From 4bb794e25d5e141fd57fd206c276d04d93e25e4a Mon Sep 17 00:00:00 2001 From: Sriraman Tallam Date: Thu, 4 Jun 2015 21:14:10 +0000 Subject: [PATCH] c-common.c (noplt): New attribute. 2015-06-04 Sriraman Tallam * c-family/c-common.c (noplt): New attribute. (handle_noplt_attribute): New handler. * calls.c (prepare_call_address): Check for noplt attribute. * config/i386/i386.c (ix86_expand_call): Check for noplt attribute. (ix86_nopic_noplt_attribute_p): New function. (ix86_output_call_insn): Output indirect call for non-pic no plt calls. * doc/extend.texi (noplt): Document new attribute. * doc/invoke.texi: Document new attribute. * testsuite/gcc.target/i386/noplt-1.c: New test. * testsuite/gcc.target/i386/noplt-2.c: New test. * testsuite/gcc.target/i386/noplt-3.c: New test. * testsuite/gcc.target/i386/noplt-4.c: New test. This patch does two things: * Adds new generic function attribute "noplt" that is similar in functionality to -fno-plt except that it applies only to calls to functions that are marked with this attribute. * For x86_64, it makes -fno-plt(and the attribute) also work for non-PIC code by directly generating an indirect call via a GOT entry. From-SVN: r224138 --- gcc/ChangeLog | 14 ++++++++ gcc/c-family/c-common.c | 22 +++++++++++++ gcc/calls.c | 8 ++++- gcc/config/i386/i386.c | 43 ++++++++++++++++++++++--- gcc/doc/extend.texi | 29 +++++++++++++++++ gcc/doc/invoke.texi | 8 +++++ gcc/testsuite/ChangeLog | 7 ++++ gcc/testsuite/gcc.target/i386/noplt-1.c | 13 ++++++++ gcc/testsuite/gcc.target/i386/noplt-2.c | 13 ++++++++ gcc/testsuite/gcc.target/i386/noplt-3.c | 12 +++++++ gcc/testsuite/gcc.target/i386/noplt-4.c | 11 +++++++ 11 files changed, 175 insertions(+), 5 deletions(-) create mode 100644 gcc/testsuite/gcc.target/i386/noplt-1.c create mode 100644 gcc/testsuite/gcc.target/i386/noplt-2.c create mode 100644 gcc/testsuite/gcc.target/i386/noplt-3.c create mode 100644 gcc/testsuite/gcc.target/i386/noplt-4.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 75516bc705f..2ad6068e15f 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,17 @@ +2015-06-04 Sriraman Tallam + + * c-family/c-common.c (noplt): New attribute. + (handle_noplt_attribute): New handler. + * calls.c (prepare_call_address): Check for noplt + attribute. + * config/i386/i386.c (ix86_expand_call): Check + for noplt attribute. + (ix86_nopic_noplt_attribute_p): New function. + (ix86_output_call_insn): Output indirect call for non-pic + no plt calls. + * doc/extend.texi (noplt): Document new attribute. + * doc/invoke.texi: Document new attribute. + 2015-06-04 Andrew MacLeod * coretypes.h: Include machmode.h, signop.h, wide-int.h, double-int.h, diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c index 8528fe46eb4..6f4393b7748 100644 --- a/gcc/c-family/c-common.c +++ b/gcc/c-family/c-common.c @@ -356,6 +356,7 @@ static tree handle_mode_attribute (tree *, tree, tree, int, bool *); static tree handle_section_attribute (tree *, tree, tree, int, bool *); static tree handle_aligned_attribute (tree *, tree, tree, int, bool *); static tree handle_weak_attribute (tree *, tree, tree, int, bool *) ; +static tree handle_noplt_attribute (tree *, tree, tree, int, bool *) ; static tree handle_alias_ifunc_attribute (bool, tree *, tree, tree, bool *); static tree handle_ifunc_attribute (tree *, tree, tree, int, bool *); static tree handle_alias_attribute (tree *, tree, tree, int, bool *); @@ -705,6 +706,8 @@ const struct attribute_spec c_common_attribute_table[] = handle_aligned_attribute, false }, { "weak", 0, 0, true, false, false, handle_weak_attribute, false }, + { "noplt", 0, 0, true, false, false, + handle_noplt_attribute, false }, { "ifunc", 1, 1, true, false, false, handle_ifunc_attribute, false }, { "alias", 1, 1, true, false, false, @@ -8184,6 +8187,25 @@ handle_weak_attribute (tree *node, tree name, return NULL_TREE; } +/* Handle a "noplt" attribute; arguments as in + struct attribute_spec.handler. */ + +static tree +handle_noplt_attribute (tree *node, tree name, + tree ARG_UNUSED (args), + int ARG_UNUSED (flags), + bool * ARG_UNUSED (no_add_attrs)) +{ + if (TREE_CODE (*node) != FUNCTION_DECL) + { + warning (OPT_Wattributes, + "%qE attribute is only applicable on functions", name); + *no_add_attrs = true; + return NULL_TREE; + } + return NULL_TREE; +} + /* Handle an "alias" or "ifunc" attribute; arguments as in struct attribute_spec.handler, except that IS_ALIAS tells us whether this is an alias as opposed to ifunc attribute. */ diff --git a/gcc/calls.c b/gcc/calls.c index bb4c6a7f7ed..330f65a3827 100644 --- a/gcc/calls.c +++ b/gcc/calls.c @@ -221,10 +221,16 @@ prepare_call_address (tree fndecl_or_type, rtx funexp, rtx static_chain_value, && targetm.small_register_classes_for_mode_p (FUNCTION_MODE)) ? force_not_mem (memory_address (FUNCTION_MODE, funexp)) : memory_address (FUNCTION_MODE, funexp)); - else if (flag_pic && !flag_plt && fndecl_or_type + else if (flag_pic + && fndecl_or_type && TREE_CODE (fndecl_or_type) == FUNCTION_DECL + && (!flag_plt + || lookup_attribute ("noplt", DECL_ATTRIBUTES (fndecl_or_type))) && !targetm.binds_local_p (fndecl_or_type)) { + /* This is done only for PIC code. There is no easy interface to force the + function address into GOT for non-PIC case. non-PIC case needs to be + handled specially by the backend. */ funexp = force_reg (Pmode, funexp); } else if (! sibcallp) diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c index 8aa4fdbd70c..153dd85babf 100644 --- a/gcc/config/i386/i386.c +++ b/gcc/config/i386/i386.c @@ -25495,13 +25495,19 @@ ix86_expand_call (rtx retval, rtx fnaddr, rtx callarg1, } else { - /* Static functions and indirect calls don't need the pic register. */ + /* Static functions and indirect calls don't need the pic register. Also, + check if PLT was explicitly avoided via no-plt or "noplt" attribute, making + it an indirect call. */ if (flag_pic && (!TARGET_64BIT || (ix86_cmodel == CM_LARGE_PIC && DEFAULT_ABI != MS_ABI)) && GET_CODE (XEXP (fnaddr, 0)) == SYMBOL_REF - && ! SYMBOL_REF_LOCAL_P (XEXP (fnaddr, 0))) + && !SYMBOL_REF_LOCAL_P (XEXP (fnaddr, 0)) + && flag_plt + && (SYMBOL_REF_DECL ((XEXP (fnaddr, 0))) == NULL_TREE + || !lookup_attribute ("noplt", + DECL_ATTRIBUTES (SYMBOL_REF_DECL (XEXP (fnaddr, 0)))))) { use_reg (&use, gen_rtx_REG (Pmode, REAL_PIC_OFFSET_TABLE_REGNUM)); if (ix86_use_pseudo_pic_reg ()) @@ -25597,6 +25603,31 @@ ix86_expand_call (rtx retval, rtx fnaddr, rtx callarg1, return call; } +/* Return true if the function being called was marked with attribute "noplt" + or using -fno-plt and we are compiling for non-PIC and x86_64. We need to + handle the non-PIC case in the backend because there is no easy interface + for the front-end to force non-PLT calls to use the GOT. This is currently + used only with 64-bit ELF targets to call the function marked "noplt" + indirectly. */ + +static bool +ix86_nopic_noplt_attribute_p (rtx call_op) +{ + if (flag_pic || ix86_cmodel == CM_LARGE + || !TARGET_64BIT || TARGET_MACHO || TARGET_SEH || TARGET_PECOFF + || SYMBOL_REF_LOCAL_P (call_op)) + return false; + + tree symbol_decl = SYMBOL_REF_DECL (call_op); + + if (!flag_plt + || (symbol_decl != NULL_TREE + && lookup_attribute ("noplt", DECL_ATTRIBUTES (symbol_decl)))) + return true; + + return false; +} + /* Output the assembly for a call instruction. */ const char * @@ -25608,7 +25639,9 @@ ix86_output_call_insn (rtx_insn *insn, rtx call_op) if (SIBLING_CALL_P (insn)) { - if (direct_p) + if (direct_p && ix86_nopic_noplt_attribute_p (call_op)) + xasm = "%!jmp\t*%p0@GOTPCREL(%%rip)"; + else if (direct_p) xasm = "%!jmp\t%P0"; /* SEH epilogue detection requires the indirect branch case to include REX.W. */ @@ -25651,7 +25684,9 @@ ix86_output_call_insn (rtx_insn *insn, rtx call_op) seh_nop_p = true; } - if (direct_p) + if (direct_p && ix86_nopic_noplt_attribute_p (call_op)) + xasm = "%!call\t*%p0@GOTPCREL(%%rip)"; + else if (direct_p) xasm = "%!call\t%P0"; else xasm = "%!call\t%A0"; diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index d9adc65cd4d..ecdd3c8023f 100644 --- a/gcc/doc/extend.texi +++ b/gcc/doc/extend.texi @@ -2916,6 +2916,35 @@ the standard C library can be guaranteed not to throw an exception with the notable exceptions of @code{qsort} and @code{bsearch} that take function pointer arguments. +@item noplt +@cindex @code{noplt} function attribute +The @code{noplt} attribute is the counterpart to option @option{-fno-plt} and +does not use PLT for calls to functions marked with this attribute in position +independent code. + +@smallexample +@group +/* Externally defined function foo. */ +int foo () __attribute__ ((noplt)); + +int +main (/* @r{@dots{}} */) +@{ + /* @r{@dots{}} */ + foo (); + /* @r{@dots{}} */ +@} +@end group +@end smallexample + +The @code{noplt} attribute on function foo tells the compiler to assume that +the function foo is externally defined and the call to foo must avoid the PLT +in position independent code. + +Additionally, a few targets also convert calls to those functions that are +marked to not use the PLT to use the GOT instead for non-position independent +code. + @item optimize @cindex @code{optimize} function attribute The @code{optimize} attribute is used to specify that a function is to diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index e25bd622036..a954d49cf97 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -23872,6 +23872,14 @@ PLT stubs expect GOT pointer in a specific register, this gives more register allocation freedom to the compiler. Lazy binding requires PLT: with @option{-fno-plt} all external symbols are resolved at load time. +Alternatively, function attribute @code{noplt} can be used to avoid PLT +for calls to specific external functions by marking those functions with +this attribute. + +Additionally, a few targets also convert calls to those functions that are +marked to not use the PLT to use the GOT instead for non-position independent +code. + @item -fno-jump-tables @opindex fno-jump-tables Do not use jump tables for switch statements even where it would be diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 4b35e727f3f..5bd68ee33d0 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,10 @@ +2015-06-04 Sriraman Tallam + + * testsuite/gcc.target/i386/noplt-1.c: New test. + * testsuite/gcc.target/i386/noplt-2.c: New test. + * testsuite/gcc.target/i386/noplt-3.c: New test. + * testsuite/gcc.target/i386/noplt-4.c: New test. + 2015-06-04 Thomas Koenig PR fortran/58749 diff --git a/gcc/testsuite/gcc.target/i386/noplt-1.c b/gcc/testsuite/gcc.target/i386/noplt-1.c new file mode 100644 index 00000000000..d9e5d6ea7ca --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/noplt-1.c @@ -0,0 +1,13 @@ +/* { dg-do compile { target x86_64-*-linux* } } */ +/* { dg-options "-fno-pic" } */ + +__attribute__ ((noplt)) +void foo(); + +int main() +{ + foo(); + return 0; +} + +/* { dg-final { scan-assembler "call\[ \t\]\\*.*foo.*@GOTPCREL\\(%rip\\)" } } */ diff --git a/gcc/testsuite/gcc.target/i386/noplt-2.c b/gcc/testsuite/gcc.target/i386/noplt-2.c new file mode 100644 index 00000000000..4df0618b679 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/noplt-2.c @@ -0,0 +1,13 @@ +/* { dg-do compile { target x86_64-*-linux* } } */ +/* { dg-options "-O2 -fno-pic" } */ + + +__attribute__ ((noplt)) +int foo(); + +int main() +{ + return foo(); +} + +/* { dg-final { scan-assembler "jmp\[ \t\]\\*.*foo.*@GOTPCREL\\(%rip\\)" } } */ diff --git a/gcc/testsuite/gcc.target/i386/noplt-3.c b/gcc/testsuite/gcc.target/i386/noplt-3.c new file mode 100644 index 00000000000..e2a6f938649 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/noplt-3.c @@ -0,0 +1,12 @@ +/* { dg-do compile { target x86_64-*-linux* } } */ +/* { dg-options "-fno-pic -fno-plt" } */ + +void foo(); + +int main() +{ + foo(); + return 0; +} + +/* { dg-final { scan-assembler "call\[ \t\]\\*.*foo.*@GOTPCREL\\(%rip\\)" } } */ diff --git a/gcc/testsuite/gcc.target/i386/noplt-4.c b/gcc/testsuite/gcc.target/i386/noplt-4.c new file mode 100644 index 00000000000..d9039dd77c1 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/noplt-4.c @@ -0,0 +1,11 @@ +/* { dg-do compile { target x86_64-*-linux* } } */ +/* { dg-options "-O2 -fno-pic -fno-plt" } */ + +int foo(); + +int main() +{ + return foo(); +} + +/* { dg-final { scan-assembler "jmp\[ \t\]\\*.*foo.*@GOTPCREL\\(%rip\\)" } } */ -- 2.30.2