Hi,
Jeff Law <jeffreya...@gmail.com> writes: > On 5/3/23 23:49, guojiufu wrote: >> Hi, >> >> On 2023-05-01 03:00, Jeff Law wrote: >>> On 3/16/23 21:39, Jiufu Guo wrote: >>>> Hi, >>>> >>>> When assigning a parameter to a variable, or assigning a variable to >>>> return value with struct type, and the parameter/return is passed >>>> through registers. >>>> For this kind of case, it would be better to use the nature mode of >>>> the registers to move the content for the assignment. >>>> >>>> As the example code (like code in PR65421): >>>> >>>> typedef struct SA {double a[3];} A; >>>> A ret_arg_pt (A *a) {return *a;} // on ppc64le, expect only 3 lfd(s) >>>> A ret_arg (A a) {return a;} // just empty fun body >>>> void st_arg (A a, A *p) {*p = a;} //only 3 stfd(s) >>>> >>>> Comparing with previous version: >>>> https://gcc.gnu.org/pipermail/gcc-patches/2023-January/609394.html >>>> This version refine code to eliminated reductant code in the sub >>>> routine "move_sub_blocks". >>>> >>>> Bootstrap and regtest pass on ppc64{,le}. >>>> Is this ok for trunk? >>>> >> ... >> >>>> diff --git a/gcc/expr.cc b/gcc/expr.cc >>>> index 15be1c8db99..97a7be9542e 100644 >>>> --- a/gcc/expr.cc >>>> +++ b/gcc/expr.cc >>>> @@ -5559,6 +5559,41 @@ mem_ref_refers_to_non_mem_p (tree ref) >>>> return non_mem_decl_p (base); >>>> } >>>> +/* Sub routine of expand_assignment, invoked when assigning from a >>>> + parameter or assigning to a return val on struct type which may >>>> + be passed through registers. The mode of register is used to >>>> + move the content for the assignment. >>>> + >>>> + This routine generates code for expression FROM which is BLKmode, >>>> + and move the generated content to TO_RTX by su-blocks in SUB_MODE. */ >>>> + >>>> +static void >>>> +move_sub_blocks (rtx to_rtx, tree from, machine_mode sub_mode) >>>> +{ >>>> + gcc_assert (MEM_P (to_rtx)); >>>> + >>>> + HOST_WIDE_INT size = MEM_SIZE (to_rtx).to_constant (); >>> Consider the case of a BLKmode return value. Isn't TO_RTX in this >>> case a BLKmode object? >> >> Thanks for this question! >> >> Yes, the mode of TO_RTX is BLKmode. >> As we know, when the function returns via registers, the mode of >> the `return-rtx` could also be BLKmode. This patch is going to >> improve these kinds of cases. >> >> For example: >> ``` >> typedef struct FLOATS >> { >> double a[3]; >> } FLOATS; >> FLOATS ret_arg_pt (FLOATS *a){return *a;} >> ``` >> >> D.3952 = *a_2(D); //this patch enhance this assignment >> return D.3952; >> >> The mode is BLKmode for the rtx of `D.3952` is BLKmode, and the >> rtx for "DECL_RESULT(current_function_decl)". And the DECL_RESULT >> represents the return registers. > I didn't think MEM_SIZE worked for BLKmode. BUt looking at its > definition, it's pulling the size out of the attributes rather than > from the mode. SO I guess there's a reasonable chance it's going to > work :-) Thanks for point out this! Yes, BLKmode rtx may not always be a MEM. MEM_SIZE is only ok for MEM after the it's known size is computed. Here MEM_SIZE is fine just because it is an stack rtx corresponding to the type of parameter and returns which has been computed. I updated the patch to resolve the conflicts with the trunk, and retest bootstrap&testsuite, and then updated the patch a new version. And this version pass bootstrap and regtest on ppc64{,le}, x86_64. The major change is 'move_sub_blocks' only handles the case when the block size can be move by same submode, or say (size % sub_size) is 0. If no objection, I would committed the new version. BR, Jeff (Jiufu) gcc/ChangeLog: * cfgexpand.cc (expand_used_vars): Update to mark DECL_USEDBY_RETURN_P for returns. * expr.cc (move_sub_blocks): New function. (expand_assignment): Update assignment code about returns/parameters. * function.cc (assign_parm_setup_block): Update to mark DECL_REGS_TO_STACK_P for parameter. * tree-core.h (struct tree_decl_common): Add comment. * tree.h (DECL_USEDBY_RETURN_P): New define. (DECL_REGS_TO_STACK_P): New define. gcc/testsuite/ChangeLog: * gcc.target/powerpc/pr65421-1.c: New test. * gcc.target/powerpc/pr65421-2.c: New test. --- gcc/cfgexpand.cc | 14 +++++ gcc/expr.cc | 62 ++++++++++++++++++++ gcc/function.cc | 3 + gcc/tree-core.h | 4 +- gcc/tree.h | 9 +++ gcc/testsuite/gcc.target/powerpc/pr65421-1.c | 6 ++ gcc/testsuite/gcc.target/powerpc/pr65421-2.c | 33 +++++++++++ 7 files changed, 130 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.target/powerpc/pr65421-1.c create mode 100644 gcc/testsuite/gcc.target/powerpc/pr65421-2.c diff --git a/gcc/cfgexpand.cc b/gcc/cfgexpand.cc index 1a1b26b1c6c..7b6a2216492 100644 --- a/gcc/cfgexpand.cc +++ b/gcc/cfgexpand.cc @@ -2158,6 +2158,20 @@ expand_used_vars (bitmap forced_stack_vars) frame_phase = off ? align - off : 0; } + /* Collect VARs on returns. */ + if (DECL_RESULT (current_function_decl)) + { + edge_iterator ei; + edge e; + FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR_FOR_FN (cfun)->preds) + if (greturn *ret = safe_dyn_cast<greturn *> (*gsi_last_bb (e->src))) + { + tree val = gimple_return_retval (ret); + if (val && VAR_P (val)) + DECL_USEDBY_RETURN_P (val) = 1; + } + } + /* Set TREE_USED on all variables in the local_decls. */ FOR_EACH_LOCAL_DECL (cfun, i, var) TREE_USED (var) = 1; diff --git a/gcc/expr.cc b/gcc/expr.cc index 758dda9ec68..5ed98b477c3 100644 --- a/gcc/expr.cc +++ b/gcc/expr.cc @@ -5556,6 +5556,42 @@ mem_ref_refers_to_non_mem_p (tree ref) return non_mem_decl_p (base); } +/* Sub routine of expand_assignment, invoked when assigning from a + parameter or assigning to a return val on struct type which may + be passed through registers. The mode of register is used to + move the content for the assignment. + + This routine generates code for expression FROM which is BLKmode, + and move the generated content to TO_RTX by su-blocks in SUB_MODE. */ + +static bool +move_sub_blocks (rtx to_rtx, tree from, machine_mode sub_mode) +{ + gcc_assert (MEM_P (to_rtx)); + + HOST_WIDE_INT size = MEM_SIZE (to_rtx).to_constant (); + HOST_WIDE_INT sub_size = GET_MODE_SIZE (sub_mode).to_constant (); + HOST_WIDE_INT len = size / sub_size; + if (size % sub_size != 0) + return false; + + push_temp_slots (); + + rtx from_rtx = expand_expr (from, NULL_RTX, GET_MODE (to_rtx), EXPAND_NORMAL); + for (int i = 0; i < len; i++) + { + rtx temp = gen_reg_rtx (sub_mode); + rtx src = adjust_address (from_rtx, sub_mode, sub_size * i); + rtx dest = adjust_address (to_rtx, sub_mode, sub_size * i); + emit_move_insn (temp, src); + emit_move_insn (dest, temp); + } + + preserve_temp_slots (to_rtx); + pop_temp_slots (); + return true; +} + /* Expand an assignment that stores the value of FROM into TO. If NONTEMPORAL is true, try generating a nontemporal store. */ @@ -6042,6 +6078,32 @@ expand_assignment (tree to, tree from, bool nontemporal) return; } + /* If it is assigning from a struct param which may be passed via registers, + it would be better to use the register's mode to move sub-blocks for the + assignment. */ + if (TREE_CODE (from) == PARM_DECL && mode == BLKmode + && DECL_REGS_TO_STACK_P (from)) + { + rtx parm = DECL_INCOMING_RTL (from); + machine_mode sub_mode + = REG_P (parm) ? word_mode : GET_MODE (XEXP (XVECEXP (parm, 0, 0), 0)); + if (move_sub_blocks (to_rtx, from, sub_mode)) + return; + } + + /* If it is assigning to a struct var which will be returned, and the + function is returning via registers, it would be better to use the + register's mode to move sub-blocks for the assignment. */ + if (VAR_P (to) && DECL_USEDBY_RETURN_P (to) && mode == BLKmode + && TREE_CODE (from) != CONSTRUCTOR + && GET_CODE (DECL_RTL (DECL_RESULT (current_function_decl))) == PARALLEL) + { + rtx ret = DECL_RTL (DECL_RESULT (current_function_decl)); + machine_mode sub_mode = GET_MODE (XEXP (XVECEXP (ret, 0, 0), 0)); + if (move_sub_blocks (to_rtx, from, sub_mode)) + return; + } + /* Compute FROM and store the value in the rtx we got. */ push_temp_slots (); diff --git a/gcc/function.cc b/gcc/function.cc index f0ae641512d..bc291a95b32 100644 --- a/gcc/function.cc +++ b/gcc/function.cc @@ -2990,6 +2990,9 @@ assign_parm_setup_block (struct assign_parm_data_all *all, mem = validize_mem (copy_rtx (stack_parm)); + if (MEM_P (mem) && size != 0 && size % UNITS_PER_WORD == 0) + DECL_REGS_TO_STACK_P (parm) = 1; + /* Handle values in multiple non-contiguous locations. */ if (GET_CODE (entry_parm) == PARALLEL && !MEM_P (mem)) emit_group_store (mem, entry_parm, data->arg.type, size); diff --git a/gcc/tree-core.h b/gcc/tree-core.h index 847f0b1e994..7543f7a57b2 100644 --- a/gcc/tree-core.h +++ b/gcc/tree-core.h @@ -1802,7 +1802,9 @@ struct GTY(()) tree_decl_common { In VAR_DECL, PARM_DECL and RESULT_DECL, this is DECL_HAS_VALUE_EXPR_P. */ unsigned decl_flag_2 : 1; - /* In FIELD_DECL, this is DECL_PADDING_P. */ + /* In FIELD_DECL, this is DECL_PADDING_P + In VAR_DECL, this is DECL_USEDBY_RETURN_P + In PARM_DECL, this is DECL_REGS_TO_STACK_P. */ unsigned decl_flag_3 : 1; /* Logically, these two would go in a theoretical base shared by var and parm decl. */ diff --git a/gcc/tree.h b/gcc/tree.h index 0b72663e6a1..6f8e7cabed3 100644 --- a/gcc/tree.h +++ b/gcc/tree.h @@ -3019,6 +3019,15 @@ extern void decl_value_expr_insert (tree, tree); #define DECL_PADDING_P(NODE) \ (FIELD_DECL_CHECK (NODE)->decl_common.decl_flag_3) +/* Used in a VAR_DECL to indicate that it is used by a return stmt. */ +#define DECL_USEDBY_RETURN_P(NODE) \ + (VAR_DECL_CHECK (NODE)->decl_common.decl_flag_3) + +/* Used in a PARM_DECL to indicate that it is struct parameter passed + by registers totally and stored to stack during setup. */ +#define DECL_REGS_TO_STACK_P(NODE) \ + (PARM_DECL_CHECK (NODE)->decl_common.decl_flag_3) + /* Used in a FIELD_DECL to indicate whether this field is not a flexible array member. This is only valid for the last array type field of a structure. */ diff --git a/gcc/testsuite/gcc.target/powerpc/pr65421-1.c b/gcc/testsuite/gcc.target/powerpc/pr65421-1.c new file mode 100644 index 00000000000..4e1f87f7939 --- /dev/null +++ b/gcc/testsuite/gcc.target/powerpc/pr65421-1.c @@ -0,0 +1,6 @@ +/* PR target/65421 */ +/* { dg-options "-O2" } */ + +typedef struct LARGE {double a[4]; int arr[32];} LARGE; +LARGE foo (LARGE a){return a;} +/* { dg-final { scan-assembler-times {\mmemcpy\M} 1 } } */ diff --git a/gcc/testsuite/gcc.target/powerpc/pr65421-2.c b/gcc/testsuite/gcc.target/powerpc/pr65421-2.c new file mode 100644 index 00000000000..fd5ad542c64 --- /dev/null +++ b/gcc/testsuite/gcc.target/powerpc/pr65421-2.c @@ -0,0 +1,33 @@ +/* PR target/65421 */ +/* { dg-options "-O2" } */ +/* { dg-require-effective-target powerpc_elfv2 } */ +/* { dg-require-effective-target has_arch_ppc64 } */ + +typedef struct FLOATS +{ + double a[3]; +} FLOATS; + +/* 3 lfd */ +FLOATS ret_arg_pt (FLOATS *a){return *a;} +/* { dg-final { scan-assembler-times {\mlfd\M} 3 } } */ + +/* 3 stfd */ +void st_arg (FLOATS a, FLOATS *p) {*p = a;} +/* { dg-final { scan-assembler-times {\mstfd\M} 3 } } */ + +/* blr */ +FLOATS ret_arg (FLOATS a) {return a;} + +typedef struct MIX +{ + double a[2]; + long l; +} MIX; + +/* std 3 param regs to return slot */ +MIX ret_arg1 (MIX a) {return a;} +/* { dg-final { scan-assembler-times {\mstd\M} 3 } } */ + +/* count insns */ +/* { dg-final { scan-assembler-times {(?n)^\s+[a-z]} 13 } } */ -- 2.31.1 > > OK for the trunk. > > jeff