[llvm] [SCEV] Use loop guards to rule out IV overflow in LT/GT exit counts. (PR #228691)
Florian Hahn via llvm-commits
llvm-commits at lists.llvm.org
Sat Oct 3 07:11:41 PDT 2026
https://github.com/fhahn updated https://github.com/llvm/llvm-project/pull/228691
>From 3095279f259b04edbed5ce839773d5904c02b51c Mon Sep 17 00:00:00 2001
From: Florian Hahn <flo at fhahn.com>
Date: Wed, 30 Sep 2026 15:04:08 +0100
Subject: [PATCH 1/2] [SCEV] precommit tests
---
.../trip-count-lt-overflow-from-guard.ll | 403 ++++++++++++++++++
1 file changed, 403 insertions(+)
create mode 100644 llvm/test/Analysis/ScalarEvolution/trip-count-lt-overflow-from-guard.ll
diff --git a/llvm/test/Analysis/ScalarEvolution/trip-count-lt-overflow-from-guard.ll b/llvm/test/Analysis/ScalarEvolution/trip-count-lt-overflow-from-guard.ll
new file mode 100644
index 0000000000000..45dbb101020a2
--- /dev/null
+++ b/llvm/test/Analysis/ScalarEvolution/trip-count-lt-overflow-from-guard.ll
@@ -0,0 +1,403 @@
+; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 6
+; RUN: opt -disable-output -passes='print<scalar-evolution>' < %s 2>&1 | FileCheck %s
+
+declare void @use(i64)
+
+; 0 < n < SMAX, stride 2: IV cannot overflow.
+define void @slt_stride2_guard(i64 %n) {
+; CHECK-LABEL: 'slt_stride2_guard'
+; CHECK-NEXT: Classifying expressions for: @slt_stride2_guard
+; CHECK-NEXT: %g = and i1 %g1, %g2
+; CHECK-NEXT: --> (%g1 umin %g2) U: full-set S: full-set
+; CHECK-NEXT: %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+; CHECK-NEXT: --> {0,+,2}<%loop> U: [0,-1) S: [-9223372036854775808,9223372036854775807) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: %iv.next = add i64 %iv, 2
+; CHECK-NEXT: --> {2,+,2}<%loop> U: [0,-1) S: [-9223372036854775808,9223372036854775807) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: Determining loop execution counts for: @slt_stride2_guard
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
+;
+entry:
+ %g1 = icmp slt i64 %n, 9223372036854775807
+ %g2 = icmp sgt i64 %n, 0
+ %g = and i1 %g1, %g2
+ br i1 %g, label %loop, label %exit
+
+loop:
+ %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+ call void @use(i64 %iv)
+ %iv.next = add i64 %iv, 2
+ %c = icmp slt i64 %iv.next, %n
+ br i1 %c, label %loop, label %exit
+
+exit:
+ ret void
+}
+
+; Same as above, but with the range known from an attribute.
+define void @slt_stride2_range_attr(i64 range(i64 1, 9223372036854775807) %n) {
+; CHECK-LABEL: 'slt_stride2_range_attr'
+; CHECK-NEXT: Classifying expressions for: @slt_stride2_range_attr
+; CHECK-NEXT: %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+; CHECK-NEXT: --> {0,+,2}<nuw><nsw><%loop> U: [0,9223372036854775805) S: [0,9223372036854775805) Exits: (2 * ((-1 + %n)<nsw> /u 2))<nuw><nsw> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: %iv.next = add i64 %iv, 2
+; CHECK-NEXT: --> {2,+,2}<nuw><nsw><%loop> U: [2,9223372036854775807) S: [2,9223372036854775807) Exits: (2 + (2 * ((-1 + %n)<nsw> /u 2))<nuw><nsw>)<nuw><nsw> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: Determining loop execution counts for: @slt_stride2_range_attr
+; CHECK-NEXT: Loop %loop: backedge-taken count is ((-1 + %n)<nsw> /u 2)
+; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i64 4611686018427387902
+; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is ((-1 + %n)<nsw> /u 2)
+; CHECK-NEXT: Loop %loop: Trip multiple is 1
+;
+entry:
+ br label %loop
+
+loop:
+ %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+ call void @use(i64 %iv)
+ %iv.next = add i64 %iv, 2
+ %c = icmp slt i64 %iv.next, %n
+ br i1 %c, label %loop, label %exit
+
+exit:
+ ret void
+}
+
+; n < SMAX from a guard, with an additional early exit.
+define void @slt_stride2_guard_multi_exit(i64 %n, i64 %m) {
+; CHECK-LABEL: 'slt_stride2_guard_multi_exit'
+; CHECK-NEXT: Classifying expressions for: @slt_stride2_guard_multi_exit
+; CHECK-NEXT: %g = and i1 %g1, %g2
+; CHECK-NEXT: --> (%g1 umin %g2) U: full-set S: full-set
+; CHECK-NEXT: %iv = phi i64 [ 0, %entry ], [ %iv.next, %latch ]
+; CHECK-NEXT: --> {0,+,2}<%loop> U: [0,-1) S: [-9223372036854775808,9223372036854775807) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: %iv.next = add i64 %iv, 2
+; CHECK-NEXT: --> {2,+,2}<%loop> U: [0,-1) S: [-9223372036854775808,9223372036854775807) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: Determining loop execution counts for: @slt_stride2_guard_multi_exit
+; CHECK-NEXT: Loop %loop: <multiple exits> Unpredictable backedge-taken count.
