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GET /api/patches/810072/?format=api
HTTP 200 OK
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{
    "id": 810072,
    "url": "http://patchwork.ozlabs.org/api/patches/810072/?format=api",
    "web_url": "http://patchwork.ozlabs.org/project/gcc/patch/CAFULd4aqW0ic2qQ5z+g4Fz92kO-9tr_9onKzoVoCQ6V+kV4sFA@mail.gmail.com/",
    "project": {
        "id": 17,
        "url": "http://patchwork.ozlabs.org/api/projects/17/?format=api",
        "name": "GNU Compiler Collection",
        "link_name": "gcc",
        "list_id": "gcc-patches.gcc.gnu.org",
        "list_email": "gcc-patches@gcc.gnu.org",
        "web_url": null,
        "scm_url": null,
        "webscm_url": null,
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        "list_archive_url_format": "",
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    },
    "msgid": "<CAFULd4aqW0ic2qQ5z+g4Fz92kO-9tr_9onKzoVoCQ6V+kV4sFA@mail.gmail.com>",
    "list_archive_url": null,
    "date": "2017-09-05T10:26:28",
    "name": "[middle-end] : Introduce memory_blockage named insn pattern",
    "commit_ref": null,
    "pull_url": null,
    "state": "new",
    "archived": false,
    "hash": "150257a2fffd45182d1ef4052d9220f993b5d856",
    "submitter": {
        "id": 808,
        "url": "http://patchwork.ozlabs.org/api/people/808/?format=api",
        "name": "Uros Bizjak",
        "email": "ubizjak@gmail.com"
    },
    "delegate": null,
    "mbox": "http://patchwork.ozlabs.org/project/gcc/patch/CAFULd4aqW0ic2qQ5z+g4Fz92kO-9tr_9onKzoVoCQ6V+kV4sFA@mail.gmail.com/mbox/",
    "series": [
        {
            "id": 1545,
            "url": "http://patchwork.ozlabs.org/api/series/1545/?format=api",
            "web_url": "http://patchwork.ozlabs.org/project/gcc/list/?series=1545",
            "date": "2017-09-05T10:26:28",
            "name": "[middle-end] : Introduce memory_blockage named insn pattern",
            "version": 1,
            "mbox": "http://patchwork.ozlabs.org/series/1545/mbox/"
        }
    ],
    "comments": "http://patchwork.ozlabs.org/api/patches/810072/comments/",
    "check": "pending",
    "checks": "http://patchwork.ozlabs.org/api/patches/810072/checks/",
    "tags": {},
    "related": [],
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        "X-Received": "by 10.176.69.243 with SMTP id u106mr2295646uau.22.1504607188723;\n\tTue, 05 Sep 2017 03:26:28 -0700 (PDT)",
        "MIME-Version": "1.0",
        "From": "Uros Bizjak <ubizjak@gmail.com>",
        "Date": "Tue, 5 Sep 2017 12:26:28 +0200",
        "Message-ID": "<CAFULd4aqW0ic2qQ5z+g4Fz92kO-9tr_9onKzoVoCQ6V+kV4sFA@mail.gmail.com>",
        "Subject": "[PATCH, middle-end]: Introduce memory_blockage named insn pattern",
        "To": "\"gcc-patches@gcc.gnu.org\" <gcc-patches@gcc.gnu.org>",
        "Content-Type": "multipart/mixed; boundary=\"94eb2c11be7402c07305586ea973\""
    },
    "content": "Hello!\n\nThis patch allows to emit memory_blockage pattern instead of default\nasm volatile as a memory blockage. This patch is needed, so targets\n(e.g. x86) can define and emit more optimal memory blockage pseudo\ninsn. And let's call scheduler memory barriers a \"memory blockage\"\npseudo insn, not \"memory barrier\" which should describe real\ninstruction.\n\n2017-09-05  Uros Bizjak  <ubizjak@gmail.com>\n\n    * optabs.c (expand_memory_blockage): New function.\n    (expand_asm_memory_barrier): Rename ...\n    (expand_asm_memory_blockage): ... to this.\n    (expand_mem_thread_fence): Call expand_memory_blockage\n    instead of expand_asm_memory_barrier.\n    (expand_mem_singnal_fence): Ditto.\n    (expand_atomic_load): Ditto.\n    (expand_atomic_store): Ditto.\n    * doc/md.texi (Standard Pattern Names For Generation):\n    Document memory_blockage instruction pattern.\n\nBootstrapped on x86_64-linux-gnu, regression test (with additional x86\npatch that fixes recent optimization regression with FP atomic loads)\nis in progress.\n\nOK for mainline?\n\nUros.",
