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clang-p2996/llvm/test/Analysis/ScalarEvolution/ne-overflow.ll
Philip Reames ea12c2cb9c [SCEV] Move mustprogress based no-self-wrap logic so it applies to all exit conditions 
This change moves logic which we'd added specifically for less than tests so that it applies to equalities and greater than tests as well. The basic idea is that if we can show an IV cycles infinitely through the same series on self-wrap, and that the exit condition must be taken to prevent UB, we can conclude that it must be taken before self-wrap and thus infer said flag.

The motivation here is simple loops with unsigned induction variables w/non-one steps and inequality tests. A toy example would be:
for (unsigned i = 0; i != N; i += 2) { body; }

If body contains no side effects, and this is a mustprogress function, we can assume that this must be a finite loop and thus that the exit count is N/2.

Differential Revision: https://reviews.llvm.org/D103991
2021-11-18 10:07:44 -08:00

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; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py
; RUN: opt %s -passes='print<scalar-evolution>' -scalar-evolution-classify-expressions=0 -disable-output 2>&1 | FileCheck %s
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
; A collection of tests focused on exercising logic to prove no-unsigned wrap
; from mustprogress semantics of loops.
define void @test(i32 %N) mustprogress {
; CHECK-LABEL: 'test'
; CHECK-NEXT: Determining loop execution counts for: @test
; CHECK-NEXT: Loop %for.body: backedge-taken count is ((-2 + %N) /u 2)
; CHECK-NEXT: Loop %for.body: max backedge-taken count is 2147483647
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is ((-2 + %N) /u 2)
; CHECK-NEXT: Predicates:
; CHECK: Loop %for.body: Trip multiple is 1
;
entry:
br label %for.body
for.body:
%iv = phi i32 [ %iv.next, %for.body ], [ 0, %entry ]
%iv.next = add i32 %iv, 2
%cmp = icmp ne i32 %iv.next, %N
br i1 %cmp, label %for.body, label %for.cond.cleanup
for.cond.cleanup:
ret void
}
define void @test_preinc(i32 %N) mustprogress {
; CHECK-LABEL: 'test_preinc'
; CHECK-NEXT: Determining loop execution counts for: @test_preinc
; CHECK-NEXT: Loop %for.body: backedge-taken count is (%N /u 2)
; CHECK-NEXT: Loop %for.body: max backedge-taken count is 2147483647
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is (%N /u 2)
; CHECK-NEXT: Predicates:
; CHECK: Loop %for.body: Trip multiple is 1
;
entry:
br label %for.body
for.body:
%iv = phi i32 [ %iv.next, %for.body ], [ 0, %entry ]
%iv.next = add i32 %iv, 2
%cmp = icmp ne i32 %iv, %N
br i1 %cmp, label %for.body, label %for.cond.cleanup
for.cond.cleanup:
ret void
}
@G = external global i32
define void @test_well_defined_infinite_st(i32 %N) mustprogress {
; CHECK-LABEL: 'test_well_defined_infinite_st'
; CHECK-NEXT: Determining loop execution counts for: @test_well_defined_infinite_st
; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable predicated backedge-taken count.
;
entry:
br label %for.body
for.body:
%iv = phi i32 [ %iv.next, %for.body ], [ 0, %entry ]
%iv.next = add i32 %iv, 2
store volatile i32 0, i32* @G
%cmp = icmp ne i32 %iv.next, %N
br i1 %cmp, label %for.body, label %for.cond.cleanup
for.cond.cleanup:
ret void
}
define void @test_well_defined_infinite_ld(i32 %N) mustprogress {
; CHECK-LABEL: 'test_well_defined_infinite_ld'
; CHECK-NEXT: Determining loop execution counts for: @test_well_defined_infinite_ld
; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable predicated backedge-taken count.
