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Lu" , Jan Beulich , Jan Hubicka , Michael Matz Subject: [PATCH v5] i386: Allow -mlarge-data-threshold with -mcmodel=large Message-ID: <20231016182447.bticawp4aps7tsso@google.com> References: <20230801195104.2183011-1-maskray@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Spam-Status: No, score=-27.4 required=5.0 tests=BAYES_00,DKIMWL_WL_MED,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,ENV_AND_HDR_SPF_MATCH,GIT_PATCH_0,KAM_SHORT,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP,USER_IN_DEF_DKIM_WL,USER_IN_DEF_SPF_WL autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: On 2023-10-16, Uros Bizjak wrote: >On Tue, Aug 1, 2023 at 9:51 PM Fangrui Song wrote: >> >> When using -mcmodel=medium, large data objects larger than the >> -mlarge-data-threshold threshold are placed into large data sections >> (.lrodata, .ldata, .lbss and some variants). GNU ld and ld.lld 17 place >> .l* sections into separate output sections. If small and medium code >> model object files are mixed, the .l* sections won't exert relocation >> overflow pressure on sections in object files built with -mcmodel=small. >> >> However, when using -mcmodel=large, -mlarge-data-threshold doesn't >> apply. This means that the .rodata/.data/.bss sections may exert >> relocation overflow pressure on sections in -mcmodel=small object files. >> >> This patch allows -mcmodel=large to generate .l* sections and drops an >> unneeded documentation restriction that the value must be the same. >> >> Link: https://groups.google.com/g/x86-64-abi/c/jnQdJeabxiU >> ("Large data sections for the large code model") >> >> Signed-off-by: Fangrui Song >> >> --- >> Changes from v1 (https://gcc.gnu.org/pipermail/gcc-patches/2023-April/616947.html): >> * Clarify commit message. Add link to https://groups.google.com/g/x86-64-abi/c/jnQdJeabxiU >> >> Changes from v2 >> * Drop an uneeded limitation in the documentation. >> >> Changes from v3 >> * Change scan-assembler directives to use \. to match literal . >> --- >> gcc/config/i386/i386.cc | 15 +++++++++------ >> gcc/config/i386/i386.opt | 2 +- >> gcc/doc/invoke.texi | 6 +++--- >> gcc/testsuite/gcc.target/i386/large-data.c | 13 +++++++++++++ >> 4 files changed, 26 insertions(+), 10 deletions(-) >> create mode 100644 gcc/testsuite/gcc.target/i386/large-data.c >> >> diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc >> index eabc70011ea..37e810cc741 100644 >> --- a/gcc/config/i386/i386.cc >> +++ b/gcc/config/i386/i386.cc >> @@ -647,7 +647,8 @@ ix86_can_inline_p (tree caller, tree callee) >> static bool >> ix86_in_large_data_p (tree exp) >> { >> - if (ix86_cmodel != CM_MEDIUM && ix86_cmodel != CM_MEDIUM_PIC) >> + if (ix86_cmodel != CM_MEDIUM && ix86_cmodel != CM_MEDIUM_PIC && >> + ix86_cmodel != CM_LARGE && ix86_cmodel != CM_LARGE_PIC) > >Please split multi-line expression before the operator, not after it, >as instructed in GNU Coding Standards [1] ... > >[1] https://www.gnu.org/prep/standards/html_node/Formatting.html > >> return false; >> >> if (exp == NULL_TREE) >> @@ -858,8 +859,9 @@ x86_elf_aligned_decl_common (FILE *file, tree decl, >> const char *name, unsigned HOST_WIDE_INT size, >> unsigned align) >> { >> - if ((ix86_cmodel == CM_MEDIUM || ix86_cmodel == CM_MEDIUM_PIC) >> - && size > (unsigned int)ix86_section_threshold) >> + if ((ix86_cmodel == CM_MEDIUM || ix86_cmodel == CM_MEDIUM_PIC || >> + ix86_cmodel == CM_LARGE || ix86_cmodel == CM_LARGE_PIC) && >> + size > (unsigned int)ix86_section_threshold) > >... also here ... > >> { >> switch_to_section (get_named_section (decl, ".lbss", 0)); >> fputs (LARGECOMM_SECTION_ASM_OP, file); >> @@ -879,9 +881,10 @@ void >> x86_output_aligned_bss (FILE *file, tree decl, const char *name, >> unsigned HOST_WIDE_INT size, unsigned align) >> { >> - if ((ix86_cmodel == CM_MEDIUM || ix86_cmodel == CM_MEDIUM_PIC) >> - && size > (unsigned int)ix86_section_threshold) >> - switch_to_section (get_named_section (decl, ".lbss", 0)); >> + if ((ix86_cmodel == CM_MEDIUM || ix86_cmodel == CM_MEDIUM_PIC || >> + ix86_cmodel == CM_LARGE || ix86_cmodel == CM_LARGE_PIC) && >> + size > (unsigned