Message ID | 31a32901-1912-988b-c641-1f23093e8563@codesourcery.com |
---|---|
State | New |
Headers | show |
Series | gcn: Add __builtin_gcn_kernarg_ptr | expand |
On 16/11/2022 11:42, Tobias Burnus wrote: > This is a part of a patch by Andrew (hi!) - namely that part that only > adds the > __builtin_gcn_kernarg_ptr. More is planned, see below. > > The short term benefit of this patch is to permit replacing hardcoded > numbers > by a builtin – like in libgomp (see patch) or in newlib (not submitted): > > --- a/newlib/libc/sys/amdgcn/write.c > +++ b/newlib/libc/sys/amdgcn/write.c > @@ -59,1 +59,5 @@ _READ_WRITE_RETURN_TYPE write (int fd, const void > *buf, size_t count) > +#if defined(__has_builtin) && __has_builtin(__builtin_gcn_kernarg_ptr) > + register void **kernargs = __builtin_gcn_kernarg_ptr (); > +#else > register void **kernargs asm("s8"); > +#endif > > It would also replace the 'asm("s8")' in reverse offload (GCN) patch, i.e. > https://gcc.gnu.org/pipermail/gcc-patches/2022-September/602339.html > > > However, this patch is only the very first step. Next one is to add > several additional builtins, namely those that are required for newlib, > i.e. newlib/libc/machine/amdgcn/mlock.c (sbrk) and > newlib/libc/machine/amdgcn/getreent.c (__getreent) use some additional > hard-coded value for heap and stack memory. > > And at some point - but only after newlib has been updated - > we can think of making stack variables non-private. > That's a general goal - and in any case required for reverse > offload to be able to transfer between the host and on-device stack > variables. > > * * * > > Regarding the patch: Besides the obvious change (addition of the builtin), > the change to DEFAULT memory space is required to avoid a memory-space > conversion > ICE when using the new builtin. The gcn_oacc_dim_size change is mainly just > picked from Andrew's patch as it seems to be reasonable. In terms of the > libgomp > testsuite, I did not spot anything except that the -O2 run now does no > longer fail > with "libgomp: target function wasn't mapped" for > libgomp.oacc-fortran/kernels-map-1.f90 - but I am not sure it is related > or not. > > In any case, the libgomp testsuite shows no fails (but the usual fails) > with the attached patch. > > OK for mainline? OK. Andrew > Tobias > > PS: The plan is to have at least all builtins in GCC and use them in > newlib by at > the end of this year (i.e. in newlib's end of year snapshot - aka as annual > release). > > PPS: I wonder whether > [Patch] libgomp/gcn: Prepare for reverse-offload callback handling > https://gcc.gnu.org/pipermail/gcc-patches/2022-September/602339.html > would be okay after this patch - with the asm("s8") replaced by the > builtin - or not. > The code itself would be fine, but it is unreachable until > GOMP_OFFLOAD_get_num_devices accepts reverse offload and the latter depends > on the support for non-private stack variables.
