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(175.177.45.181 with ) by smtp5007.mail.kks.ynwp.yahoo.co.jp with SMTP; 1 Sep 2022 05:50:32 -0000 X-YMail-JAS: 9YLsIacVM1mZWLhetfnF5MFKCihWQUSEn990WsIhL80XCajopVtikhRF.G8N9OJzW5y1iF50wt8EzfG3I6EoyIiZLwOixwdCk2qEiVfHzlXpNoSgpNnPnj__k6gmAP12azUQIr4MxQ-- X-Apparently-From: X-YMail-OSG: 8Cj2g7gVM1nVrcjs5l6HoHqMqIFChaNPVc7ywss7cEzoVAN Qjy3XZOKiZSXxDhsS7ksqmTSwvye_Vsy33BrqWJ5Ei7zv_4e8PUf7wC5syex rlRcjIuH6Zncd7r6uWur0wRvZ_h02KV6KMGpCWcDdcMk5Uh8ncbfmpMENQXA 0qMgQl2I.L1EZudCAEAK4sBC6Cqgak0IDSIGlGNYttbSLb51l.TV4e_z6J3Y COEOb.vz8wJsIU_E2RI59UfxL7Tn1ADpvTbpB_F0A0PmRclzarE95iYbp5ID KeTaNdt0u.3AnrnGyB3nUiKLFBGTWcuGuhQQ72UWRW_oVJwzMyMT.uJjZX4u Ox.CEanDgXOk5wevaY300R7d3MjcJwV7sGLEsoSJwjAK8G5D1.9846coFC6W EWpw6bhqQ4iF3tzlci0XWeaWiu0G9xpuHdCW9QORcdt6SiNuKFWfq_GlD31E Syk9DlxtBq4gMSC7tUwJY3FqfCb62q41ccnwd6yAQRB2U6TLARmDpV0eQCuz 7bt22nXhK9.wNmtSIzgjyO77pNt0VBJEdvLfGWrk_XY1Me38G534u9JuGDxZ tzjWjx1suTkcXSODYOZVwzoWwPt7ComRuNS6Ug4aW_OCuyrUJRLYbP2L76Eh bhxMX2QyQOD3sxNkJT6TCfj2eCl3AqUNYEdiDeu_sTaGPsQsr1iYk6kVId0_ BFSgGgeLiC5IwxMs5W27gHd6x0oYj6ej47_LOPCU78uFVsOoSd7kvnKfl1CW iEEESR0.eneSR5SzYC0hh00fwQjtZ68ZXx5NdCJKwHXoKOCGnYhUiDIi0pTx lF1HzKDcTRyVi1yZHnQljAOb0L6s2xu9uJcfk8EJIr7mCJ9xeGuVPDM2CHmc hqpr9bIW2vigMn6lhlW1zDUidqan8AfeZpWRWSBO_47XrTLjPK6FnGAikegb qcxJVE8CQcsee5xROTQ-- Message-ID: Date: Thu, 1 Sep 2022 14:47:11 +0900 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.1 To: GCC Patches Subject: [PATCH 1/2] xtensa: Eliminate unused stack frame allocation/freeing X-Spam-Status: No, score=-12.8 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_ENVFROM_END_DIGIT, FREEMAIL_FROM, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Takayuki 'January June' Suwa via Gcc-patches From: Takayuki 'January June' Suwa Reply-To: Takayuki 'January June' Suwa Errors-To: gcc-patches-bounces+patchwork=sourceware.org@gcc.gnu.org Sender: "Gcc-patches" In the example below, 'x' is once placed on the stack frame and then read into registers as the argument value of bar(): /* example */ struct foo { int a, b; }; extern struct foo bar(struct foo); struct foo test(void) { struct foo x = { 0, 1 }; return bar(x); } Thanks to the dead store elimination, the initialization of 'x' turns into merely loading the immediates to registers, but corresponding stack frame growth is not rolled back. As a result: ;; prereq: the CALL0 ABI ;; before test: addi sp, sp, -16 // unused stack frame allocation/freeing movi.n a2, 0 movi.n a3, 1 addi sp, sp, 16 // because no instructions that refer to j.l bar, a9 // the stack pointer between the two This patch eliminates such unused stack frame allocation/freeing: ;; after test: movi.n a2, 0 movi.n a3, 1 j.l bar, a9 gcc/ChangeLog: * config/xtensa/xtensa.cc (machine_function): New member to track the insns for stack pointer adjustment inside of the pro/epilogue. (xtensa_emit_adjust_stack_pointer): New function to share the common codes and to record the insns for stack pointer adjustment. (xtensa_expand_prologue): Change to use the function mentioned above when using the CALL0 