int)ix86_section_threshold) > >... and here. > >OK with these formatting changes. > >Thanks, >Uros. Thank you for the review! Posted PATCH v5 https://gcc.gnu.org/pipermail/gcc-patches/2023-October/633153.html with the formatting. I don't have write access to the gcc repository:) (Hmmm... in emacs, C-c . gnu RET C-M-\ doesn't fix the && || formatting errors.) >> + switch_to_section(get_named_section(decl, ".lbss", 0)); >> else >> switch_to_section (bss_section); >> ASM_OUTPUT_ALIGN (file, floor_log2 (align / BITS_PER_UNIT)); >> diff --git a/gcc/config/i386/i386.opt b/gcc/config/i386/i386.opt >> index 1cc8563477a..52fad492353 100644 >> --- a/gcc/config/i386/i386.opt >> +++ b/gcc/config/i386/i386.opt >> @@ -282,7 +282,7 @@ Branches are this expensive (arbitrary units). >> >> mlarge-data-threshold= >> Target RejectNegative Joined UInteger Var(ix86_section_threshold) Init(DEFAULT_LARGE_SECTION_THRESHOLD) >> --mlarge-data-threshold= Data greater than given threshold will go into .ldata section in x86-64 medium model. >> +-mlarge-data-threshold= Data greater than given threshold will go into a large data section in x86-64 medium and large code models. >> >> mcmodel= >> Target RejectNegative Joined Enum(cmodel) Var(ix86_cmodel) Init(CM_32) >> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi >> index 104766f446d..bf6fe3e1a20 100644 >> --- a/gcc/doc/invoke.texi >> +++ b/gcc/doc/invoke.texi >> @@ -33207,9 +33207,9 @@ the cache line size. @samp{compat} is the default. >> >> @opindex mlarge-data-threshold >> @item -mlarge-data-threshold=@var{threshold} >> -When @option{-mcmodel=medium} is specified, data objects larger than >> -@var{threshold} are placed in the large data section. This value must be the >> -same across all objects linked into the binary, and defaults to 65535. >> +When @option{-mcmodel=medium} or @option{-mcmodel=large} is specified, data >> +objects larger than @var{threshold} are placed in large data sections. The >> +default is 65535. >> >> @opindex mrtd >> @item -mrtd >> diff --git a/gcc/testsuite/gcc.target/i386/large-data.c b/gcc/testsuite/gcc.target/i386/large-data.c >> new file mode 100644 >> index 00000000000..bdd4acd30b8 >> --- /dev/null >> +++ b/gcc/testsuite/gcc.target/i386/large-data.c >> @@ -0,0 +1,13 @@ >> +/* { dg-do compile } */ >> +/* { dg-require-effective-target lp64 } */ >> +/* { dg-options "-O2 -mcmodel=large -mlarge-data-threshold=4" } */ >> +/* { dg-final { scan-assembler {\.lbss} } } */ >> +/* { dg-final { scan-assembler {\.bss} } } */ >> +/* { dg-final { scan-assembler {\.ldata} } } */ >> +/* { dg-final { scan-assembler {\.data} } } */ >> +/* { dg-final { scan-assembler {\.lrodata} } } */ >> +/* { dg-final { scan-assembler {\.rodata} } } */ >> + >> +const char rodata_a[] = "abc", rodata_b[] = "abcd"; >> +char data_a[4] = {1}, data_b[5] = {1}; >> +char bss_a[4], bss_b[5]; >> -- >> 2.41.0.585.gd2178a4bd4-goog >> From da49445a50c57b583201e3fb48fa91781b9ec761 Mon Sep 17 00:00:00 2001 From: Fangrui Song Date: Thu, 27 Apr 2023 12:29:31 -0700 Subject: [PATCH v5] i386: Allow -mlarge-data-threshold with -mcmodel=large When using -mcmodel=medium, large data objects larger than the -mlarge-data-threshold threshold are placed into large data sections (.lrodata, .ldata, .lbss and some variants). GNU ld and ld.lld 17 place .l* sections into separate output sections. If small and medium code model object files are mixed, the .l* sections won't exert relocation overflow pressure on sections in object files built with -mcmodel=small. However, when using -mcmodel=large, -mlarge-data-threshold doesn't apply. This means that the .rodata/.data/.bss sections may exert relocation overflow pressure on sections in -mcmodel=small object files. This patch allows -mcmodel=large to generate .l* sections and drops an unneeded documentation restriction that the value must be the same. Link: https://groups.google.com/g/x86-64-abi/c/jnQdJeabxiU ("Large data sections for the large code model") Signed-off-by: Fangrui Song --- Changes from v1 (https://gcc.gnu.org/pipermail/gcc-patches/2023-April/616947.html): * Clarify commit message. Add link to https://groups.google.com/g/x86-64-abi/c/jnQdJeabxiU Changes