From c61f37b9841ce4532588492e87ce5232801aea64 Mon Sep 17 00:00:00 2001
From: Max Kazantsev <mkazantsev@azul.com>
Date: Mon, 21 Nov 2022 13:14:13 +0700
Subject: [PATCH] [Test] Add some examples where IndVars fails to turn
 condition into invariant

---
 .../Transforms/IndVarSimplify/turn-to-invariant.ll | 169 +++++++++++++++++++++
 1 file changed, 169 insertions(+)
 create mode 100644 llvm/test/Transforms/IndVarSimplify/turn-to-invariant.ll

diff --git a/llvm/test/Transforms/IndVarSimplify/turn-to-invariant.ll b/llvm/test/Transforms/IndVarSimplify/turn-to-invariant.ll
new file mode 100644
index 0000000..242f96b
--- /dev/null
+++ b/llvm/test/Transforms/IndVarSimplify/turn-to-invariant.ll
@@ -0,0 +1,169 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -passes=indvars -S < %s | FileCheck %s
+
+declare i1 @cond()
+
+; Range check here can be turned into invariant check.
+define i32 @test_simple_case(i32 %start, i32 %len) {
+; CHECK-LABEL: @test_simple_case(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[TMP0:%.*]] = add i32 [[START:%.*]], -1
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ [[START]], [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT:    [[ZERO_CHECK:%.*]] = icmp ne i32 [[IV]], 0
+; CHECK-NEXT:    br i1 [[ZERO_CHECK]], label [[RANGE_CHECK_BLOCK:%.*]], label [[FAILED_1:%.*]]
+; CHECK:       range_check_block:
+; CHECK-NEXT:    [[RANGE_CHECK3:%.*]] = icmp ult i32 [[TMP0]], [[LEN:%.*]]
+; CHECK-NEXT:    br i1 [[RANGE_CHECK3]], label [[BACKEDGE]], label [[FAILED_2:%.*]]
+; CHECK:       backedge:
+; CHECK-NEXT:    [[IV_NEXT]] = add i32 [[IV]], -1
+; CHECK-NEXT:    [[LOOP_COND:%.*]] = call i1 @cond()
+; CHECK-NEXT:    br i1 [[LOOP_COND]], label [[DONE:%.*]], label [[LOOP]]
+; CHECK:       done:
+; CHECK-NEXT:    [[IV_LCSSA2:%.*]] = phi i32 [ [[IV]], [[BACKEDGE]] ]
+; CHECK-NEXT:    ret i32 [[IV_LCSSA2]]
+; CHECK:       failed_1:
+; CHECK-NEXT:    ret i32 -1
+; CHECK:       failed_2:
+; CHECK-NEXT:    ret i32 -2
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i32 [%start, %entry], [%iv.next, %backedge]
+  %zero_check = icmp ne i32 %iv, 0
+  br i1 %zero_check, label %range_check_block, label %failed_1
+
+range_check_block:
+  %iv.minus.1 = add i32 %iv, -1
+  %range_check = icmp ult i32 %iv.minus.1, %len
+  br i1 %range_check, label %backedge, label %failed_2
+
+backedge:
+  %iv.next = add i32 %iv, -1
+  %loop_cond = call i1 @cond()
+  br i1 %loop_cond, label %done, label %loop
+
+done:
+  ret i32 %iv
+
+failed_1:
+  ret i32 -1
+
+failed_2:
+  ret i32 -2
+}
+
+; TODO: This example is equivalent to @test_simple_case, with only difference that
+;       both checks are littered with extra irrelevant conditions. We should be able
+;       to replace it with invariant despite this fact.
