[llvm] bdd40e3 - [SCEV] Add tests for umin_seq change in #92177

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2024-10-02T11:06:00+01:00
New Revision: bdd40e39a4d6540a80f1f5ebadfebee25381f670

URL: https://github.com/llvm/llvm-project/commit/bdd40e39a4d6540a80f1f5ebadfebee25381f670
DIFF: https://github.com/llvm/llvm-project/commit/bdd40e39a4d6540a80f1f5ebadfebee25381f670.diff

LOG: [SCEV] Add tests for umin_seq change in #92177

SCEV-only tests for https://github.com/llvm/llvm-project/pull/92177

Added: 
    llvm/test/Analysis/ScalarEvolution/umin-seq-operand-may-trigger-ub.ll

Modified: 
    

Removed: 
    


################################################################################
diff  --git a/llvm/test/Analysis/ScalarEvolution/umin-seq-operand-may-trigger-ub.ll b/llvm/test/Analysis/ScalarEvolution/umin-seq-operand-may-trigger-ub.ll
new file mode 100644
index 00000000000000..8085592111ff5a
--- /dev/null
+++ b/llvm/test/Analysis/ScalarEvolution/umin-seq-operand-may-trigger-ub.ll
@@ -0,0 +1,111 @@
+; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -passes='print<scalar-evolution>' -scalar-evolution-classify-expressions=0 -disable-output %s 2>&1 | FileCheck %s
+
+; The UDiv in the latch may never be executed. The backedge-taken-count
+; expressions must account for the fact that evaluating the UDiv
+; unconditionally may trigger UB.
+; FIXME: umin_seq should be used instead of umin  for BTCs.
+define i64 @multi_exit_exit_count_with_udiv_by_value_in_latch(ptr %dst, i64 %N) {
+; CHECK-LABEL: 'multi_exit_exit_count_with_udiv_by_value_in_latch'
+; CHECK-NEXT:  Determining loop execution counts for: @multi_exit_exit_count_with_udiv_by_value_in_latch
+; CHECK-NEXT:  Loop %loop.header: <multiple exits> backedge-taken count is ((42 /u %N) umin (0 smax %N))
+; CHECK-NEXT:    exit count for loop.header: (0 smax %N)
+; CHECK-NEXT:    exit count for loop.latch: (42 /u %N)
+; CHECK-NEXT:  Loop %loop.header: constant max backedge-taken count is i64 42
+; CHECK-NEXT:  Loop %loop.header: symbolic max backedge-taken count is ((42 /u %N) umin (0 smax %N))
+; CHECK-NEXT:    symbolic max exit count for loop.header: (0 smax %N)
+; CHECK-NEXT:    symbolic max exit count for loop.latch: (42 /u %N)
+; CHECK-NEXT:  Loop %loop.header: Trip multiple is 1
+;
+entry:
+  br label %loop.header
+
+loop.header:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop.latch ]
+  %gep = getelementptr inbounds i32, ptr %dst, i64 %iv
+  store i32 1, ptr %gep
+  %c.0 = icmp slt i64 %iv, %N
+  br i1 %c.0, label %loop.latch, label %exit
+
+loop.latch:
+  %iv.next = add i64 %iv, 1
+  %d = udiv i64 42, %N
+  %c.1 = icmp slt i64 %iv, %d
+  br i1 %c.1, label %loop.header, label %exit
+
+exit:
+  %p = phi i64 [ 1, %loop.header ], [ 0, %loop.latch]
+  ret i64 %p
+}
+
+; The UDiv in the latch may never be executed. The backedge-taken-count
+; expressions must account for the fact that evaluating the UDiv
+; unconditionally may trigger UB.
+; FIXME: umin_seq should be used instead of umin  for BTCs.
+define i64 @multi_exit_exit_count_with_udiv_by_value_in_latch_
diff erent_bounds(ptr %dst, i64 %N, i64 %M) {
+; CHECK-LABEL: 'multi_exit_exit_count_with_udiv_by_value_in_latch_
diff erent_bounds'
+; CHECK-NEXT:  Determining loop execution counts for: @multi_exit_exit_count_with_udiv_by_value_in_latch_
diff erent_bounds
+; CHECK-NEXT:  Loop %loop.header: <multiple exits> backedge-taken count is ((0 smax %N) umin_seq (42 /u %M))
+; CHECK-NEXT:    exit count for loop.header: (0 smax %N)
+; CHECK-NEXT:    exit count for loop.latch: (42 /u %M)
+; CHECK-NEXT:  Loop %loop.header: constant max backedge-taken count is i64 42
+; CHECK-NEXT:  Loop %loop.header: symbolic max backedge-taken count is ((0 smax %N) umin_seq (42 /u %M))
+; CHECK-NEXT:    symbolic max exit count for loop.header: (0 smax %N)
+; CHECK-NEXT:    symbolic max exit count for loop.latch: (42 /u %M)
+; CHECK-NEXT:  Loop %loop.header: Trip multiple is 1
+;
+entry:
+  br label %loop.header
+
+loop.header:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop.latch ]
+  %gep = getelementptr inbounds i32, ptr %dst, i64 %iv
+  store i32 1, ptr %gep
+  %c.0 = icmp slt i64 %iv, %N
+  br i1 %c.0, label %loop.latch, label %exit
+
+loop.latch:
+  %iv.next = add i64 %iv, 1
+  %d = udiv i64 42, %M
+  %c.1 = icmp slt i64 %iv, %d
+  br i1 %c.1, label %loop.header, label %exit
+
+exit:
+  %p = phi i64 [ 1, %loop.header ], [ 0, %loop.latch]
+  ret i64 %p
+}
+
+; The UDiv in the latch cannot trigger UB, evaluating it unconditionally in the
+; trip count expression is fine.
+define i64 @multi_exit_exit_count_with_udiv_by_constant_in_latch(ptr %dst, i64 %N) {
+; CHECK-LABEL: 'multi_exit_exit_count_with_udiv_by_constant_in_latch'
+; CHECK-NEXT:  Determining loop execution counts for: @multi_exit_exit_count_with_udiv_by_constant_in_latch
+; CHECK-NEXT:  Loop %loop.header: <multiple exits> backedge-taken count is ((%N /u 42) umin (0 smax %N))
+; CHECK-NEXT:    exit count for loop.header: (0 smax %N)
+; CHECK-NEXT:    exit count for loop.latch: (%N /u 42)
+; CHECK-NEXT:  Loop %loop.header: constant max backedge-taken count is i64 439208192231179800
+; CHECK-NEXT:  Loop %loop.header: symbolic max backedge-taken count is ((%N /u 42) umin (0 smax %N))
+; CHECK-NEXT:    symbolic max exit count for loop.header: (0 smax %N)
+; CHECK-NEXT:    symbolic max exit count for loop.latch: (%N /u 42)
+; CHECK-NEXT:  Loop %loop.header: Trip multiple is 1
+;
+entry:
+  br label %loop.header
+
+loop.header:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop.latch ]
+  %gep = getelementptr inbounds i32, ptr %dst, i64 %iv
+  store i32 1, ptr %gep
+  %c.0 = icmp slt i64 %iv, %N
+  br i1 %c.0, label %loop.latch, label %exit
+
+loop.latch:
+  %iv.next = add i64 %iv, 1
+  %d = udiv i64 %N, 42
+  %c.1 = icmp slt i64 %iv, %d
+  br i1 %c.1, label %loop.header, label %exit
+
+exit:
+  %p = phi i64 [ 1, %loop.header ], [ 0, %loop.latch]
+  ret i64 %p
+}