[llvm] [UTC] CHECK-EMPTY instead of skipping blank lines (PR #165718)
Kunqiu Chen via llvm-commits
llvm-commits at lists.llvm.org
Thu Oct 30 06:43:55 PDT 2025
https://github.com/Camsyn created https://github.com/llvm/llvm-project/pull/165718
Previously, any blank lines in IR were ignored by UTC, leading to more fragile `CHECK`s being generated.
This change lets UTC, 1) emit `CHECK-EMPTY` to check blank lines, and 2) generate more `CHECK-NEXT`s, landing the discussion https://github.com/llvm/llvm-project/pull/165419#issuecomment-3457572422.
Moreover, this change also aligns the behavior of IR check-gen to ASM check-gen, which has been emitting CHECK-EMPTY since https://github.com/llvm/llvm-project/commit/a8a89c77ea3c16b45763fca6940bbfd3bef7884f.
>From 795b21788d85196643a68673b2c17a5920ed474e Mon Sep 17 00:00:00 2001
From: Camsyn <camsyn at foxmail.com>
Date: Thu, 30 Oct 2025 21:24:04 +0800
Subject: [PATCH 1/2] [UTC] CHECK-EMPTY instead of skiping blank lines
---
llvm/utils/UpdateTestChecks/common.py | 36 +++++++--------------------
1 file changed, 9 insertions(+), 27 deletions(-)
diff --git a/llvm/utils/UpdateTestChecks/common.py b/llvm/utils/UpdateTestChecks/common.py
index 8cd200c93a482..d9ef660ebdca8 100644
--- a/llvm/utils/UpdateTestChecks/common.py
+++ b/llvm/utils/UpdateTestChecks/common.py
@@ -2282,41 +2282,23 @@ def add_checks(
original_check_lines=original_check_lines.get(checkprefix),
)
- # This could be selectively enabled with an optional invocation argument.
- # Disabled for now: better to check everything. Be safe rather than sorry.
-
- # Handle the first line of the function body as a special case because
- # it's often just noise (a useless asm comment or entry label).
- # if func_body[0].startswith("#") or func_body[0].startswith("entry:"):
- # is_blank_line = True
- # else:
- # output_lines.append('%s %s: %s' % (comment_marker, checkprefix, func_body[0]))
- # is_blank_line = False
-
- is_blank_line = False
for func_line in func_body:
if func_line.strip() == "":
- is_blank_line = True
+ # Instead of skipping blank lines, using CHECK_EMPTY is more defensive.
+ output_lines.append(
+ "{} {}-EMPTY:".format(comment_marker, checkprefix)
+ )
continue
# Do not waste time checking IR comments.
func_line = SCRUB_IR_COMMENT_RE.sub(r"", func_line)
- # Skip blank lines instead of checking them.
- if is_blank_line:
- output_lines.append(
- "{} {}: {}".format(
- comment_marker, checkprefix, func_line
- )
- )
- else:
- check_suffix = "-NEXT" if not is_filtered else ""
- output_lines.append(
- "{} {}{}: {}".format(
- comment_marker, checkprefix, check_suffix, func_line
- )
+ check_suffix = "-NEXT" if not is_filtered else ""
+ output_lines.append(
+ "{} {}{}: {}".format(
+ comment_marker, checkprefix, check_suffix, func_line
)
- is_blank_line = False
+ )
# Add space between different check prefixes and also before the first
# line of code in the test function.
>From cb10fe64d391e01c41cc09da6fbc064506715587 Mon Sep 17 00:00:00 2001
From: Camsyn <camsyn at foxmail.com>
Date: Thu, 30 Oct 2025 21:24:17 +0800
Subject: [PATCH 2/2] Add a test
---
.../update_test_checks/Inputs/check_empty.ll | 29 ++++++++++
.../Inputs/check_empty.ll.expected | 57 +++++++++++++++++++
.../update_test_checks/check_empty.test | 3 +
3 files changed, 89 insertions(+)
create mode 100644 llvm/test/tools/UpdateTestChecks/update_test_checks/Inputs/check_empty.ll
create mode 100644 llvm/test/tools/UpdateTestChecks/update_test_checks/Inputs/check_empty.ll.expected
create mode 100644 llvm/test/tools/UpdateTestChecks/update_test_checks/check_empty.test
diff --git a/llvm/test/tools/UpdateTestChecks/update_test_checks/Inputs/check_empty.ll b/llvm/test/tools/UpdateTestChecks/update_test_checks/Inputs/check_empty.ll
new file mode 100644
index 0000000000000..abaa0ce2dd3b4
--- /dev/null
+++ b/llvm/test/tools/UpdateTestChecks/update_test_checks/Inputs/check_empty.ll
@@ -0,0 +1,29 @@
+; RUN: opt < %s -S | FileCheck %s
+
+; Test whether the UTC check empty lines instead of skipping them.