gcn: Add __builtin_gcn_kernarg_ptr Add __builtin_gcn_kernarg_ptr to avoid using hard-coded register values and permit future ABI changes while keeping the API. gcc/ChangeLog: * config/gcn/gcn-builtins.def (KERNARG_PTR): Add. * config/gcn/gcn.cc (gcn_init_builtin_types): Change siptr_type_node, sfptr_type_node and voidptr_type_node from FLAT to ADDR_SPACE_DEFAULT. (gcn_expand_builtin_1): Handle GCN_BUILTIN_KERNARG_PTR. (gcn_oacc_dim_size): Return in ADDR_SPACE_FLAT. libgomp/ChangeLog: * config/gcn/team.c (gomp_gcn_enter_kernel): Use __builtin_gcn_kernarg_ptr instead of asm ("s8"). Co-Authored-By: Andrew Stubbs <ams@codesourcery.com> gcc/config/gcn/gcn-builtins.def | 4 ++++ gcc/config/gcn/gcn.cc | 24 ++++++++++++++++++++---- libgomp/config/gcn/team.c | 2 +- 3 files changed, 25 insertions(+), 5 deletions(-) diff --git a/gcc/config/gcn/gcn-builtins.def b/gcc/config/gcn/gcn-builtins.def index c50777bd..eeeaebf 100644 --- a/gcc/config/gcn/gcn-builtins.def +++ b/gcc/config/gcn/gcn-builtins.def @@ -158,6 +158,10 @@ DEF_BUILTIN (ACC_SINGLE_COPY_END, -1, "single_copy_end", B_INSN, DEF_BUILTIN (ACC_BARRIER, -1, "acc_barrier", B_INSN, _A1 (GCN_BTI_VOID), gcn_expand_builtin_1) +/* Kernel inputs. */ + +DEF_BUILTIN (KERNARG_PTR, -1, "kernarg_ptr", B_INSN, _A1 (GCN_BTI_VOIDPTR), + gcn_expand_builtin_1) #undef _A1 #undef _A2 diff --git a/gcc/config/gcn/gcn.cc b/gcc/config/gcn/gcn.cc index 5e6f3b8..b3814c2 100644 --- a/gcc/config/gcn/gcn.cc +++ b/gcc/config/gcn/gcn.cc @@ -4058,15 +4058,15 @@ gcn_init_builtin_types (void) (integer_type_node) */ , 64); tree tmp = build_distinct_type_copy (intSI_type_node); - TYPE_ADDR_SPACE (tmp) = ADDR_SPACE_FLAT; + TYPE_ADDR_SPACE (tmp) = ADDR_SPACE_DEFAULT; siptr_type_node = build_pointer_type (tmp); tmp = build_distinct_type_copy (float_type_node); - TYPE_ADDR_SPACE (tmp) = ADDR_SPACE_FLAT; + TYPE_ADDR_SPACE (tmp) = ADDR_SPACE_DEFAULT; sfptr_type_node = build_pointer_type (tmp); tmp = build_distinct_type_copy (void_type_node); - TYPE_ADDR_SPACE (tmp) = ADDR_SPACE_FLAT; + TYPE_ADDR_SPACE (tmp) = ADDR_SPACE_DEFAULT; voidptr_type_node = build_pointer_type (tmp); tmp = build_distinct_type_copy (void_type_node); @@ -4493,6 +4493,20 @@ gcn_expand_builtin_1 (tree exp, rtx target, rtx /*subtarget */ , emit_insn (gen_gcn_wavefront_barrier ()); return target; + case GCN_BUILTIN_KERNARG_PTR: + { + rtx ptr; + if (cfun->machine->args.reg[KERNARG_SEGMENT_PTR_ARG] >= 0) + ptr = gen_rtx_REG (DImode, + cfun->machine->args.reg[KERNARG_SEGMENT_PTR_ARG]); + else + { + ptr = gen_reg_rtx (DImode); + emit_move_insn (ptr, const0_rtx); + } + return ptr; + } + default: gcc_unreachable (); } @@ -5700,7 +5714,9 @@ gcn_oacc_dim_size (int dim) cfun->machine->args. reg[DISPATCH_PTR_ARG]), GEN_INT (offset[dim])); - return gen_rtx_MEM (SImode, addr); + rtx mem = gen_rtx_MEM (SImode, addr); + set_mem_addr_space (mem, ADDR_SPACE_SCALAR_FLAT); + return mem; } /* Helper function for oacc_dim_pos instruction. diff --git a/libgomp/config/gcn/team.c b/libgomp/config/gcn/team.c index 254dd4d..4fc7b62 100644 --- a/libgomp/config/gcn/team.c +++ b/libgomp/config/gcn/team.c @@ -60,7 +60,7 @@ gomp_gcn_enter_kernel (void) /* Initialize the team arena for optimized memory allocation. The arena has been allocated on the host side, and the address passed in via the kernargs. Each team takes a small slice of it. */ - register void **kernargs asm("s8"); + void **kernargs = (void**) __builtin_gcn_kernarg_ptr (); void *team_arena = (kernargs[4] + TEAM_ARENA_SIZE*teamid); void * __lds *arena_start = (void * __lds *)TEAM_ARENA_START; void * __lds *arena_free = (void * __lds *)TEAM_ARENA_FREE;