+; CHECK-NEXT: exit count for loop: ***COULDNOTCOMPUTE***
+; CHECK-NEXT: predicated exit count for loop: (%m /u 2)
+; CHECK-NEXT: Predicates:
+; CHECK-NEXT: Equal predicate: (zext i1 (trunc i64 %m to i1) to i64) == 0
+; CHECK-EMPTY:
+; CHECK-NEXT: exit count for latch: ***COULDNOTCOMPUTE***
+; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
+; CHECK-NEXT: symbolic max exit count for loop: ***COULDNOTCOMPUTE***
+; CHECK-NEXT: predicated symbolic max exit count for loop: (%m /u 2)
+; CHECK-NEXT: Predicates:
+; CHECK-NEXT: Equal predicate: (zext i1 (trunc i64 %m to i1) to i64) == 0
+; CHECK-EMPTY:
+; CHECK-NEXT: symbolic max exit count for latch: ***COULDNOTCOMPUTE***
+; CHECK-NEXT: Loop %loop: Predicated constant max backedge-taken count is i64 9223372036854775807
+; CHECK-NEXT: Predicates:
+; CHECK-NEXT: Equal predicate: (zext i1 (trunc i64 %m to i1) to i64) == 0
+; CHECK-NEXT: Loop %loop: Predicated symbolic max backedge-taken count is (%m /u 2)
+; CHECK-NEXT: Predicates:
+; CHECK-NEXT: Equal predicate: (zext i1 (trunc i64 %m to i1) to i64) == 0
+;
+entry:
+ %g1 = icmp slt i64 %n, 9223372036854775807
+ %g2 = icmp sgt i64 %n, 0
+ %g = and i1 %g1, %g2
+ br i1 %g, label %loop, label %exit
+
+loop:
+ %iv = phi i64 [ 0, %entry ], [ %iv.next, %latch ]
+ %ec = icmp eq i64 %iv, %m
+ br i1 %ec, label %exit, label %latch
+
+latch:
+ call void @use(i64 %iv)
+ %iv.next = add i64 %iv, 2
+ %c = icmp slt i64 %iv.next, %n
+ br i1 %c, label %loop, label %exit
+
+exit:
+ ret void
+}
+
+; n <s SMAX - 1 (i.e. n <=s SMAX - 2), stride 3: IV cannot overflow.
+define void @slt_stride3_guard_smax_minus_1(i64 %n) {
+; CHECK-LABEL: 'slt_stride3_guard_smax_minus_1'
+; CHECK-NEXT: Classifying expressions for: @slt_stride3_guard_smax_minus_1
+; CHECK-NEXT: %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+; CHECK-NEXT: --> {0,+,3}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: %iv.next = add i64 %iv, 3
+; CHECK-NEXT: --> {3,+,3}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: Determining loop execution counts for: @slt_stride3_guard_smax_minus_1
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
+;
+entry:
+ %g = icmp slt i64 %n, 9223372036854775806
+ br i1 %g, label %loop, label %exit
+
+loop:
+ %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+ call void @use(i64 %iv)
+ %iv.next = add i64 %iv, 3
+ %c = icmp slt i64 %iv.next, %n
+ br i1 %c, label %loop, label %exit
+
+exit:
+ ret void
+}
+
+; n <s SMAX is insufficient for stride 3.
+define void @slt_stride3_guard_smax_insufficient(i64 %n) {
+; CHECK-LABEL: 'slt_stride3_guard_smax_insufficient'
+; CHECK-NEXT: Classifying expressions for: @slt_stride3_guard_smax_insufficient
+; CHECK-NEXT: %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+; CHECK-NEXT: --> {0,+,3}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: %iv.next = add i64 %iv, 3
+; CHECK-NEXT: --> {3,+,3}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: Determining loop execution counts for: @slt_stride3_guard_smax_insufficient
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
+;
+entry:
+ %g = icmp slt i64 %n, 9223372036854775807
+ br i1 %g, label %loop, label %exit
+
+loop:
+ %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+ call void @use(i64 %iv)
+ %iv.next = add i64 %iv, 3
+ %c = icmp slt i64 %iv.next, %n
+ br i1 %c, label %loop, label %exit
+
+exit:
+ ret void
+}
+
+define void @slt_stride2_guard_not_dominating(i64 %n, i1 %c.0) {
+; CHECK-LABEL: 'slt_stride2_guard_not_dominating'
+; CHECK-NEXT: Classifying expressions for: @slt_stride2_guard_not_dominating
+; CHECK-NEXT: %iv = phi i64 [ 0, %ph ], [ %iv.next, %loop ]
+; CHECK-NEXT: --> {0,+,2}<%loop> U: [0,-1) S: [-9223372036854775808,9223372036854775807) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: %iv.next = add i64 %iv, 2
+; CHECK-NEXT: --> {2,+,2}<%loop> U: [0,-1) S: [-9223372036854775808,9223372036854775807) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: Determining loop execution counts for: @slt_stride2_guard_not_dominating
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
+;
+entry:
+ br i1 %c.0, label %guard, label %ph
+
+guard:
+ %g = icmp slt i64 %n, 9223372036854775807
+ br i1 %g, label %ph, label %exit
+
+ph:
+ br label %loop
+
+loop:
+ %iv = phi i64 [ 0, %ph ], [ %iv.next, %loop ]
+ call void @use(i64 %iv)
+ %iv.next = add i64 %iv, 2
+ %c = icmp slt i64 %iv.next, %n
+ br i1 %c, label %loop, label %exit
+
+exit:
+ ret void
+}
+
+; n <u UMAX, stride 2: IV cannot overflow.