+define i32 @test(i32 %x) {
+entry:
+ br label %block1
+
+block1:
+ %cmp = icmp eq i32 %x, 0
+ br i1 %cmp, label %block2, label %exit1
+
+block2:
+ br i1 %cmp, label %block3, label %exit2
+
+block3:
+ br i1 %cmp, label %exit3, label %exit4
+
+exit1:
+ ret i32 0
+
+exit2:
+ ret i32 %x
+
+exit3:
+ ret i32 %x
+
+exit4:
+ ret i32 %x
+}
diff --git a/llvm/test/tools/UpdateTestChecks/update_test_checks/Inputs/check_empty.ll.expected b/llvm/test/tools/UpdateTestChecks/update_test_checks/Inputs/check_empty.ll.expected
new file mode 100644
index 0000000000000..dc2a37907039e
--- /dev/null
+++ b/llvm/test/tools/UpdateTestChecks/update_test_checks/Inputs/check_empty.ll.expected
@@ -0,0 +1,57 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
+; RUN: opt < %s -S | FileCheck %s
+
+; Test whether the UTC check empty lines instead of skipping them.
+define i32 @test(i32 %x) {
+; CHECK-LABEL: define i32 @test(
+; CHECK-SAME: i32 [[X:%.*]]) {
+; CHECK-NEXT: [[ENTRY:.*:]]
+; CHECK-NEXT: br label %[[BLOCK1:.*]]
+; CHECK-EMPTY:
+; CHECK-NEXT: [[BLOCK1]]:
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[X]], 0
+; CHECK-NEXT: br i1 [[CMP]], label %[[BLOCK2:.*]], label %[[EXIT1:.*]]
+; CHECK-EMPTY:
+; CHECK-NEXT: [[BLOCK2]]:
+; CHECK-NEXT: br i1 [[CMP]], label %[[BLOCK3:.*]], label %[[EXIT2:.*]]
+; CHECK-EMPTY:
+; CHECK-NEXT: [[BLOCK3]]:
+; CHECK-NEXT: br i1 [[CMP]], label %[[EXIT3:.*]], label %[[EXIT4:.*]]
+; CHECK-EMPTY:
+; CHECK-NEXT: [[EXIT1]]:
+; CHECK-NEXT: ret i32 0
+; CHECK-EMPTY:
+; CHECK-NEXT: [[EXIT2]]:
+; CHECK-NEXT: ret i32 [[X]]
+; CHECK-EMPTY:
+; CHECK-NEXT: [[EXIT3]]:
+; CHECK-NEXT: ret i32 [[X]]
+; CHECK-EMPTY:
+; CHECK-NEXT: [[EXIT4]]:
+; CHECK-NEXT: ret i32 [[X]]
+;
+entry:
+ br label %block1
+
+block1:
+ %cmp = icmp eq i32 %x, 0
+ br i1 %cmp, label %block2, label %exit1
+
+block2:
+ br i1 %cmp, label %block3, label %exit2
+
+block3:
+ br i1 %cmp, label %exit3, label %exit4
+
+exit1:
+ ret i32 0
+
+exit2:
+ ret i32 %x
+
+exit3:
+ ret i32 %x
+
+exit4:
+ ret i32 %x
+}
diff --git a/llvm/test/tools/UpdateTestChecks/update_test_checks/check_empty.test b/llvm/test/tools/UpdateTestChecks/update_test_checks/check_empty.test
new file mode 100644
index 0000000000000..61e85152db951
--- /dev/null
+++ b/llvm/test/tools/UpdateTestChecks/update_test_checks/check_empty.test
@@ -0,0 +1,3 @@
+## test whether the UTC generates CHECK-EMPTY for blank lines
+# RUN: cp -f %S/Inputs/check_empty.ll %t.ll && %update_test_checks %t.ll
+# RUN: diff -u %t.ll %S/Inputs/check_empty.ll.expected
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