [ 3, %for.end ], [ %dec.3, %for.end.3 ]
%idxprom20.3 = zext i32 %storemerge1921.3 to i64
%arrayidx7.3 = getelementptr inbounds [1 x [4 x i16]], ptr @__const.f.g, i64 0, i64 0, i64 %idxprom20.3
%i7 = load i16, ptr %arrayidx7.3, align 2
%tobool8.3 = icmp eq i16 %i7, 0
br i1 %tobool8.3, label %if.end.loopexit31, label %for.end.3
for.end.3: ; preds = %inner.loop
%i8 = load volatile i32, ptr @b, align 4
%tobool9.3 = icmp eq i32 %i8, 0
%dec.3 = add nsw i32 %storemerge1921.3, -1
br i1 %tobool9.3, label %inner.loop, label %for.inc13.3
for.inc13.3: ; preds = %for.end.3
%storemerge1921.lcssa25.3 = phi i32 [ %storemerge1921.3, %for.end.3 ]
store i32 %storemerge1921.lcssa25.3, ptr @d, align 4
%dec16 = add nsw i32 %storemerge23, -1
store i32 %dec16, ptr @a, align 4
%tobool = icmp eq i32 %dec16, 0
br i1 %tobool, label %cleanup.loopexit, label %outer.loop
}
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