+define void @ult_stride2_guard(i64 %n) {
+; CHECK-LABEL: 'ult_stride2_guard'
+; CHECK-NEXT: Classifying expressions for: @ult_stride2_guard
+; CHECK-NEXT: %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+; CHECK-NEXT: --> {0,+,2}<%loop> U: [0,-1) S: [-9223372036854775808,9223372036854775807) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: %iv.next = add i64 %iv, 2
+; CHECK-NEXT: --> {2,+,2}<%loop> U: [0,-1) S: [-9223372036854775808,9223372036854775807) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: Determining loop execution counts for: @ult_stride2_guard
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
+;
+entry:
+ %g = icmp ult i64 %n, -1
+ br i1 %g, label %loop, label %exit
+
+loop:
+ %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+ call void @use(i64 %iv)
+ %iv.next = add i64 %iv, 2
+ %c = icmp ult i64 %iv.next, %n
+ br i1 %c, label %loop, label %exit
+
+exit:
+ ret void
+}
+
+; n <u UMAX is insufficient for stride 3.
+define void @ult_stride3_guard_insufficient(i64 %n) {
+; CHECK-LABEL: 'ult_stride3_guard_insufficient'
+; CHECK-NEXT: Classifying expressions for: @ult_stride3_guard_insufficient
+; CHECK-NEXT: %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+; CHECK-NEXT: --> {0,+,3}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: %iv.next = add i64 %iv, 3
+; CHECK-NEXT: --> {3,+,3}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: Determining loop execution counts for: @ult_stride3_guard_insufficient
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
+;
+entry:
+ %g = icmp ult i64 %n, -1
+ br i1 %g, label %loop, label %exit
+
+loop:
+ %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
+ call void @use(i64 %iv)
+ %iv.next = add i64 %iv, 3
+ %c = icmp ult i64 %iv.next, %n
+ br i1 %c, label %loop, label %exit
+
+exit:
+ ret void
+}
+
+; n >s SMIN, stride -2: IV cannot overflow.
+define void @sgt_stride2_guard(i64 %n, i64 %start) {
+; CHECK-LABEL: 'sgt_stride2_guard'
+; CHECK-NEXT: Classifying expressions for: @sgt_stride2_guard
+; CHECK-NEXT: %iv = phi i64 [ %start, %entry ], [ %iv.next, %loop ]
+; CHECK-NEXT: --> {%start,+,-2}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: %iv.next = add i64 %iv, -2
+; CHECK-NEXT: --> {(-2 + %start),+,-2}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: Determining loop execution counts for: @sgt_stride2_guard
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
+;
+entry:
+ %g = icmp sgt i64 %n, -9223372036854775808
+ br i1 %g, label %loop, label %exit
+
+loop:
+ %iv = phi i64 [ %start, %entry ], [ %iv.next, %loop ]
+ call void @use(i64 %iv)
+ %iv.next = add i64 %iv, -2
+ %c = icmp sgt i64 %iv.next, %n
+ br i1 %c, label %loop, label %exit
+
+exit:
+ ret void
+}
+
+; n >s SMIN is insufficient for stride -3.
+define void @sgt_stride3_guard_insufficient(i64 %n, i64 %start) {
+; CHECK-LABEL: 'sgt_stride3_guard_insufficient'
+; CHECK-NEXT: Classifying expressions for: @sgt_stride3_guard_insufficient
+; CHECK-NEXT: %iv = phi i64 [ %start, %entry ], [ %iv.next, %loop ]
+; CHECK-NEXT: --> {%start,+,-3}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: %iv.next = add i64 %iv, -3
+; CHECK-NEXT: --> {(-3 + %start),+,-3}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: Determining loop execution counts for: @sgt_stride3_guard_insufficient
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
+;
+entry:
+ %g = icmp sgt i64 %n, -9223372036854775808
+ br i1 %g, label %loop, label %exit
+
+loop:
+ %iv = phi i64 [ %start, %entry ], [ %iv.next, %loop ]
+ call void @use(i64 %iv)
+ %iv.next = add i64 %iv, -3
+ %c = icmp sgt i64 %iv.next, %n
+ br i1 %c, label %loop, label %exit
+
+exit:
+ ret void
+}
+
+; n >s SMIN + 1 (i.e. n >=s SMIN + 2), stride -3: IV cannot overflow.
