commit 126dab7c9d84294f256b1f7bf91c24a9e7103249 Author: qinzhao Date: Thu Nov 29 16:06:03 2018 +0000 Add a new option -flive-patching={inline-only-static|inline-clone} to support live patching in GCC. 2018-11-29 qing zhao gcc/ChangeLog: * cif-code.def (EXTERN_LIVE_ONLY_STATIC): New CIF code. * common.opt: Add -flive-patching flag. * doc/invoke.texi: Document -flive-patching. * flag-types.h (enum live_patching_level): New enum. * ipa-inline.c (can_inline_edge_p): Disable external functions from inlining when flag_live_patching is LIVE_PATCHING_INLINE_ONLY_STATIC. * opts.c (control_options_for_live_patching): New function. (finish_options): Make flag_live_patching incompatible with flag_lto. Control IPA optimizations based on different levels of flag_live_patching. gcc/testsuite/ChangeLog: * gcc.dg/live-patching-1.c: New test. * gcc.dg/live-patching-2.c: New test. * gcc.dg/live-patching-3.c: New test. * gcc.dg/tree-ssa/writeonly-3.c: New test. * gcc.target/i386/ipa-stack-alignment-2.c: New test. git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@266627 138bc75d-0d04-0410-961f-82ee72b054a4 --- gcc/cif-code.def +++ gcc/cif-code.def @@ -132,6 +132,12 @@ DEFCIFCODE(USES_COMDAT_LOCAL, CIF_FINAL_ERROR, DEFCIFCODE(ATTRIBUTE_MISMATCH, CIF_FINAL_ERROR, N_("function attribute mismatch")) +/* We can't inline because the user requests only static functions + but the function has external linkage for live patching purpose. */ +DEFCIFCODE(EXTERN_LIVE_ONLY_STATIC, CIF_FINAL_ERROR, + N_("function has external linkage when the user requests only" + " inlining static for live patching")) + /* We proved that the call is unreachable. */ DEFCIFCODE(UNREACHABLE, CIF_FINAL_ERROR, N_("unreachable")) --- gcc/common.opt +++ gcc/common.opt @@ -2181,6 +2181,24 @@ starts and when the destructor finishes. flifetime-dse= Common Joined RejectNegative UInteger Var(flag_lifetime_dse) Optimization IntegerRange(0, 2) +flive-patching +Common RejectNegative Alias(flive-patching=,inline-clone) Optimization + +flive-patching= +Common Report Joined RejectNegative Enum(live_patching_level) Var(flag_live_patching) Init(LIVE_PATCHING_NONE) Optimization +-flive-patching=[inline-only-static|inline-clone] Control IPA +optimizations to provide a safe compilation for live-patching. At the same +time, provides multiple-level control on the enabled IPA optimizations. + +Enum +Name(live_patching_level) Type(enum live_patching_level) UnknownError(unknown Live-Patching Level %qs) + +EnumValue +Enum(live_patching_level) String(inline-only-static) Value(LIVE_PATCHING_INLINE_ONLY_STATIC) + +EnumValue +Enum(live_patching_level) String(inline-clone) Value(LIVE_PATCHING_INLINE_CLONE) + flive-range-shrinkage Common Report Var(flag_live_range_shrinkage) Init(0) Optimization Relief of register pressure through live range shrinkage. --- gcc/doc/invoke.texi +++ gcc/doc/invoke.texi @@ -389,6 +389,7 @@ Objective-C and Objective-C++ Dialects}. -fipa-bit-cp -fipa-vrp @gol -fipa-pta -fipa-profile -fipa-pure-const -fipa-reference -fipa-icf @gol -fira-algorithm=@var{algorithm} @gol +-flive-patching=@var{level} @gol -fira-region=@var{region} -fira-hoist-pressure @gol -fira-loop-pressure -fno-ira-share-save-slots @gol -fno-ira-share-spill-slots @gol @@ -9291,6 +9292,65 @@ equivalences that are found only by GCC and equivalences found only by Gold. This flag is enabled by default at @option{-O2} and @option{-Os}. +@item -flive-patching=@var{level} +@opindex flive-patching +Control GCC's optimizations to provide a safe compilation for live-patching. + +If the compiler's optimization uses a function's body or information extracted +from its body to optimize/change another function, the latter is called an +impacted function of the former. If a function is patched, its impacted +functions should be patched too. + +The impacted functions are decided by the compiler's interprocedural +optimizations. For example, inlining a function into its caller, cloning +a function and changing its caller to call this new clone, or extracting +a function's pureness/constness information to optimize its direct or +indirect callers, etc. + +Usually, the more IPA optimizations enabled, the larger the number of +impacted functions for each function. In order to control the number of +impacted functions and computed the list of impacted function easily, +we provide control to partially enable IPA optimizations on two different +levels. + +The @var{level} argument should be one of the following: + +@table @samp + +@item inline-clone + +Only enable inlining and cloning optimizations, which includes inlining, +cloning, interprocedural scalar replacement of aggregates and partial inlining. +As a result, when patching a function, all its callers and its clones' +callers need to be patched as well. + +@option{-flive-patching=inline-clone} disables the following optimization flags: +@gccoptlist{-fwhole-program -fipa-pta -fipa-reference -fipa-ra @gol +-fipa-icf -fipa-icf-functions -fipa-icf-variables @gol +-fipa-bit-cp -fipa-vrp -fipa-pure-const -fipa-reference-addressable @gol +-fipa-stack-alignment} + +@item inline-only-static + +Only enable inlining of static functions. +As a result, when patching a static function, all its callers need to be +patches as well. + +In addition to all the flags that -flive-patching=inline-clone disables, +@option{-flive-patching=inline-only-static} disables the following additional +optimization flags: +@gccoptlist{-fipa-cp-clone -fipa-sra -fpartial-inlining -fipa-cp} + +@end table + +When -flive-patching specified without any value, the default value +is "inline-clone". + +This flag is disabled by default. + +Note that -flive-patching is not supported with link-time optimizer. +(@option{-flto}). + @item -fisolate-erroneous-paths-dereference @opindex fisolate-erroneous-paths-dereference Detect paths that trigger erroneous or undefined behavior due to --- gcc/flag-types.h +++ gcc/flag-types.h @@ -123,6 +123,14 @@ enum stack_reuse_level SR_ALL }; +/* The live patching level. */ +enum live_patching_level +{ + LIVE_PATCHING_NONE = 0, + LIVE_PATCHING_INLINE_ONLY_STATIC, + LIVE_PATCHING_INLINE_CLONE +}; + /* The algorithm used for basic block reordering. */ enum reorder_blocks_algorithm { --- gcc/ipa-inline.c +++ gcc/ipa-inline.c @@ -379,6 +379,12 @@ can_inline_edge_p (struct cgraph_edge *e, bool report, e->inline_failed = CIF_ATTRIBUTE_MISMATCH; inlinable = false; } + else if (callee->externally_visible + && flag_live_patching == LIVE_PATCHING_INLINE_ONLY_STATIC) + { + e->inline_failed = CIF_EXTERN_LIVE_ONLY_STATIC; + inlinable = false; + } if (!inlinable && report) report_inline_failed_reason (e); return inlinable; --- gcc/opts.c +++ gcc/opts.c @@ -699,6 +699,152 @@ default_options_optimization (struct gcc lang_mask, handlers, loc, dc); } +/* Control IPA optimizations based on different live patching LEVEL. */ +static void +control_options_for_live_patching (struct gcc_options *opts, + struct gcc_options *opts_set, + enum live_patching_level level, + location_t loc) +{ + gcc_assert (level > LIVE_PATCHING_NONE); + + switch (level) + { + case LIVE_PATCHING_INLINE_ONLY_STATIC: + if (opts_set->x_flag_ipa_cp_clone && opts->x_flag_ipa_cp_clone) + error_at (loc, + "%<-fipa-cp-clone%> is incompatible with " + "%<-flive-patching=inline-only-static%>"); + else + opts->x_flag_ipa_cp_clone = 0; + + if (opts_set->x_flag_ipa_sra && opts->x_flag_ipa_sra) + error_at (loc, + "%<-fipa-sra%> is incompatible with " + "%<-flive-patching=inline-only-static%>"); + else + opts->x_flag_ipa_sra = 0; + + if (opts_set->x_flag_partial_inlining && opts->x_flag_partial_inlining) + error_at (loc, + "%<-fpartial-inlining%> is incompatible with " + "%<-flive-patching=inline-only-static%>"); + else + opts->x_flag_partial_inlining = 0; + + if (opts_set->x_flag_ipa_cp && opts->x_flag_ipa_cp) + error_at (loc, + "%<-fipa-cp%> is incompatible with " + "%<-flive-patching=inline-only-static%>"); + else + opts->x_flag_ipa_cp = 0; + + /* FALLTHROUGH. */ + case LIVE_PATCHING_INLINE_CLONE: + /* live patching should disable whole-program optimization. */ + if (opts_set->x_flag_whole_program && opts->x_flag_whole_program) + error_at (loc, + "%<-fwhole-program%> is incompatible with " + "%<-flive-patching=inline-only-static|inline-clone%>"); + else + opts->x_flag_whole_program = 0; + + /* visibility change should be excluded by !flag_whole_program + && !in_lto_p && !flag_ipa_cp_clone && !flag_ipa_sra + && !flag_partial_inlining. */ + + if (opts_set->x_flag_ipa_pta && opts->x_flag_ipa_pta) + error_at (loc, + "%<-fipa-pta%> is incompatible with " + "%<-flive-patching=inline-only-static|inline-clone%>"); + else + opts->x_flag_ipa_pta = 0; + + if (opts_set->x_flag_ipa_reference && opts->x_flag_ipa_reference) + error_at (loc, + "%<-fipa-reference%> is incompatible with " + "%<-flive-patching=inline-only-static|inline-clone%>"); + else + opts->x_flag_ipa_reference = 0; + + if (opts_set->x_flag_ipa_ra && opts->x_flag_ipa_ra) + error_at (loc, + "%<-fipa-ra%> is incompatible with " + "%<-flive-patching=inline-only-static|inline-clone%>"); + else + opts->x_flag_ipa_ra = 0; + + if (opts_set->x_flag_ipa_icf && opts->x_flag_ipa_icf) + error_at (loc, + "%<-fipa-icf%> is incompatible with " + "%<-flive-patching=inline-only-static|inline-clone%>"); + else + opts->x_flag_ipa_icf = 0; + + if (opts_set->x_flag_ipa_icf_functions && opts->x_flag_ipa_icf_functions) + error_at (loc, + "%<-fipa-icf-functions%> is incompatible with " + "%<-flive-patching=inline-only-static|inline-clone%>"); + else + opts->x_flag_ipa_icf_functions = 0; + + if (opts_set->x_flag_ipa_icf_variables && opts->x_flag_ipa_icf_variables) + error_at (loc, + "%<-fipa-icf-variables%> is incompatible with " + "%<-flive-patching=inline-only-static|inline-clone%>"); + else + opts->x_flag_ipa_icf_variables = 0; + + if (opts_set->x_flag_ipa_bit_cp && opts->x_flag_ipa_bit_cp) + error_at (loc, + "%<-fipa-bit-cp%> is incompatible with " + "%<-flive-patching=inline-only-static|inline-clone%>"); + else + opts->x_flag_ipa_bit_cp = 0; + + if (opts_set->x_flag_ipa_vrp && opts->x_flag_ipa_vrp) + error_at (loc, + "%<-fipa-vrp%> is incompatible with " + "%<-flive-patching=inline-only-static|inline-clone%>"); + else + opts->x_flag_ipa_vrp = 0; + + if (opts_set->x_flag_ipa_pure_const && opts->x_flag_ipa_pure_const) + error_at (loc, + "%<-fipa-pure-const%> is incompatible with " + "%<-flive-patching=inline-only-static|inline-clone%>"); + else + opts->x_flag_ipa_pure_const = 0; + + /* FIXME: disable unreachable code removal. */ + + /* discovery of functions/variables with no address taken. */ +// GCC 8 doesn't have these options. +#if 0 + if (opts_set->x_flag_ipa_reference_addressable + && opts->x_flag_ipa_reference_addressable) + error_at (loc, + "%<-fipa-reference-addressable%> is incompatible with " + "%<-flive-patching=inline-only-static|inline-clone%>"); + else + opts->x_flag_ipa_reference_addressable = 0; + + /* ipa stack alignment propagation. */ + if (opts_set->x_flag_ipa_stack_alignment + && opts->x_flag_ipa_stack_alignment) + error_at (loc, + "%<-fipa-stack-alignment%> is incompatible with " + "%<-flive-patching=inline-only-static|inline-clone%>"); + else + opts->x_flag_ipa_stack_alignment = 0; +#endif + + break; + default: + gcc_unreachable (); + } +} + /* After all options at LOC have been read into OPTS and OPTS_SET, finalize settings of those options and diagnose incompatible combinations. */ @@ -1057,6 +1203,18 @@ finish_options (struct gcc_options *opts sorry ("transactional memory is not supported with " "%<-fsanitize=kernel-address%>"); + /* Currently live patching is not support for LTO. */ + if (opts->x_flag_live_patching && opts->x_flag_lto) + sorry ("live patching is not supported with LTO"); + + /* Control IPA optimizations based on different -flive-patching level. */ + if (opts->x_flag_live_patching) + { + control_options_for_live_patching (opts, opts_set, + opts->x_flag_live_patching, + loc); + } + /* Comes from final.c -- no real reason to change it. */ #define MAX_CODE_ALIGN 16 #define MAX_CODE_ALIGN_VALUE (1 << MAX_CODE_ALIGN) --- /dev/null +++ gcc/testsuite/gcc.dg/live-patching-1.c @@ -0,0 +1,22 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -flive-patching=inline-only-static -fdump-ipa-inline" } */ + +extern int sum, n, m; + +int foo (int a) +{ + return a + n; +} + +static int bar (int b) +{ + return b * m; +} + +int main() +{ + sum = foo (m) + bar (n); + return 0; +} + +/* { dg-final { scan-ipa-dump "foo/0 function has external linkage when the user requests only inlining static for live patching" "inline" } } */ --- /dev/null +++ gcc/testsuite/gcc.dg/live-patching-2.c @@ -0,0 +1,9 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -flive-patching -flto" } */ + +int main() +{ + return 0; +} + +/* { dg-message "sorry, unimplemented: live patching is not supported with LTO" "-flive-patching and -flto together" { target *-*-* } 0 } */ --- /dev/null +++ gcc/testsuite/gcc.dg/live-patching-3.c @@ -0,0 +1,9 @@ +/* { dg-do compile } */ +/* { dg-options "-O1 -flive-patching -fwhole-program" } */ + +int main() +{ + return 0; +} + +/* { dg-message "'-fwhole-program' is incompatible with '-flive-patching=inline-only-static|inline-clone’" "" {target "*-*-*"} 0 } */