ABI. (xtensa_expand_prologue): Ditto. And also change to cancel emitting the insns for the stack pointer adjustment if only used for its own. --- gcc/config/xtensa/xtensa.cc | 221 ++++++++++++++++++------------------ 1 file changed, 110 insertions(+), 111 deletions(-) diff --git a/gcc/config/xtensa/xtensa.cc b/gcc/config/xtensa/xtensa.cc index b673b6764da..cd509876fd2 100644 --- a/gcc/config/xtensa/xtensa.cc +++ b/gcc/config/xtensa/xtensa.cc @@ -102,6 +102,7 @@ struct GTY(()) machine_function int callee_save_size; bool frame_laid_out; bool epilogue_done; + hash_set *logues_a1_adjusts; }; /* Vector, indexed by hard register number, which contains 1 for a @@ -3048,7 +3049,7 @@ xtensa_output_literal (FILE *file, rtx x, machine_mode mode, int labelno) } static bool -xtensa_call_save_reg(int regno) +xtensa_call_save_reg (int regno) { if (TARGET_WINDOWED_ABI) return false; @@ -3084,7 +3085,7 @@ compute_frame_size (poly_int64 size) cfun->machine->callee_save_size = 0; for (regno = 0; regno < FIRST_PSEUDO_REGISTER; ++regno) { - if (xtensa_call_save_reg(regno)) + if (xtensa_call_save_reg (regno)) cfun->machine->callee_save_size += UNITS_PER_WORD; } @@ -3143,6 +3144,49 @@ xtensa_initial_elimination_offset (int from, int to ATTRIBUTE_UNUSED) and the total number of words must be a multiple of 128 bits. */ #define MIN_FRAME_SIZE (8 * UNITS_PER_WORD) +static rtx_insn * +xtensa_emit_adjust_stack_pointer (HOST_WIDE_INT offset, bool need_note) +{ + rtx_insn *insn; + + if (xtensa_simm8 (offset) + || xtensa_simm8x256 (offset)) + insn = emit_insn (gen_addsi3 (stack_pointer_rtx, stack_pointer_rtx, + GEN_INT (offset))); + else + { + rtx tmp_reg = gen_rtx_REG (Pmode, A9_REG); + rtx_insn* tmp_insn; + + if (offset < 0) + { + tmp_insn = emit_move_insn (tmp_reg, GEN_INT (-offset)); + insn = emit_insn (gen_subsi3 (stack_pointer_rtx, stack_pointer_rtx, + tmp_reg)); + } + else + { + tmp_insn = emit_move_insn (tmp_reg, GEN_INT (offset)); + insn = emit_insn (gen_addsi3 (stack_pointer_rtx, stack_pointer_rtx, + tmp_reg)); + } + cfun->machine->logues_a1_adjusts->add (tmp_insn); + } + + if (need_note) + { + rtx note_rtx = gen_rtx_SET (stack_pointer_rtx, + plus_constant (Pmode, stack_pointer_rtx, + offset)); + + RTX_FRAME_RELATED_P (insn) = 1; + add_reg_note (insn, REG_FRAME_RELATED_EXPR, note_rtx); + } + + cfun->machine->logues_a1_adjusts->add (insn); + return insn; +} + void xtensa_expand_prologue (void) { @@ -3175,16 +3219,12 @@ xtensa_expand_prologue (void) HOST_WIDE_INT offset = 0; int callee_save_size = cfun->machine->callee_save_size; + cfun->machine->logues_a1_adjusts = new hash_set; + /* -128 is a limit of single addi instruction. */ if (IN_RANGE (total_size, 1, 128)) { - insn = emit_insn (gen_addsi3 (stack_pointer_rtx, stack_pointer_rtx, - GEN_INT (-total_size))); - RTX_FRAME_RELATED_P (insn) = 1; - note_rtx = gen_rtx_SET (stack_pointer_rtx, - plus_constant (Pmode, stack_pointer_rtx, - -total_size)); - add_reg_note (insn, REG_FRAME_RELATED_EXPR, note_rtx); + insn = xtensa_emit_adjust_stack_pointer (-total_size, true); offset = total_size - UNITS_PER_WORD; } else