On Tue, Nov 28, 2023 at 03:56:47PM +0800, juzhe.zh...@rivai.ai wrote:
> Hi, there is a regression in RISC-V caused by this patch:
>
> FAIL: gcc.dg/vect/pr111754.c -flto -ffat-lto-objects scan-tree-dump
> optimized "return { 0.0, 9.0e\\+0, 0.0, 0.0 }"
> FAIL: gcc.dg/vect/pr111754.c scan-tree-dump optimized "return { 0.0,
> 9.0e\\+0, 0.0, 0.0 }"
>
> I have checked the dump is :
> F foo (F a, F b)
> {
> <bb 2> [local count: 1073741824]:
> <retval> = { 0.0, 9.0e+0, 0.0, 0.0 };
> return <retval>;
>
> }
>
> The dump IR seems reasonable to me.
> I wonder whether we should walk around in RISC-V backend to generate the same
> IR as ARM SVE ?
> Or we should adjust the test ?
Note, the test also FAILs on i686-linux (but not e.g. on x86_64-linux):
/home/jakub/src/gcc/obj67/gcc/xgcc -B/home/jakub/src/gcc/obj67/gcc/
/home/jakub/src/gcc/gcc/testsuite/gcc.dg/vect/pr111754.c
-fdiagnostics-plain-output -O2 -fdump-tree-optimized -S -o pr111754.s
/home/jakub/src/gcc/gcc/testsuite/gcc.dg/vect/pr111754.c: In function 'foo':
/home/jakub/src/gcc/gcc/testsuite/gcc.dg/vect/pr111754.c:7:1: warning: SSE
vector return without SSE enabled changes the ABI [-Wpsabi]
/home/jakub/src/gcc/gcc/testsuite/gcc.dg/vect/pr111754.c:6:3: note: the ABI for
passing parameters with 16-byte alignment has changed in GCC 4.6
/home/jakub/src/gcc/gcc/testsuite/gcc.dg/vect/pr111754.c:6:3: warning: SSE
vector argument without SSE enabled changes the ABI [-Wpsabi]
FAIL: gcc.dg/vect/pr111754.c (test for excess errors)
Excess errors:
/home/jakub/src/gcc/gcc/testsuite/gcc.dg/vect/pr111754.c:7:1: warning: SSE
vector return without SSE enabled changes the ABI [-Wpsabi]
/home/jakub/src/gcc/gcc/testsuite/gcc.dg/vect/pr111754.c:6:3: warning: SSE
vector argument without SSE enabled changes the ABI [-Wpsabi]
PASS: gcc.dg/vect/pr111754.c scan-tree-dump-not optimized "VEC_PERM_EXPR"
FAIL: gcc.dg/vect/pr111754.c scan-tree-dump optimized "return { 0.0, 9.0e\\+0,
0.0, 0.0 }"
So, I think it is wrong to specify
/* { dg-options "-O2 -fdump-tree-optimized" } */
in the test, should be dg-additional-options instead, so that it gets
the implied vector compilation options e.g. for i686-linux (-msse2 in that
case at least), question is if -Wno-psabi should be added as well or not,
and certainly the scan-tree-dump needs to be guarded by appropriate
vect_* effective target (but dunno which, one which asserts support for
V4SFmode and returning it).
Alternatively, perhaps don't check optimized dump but some earlier one
before generic vector lowering, then hopefully it could match on all
targets? Maybe with the <retval> = ... vs. return ... variants.
Jakub