+define void @sgt_stride3_guard_smin_plus_1(i64 %n, i64 %start) {
+; CHECK-LABEL: 'sgt_stride3_guard_smin_plus_1'
+; CHECK-NEXT: Classifying expressions for: @sgt_stride3_guard_smin_plus_1
+; CHECK-NEXT: %iv = phi i64 [ %start, %entry ], [ %iv.next, %loop ]
+; CHECK-NEXT: --> {%start,+,-3}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: %iv.next = add i64 %iv, -3
+; CHECK-NEXT: --> {(-3 + %start),+,-3}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: Determining loop execution counts for: @sgt_stride3_guard_smin_plus_1
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
+;
+entry:
+ %g = icmp sgt i64 %n, -9223372036854775807
+ br i1 %g, label %loop, label %exit
+
+loop:
+ %iv = phi i64 [ %start, %entry ], [ %iv.next, %loop ]
+ call void @use(i64 %iv)
+ %iv.next = add i64 %iv, -3
+ %c = icmp sgt i64 %iv.next, %n
+ br i1 %c, label %loop, label %exit
+
+exit:
+ ret void
+}
+
+; n >u 1 (i.e. n >=u 2), stride -3: IV cannot overflow.
+define void @ugt_stride3_guard(i64 %n, i64 %start) {
+; CHECK-LABEL: 'ugt_stride3_guard'
+; CHECK-NEXT: Classifying expressions for: @ugt_stride3_guard
+; CHECK-NEXT: %iv = phi i64 [ %start, %entry ], [ %iv.next, %loop ]
+; CHECK-NEXT: --> {%start,+,-3}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: %iv.next = add i64 %iv, -3
+; CHECK-NEXT: --> {(-3 + %start),+,-3}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: Determining loop execution counts for: @ugt_stride3_guard
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
+;
+entry:
+ %g = icmp ugt i64 %n, 1
+ br i1 %g, label %loop, label %exit
+
+loop:
+ %iv = phi i64 [ %start, %entry ], [ %iv.next, %loop ]
+ call void @use(i64 %iv)
+ %iv.next = add i64 %iv, -3
+ %c = icmp ugt i64 %iv.next, %n
+ br i1 %c, label %loop, label %exit
+
+exit:
+ ret void
+}
+
+; n >u 0 is insufficient for stride -3.
+define void @ugt_stride3_guard_insufficient(i64 %n, i64 %start) {
+; CHECK-LABEL: 'ugt_stride3_guard_insufficient'
+; CHECK-NEXT: Classifying expressions for: @ugt_stride3_guard_insufficient
+; CHECK-NEXT: %iv = phi i64 [ %start, %entry ], [ %iv.next, %loop ]
+; CHECK-NEXT: --> {%start,+,-3}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: %iv.next = add i64 %iv, -3
+; CHECK-NEXT: --> {(-3 + %start),+,-3}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: Determining loop execution counts for: @ugt_stride3_guard_insufficient
+; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
+; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
+;
+entry:
+ %g = icmp ugt i64 %n, 0
+ br i1 %g, label %loop, label %exit
+
+loop:
+ %iv = phi i64 [ %start, %entry ], [ %iv.next, %loop ]
+ call void @use(i64 %iv)
+ %iv.next = add i64 %iv, -3
+ %c = icmp ugt i64 %iv.next, %n
+ br i1 %c, label %loop, label %exit
+
+exit:
+ ret void
+}
>From 0475c7c70fff2f7d9a2d0c053bf41c575cb31b7e Mon Sep 17 00:00:00 2001
From: Florian Hahn <flo at fhahn.com>
Date: Thu, 1 Oct 2026 13:52:26 +0100
Subject: [PATCH 2/2] [SCEV] Use loop guards to rule out IV overflow in LT/GT
exit counts.
In some cases, loop guards can provide tighter bounds on RHS, which
allows ruling out overflow in more cases.
This enables additional vectorization, unrolling, IndVarSimplify and a
few more folds: https://github.com/dtcxzyw/llvm-opt-benchmark-nightly/pull/1539
Compile-time impact in the noise:
https://llvm-compile-time-tracker.com/compare.php?from=c0359c6d8bd87f3a0f1823a800304c0e7fe6efa1&to=e4b344c980ea293e3ec189801a5dffbe5e44b663&stat=instructions:u
---
llvm/lib/Analysis/ScalarEvolution.cpp | 4 +-
.../exit-count-greater-than.ll | 4 +-
.../trip-count-lt-overflow-from-guard.ll | 82 ++++++++++---------
.../trip-multiple-guard-info.ll | 13 +--
.../constraint-eliminiation-interactions.ll | 20 ++---
5 files changed, 66 insertions(+), 57 deletions(-)
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 0cdfd4f5c8933..284d919b21cdf 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -13576,7 +13576,9 @@ ScalarEvolution::howManyLessThans(const SCEV *LHS, const SCEV *RHS,
} else {
// Avoid proven overflow cases: this will ensure that the backedge taken
// count will not generate any unsigned overflow.
