Christophe Lyon <christophe.l...@linaro.org> writes: > On Thu, 13 Aug 2020 at 03:54, qiaopeixin <qiaopei...@huawei.com> wrote: >> >> Thanks for the review and commit. >> >> All the best, >> Peixin >> >> -----Original Message----- >> From: Richard Sandiford [mailto:richard.sandif...@arm.com] >> Sent: 2020年8月13日 0:25 >> To: qiaopeixin <qiaopei...@huawei.com> >> Cc: gcc-patches@gcc.gnu.org >> Subject: Re: [PATCH] AArch64: Add if condition in aarch64_function_value >> [PR96479] >> >> qiaopeixin <qiaopei...@huawei.com> writes: >> > Hi, >> > >> > The test case vector-subscript-2.c in the gcc testsuit will report an ICE >> > in the expand pass since '-mgeneral-regs-only' is incompatible with the >> > use of V4SI mode. I propose to report the diagnostic information instead >> > of ICE, and the problem has been discussed on PR 96479. >> > >> > I attached the patch to solve the problem. Bootstrapped and tested on >> > aarch64-linux-gnu. Any suggestions? >> >> Thanks, pushed. I was initially sceptical because raising an error here and >> in aarch64_layout_arg is a hack. Both functions are just query functions >> and shouldn't have any side effects. >> >> The approach we took for FP modes seemed better: we define the FP move >> patterns unconditionally, and raise an error if we try to emit an FP move >> with !TARGET_FLOAT. This defers any error reporting until we actually try >> to generate code that depends on TARGET_FLOAT. >> >> But I guess SIMD stuff is different. There's no reason in principle why you >> can't use: >> >> unsigned short __attribute__((vector_size(8))) >> >> *within* a function with -mgeneral-regs-only. It would just need to be >> emulated, in the same way as for: >> >> unsigned short __attribute__((vector_size(4))) >> >> So it would be wrong to define the SIMD move patterns unconditionally and >> raise an error there. >> >> So all in all, I agree this is the best we can do given the current >> infrastructure. >> > > Since this patch was committed my buildbot is broken for > aarch64-linux-gnu because it now fails to build glibc-2.29: > ../stdlib/bits/stdlib-float.h: In function 'atof': > ../stdlib/bits/stdlib-float.h:26:1: error: '-mgeneral-regs-only' is > incompatible with the use of floating-point types
Thanks for the heads-up. I've reverted the patch for now. Looking more closely, it seems like aarch64_init_cumulative_args already tries to catch the problem that the patch was fixing: if (!silent_p && !TARGET_FLOAT && fndecl && TREE_PUBLIC (fndecl) && fntype && fntype != error_mark_node) { const_tree type = TREE_TYPE (fntype); machine_mode mode ATTRIBUTE_UNUSED; /* To pass pointer as argument. */ int nregs ATTRIBUTE_UNUSED; /* Likewise. */ if (aarch64_vfp_is_call_or_return_candidate (TYPE_MODE (type), type, &mode, &nregs, NULL, false)) aarch64_err_no_fpadvsimd (TYPE_MODE (type)); } The only reason it doesn't work for the testcase is that TREE_PUBLIC condition. TBH I'm not sure why it or the fndecl test is there: this is just as problematic when calling via a function pointer or when calling a static function. Richard