;
entry:
br label %for.body
for.body:
%iv = phi i32 [ %iv.next, %for.body ], [ 0, %entry ]
%iv.next = add i32 %iv, 2
%val = load volatile i32, i32* @G
%cmp = icmp ne i32 %iv.next, %N
br i1 %cmp, label %for.body, label %for.cond.cleanup
for.cond.cleanup:
ret void
}
define void @test_no_mustprogress(i32 %N) {
; CHECK-LABEL: 'test_no_mustprogress'
; CHECK-NEXT: Determining loop execution counts for: @test_no_mustprogress
; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable predicated backedge-taken count.
;
entry:
br label %for.body
for.body:
%iv = phi i32 [ %iv.next, %for.body ], [ 0, %entry ]
%iv.next = add i32 %iv, 2
%cmp = icmp ne i32 %iv.next, %N
br i1 %cmp, label %for.body, label %for.cond.cleanup
for.cond.cleanup:
ret void
}
define void @test_1024(i32 %N) mustprogress {
; CHECK-LABEL: 'test_1024'
; CHECK-NEXT: Determining loop execution counts for: @test_1024
; CHECK-NEXT: Loop %for.body: backedge-taken count is ((-1024 + %N) /u 1024)
; CHECK-NEXT: Loop %for.body: max backedge-taken count is 4194303
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is ((-1024 + %N) /u 1024)
; CHECK-NEXT: Predicates:
; CHECK: Loop %for.body: Trip multiple is 1
;
entry:
br label %for.body
for.body:
%iv = phi i32 [ %iv.next, %for.body ], [ 0, %entry ]
%iv.next = add i32 %iv, 1024
%cmp = icmp ne i32 %iv.next, %N
br i1 %cmp, label %for.body, label %for.cond.cleanup
for.cond.cleanup:
ret void
}
define void @test_uneven_divide(i32 %N) mustprogress {
; CHECK-LABEL: 'test_uneven_divide'
; CHECK-NEXT: Determining loop execution counts for: @test_uneven_divide
; CHECK-NEXT: Loop %for.body: backedge-taken count is (-1 + (-1431655765 * %N))
; CHECK-NEXT: Loop %for.body: max backedge-taken count is -1
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is (-1 + (-1431655765 * %N))
; CHECK-NEXT: Predicates:
; CHECK: Loop %for.body: Trip multiple is 1
;
entry:
br label %for.body
for.body:
%iv = phi i32 [ %iv.next, %for.body ], [ 0, %entry ]
%iv.next = add i32 %iv, 3
%cmp = icmp ne i32 %iv.next, %N
br i1 %cmp, label %for.body, label %for.cond.cleanup
for.cond.cleanup:
ret void
}
define void @test_non_invariant_rhs() mustprogress {
; CHECK-LABEL: 'test_non_invariant_rhs'
; CHECK-NEXT: Determining loop execution counts for: @test_non_invariant_rhs
; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable predicated backedge-taken count.
;
entry:
br label %for.body
for.body:
%iv = phi i32 [ %iv.next, %for.body ], [ 0, %entry ]
%iv.next = add i32 %iv, 2
%N = load i32, i32* @G
%cmp = icmp ne i32 %iv.next, %N
br i1 %cmp, label %for.body, label %for.cond.cleanup
for.cond.cleanup:
ret void
}
declare void @mayexit()
define void @test_abnormal_exit(i32 %N) mustprogress {
; CHECK-LABEL: 'test_abnormal_exit'
; CHECK-NEXT: Determining loop execution counts for: @test_abnormal_exit
; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable predicated backedge-taken count.
;
entry:
br label %for.body
for.body:
%iv = phi i32 [ %iv.next, %for.body ], [ 0, %entry ]
%iv.next = add i32 %iv, 2
call void @mayexit()
%cmp = icmp ne i32 %iv.next, %N
br i1 %cmp, label %for.body, label %for.cond.cleanup
for.cond.cleanup:
ret void
}
define void @test_other_exit(i32 %N) mustprogress {
; CHECK-LABEL: 'test_other_exit'
; CHECK-NEXT: Determining loop execution counts for: @test_other_exit
; CHECK-NEXT: Loop %for.body: <multiple exits> Unpredictable backedge-taken count.
