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[rfc, ppc64] Support "generic" vector ABI
- From: "Ulrich Weigand" <uweigand at de dot ibm dot com>
- To: gdb-patches at sourceware dot org
- Date: Fri, 11 Mar 2011 23:51:20 +0100 (CET)
- Subject: [rfc, ppc64] Support "generic" vector ABI
Hello,
the altivec-abi.exp test case results in a number of failures for
the "generic" variant on 64-bit PowerPC Linux, when using a current
compiler (4.3 or newer).
It turns out this is because ppc-sysv-tdep.c actually does not
support "generic" vectors at all for the 64-bit case; it always
treats all vectors as AltiVec.
This used to work, because GCC 4.1 and 4.2 likewise had a bug that
made -mabi=no-altivec a complete no-op: even in the presence of
this flag, the compiler would treat vectors as AltiVec.
Now this has been fixed with GCC 4.3, see the bugzilla:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34526
which causes GDB to fail on those cases now.
The following patch adds support for "generic" vectors in ppc64,
as implemented by GCC versions >= 4.3. Since this would now
cause failures on GCC 4.1 or 4.2, I've added a check in the
test case to skip the "generic" tests on those compilers.
I've also added an additional run "generic ABI, auto" to better
test automatic detection on 32-bit; this used to be redundant
since the GCC would default to the generic case, but the GCC
patch refered to above also changed the 32-bit default to
-mabi=altivec. The additional test now makes sure both
generic and AltiVec cases are tested, no matter what the
GCC default is.
Note that in the 64-bit generic case, vectors are returned by
reference. This caused three failures in the test suite; two
of them are fixed by this additional patch:
http://sourceware.org/ml/gdb-patches/2011-03/msg00687.html
and the final one is resolved by changing the test, see below.
Tested with no regressions on powerpc64-linux with -m32 and -m64,
both on a GCC 4.1 and a GCC 4.4 based system.
Any comments? I'm planning to commit this in a couple of days ...
Bye,
Ulrich
ChangeLog:
gdb/
* ppc-sysv-tdep.c (ppc64_sysv_abi_push_dummy_call): Add support
for the "generic" vector ABI used with GCC 4.3 and later.
(ppc64_sysv_abi_return_value): Likewise.
gdb/testsuite:
* gdb.arch/altivec-abi.exp: Skip "generic" tests on 64-bit when
using a GCC 4.1 or 4.2 compiler. Add an additional test variant
"generic ABI, auto".
(altivec_abi_tests): Accept vectors returned by reference.
Index: gdb/ppc-sysv-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/ppc-sysv-tdep.c,v
retrieving revision 1.62
diff -u -p -r1.62 ppc-sysv-tdep.c
--- gdb/ppc-sysv-tdep.c 8 Feb 2011 13:30:08 -0000 1.62
+++ gdb/ppc-sysv-tdep.c 11 Mar 2011 20:25:04 -0000
@@ -1119,6 +1119,9 @@ ppc64_sysv_abi_push_dummy_call (struct g
ULONGEST back_chain;
/* See for-loop comment below. */
int write_pass;
+ /* Size of the by-reference parameter copy region, the final value is
+ computed in the for-loop below. */
+ LONGEST refparam_size = 0;
/* Size of the general parameter region, the final value is computed
in the for-loop below. */
LONGEST gparam_size = 0;
@@ -1171,19 +1174,26 @@ ppc64_sysv_abi_push_dummy_call (struct g
/* The address, at which the next general purpose parameter
(integer, struct, float, vector, ...) should be saved. */
CORE_ADDR gparam;
+ /* The address, at which the next by-reference parameter
+ (non-Altivec vector, variably-sized type) should be saved. */
+ CORE_ADDR refparam;
if (!write_pass)
{
- /* During the first pass, GPARAM is more like an offset
- (start address zero) than an address. That way it
- accumulates the total stack space required. */
+ /* During the first pass, GPARAM and REFPARAM are more like
+ offsets (start address zero) than addresses. That way
+ they accumulate the total stack space each region
+ requires. */
gparam = 0;
+ refparam = 0;
}
else
{
- /* Decrement the stack pointer making space for the on-stack
- stack parameters. Set gparam to that region. */
- gparam = align_down (sp - gparam_size, 16);
+ /* Decrement the stack pointer making space for the Altivec
+ and general on-stack parameters. Set refparam and gparam
+ to their corresponding regions. */
+ refparam = align_down (sp - refparam_size, 16);
+ gparam = align_down (refparam - gparam_size, 16);
/* Add in space for the TOC, link editor double word,
compiler double word, LR save area, CR save area. */
sp = align_down (gparam - 48, 16);
@@ -1462,7 +1472,7 @@ ppc64_sysv_abi_push_dummy_call (struct g
}
else if (TYPE_LENGTH (type) == 16 && TYPE_VECTOR (type)
&& TYPE_CODE (type) == TYPE_CODE_ARRAY
- && tdep->ppc_vr0_regnum >= 0)
+ && tdep->vector_abi == POWERPC_VEC_ALTIVEC)
{
/* In the Altivec ABI, vectors go in the vector registers
v2 .. v13, as well as the parameter area -- always at
@@ -1484,6 +1494,30 @@ ppc64_sysv_abi_push_dummy_call (struct g
vreg++;
gparam += 16;
}
+ else if (TYPE_LENGTH (type) >= 16 && TYPE_VECTOR (type)
+ && TYPE_CODE (type) == TYPE_CODE_ARRAY)
+ {
+ /* Non-Altivec vectors are passed by reference. */
+
+ /* Copy value onto the stack ... */
+ refparam = align_up (refparam, 16);
+ if (write_pass)
+ write_memory (refparam, val, TYPE_LENGTH (type));
+
+ /* ... and pass a pointer to the copy as parameter. */
+ if (write_pass)
+ {
+ if (greg <= 10)
+ regcache_cooked_write_unsigned (regcache,
+ tdep->ppc_gp0_regnum +
+ greg, refparam);
+ write_memory_unsigned_integer (gparam, tdep->wordsize,
+ byte_order, refparam);
+ }
+ greg++;
+ gparam = align_up (gparam + tdep->wordsize, tdep->wordsize);
+ refparam = align_up (refparam + TYPE_LENGTH (type), tdep->wordsize);
+ }
else if ((TYPE_CODE (type) == TYPE_CODE_INT
|| TYPE_CODE (type) == TYPE_CODE_ENUM
|| TYPE_CODE (type) == TYPE_CODE_BOOL
@@ -1625,8 +1659,9 @@ ppc64_sysv_abi_push_dummy_call (struct g
if (!write_pass)
{
- /* Save the true region sizes ready for the second pass.
