llvm-cov: Document the llvm-cov tests

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200739 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 31 insertions, 9 deletions

diff --git a/test/tools/llvm-cov/llvm-cov.test b/test/tools/llvm-cov/llvm-cov.test
index 411ac1f873..cb0c99b747 100644
--- a/test/tools/llvm-cov/llvm-cov.test
+++ b/test/tools/llvm-cov/llvm-cov.test
@@ -1,38 +1,60 @@
+# Tests for compatibility between llvm-cov and gcov. These work by
+# comparing llvm-cov against reference outputs generated by gcov 4.2.
+
 # "cd" and globbing are unsupported in lit internal runner.
 REQUIRES: shell
+
 RUN: rm -rf %t
 RUN: mkdir %t
 RUN: cd %t
 RUN: cp %p/Inputs/test* .
 
-RUN: llvm-cov test.c | diff test_no_options.output -
-RUN: llvm-cov test.c -f | diff test_-f.output -
+# Basic behaviour with no flags
+RUN: llvm-cov test.c | diff -u test_no_options.output -
+RUN: diff -aub test_no_options.cpp.gcov test.cpp.gcov
+RUN: diff -aub test_no_options.h.gcov test.h.gcov
+
+# Function summaries. This changes stdout, but not the gcov files.
+RUN: llvm-cov test.c -f | diff -u test_-f.output -
 RUN: diff -aub test_no_options.cpp.gcov test.cpp.gcov
 RUN: diff -aub test_no_options.h.gcov test.h.gcov
 
-RUN: llvm-cov test.c -a
+# All blocks. This doesn't affect stdout, only the gcov files.
+RUN: llvm-cov test.c -a | diff -u test_no_options.output -
 RUN: diff -aub test_-a.cpp.gcov test.cpp.gcov
 RUN: diff -aub test_-a.h.gcov test.h.gcov
 
-RUN: llvm-cov test.c -a -b | diff test_-b.output -
-# This is expected to fail because gcov doesn't actually output real branch or
-# call statistics on a per function basis.
-RUN: llvm-cov test.c -a -b -f | not diff test_-b_-f.output -
+# Branch probabilities.
+RUN: llvm-cov test.c -a -b | diff -u test_-b.output -
+RUN: diff -aub test_-a_-b.cpp.gcov test.cpp.gcov
+RUN: diff -aub test_-a_-b.h.gcov test.h.gcov
+
+# Function summaries including branch probabilities.
+
+# FIXME: We don't correctly handle calls when -b and -f are used
+# together, so our output differs from gcov. Remove the 'not' from
+# this test once this is fixed.
+RUN: llvm-cov test.c -a -b -f | not diff -u test_-b_-f.output - >/dev/null
 RUN: diff -aub test_-a_-b.cpp.gcov test.cpp.gcov
 RUN: diff -aub test_-a_-b.h.gcov test.h.gcov
 
-RUN: llvm-cov test.c -a -b -u
+# Summarize unconditional branches too.
+RUN: llvm-cov test.c -a -b -u | diff -u test_-b.output -
 RUN: diff -aub test_-a_-b_-u.cpp.gcov test.cpp.gcov
 RUN: diff -aub test_-a_-b_-u.h.gcov test.h.gcov
 
-RUN: llvm-cov test.c -a -b -c -u
+# Absolute counts for branches.
+RUN: llvm-cov test.c -a -b -c -u | diff -u test_-b.output -
 RUN: diff -aub test_-a_-b_-c_-u.cpp.gcov test.cpp.gcov
 RUN: diff -aub test_-a_-b_-c_-u.h.gcov test.h.gcov
 
+# Invalid gcno file.
 RUN: not llvm-cov test.c -gcno=test_read_fail.gcno
 
+# Bad file checksum on gcda.
 RUN: not llvm-cov test.c -gcda=test_file_checksum_fail.gcda
 
+# Bad function checksum on gcda
 RUN: not llvm-cov test.c -gcda=test_func_checksum_fail.gcda
 
 XFAIL: powerpc64, s390x, mips, sparc