; CHECK-NEXT: exit count for for.body: 9
; CHECK-NEXT: exit count for for.latch: ***COULDNOTCOMPUTE***
; CHECK-NEXT: Loop %for.body: max backedge-taken count is 9
; CHECK-NEXT: Loop %for.body: Unpredictable predicated backedge-taken count.
;
entry:
br label %for.body
for.body:
%iv = phi i32 [ %iv.next, %for.latch ], [ 0, %entry ]
%iv.next = add i32 %iv, 2
%cmp1 = icmp ne i32 %iv.next, 20
br i1 %cmp1, label %for.latch, label %for.cond.cleanup
for.latch:
%cmp2 = icmp ne i32 %iv.next, %N
br i1 %cmp2, label %for.body, label %for.cond.cleanup
for.cond.cleanup:
ret void
}
define void @test_zext(i64 %N) mustprogress {
; CHECK-LABEL: 'test_zext'
; CHECK-NEXT: Determining loop execution counts for: @test_zext
; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Predicated backedge-taken count is (%N /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: {0,+,2}<nuw><%for.body> Added Flags: <nusw>
;
entry:
br label %for.body
for.body:
%iv = phi i32 [ %iv.next, %for.body ], [ 0, %entry ]
%iv.next = add i32 %iv, 2
%zext = zext i32 %iv to i64
%cmp = icmp ne i64 %zext, %N
br i1 %cmp, label %for.body, label %for.cond.cleanup
for.cond.cleanup:
ret void
}
define void @test_sext(i64 %N) mustprogress {
; CHECK-LABEL: 'test_sext'
; CHECK-NEXT: Determining loop execution counts for: @test_sext
; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable predicated backedge-taken count.
;
entry:
br label %for.body
for.body:
%iv = phi i32 [ %iv.next, %for.body ], [ 0, %entry ]
%iv.next = add i32 %iv, 2
%sext = sext i32 %iv to i64
%cmp = icmp ne i64 %sext, %N
br i1 %cmp, label %for.body, label %for.cond.cleanup
for.cond.cleanup:
ret void
}
define void @test_zext_of_sext(i64 %N) mustprogress {
; CHECK-LABEL: 'test_zext_of_sext'
; CHECK-NEXT: Determining loop execution counts for: @test_zext_of_sext
; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable predicated backedge-taken count.
;
entry:
br label %for.body
for.body:
%iv = phi i32 [ %iv.next, %for.body ], [ 0, %entry ]
%iv.next = add i32 %iv, 2
%sext = sext i32 %iv to i48
%zext = zext i48 %sext to i64
%cmp = icmp ne i64 %zext, %N
br i1 %cmp, label %for.body, label %for.cond.cleanup
for.cond.cleanup:
ret void
}
define void @test_zext_offset(i64 %N) mustprogress {
; CHECK-LABEL: 'test_zext_offset'
; CHECK-NEXT: Determining loop execution counts for: @test_zext_offset
; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable predicated backedge-taken count.
;
entry:
br label %for.body
for.body:
%iv = phi i32 [ %iv.next, %for.body ], [ 0, %entry ]
%iv.next = add i32 %iv, 2
%zext = zext i32 %iv to i64
%offset = add i64 %zext, 21
%cmp = icmp ne i64 %offset, %N
br i1 %cmp, label %for.body, label %for.cond.cleanup
for.cond.cleanup:
ret void
}
define void @test_sext_offset(i64 %N) mustprogress {
; CHECK-LABEL: 'test_sext_offset'
; CHECK-NEXT: Determining loop execution counts for: @test_sext_offset
; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable max backedge-taken count.
; CHECK-NEXT: Loop %for.body: Unpredictable predicated backedge-taken count.
;
entry:
br label %for.body
for.body:
%iv = phi i32 [ %iv.next, %for.body ], [ 0, %entry ]
%iv.next = add i32 %iv, 2
%sext = sext i32 %iv to i64
%offset = add i64 %sext, 21
%cmp = icmp ne i64 %offset, %N
br i1 %cmp, label %for.body, label %for.cond.cleanup
for.cond.cleanup:
ret void
}
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