+;       https://alive2.llvm.org/ce/z/G4iW8c
+define i32 @test_litter_conditions(i32 %start, i32 %len) {
+; CHECK-LABEL: @test_litter_conditions(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ [[START:%.*]], [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT:    [[ZERO_CHECK:%.*]] = icmp ne i32 [[IV]], 0
+; CHECK-NEXT:    [[FAKE_1:%.*]] = call i1 @cond()
+; CHECK-NEXT:    [[AND_1:%.*]] = and i1 [[ZERO_CHECK]], [[FAKE_1]]
+; CHECK-NEXT:    br i1 [[AND_1]], label [[RANGE_CHECK_BLOCK:%.*]], label [[FAILED_1:%.*]]
+; CHECK:       range_check_block:
+; CHECK-NEXT:    [[IV_MINUS_1:%.*]] = add i32 [[IV]], -1
+; CHECK-NEXT:    [[RANGE_CHECK:%.*]] = icmp ult i32 [[IV_MINUS_1]], [[LEN:%.*]]
+; CHECK-NEXT:    [[FAKE_2:%.*]] = call i1 @cond()
+; CHECK-NEXT:    [[AND_2:%.*]] = and i1 [[RANGE_CHECK]], [[FAKE_2]]
+; CHECK-NEXT:    br i1 [[AND_2]], label [[BACKEDGE]], label [[FAILED_2:%.*]]
+; CHECK:       backedge:
+; CHECK-NEXT:    [[IV_NEXT]] = add i32 [[IV]], -1
+; CHECK-NEXT:    [[LOOP_COND:%.*]] = call i1 @cond()
+; CHECK-NEXT:    br i1 [[LOOP_COND]], label [[DONE:%.*]], label [[LOOP]]
+; CHECK:       done:
+; CHECK-NEXT:    [[IV_LCSSA2:%.*]] = phi i32 [ [[IV]], [[BACKEDGE]] ]
+; CHECK-NEXT:    ret i32 [[IV_LCSSA2]]
+; CHECK:       failed_1:
+; CHECK-NEXT:    ret i32 -1
+; CHECK:       failed_2:
+; CHECK-NEXT:    ret i32 -2
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i32 [%start, %entry], [%iv.next, %backedge]
+  %zero_check = icmp ne i32 %iv, 0
+  %fake_1 = call i1 @cond()
+  %and_1 = and i1 %zero_check, %fake_1
+  br i1 %and_1, label %range_check_block, label %failed_1
+
+range_check_block:
+  %iv.minus.1 = add i32 %iv, -1
+  %range_check = icmp ult i32 %iv.minus.1, %len
+  %fake_2 = call i1 @cond()
+  %and_2 = and i1 %range_check, %fake_2
+  br i1 %and_2, label %backedge, label %failed_2
+
+backedge:
+  %iv.next = add i32 %iv, -1
+  %loop_cond = call i1 @cond()
+  br i1 %loop_cond, label %done, label %loop
+
+done:
+  ret i32 %iv
+
+failed_1:
+  ret i32 -1
+
+failed_2:
+  ret i32 -2
+}
+
+; TODO: This test is equivalent to @test_simple_case, with only difference
+;       that both checks are merged together into one 'and' check. This
+;       should not prevent turning the range check into invariant.
+;       https://alive2.llvm.org/ce/z/G-2ERB
+define i32 @test_and_conditions(i32 %start, i32 %len) {
+; CHECK-LABEL: @test_and_conditions(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[IV:%.*]] = phi i32 [ [[START:%.*]], [[ENTRY:%.*]] ], [ [[IV_NEXT:%.*]], [[BACKEDGE:%.*]] ]
+; CHECK-NEXT:    [[ZERO_CHECK:%.*]] = icmp ne i32 [[IV]], 0
+; CHECK-NEXT:    [[IV_MINUS_1:%.*]] = add i32 [[IV]], -1
+; CHECK-NEXT:    [[RANGE_CHECK:%.*]] = icmp ult i32 [[IV_MINUS_1]], [[LEN:%.*]]
+; CHECK-NEXT:    [[BOTH_CHECKS:%.*]] = and i1 [[ZERO_CHECK]], [[RANGE_CHECK]]
+; CHECK-NEXT:    br i1 [[BOTH_CHECKS]], label [[BACKEDGE]], label [[FAILED:%.*]]
+; CHECK:       backedge:
+; CHECK-NEXT:    [[IV_NEXT]] = add i32 [[IV]], -1
+; CHECK-NEXT:    [[LOOP_COND:%.*]] = call i1 @cond()
+; CHECK-NEXT:    br i1 [[LOOP_COND]], label [[DONE:%.*]], label [[LOOP]]
+; CHECK:       done:
+; CHECK-NEXT:    [[IV_LCSSA1:%.*]] = phi i32 [ [[IV]], [[BACKEDGE]] ]
+; CHECK-NEXT:    ret i32 [[IV_LCSSA1]]
+; CHECK:       failed:
+; CHECK-NEXT:    ret i32 -3
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i32 [%start, %entry], [%iv.next, %backedge]
+  %zero_check = icmp ne i32 %iv, 0
+  %iv.minus.1 = add i32 %iv, -1
+  %range_check = icmp ult i32 %iv.minus.1, %len
+  %both_checks = and i1 %zero_check, %range_check
+  br i1 %both_checks, label %backedge, label %failed
+
+backedge:
+  %iv.next = add i32 %iv, -1
+  %loop_cond = call i1 @cond()
+  br i1 %loop_cond, label %done, label %loop
+
+done:
+  ret i32 %iv
+
+failed:
+  ret i32 -3
+}
-- 
2.7.4