- IVMayOverflow = canIVOverflowOnLT(RHS, GuardedStride, IsSigned, Invert);
+ IVMayOverflow = canIVOverflowOnLT(RHS, GuardedStride, IsSigned, Invert) &&
+ canIVOverflowOnLT(applyLoopGuards(RHS, getGuards()),
+ GuardedStride, IsSigned, Invert);
if (IVMayOverflow && !NoWrap)
return getCouldNotCompute();
}
diff --git a/llvm/test/Analysis/ScalarEvolution/exit-count-greater-than.ll b/llvm/test/Analysis/ScalarEvolution/exit-count-greater-than.ll
index 6ff3d51714c55..da44d225b56c4 100644
--- a/llvm/test/Analysis/ScalarEvolution/exit-count-greater-than.ll
+++ b/llvm/test/Analysis/ScalarEvolution/exit-count-greater-than.ll
@@ -147,9 +147,9 @@ ret:
define i32 @sgt_stride_3_variable_bound(i32 %n, i32 %m) {
; CHECK-LABEL: 'sgt_stride_3_variable_bound'
; CHECK-NEXT: Determining loop execution counts for: @sgt_stride_3_variable_bound
-; CHECK-NEXT: Loop %loop: backedge-taken count is ((((-1 * (1 umin ((-1 * (%n smin %m)) + %n)))<nuw><nsw> + (-1 * (%n smin %m)) + %n) /u 3) + (1 umin ((-1 * (%n smin %m)) + %n)))
+; CHECK-NEXT: Loop %loop: backedge-taken count is ((2 + (-1 * %m) + %n) /u 3)
; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i32 1431655765
-; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is ((((-1 * (1 umin ((-1 * (%n smin %m)) + %n)))<nuw><nsw> + (-1 * (%n smin %m)) + %n) /u 3) + (1 umin ((-1 * (%n smin %m)) + %n)))
+; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is ((2 + (-1 * %m) + %n) /u 3)
; CHECK-NEXT: Loop %loop: Trip multiple is 1
;
entry:
diff --git a/llvm/test/Analysis/ScalarEvolution/trip-count-lt-overflow-from-guard.ll b/llvm/test/Analysis/ScalarEvolution/trip-count-lt-overflow-from-guard.ll
index 45dbb101020a2..c7e602cf07a12 100644
--- a/llvm/test/Analysis/ScalarEvolution/trip-count-lt-overflow-from-guard.ll
+++ b/llvm/test/Analysis/ScalarEvolution/trip-count-lt-overflow-from-guard.ll
@@ -10,13 +10,14 @@ define void @slt_stride2_guard(i64 %n) {
; CHECK-NEXT: %g = and i1 %g1, %g2
; CHECK-NEXT: --> (%g1 umin %g2) U: full-set S: full-set
; CHECK-NEXT: %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
-; CHECK-NEXT: --> {0,+,2}<%loop> U: [0,-1) S: [-9223372036854775808,9223372036854775807) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {0,+,2}<nuw><nsw><%loop> U: [0,9223372036854775805) S: [0,9223372036854775805) Exits: (2 * ((-1 + %n) /u 2))<nuw> LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %iv.next = add i64 %iv, 2
-; CHECK-NEXT: --> {2,+,2}<%loop> U: [0,-1) S: [-9223372036854775808,9223372036854775807) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {2,+,2}<nuw><nsw><%loop> U: [2,9223372036854775807) S: [2,9223372036854775807) Exits: (2 + (2 * ((-1 + %n) /u 2))<nuw>)<u nuw> LoopDispositions: { %loop: Computable }
; CHECK-NEXT: Determining loop execution counts for: @slt_stride2_guard
-; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
+; CHECK-NEXT: Loop %loop: backedge-taken count is ((-1 + %n) /u 2)
+; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i64 4611686018427387902
+; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is ((-1 + %n) /u 2)
+; CHECK-NEXT: Loop %loop: Trip multiple is 1
;
entry:
%g1 = icmp slt i64 %n, 9223372036854775807
@@ -70,9 +71,9 @@ define void @slt_stride2_guard_multi_exit(i64 %n, i64 %m) {
; CHECK-NEXT: %g = and i1 %g1, %g2
; CHECK-NEXT: --> (%g1 umin %g2) U: full-set S: full-set
; CHECK-NEXT: %iv = phi i64 [ 0, %entry ], [ %iv.next, %latch ]
-; CHECK-NEXT: --> {0,+,2}<%loop> U: [0,-1) S: [-9223372036854775808,9223372036854775807) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {0,+,2}<nuw><nsw><%loop> U: [0,9223372036854775805) S: [0,9223372036854775805) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %iv.next = add i64 %iv, 2
-; CHECK-NEXT: --> {2,+,2}<%loop> U: [0,-1) S: [-9223372036854775808,9223372036854775807) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {2,+,2}<nuw><nsw><%loop> U: [2,9223372036854775807) S: [2,9223372036854775807) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
; CHECK-NEXT: Determining loop execution counts for: @slt_stride2_guard_multi_exit
; CHECK-NEXT: Loop %loop: <multiple exits> Unpredictable backedge-taken count.
