Re: Several regressions and we branch soon.

Andreas Arnez
2015-07-20T15:08:49Z

On Fri, Jul 10 2015, Ulrich Weigand wrote:

> Andreas Arnez wrote:
>> On Fri, Jul 10 2015, Yao Qi wrote:
>
>> GCC5 on ppc64le emits the ABI warning even in absence of "-mcpu=".
>> Again it should help to add "-Wno-psabi".
>
> Yes, for ppc64 we definitely should add -Wno-psabi.

OK.

>> Yes. But in this case no vector ABI is used, because that test machine
>> does not have a vector facility and because -march=native is not
>> supported by GCC (yet). Thus vector return values are not passed in
>> vector registers, but according to RETURN_VALUE_STRUCT_CONVENTION. And
>> then we hit the problem that displaying such return values is not
>> supported by GDB: https://sourceware.org/bugzilla/show_bug.cgi?id=8549
>
> Hmm. Since this is a separate problem independent of vector support,
> maybe this test case should accept the failure to display struct return
> values, and pass the test (or maybe KFAIL?).

Sure, that's an option. I prefer KFAIL, such that it's easy to find
(and remove) when the bug is fixed.

Here's a patch for both of the suggested changes. OK to apply?

-- >8 --
Subject: [PATCH] gnu_vector.exp: Avoid some more known FAILs

This avoids two more types of FAILs with the gnu_vector test case.

First, for POWER targets newer GCCs emit an ABI note when invoked with
"-mcpu=native". Then the test case fell back to non-native compile,
producing code for a non-vector ABI. But that is not supported by GDB.
Thus the compiler note is now suppressed with "-Wno-psabi".

Second, on s390 the test case produced FAILs after falling back to a
non-vector ABI when using "finish" or "return" in a vector-valued
function. This was due to a long-standing known bug (Bug 8549). This
case is now detected, and KFAILs are emitted instead.

gdb/testsuite/ChangeLog:

* gdb.base/gnu_vector.exp: Try compilation with "-mcpu=native
-Wno-psabi" if "-mcpu=native" fails. For the tests with "finish"
and "return" use KFAIL when GDB can not read/write the vector
return value.
---
gdb/testsuite/gdb.base/gnu_vector.exp | 57 +++++++++++++++++++++++++++--------
1 file changed, 44 insertions(+), 13 deletions(-)

diff --git a/gdb/testsuite/gdb.base/gnu_vector.exp b/gdb/testsuite/gdb.base/gnu_vector.exp
index 173da4d..0bef3f8 100644
--- a/gdb/testsuite/gdb.base/gnu_vector.exp
+++ b/gdb/testsuite/gdb.base/gnu_vector.exp
@@ -25,11 +25,19 @@ standard_testfile .c
# without a CPU option. If all variants fail, assume that the
# compiler can not handle GNU vectors.

-if { [gdb_compile "${srcdir}/${subdir}/${srcfile}" ${binfile} executable {debug quiet additional_flags=-mcpu=native}] != ""
- && [gdb_compile "${srcdir}/${subdir}/${srcfile}" ${binfile} executable {debug quiet additional_flags=-march=native}] != ""
- && [gdb_compile "${srcdir}/${subdir}/${srcfile}" ${binfile} executable {debug quiet}] != ""} {
- untested "compiler can't handle the vector_size attribute?"
- return -1
+proc do_compile { {opts {}} } {
+ global srcdir subdir srcfile binfile
+ set ccopts {debug quiet}
+ foreach opt $opts {lappend ccopts "additional_flags=$opt"}
+ gdb_compile "${srcdir}/${subdir}/${srcfile}" "$binfile" executable $ccopts
+}
+
+if { [do_compile {-mcpu=native}] != ""
+ && [do_compile {-mcpu=native -Wno-psabi}] != ""
+ && [do_compile {-march=native}] != ""
+ && [do_compile] != ""} {
+ untested "compiler can't handle vector_size attribute?"
+ return -1
}

clean_restart ${binfile}
@@ -195,14 +203,37 @@ gdb_test "print add_structvecs(i2, (struct just_int2)\{2*i2\}, (struct two_int2)
gdb_test "print add_singlevecs((char1) \{6\}, (int1) \{12\}, (double1) \{24\})" "= \\{42\\}" \
"call add_singlevecs"

-# Test vector return value handling with "finish" and "return".
+# Test "finish" from vector-valued function.
gdb_breakpoint "add_some_intvecs"
gdb_continue "add_some_intvecs"
-gdb_test "finish" "Value returned is .* = \\{10, 20, 48, 72\\}" \
- "finish shows vector return value"
+set test "finish shows vector return value"
+gdb_test_multiple "finish" $test {
+ -re "Value returned is .* = \\{10, 20, 48, 72\\}.*$gdb_prompt $" {
+ pass $test
+ }
+ -re "Value returned has type: .* Cannot determine contents.*$gdb_prompt $" {
+ kfail "gdb/8549" $test
+ }
+}
+
+# Test "return" from vector-valued function.
gdb_continue "add_some_intvecs"
-gdb_test "return (int4) \{4, 2, 7, 6\}" \
- "#0 .* main .*" \
- "set vector return value" \
- "Make add_some_intvecs return now. .y or n.*" "y"
-gdb_test "continue" "4 2 7 6\r\n.*" "verify vector return value"
+set test "set vector return value"
+set ok 1
+gdb_test_multiple "return (int4) \{4, 2, 7, 6\}" $test {
+ -re "#0 .* main .*$gdb_prompt $" {
+ if { $ok } {
+ pass $test
+ gdb_test "continue" "4 2 7 6\r\n.*" "verify vector return value"
+ }
+ }
+ -re "The location .* is unknown.\r\n.* return value .* will be ignored.\r\n" {
+ kfail "gdb/8549" $test
+ set ok 0
+ exp_continue
+ }
+ -re "Make add_some_intvecs return now. .y or n. $" {
+ send_gdb "y\n"
+ exp_continue
+ }
+}
--
2.4.6