Re: Several regressions and we branch soon.

[Andreas Arnez <arnez@linux.vnet.ibm.com>]

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