; CHECK-NEXT: exit count for loop: ***COULDNOTCOMPUTE***
@@ -80,19 +81,19 @@ define void @slt_stride2_guard_multi_exit(i64 %n, i64 %m) {
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i64 %m to i1) to i64) == 0
; CHECK-EMPTY:
-; CHECK-NEXT: exit count for latch: ***COULDNOTCOMPUTE***
-; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
+; CHECK-NEXT: exit count for latch: ((-1 + %n) /u 2)
+; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i64 4611686018427387902
+; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is ((-1 + %n) /u 2)
; CHECK-NEXT: symbolic max exit count for loop: ***COULDNOTCOMPUTE***
; CHECK-NEXT: predicated symbolic max exit count for loop: (%m /u 2)
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i64 %m to i1) to i64) == 0
; CHECK-EMPTY:
-; CHECK-NEXT: symbolic max exit count for latch: ***COULDNOTCOMPUTE***
-; CHECK-NEXT: Loop %loop: Predicated constant max backedge-taken count is i64 9223372036854775807
+; CHECK-NEXT: symbolic max exit count for latch: ((-1 + %n) /u 2)
+; CHECK-NEXT: Loop %loop: Predicated backedge-taken count is (((-1 + %n) /u 2) umin (%m /u 2))
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i64 %m to i1) to i64) == 0
-; CHECK-NEXT: Loop %loop: Predicated symbolic max backedge-taken count is (%m /u 2)
+; CHECK-NEXT: Loop %loop: Predicated symbolic max backedge-taken count is (((-1 + %n) /u 2) umin (%m /u 2))
; CHECK-NEXT: Predicates:
; CHECK-NEXT: Equal predicate: (zext i1 (trunc i64 %m to i1) to i64) == 0
;
@@ -122,13 +123,14 @@ define void @slt_stride3_guard_smax_minus_1(i64 %n) {
; CHECK-LABEL: 'slt_stride3_guard_smax_minus_1'
; CHECK-NEXT: Classifying expressions for: @slt_stride3_guard_smax_minus_1
; CHECK-NEXT: %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
-; CHECK-NEXT: --> {0,+,3}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {0,+,3}<nuw><nsw><%loop> U: [0,9223372036854775804) S: [0,9223372036854775804) Exits: (3 * ((-1 + (3 smax %n))<nsw> /u 3))<nuw><nsw> LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %iv.next = add i64 %iv, 3
-; CHECK-NEXT: --> {3,+,3}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {3,+,3}<nuw><nsw><%loop> U: [3,9223372036854775807) S: [3,9223372036854775807) Exits: (3 + (3 * ((-1 + (3 smax %n))<nsw> /u 3))<nuw><nsw>)<nuw> LoopDispositions: { %loop: Computable }
; CHECK-NEXT: Determining loop execution counts for: @slt_stride3_guard_smax_minus_1
-; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
+; CHECK-NEXT: Loop %loop: backedge-taken count is ((-1 + (3 smax %n))<nsw> /u 3)
+; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i64 3074457345618258601
+; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is ((-1 + (3 smax %n))<nsw> /u 3)
+; CHECK-NEXT: Loop %loop: Trip multiple is 1
;
entry:
%g = icmp slt i64 %n, 9223372036854775806
@@ -211,13 +213,14 @@ define void @ult_stride2_guard(i64 %n) {
; CHECK-LABEL: 'ult_stride2_guard'
; CHECK-NEXT: Classifying expressions for: @ult_stride2_guard
; CHECK-NEXT: %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ]
-; CHECK-NEXT: --> {0,+,2}<%loop> U: [0,-1) S: [-9223372036854775808,9223372036854775807) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {0,+,2}<nuw><%loop> U: [0,-3) S: [-9223372036854775808,9223372036854775807) Exits: (2 * ((-1 + (2 umax %n)) /u 2))<nuw> LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %iv.next = add i64 %iv, 2
-; CHECK-NEXT: --> {2,+,2}<%loop> U: [0,-1) S: [-9223372036854775808,9223372036854775807) Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {2,+,2}<nuw><%loop> U: [2,-1) S: [-9223372036854775808,9223372036854775807) Exits: (2 + (2 * ((-1 + (2 umax %n)) /u 2))<nuw>)<u nuw> LoopDispositions: { %loop: Computable }
; CHECK-NEXT: Determining loop execution counts for: @ult_stride2_guard
-; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
+; CHECK-NEXT: Loop %loop: backedge-taken count is ((-1 + (2 umax %n)) /u 2)
+; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i64 9223372036854775806
+; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is ((-1 + (2 umax %n)) /u 2)
+; CHECK-NEXT: Loop %loop: Trip multiple is 1
;
entry:
%g = icmp ult i64 %n, -1
@@ -267,13 +270,14 @@ define void @sgt_stride2_guard(i64 %n, i64 %start) {
; CHECK-LABEL: 'sgt_stride2_guard'
; CHECK-NEXT: Classifying expressions for: @sgt_stride2_guard
; CHECK-NEXT: %iv = phi i64 [ %start, %entry ], [ %iv.next, %loop ]
-; CHECK-NEXT: --> {%start,+,-2}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {%start,+,-2}<%loop> U: full-set S: full-set Exits: ((-2 * ((-1 + (-1 * ((-2 + %start) smin %n)) + %start) /u 2)) + %start) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %iv.next = add i64 %iv, -2
-; CHECK-NEXT: --> {(-2 + %start),+,-2}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {(-2 + %start),+,-2}<%loop> U: full-set S: full-set Exits: (-2 + (-2 * ((-1 + (-1 * ((-2 + %start) smin %n)) + %start) /u 2)) + %start) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: Determining loop execution counts for: @sgt_stride2_guard
-; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