    "diff": "diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi\nindex 14aab9474bc2..df4dc8ccd0e1 100644\n--- a/gcc/doc/md.texi\n+++ b/gcc/doc/md.texi\n@@ -6734,6 +6734,13 @@ scheduler and other passes from moving instructions and using register\n equivalences across the boundary defined by the blockage insn.\n This needs to be an UNSPEC_VOLATILE pattern or a volatile ASM.\n \n+@cindex @code{memmory_blockage} instruction pattern\n+@item @samp{memory_blockage}\n+This pattern defines a pseudo insn that prevents the instruction\n+scheduler and other passes from moving instructions accessing memory\n+across the boundary defined by the blockage insn.  This instruction\n+needs to read and write volatile BLKmode memory.\n+\n @cindex @code{memory_barrier} instruction pattern\n @item @samp{memory_barrier}\n If the target memory model is not fully synchronous, then this pattern\ndiff --git a/gcc/optabs.c b/gcc/optabs.c\nindex b65707080eee..c3b1bc848bf7 100644\n--- a/gcc/optabs.c\n+++ b/gcc/optabs.c\n@@ -6276,10 +6276,10 @@ expand_atomic_compare_and_swap (rtx *ptarget_bool, rtx *ptarget_oval,\n   return true;\n }\n \n-/* Generate asm volatile(\"\" : : : \"memory\") as the memory barrier.  */\n+/* Generate asm volatile(\"\" : : : \"memory\") as the memory blockage.  */\n \n static void\n-expand_asm_memory_barrier (void)\n+expand_asm_memory_blockage (void)\n {\n   rtx asm_op, clob;\n \n@@ -6295,6 +6295,18 @@ expand_asm_memory_barrier (void)\n   emit_insn (gen_rtx_PARALLEL (VOIDmode, gen_rtvec (2, asm_op, clob)));\n }\n \n+/* Do not schedule instructions accessing memory across this point.  */\n+\n+static void\n+expand_memory_blockage (void)\n+{\n+#ifdef HAVE_memory_blockage\n+  emit_insn (gen_memory_blockage ());\n+#else\n+  expand_asm_memory_blockage ();\n+#endif\n+}\n+\n /* This routine will either emit the mem_thread_fence pattern or issue a \n    sync_synchronize to generate a fence for memory model MEMMODEL.  */\n \n@@ -6306,14 +6318,14 @@ expand_mem_thread_fence (enum memmodel model)\n   if (targetm.have_mem_thread_fence ())\n     {\n       emit_insn (targetm.gen_mem_thread_fence (GEN_INT (model)));\n-      expand_asm_memory_barrier ();\n+      expand_memory_blockage ();\n     }\n   else if (targetm.have_memory_barrier ())\n     emit_insn (targetm.gen_memory_barrier ());\n   else if (synchronize_libfunc != NULL_RTX)\n     emit_library_call (synchronize_libfunc, LCT_NORMAL, VOIDmode);\n   else\n-    expand_asm_memory_barrier ();\n+    expand_memory_blockage ();\n }\n \n /* Emit a signal fence with given memory model.  */\n@@ -6324,7 +6336,7 @@ expand_mem_signal_fence (enum memmodel model)\n   /* No machine barrier is required to implement a signal fence, but\n      a compiler memory barrier must be issued, except for relaxed MM.  */\n   if (!is_mm_relaxed (model))\n-    expand_asm_memory_barrier ();\n+    expand_memory_blockage ();\n }\n \n /* This function expands the atomic load operation:\n@@ -6346,7 +6358,7 @@ expand_atomic_load (rtx target, rtx mem, enum memmodel model)\n       struct expand_operand ops[3];\n       rtx_insn *last = get_last_insn ();\n       if (is_mm_seq_cst (model))\n-\texpand_asm_memory_barrier ();\n+\texpand_memory_blockage ();\n \n       create_output_operand (&ops[0], target, mode);\n       create_fixed_operand (&ops[1], mem);\n@@ -6354,7 +6366,7 @@ expand_atomic_load (rtx target, rtx mem, enum memmodel model)\n       if (maybe_expand_insn (icode, 3, ops))\n \t{\n \t  if (!is_mm_relaxed (model))\n-\t    expand_asm_memory_barrier ();\n+\t    expand_memory_blockage ();\n \t  return ops[0].value;\n \t}\n       delete_insns_since (last);\n@@ -6404,14 +6416,14 @@ expand_atomic_store (rtx mem, rtx val, enum memmodel model, bool use_release)\n     {\n       rtx_insn *last = get_last_insn ();\n       if (!is_mm_relaxed (model))\n-\texpand_asm_memory_barrier ();\n+\texpand_memory_blockage ();\n       create_fixed_operand (&ops[0], mem);\n       create_input_operand (&ops[1], val, mode);\n       create_integer_operand (&ops[2], model);\n       if (maybe_expand_insn (icode, 3, ops))\n \t{\n \t  if (is_mm_seq_cst (model))\n-\t    expand_asm_memory_barrier ();\n+\t    expand_memory_blockage ();\n \t  return const0_rtx;\n \t}\n       delete_insns_since (last);\n",
    "prefixes": [
        "middle-end"
    ]
}