from v2 * Drop an uneeded limitation in the documentation. Changes from v3 * Change scan-assembler directives to use \. to match literal . Changes from v4 (https://gcc.gnu.org/pipermail/gcc-patches/2023-October/633145.html) * "When you split an expression into multiple lines, split it before an operator, not after one." --- gcc/config/i386/i386.cc | 9 ++++++--- gcc/config/i386/i386.opt | 2 +- gcc/doc/invoke.texi | 6 +++--- gcc/testsuite/gcc.target/i386/large-data.c | 13 +++++++++++++ 4 files changed, 23 insertions(+), 7 deletions(-) create mode 100644 gcc/testsuite/gcc.target/i386/large-data.c diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc index 8251b67e2d6..641e7680335 100644 --- a/gcc/config/i386/i386.cc +++ b/gcc/config/i386/i386.cc @@ -663,7 +663,8 @@ ix86_can_inline_p (tree caller, tree callee) static bool ix86_in_large_data_p (tree exp) { - if (ix86_cmodel != CM_MEDIUM && ix86_cmodel != CM_MEDIUM_PIC) + if (ix86_cmodel != CM_MEDIUM && ix86_cmodel != CM_MEDIUM_PIC + && ix86_cmodel != CM_LARGE && ix86_cmodel != CM_LARGE_PIC) return false; if (exp == NULL_TREE) @@ -874,7 +875,8 @@ x86_elf_aligned_decl_common (FILE *file, tree decl, const char *name, unsigned HOST_WIDE_INT size, unsigned align) { - if ((ix86_cmodel == CM_MEDIUM || ix86_cmodel == CM_MEDIUM_PIC) + if ((ix86_cmodel == CM_MEDIUM || ix86_cmodel == CM_MEDIUM_PIC + || ix86_cmodel == CM_LARGE || ix86_cmodel == CM_LARGE_PIC) && size > (unsigned int)ix86_section_threshold) { switch_to_section (get_named_section (decl, ".lbss", 0)); @@ -895,7 +897,8 @@ void x86_output_aligned_bss (FILE *file, tree decl, const char *name, unsigned HOST_WIDE_INT size, unsigned align) { - if ((ix86_cmodel == CM_MEDIUM || ix86_cmodel == CM_MEDIUM_PIC) + if ((ix86_cmodel == CM_MEDIUM || ix86_cmodel == CM_MEDIUM_PIC + || ix86_cmodel == CM_LARGE || ix86_cmodel == CM_LARGE_PIC) && size > (unsigned int)ix86_section_threshold) switch_to_section (get_named_section (decl, ".lbss", 0)); else diff --git a/gcc/config/i386/i386.opt b/gcc/config/i386/i386.opt index b8382c48099..0c3b8f4b621 100644 --- a/gcc/config/i386/i386.opt +++ b/gcc/config/i386/i386.opt @@ -282,7 +282,7 @@ Branches are this expensive (arbitrary units). mlarge-data-threshold= Target RejectNegative Joined UInteger Var(ix86_section_threshold) Init(DEFAULT_LARGE_SECTION_THRESHOLD) --mlarge-data-threshold= Data greater than given threshold will go into .ldata section in x86-64 medium model. +-mlarge-data-threshold= Data greater than given threshold will go into a large data section in x86-64 medium and large code models. mcmodel= Target RejectNegative Joined Enum(cmodel) Var(ix86_cmodel) Init(CM_32) diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index eb714d18511..50745a3a195 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -33390,9 +33390,9 @@ the cache line size. @samp{compat} is the default. @opindex mlarge-data-threshold @item -mlarge-data-threshold=@var{threshold} -When @option{-mcmodel=medium} is specified, data objects larger than -@var{threshold} are placed in the large data section. This value must be the -same across all objects linked into the binary, and defaults to 65535. +When @option{-mcmodel=medium} or @option{-mcmodel=large} is specified, data +objects larger than @var{threshold} are placed in large data sections. The +default is 65535. @opindex mrtd @item -mrtd diff --git a/gcc/testsuite/gcc.target/i386/large-data.c b/gcc/testsuite/gcc.target/i386/large-data.c new file mode 100644 index 00000000000..bdd4acd30b8 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/large-data.c @@ -0,0 +1,13 @@ +/* { dg-do compile } */ +/* { dg-require-effective-target lp64 } */ +/* { dg-options "-O2 -mcmodel=large -mlarge-data-threshold=4" } */ +/* { dg-final { scan-assembler {\.lbss} } } */ +/* { dg-final { scan-assembler {\.bss} } } */ +/* { dg-final { scan-assembler {\.ldata} } } */ +/* { dg-final { scan-assembler {\.data} } } */ +/* { dg-final { scan-assembler {\.lrodata} } } */ +/* { dg-final { scan-assembler {\.rodata} } } */ + +const char rodata_a[] = "abc", rodata_b[] = "abcd"; +char data_a[4] = {1}, data_b[5] = {1}; +char bss_a[4], bss_b[5]; -- 2.42.0.655.g421f12c284-goog