+; CHECK-NEXT: Loop %loop: backedge-taken count is ((-1 + (-1 * ((-2 + %start) smin %n)) + %start) /u 2)
+; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i64 9223372036854775807
+; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is ((-1 + (-1 * ((-2 + %start) smin %n)) + %start) /u 2)
+; CHECK-NEXT: Loop %loop: Trip multiple is 1
;
entry:
%g = icmp sgt i64 %n, -9223372036854775808
@@ -323,13 +327,14 @@ define void @sgt_stride3_guard_smin_plus_1(i64 %n, i64 %start) {
; CHECK-LABEL: 'sgt_stride3_guard_smin_plus_1'
; CHECK-NEXT: Classifying expressions for: @sgt_stride3_guard_smin_plus_1
; CHECK-NEXT: %iv = phi i64 [ %start, %entry ], [ %iv.next, %loop ]
-; CHECK-NEXT: --> {%start,+,-3}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {%start,+,-3}<%loop> U: full-set S: full-set Exits: ((-3 * ((-1 + (-1 * ((-3 + %start) smin %n)) + %start) /u 3)) + %start) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %iv.next = add i64 %iv, -3
-; CHECK-NEXT: --> {(-3 + %start),+,-3}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {(-3 + %start),+,-3}<%loop> U: full-set S: full-set Exits: (-3 + (-3 * ((-1 + (-1 * ((-3 + %start) smin %n)) + %start) /u 3)) + %start) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: Determining loop execution counts for: @sgt_stride3_guard_smin_plus_1
-; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
+; CHECK-NEXT: Loop %loop: backedge-taken count is ((-1 + (-1 * ((-3 + %start) smin %n)) + %start) /u 3)
+; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i64 6148914691236517205
+; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is ((-1 + (-1 * ((-3 + %start) smin %n)) + %start) /u 3)
+; CHECK-NEXT: Loop %loop: Trip multiple is 1
;
entry:
%g = icmp sgt i64 %n, -9223372036854775807
@@ -351,13 +356,14 @@ define void @ugt_stride3_guard(i64 %n, i64 %start) {
; CHECK-LABEL: 'ugt_stride3_guard'
; CHECK-NEXT: Classifying expressions for: @ugt_stride3_guard
; CHECK-NEXT: %iv = phi i64 [ %start, %entry ], [ %iv.next, %loop ]
-; CHECK-NEXT: --> {%start,+,-3}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {%start,+,-3}<%loop> U: full-set S: full-set Exits: ((-3 * ((-1 + (-1 * ((-3 + %start) umin %n)) + %start) /u 3)) + %start) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: %iv.next = add i64 %iv, -3
-; CHECK-NEXT: --> {(-3 + %start),+,-3}<%loop> U: full-set S: full-set Exits: <<Unknown>> LoopDispositions: { %loop: Computable }
+; CHECK-NEXT: --> {(-3 + %start),+,-3}<%loop> U: full-set S: full-set Exits: (-3 + (-3 * ((-1 + (-1 * ((-3 + %start) umin %n)) + %start) /u 3)) + %start) LoopDispositions: { %loop: Computable }
; CHECK-NEXT: Determining loop execution counts for: @ugt_stride3_guard
-; CHECK-NEXT: Loop %loop: Unpredictable backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable constant max backedge-taken count.
-; CHECK-NEXT: Loop %loop: Unpredictable symbolic max backedge-taken count.
+; CHECK-NEXT: Loop %loop: backedge-taken count is ((-1 + (-1 * ((-3 + %start) umin %n)) + %start) /u 3)
+; CHECK-NEXT: Loop %loop: constant max backedge-taken count is i64 6148914691236517205
+; CHECK-NEXT: Loop %loop: symbolic max backedge-taken count is ((-1 + (-1 * ((-3 + %start) umin %n)) + %start) /u 3)
+; CHECK-NEXT: Loop %loop: Trip multiple is 1
;
entry:
%g = icmp ugt i64 %n, 1
diff --git a/llvm/test/Analysis/ScalarEvolution/trip-multiple-guard-info.ll b/llvm/test/Analysis/ScalarEvolution/trip-multiple-guard-info.ll
index 512e583928804..fd9765f2697e1 100644
--- a/llvm/test/Analysis/ScalarEvolution/trip-multiple-guard-info.ll
+++ b/llvm/test/Analysis/ScalarEvolution/trip-multiple-guard-info.ll
@@ -543,20 +543,21 @@ exit:
ret void
}
-; TODO: Even though %num is known to divide by 4, and the loop's IV advances by 4, SCEV can't compute the trip count.
+; %num is known to divide by 4, and the loop's IV advances by 4.
define void @test_trip_multiple_4_vectorized_iv(i32 %num) {
; CHECK-LABEL: 'test_trip_multiple_4_vectorized_iv'
; CHECK-NEXT: Classifying expressions for: @test_trip_multiple_4_vectorized_iv
; CHECK-NEXT: %u = urem i32 %num, 4
; CHECK-NEXT: --> (zext i2 (trunc i32 %num to i2) to i32) U: [0,4) S: [0,4)
; CHECK-NEXT: %i.010 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
-; CHECK-NEXT: --> {0,+,4}<%for.body> U: [0,-3) S: [-2147483648,2147483645) Exits: <<Unknown>> LoopDispositions: { %for.body: Computable }
+; CHECK-NEXT: --> {0,+,4}<nuw><%for.body> U: [0,-7) S: [-2147483648,2147483645) Exits: (4 * ((-1 + (4 umax %num)) /u 4))<nuw> LoopDispositions: { %for.body: Computable }
; CHECK-NEXT: %inc = add i32 %i.010, 4
-; CHECK-NEXT: --> {4,+,4}<%for.body> U: [0,-3) S: [-2147483648,2147483645) Exits: <<Unknown>> LoopDispositions: { %for.body: Computable }
+; CHECK-NEXT: --> {4,+,4}<nuw><%for.body> U: [4,-3) S: [-2147483648,2147483645) Exits: (4 + (4 * ((-1 + (4 umax %num)) /u 4))<nuw>)<u nuw> LoopDispositions: { %for.body: Computable }
; CHECK-NEXT: Determining loop execution counts for: @test_trip_multiple_4_vectorized_iv
-; CHECK-NEXT: Loop %for.body: Unpredictable backedge-taken count.