if (callee_save_size) @@ -3194,75 +3234,34 @@ xtensa_expand_prologue (void) * move it to its final location. */ if (total_size > 1024) { - insn = emit_insn (gen_addsi3 (stack_pointer_rtx, stack_pointer_rtx, - GEN_INT (-callee_save_size))); - RTX_FRAME_RELATED_P (insn) = 1; - note_rtx = gen_rtx_SET (stack_pointer_rtx, - plus_constant (Pmode, stack_pointer_rtx, - -callee_save_size)); - add_reg_note (insn, REG_FRAME_RELATED_EXPR, note_rtx); + insn = xtensa_emit_adjust_stack_pointer (-callee_save_size, + true); offset = callee_save_size - UNITS_PER_WORD; } else { - if (xtensa_simm8x256 (-total_size)) - insn = emit_insn (gen_addsi3 (stack_pointer_rtx, - stack_pointer_rtx, - GEN_INT (-total_size))); - else - { - rtx tmp_reg = gen_rtx_REG (Pmode, A9_REG); - emit_move_insn (tmp_reg, GEN_INT (total_size)); - insn = emit_insn (gen_subsi3 (stack_pointer_rtx, - stack_pointer_rtx, tmp_reg)); - } - RTX_FRAME_RELATED_P (insn) = 1; - note_rtx = gen_rtx_SET (stack_pointer_rtx, - plus_constant (Pmode, stack_pointer_rtx, - -total_size)); - add_reg_note (insn, REG_FRAME_RELATED_EXPR, note_rtx); + insn = xtensa_emit_adjust_stack_pointer (-total_size, true); offset = total_size - UNITS_PER_WORD; } } for (regno = 0; regno < FIRST_PSEUDO_REGISTER; ++regno) - { - if (xtensa_call_save_reg(regno)) - { - rtx x = gen_rtx_PLUS (Pmode, stack_pointer_rtx, GEN_INT (offset)); - rtx mem = gen_frame_mem (SImode, x); - rtx reg = gen_rtx_REG (SImode, regno); - - offset -= UNITS_PER_WORD; - insn = emit_move_insn (mem, reg); - RTX_FRAME_RELATED_P (insn) = 1; - add_reg_note (insn, REG_FRAME_RELATED_EXPR, - gen_rtx_SET (mem, reg)); - } - } + if (xtensa_call_save_reg (regno)) + { + rtx x = gen_rtx_PLUS (Pmode, stack_pointer_rtx, GEN_INT (offset)); + rtx mem = gen_frame_mem (SImode, x); + rtx reg = gen_rtx_REG (SImode, regno); + + offset -= UNITS_PER_WORD; + insn = emit_move_insn (mem, reg); + RTX_FRAME_RELATED_P (insn) = 1; + add_reg_note (insn, REG_FRAME_RELATED_EXPR, + gen_rtx_SET (mem, reg)); + } if (total_size > 1024 || (!callee_save_size && total_size > 128)) - { - if (xtensa_simm8x256 (callee_save_size - total_size)) - insn = emit_insn (gen_addsi3 (stack_pointer_rtx, - stack_pointer_rtx, - GEN_INT (callee_save_size - - total_size))); - else - { - rtx tmp_reg = gen_rtx_REG (Pmode, A9_REG); - emit_move_insn (tmp_reg, GEN_INT (total_size - - callee_save_size)); - insn = emit_insn (gen_subsi3 (stack_pointer_rtx, - stack_pointer_rtx, tmp_reg)); - } - RTX_FRAME_RELATED_P (insn) = 1; - note_rtx = gen_rtx_SET (stack_pointer_rtx, - plus_constant (Pmode, stack_pointer_rtx, - callee_save_size - - total_size)); - add_reg_note (insn, REG_FRAME_RELATED_EXPR, note_rtx); - } + insn = xtensa_emit_adjust_stack_pointer (callee_save_size - total_size, + true); } if (frame_pointer_needed) @@ -3326,24 +3325,14 @@ xtensa_expand_epilogue (bool sibcall_p) { int regno; HOST_WIDE_INT offset; + df_ref ref; + bool stack_pointer_used = false; if (cfun->machine->current_frame_size > (frame_pointer_needed ? 