| Message ID | 201407170037.s6H0blC4022458@d06av02.portsmouth.uk.ibm.com |
|---|---|
| State | New |
| Headers | show |
On Wed, Jul 16, 2014 at 8:37 PM, Ulrich Weigand <uweigand@de.ibm.com> wrote: > Hello, > > this is the variant intended for the 4.8/4.9 branches of the patch: > https://gcc.gnu.org/ml/gcc-patches/2014-07/msg00994.html > > As discussed, it does *not* actually change ABI, but only warn when > encountering a situation where the ABI will change in a future GCC. > (Avoiding the specific term "GCC 4.10" here since I'm not certain > whether the next GCC release will in fact be called that ...) > > Tested on powerpc64-linux and powerpc64le-linux; also verified using > the ABI compat suite (against an unpatched GCC) that this patch does > not change the ABI. > > OK for 4.8/4.9 once the mainline patch is in? > > Bye, > Ulrich > > > gcc/ChangeLog: > > * config/rs6000/rs6000.c (rs6000_function_arg): If a float argument > does not fit fully into floating-point registers, and there is still > space in the register parameter area, issue -Wpsabi note that the ABI > will change in a future GCC release. > > gcc/testsuite/ChangeLog: > > * gcc.target/powerpc/ppc64-abi-warn-1.c: New test. This patch is okay if okay with the Release Managers. Thanks, David
On Fri, Jul 18, 2014 at 12:13:09PM -0400, David Edelsohn wrote: > > gcc/ChangeLog: > > > > * config/rs6000/rs6000.c (rs6000_function_arg): If a float argument > > does not fit fully into floating-point registers, and there is still > > space in the register parameter area, issue -Wpsabi note that the ABI > > will change in a future GCC release. > > > > gcc/testsuite/ChangeLog: > > > > * gcc.target/powerpc/ppc64-abi-warn-1.c: New test. > > This patch is okay if okay with the Release Managers. Ok. Jakub
Index: gcc-4_9-branch/gcc/config/rs6000/rs6000.c =================================================================== --- gcc-4_9-branch.orig/gcc/config/rs6000/rs6000.c +++ gcc-4_9-branch/gcc/config/rs6000/rs6000.c @@ -10225,6 +10225,7 @@ rs6000_function_arg (cumulative_args_t c rtx r, off; int i, k = 0; unsigned long n_fpreg = (GET_MODE_SIZE (elt_mode) + 7) >> 3; + int fpr_words; /* Do we also need to pass this argument in the parameter save area? */ @@ -10253,6 +10254,37 @@ rs6000_function_arg (cumulative_args_t c rvec[k++] = gen_rtx_EXPR_LIST (VOIDmode, r, off); } + /* If there were not enough FPRs to hold the argument, the rest + usually goes into memory. However, if the current position + is still within the register parameter area, a portion may + actually have to go into GPRs. + + Note that it may happen that the portion of the argument + passed in the first "half" of the first GPR was already + passed in the last FPR as well. + + For unnamed arguments, we already set up GPRs to cover the + whole argument in rs6000_psave_function_arg, so there is + nothing further to do at this point. + + GCC 4.8/4.9 Note: This was implemented incorrectly in earlier + GCC releases. To avoid any ABI change on the release branch, + we retain that original implementation here, but warn if we + encounter a case where the ABI will change in the future. */ + fpr_words = (i * GET_MODE_SIZE (elt_mode)) / (TARGET_32BIT ? 4 : 8); + if (i < n_elts && align_words + fpr_words < GP_ARG_NUM_REG + && cum->nargs_prototype > 0) + { + static bool warned; + if (!warned && warn_psabi) + { + warned = true; + inform (input_location, + "the ABI of passing homogeneous float aggregates" + " will change in a future GCC release"); + } + } + return rs6000_finish_function_arg (mode, rvec, k); } else if (align_words < GP_ARG_NUM_REG) Index: gcc-4_9-branch/gcc/testsuite/gcc.target/powerpc/ppc64-abi-warn-1.c =================================================================== --- /dev/null +++ gcc-4_9-branch/gcc/testsuite/gcc.target/powerpc/ppc64-abi-warn-1.c @@ -0,0 +1,12 @@ +/* { dg-do compile { target { powerpc*-*-linux* && lp64 } } } */ +/* { dg-options "-mabi=elfv2" } */ + +struct f8 + { + float x[8]; + }; + +void test (struct f8 a, struct f8 b) /* { dg-message "note: the ABI of passing homogeneous float aggregates will change" } */ +{ +} +