-; CHECK-NEXT: Loop %for.body: Unpredictable constant max backedge-taken count.
-; CHECK-NEXT: Loop %for.body: Unpredictable symbolic max backedge-taken count.
+; CHECK-NEXT: Loop %for.body: backedge-taken count is ((-1 + (4 umax %num)) /u 4)
+; CHECK-NEXT: Loop %for.body: constant max backedge-taken count is i32 1073741822
+; CHECK-NEXT: Loop %for.body: symbolic max backedge-taken count is ((-1 + (4 umax %num)) /u 4)
+; CHECK-NEXT: Loop %for.body: Trip multiple is 1
;
entry:
%u = urem i32 %num, 4
diff --git a/llvm/test/Transforms/PhaseOrdering/constraint-eliminiation-interactions.ll b/llvm/test/Transforms/PhaseOrdering/constraint-eliminiation-interactions.ll
index 1c53b64495a14..9715d85321d4d 100644
--- a/llvm/test/Transforms/PhaseOrdering/constraint-eliminiation-interactions.ll
+++ b/llvm/test/Transforms/PhaseOrdering/constraint-eliminiation-interactions.ll
@@ -284,20 +284,20 @@ define i64 @even_index_sum_uadd_with_overflow(ptr %p, i64 %count) {
; CHECK-NEXT: tail call void @llvm.assume(i1 [[NN]])
; CHECK-NEXT: [[EZ:%.*]] = icmp eq i64 [[COUNT]], 0
; CHECK-NEXT: br i1 [[EZ]], label %[[EXIT:.*]], label %[[LOOP_HEADER:.*]]
+; CHECK: [[LOOP_HEADER1:.*]]:
+; CHECK-NEXT: [[OOB:%.*]] = icmp ult i64 [[IV:%.*]], [[COUNT]]
+; CHECK-NEXT: br i1 [[OOB]], label %[[LOOP_HEADER]], label %[[TRAP:.*]]
; CHECK: [[LOOP_HEADER]]:
-; CHECK-NEXT: [[ACC:%.*]] = phi i64 [ [[ACC_NEXT:%.*]], %[[BODY:.*]] ], [ 0, %[[ENTRY]] ]
-; CHECK-NEXT: [[IV:%.*]] = phi i64 [ [[IV_NEXT:%.*]], %[[BODY]] ], [ 0, %[[ENTRY]] ]
-; CHECK-NEXT: [[OOB:%.*]] = icmp ult i64 [[IV]], [[COUNT]]
-; CHECK-NEXT: br i1 [[OOB]], label %[[BODY]], label %[[TRAP:.*]]
-; CHECK: [[BODY]]:
-; CHECK-NEXT: [[A:%.*]] = getelementptr inbounds nuw [8 x i8], ptr [[P]], i64 [[IV]]
+; CHECK-NEXT: [[IV2:%.*]] = phi i64 [ [[IV]], %[[LOOP_HEADER1]] ], [ 0, %[[ENTRY]] ]
+; CHECK-NEXT: [[ACC:%.*]] = phi i64 [ [[ACC_NEXT:%.*]], %[[LOOP_HEADER1]] ], [ 0, %[[ENTRY]] ]
+; CHECK-NEXT: [[A:%.*]] = getelementptr inbounds nuw [8 x i8], ptr [[P]], i64 [[IV2]]
; CHECK-NEXT: [[V:%.*]] = load i64, ptr [[A]], align 8
; CHECK-NEXT: [[ACC_NEXT]] = add i64 [[V]], [[ACC]]
-; CHECK-NEXT: [[IV_NEXT]] = add nuw i64 [[IV]], 2
-; CHECK-NEXT: [[EC_NOT:%.*]] = icmp slt i64 [[IV_NEXT]], [[COUNT]]
-; CHECK-NEXT: br i1 [[EC_NOT]], label %[[LOOP_HEADER]], label %[[EXIT]]
+; CHECK-NEXT: [[IV]] = add nuw i64 [[IV2]], 2
+; CHECK-NEXT: [[EC_NOT:%.*]] = icmp slt i64 [[IV]], [[COUNT]]
+; CHECK-NEXT: br i1 [[EC_NOT]], label %[[LOOP_HEADER1]], label %[[EXIT]]
; CHECK: [[EXIT]]:
-; CHECK-NEXT: [[R:%.*]] = phi i64 [ 0, %[[ENTRY]] ], [ [[ACC_NEXT]], %[[BODY]] ]
+; CHECK-NEXT: [[R:%.*]] = phi i64 [ 0, %[[ENTRY]] ], [ [[ACC_NEXT]], %[[LOOP_HEADER]] ]
; CHECK-NEXT: ret i64 [[R]]
; CHECK: [[TRAP]]:
; CHECK-NEXT: tail call void @llvm.trap()
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