127 : 1024)) { - if (xtensa_simm8x256 (cfun->machine->current_frame_size - - cfun->machine->callee_save_size)) - emit_insn (gen_addsi3 (stack_pointer_rtx, frame_pointer_needed ? - hard_frame_pointer_rtx : stack_pointer_rtx, - GEN_INT (cfun->machine->current_frame_size - - cfun->machine->callee_save_size))); - else - { - rtx tmp_reg = gen_rtx_REG (Pmode, A9_REG); - emit_move_insn (tmp_reg, GEN_INT (cfun->machine->current_frame_size - - cfun->machine->callee_save_size)); - emit_insn (gen_addsi3 (stack_pointer_rtx, frame_pointer_needed ? - hard_frame_pointer_rtx : stack_pointer_rtx, - tmp_reg)); - } + xtensa_emit_adjust_stack_pointer (cfun->machine->current_frame_size - + cfun->machine->callee_save_size, + false); offset = cfun->machine->callee_save_size - UNITS_PER_WORD; } else @@ -3359,19 +3348,18 @@ xtensa_expand_epilogue (bool sibcall_p) emit_insn (gen_blockage ()); for (regno = 0; regno < FIRST_PSEUDO_REGISTER; ++regno) - { - if (xtensa_call_save_reg(regno)) - { - rtx x = gen_rtx_PLUS (Pmode, stack_pointer_rtx, GEN_INT (offset)); - rtx reg; - - offset -= UNITS_PER_WORD; - emit_move_insn (reg = gen_rtx_REG (SImode, regno), - gen_frame_mem (SImode, x)); - if (regno == A0_REG && sibcall_p) - emit_use (reg); - } - } + if (xtensa_call_save_reg (regno)) + { + rtx x = gen_rtx_PLUS (Pmode, stack_pointer_rtx, GEN_INT (offset)); + rtx reg; + + offset -= UNITS_PER_WORD; + emit_move_insn (reg = gen_rtx_REG (SImode, regno), + gen_frame_mem (SImode, x)); + if (regno == A0_REG && sibcall_p) + emit_use (reg); + stack_pointer_used = true; + } if (cfun->machine->current_frame_size > 0) { @@ -3384,31 +3372,42 @@ xtensa_expand_epilogue (bool sibcall_p) else offset = cfun->machine->callee_save_size; if (offset) - emit_insn (gen_addsi3 (stack_pointer_rtx, - stack_pointer_rtx, - GEN_INT (offset))); + xtensa_emit_adjust_stack_pointer (offset, false); } else - { - if (xtensa_simm8x256 (cfun->machine->current_frame_size)) - emit_insn (gen_addsi3 (stack_pointer_rtx, stack_pointer_rtx, - GEN_INT (cfun->machine->current_frame_size))); - else - { - rtx tmp_reg = gen_rtx_REG (Pmode, A9_REG); - emit_move_insn (tmp_reg, - GEN_INT (cfun->machine->current_frame_size)); - emit_insn (gen_addsi3 (stack_pointer_rtx, stack_pointer_rtx, - tmp_reg)); - } - } + xtensa_emit_adjust_stack_pointer (cfun->machine->current_frame_size, + false); } if (crtl->calls_eh_return) emit_insn (gen_add3_insn (stack_pointer_rtx, stack_pointer_rtx, EH_RETURN_STACKADJ_RTX)); + + /* Check if the function body uses the stack pointer. */ + for (ref = DF_REG_USE_CHAIN (A1_REG); + ref; ref = DF_REF_NEXT_REG (ref)) + if (DF_REF_CLASS (ref) == DF_REF_REGULAR) + { + stack_pointer_used = true; + break; + } + + /* Undo the insns if the stack pointer is only used for its own + adjustment. */ + if (! (stack_pointer_used + || frame_pointer_needed + || crtl->calls_eh_return)) + for (const auto &insn : *cfun->machine->logues_a1_adjusts) + { + rtx note = find_reg_note (insn, REG_FRAME_RELATED_EXPR, NULL); + + if (note) + remove_note (insn, note); + PATTERN (insn) = const0_rtx; + } } + cfun->machine->epilogue_done = true; if (!sibcall_p) emit_jump_insn (gen_return ());