- Make certain that the general parameter save area is at
+ /* Save the true region sizes ready for the second pass. */
+ refparam_size = refparam;
+ /* Make certain that the general parameter save area is at
least the minimum 8 registers (or doublewords) in size. */
if (greg < 8)
gparam_size = 8 * tdep->wordsize;
@@ -1849,7 +1884,8 @@ ppc64_sysv_abi_return_value (struct gdba
}
/* A VMX vector is returned in v2. */
if (TYPE_CODE (valtype) == TYPE_CODE_ARRAY
- && TYPE_VECTOR (valtype) && tdep->ppc_vr0_regnum >= 0)
+ && TYPE_VECTOR (valtype)
+ && tdep->vector_abi == POWERPC_VEC_ALTIVEC)
{
if (readbuf)
regcache_cooked_read (regcache, tdep->ppc_vr0_regnum + 2, readbuf);
Index: gdb/testsuite/gdb.arch/altivec-abi.exp
===================================================================
RCS file: /cvs/src/src/gdb/testsuite/gdb.arch/altivec-abi.exp,v
retrieving revision 1.24
diff -u -p -r1.24 altivec-abi.exp
--- gdb/testsuite/gdb.arch/altivec-abi.exp 8 Feb 2011 13:25:01 -0000 1.24
+++ gdb/testsuite/gdb.arch/altivec-abi.exp 11 Mar 2011 20:25:04 -0000
@@ -118,8 +118,17 @@ proc altivec_abi_tests { extra_flags for
append pattern2 " at.*altivec-abi.c.*main.*result = vec_func .vshort,.*goes in v2.*Value returned is.*= .14, 36, 58, 80."
# Let's see if the result is returned correctly.
- gdb_test "finish" "Run till exit from .0.*$pattern2" \
- "vector value returned correctly"
+ set message "vector value returned correctly"
+ gdb_test_multiple "finish" $message {
+ -re "Run till exit from .0.*$pattern2.*$gdb_prompt $" {
+ pass $message
+ }
+ -re "Run till exit from .0.*Cannot determine contents.*$gdb_prompt $" {
+ # This happens in those cases where the vector is returned by
+ # reference (generic vectors on 64-bit GNU/Linux).
+ pass $message
+ }
+ }
# can we print the args correctly for this function?
gdb_test "break struct_of_vector_func" "" ""
@@ -150,9 +159,17 @@ if [test_compiler_info gcc*] {
# On GNU/Linux, we can mix -mabi=no-altivec and -mabi=altivec.
# So test some combinations.
if { [istarget "powerpc*-linux*"] } {
- set binfile ${objdir}/${subdir}/${testfile}-ge-ge
- set pf_prefix "${saved_prefix} generic ABI, forced:"
- altivec_abi_tests "additional_flags=-maltivec additional_flags=-mabi=no-altivec" "generic"
+ # On 64-bit GNU/Linux with GCC 4.1 and 4.2, -mabi=no-altivec
+ # was broken, so skip those tests there.
+ if { ![is_lp64_target] || ![test_compiler_info "gcc-4-\[12\]-*"] } {
+ set binfile ${objdir}/${subdir}/${testfile}-ge-ge
+ set pf_prefix "${saved_prefix} generic ABI, forced:"
+ altivec_abi_tests "additional_flags=-maltivec additional_flags=-mabi=no-altivec" "generic"
+
+ set binfile ${objdir}/${subdir}/${testfile}-ge-auto
+ set pf_prefix "${saved_prefix} generic ABI, auto:"
+ altivec_abi_tests "additional_flags=-maltivec additional_flags=-mabi=no-altivec" "auto"
+ }
set binfile ${objdir}/${subdir}/${testfile}-av-av
set pf_prefix "${saved_prefix} AltiVec ABI, forced:"
--
Dr. Ulrich Weigand
GNU Toolchain for Linux on System z and Cell BE
Ulrich.Weigand@de.ibm.com