From 96583f22d708d874ca90a012d8587e7ad484faed Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Fri, 17 Apr 2015 16:23:24 +0000 Subject: [PATCH] Properly handle uninitialized common symbol Uninitialized common symbol behavior in executables is target and linker dependent. default_binds_local_p_3 is made public and updated to take an argument to indicate if the linker can guarantee that an uninitialized common symbol in the executable will still be defined (through COPY relocation) in the executable. If common symbol is local to executable, default_binds_local_p_3 will treat non-external variable as defined locally. default_binds_local_p_2 is changed to treat common symbol as local for non-PIE binaries. For i386, common symbol is local only for non-PIE binaries. For x86-64, common symbol is local only for non-PIE binaries or linker supports copy reloc in PIE binaries. If a target treats common symbol as local only for non-PIE binaries, it can define TARGET_BINDS_LOCAL_P as default_binds_local_p_2. gcc/ PR target/65780 * output.h (default_binds_local_p_3): New. * varasm.c (default_binds_local_p_3): Make it public. Take an argument to indicate if common symbol may be local. If common symbol may be local, treat non-external variable as defined locally. (default_binds_local_p_2): Pass !flag_pic to default_binds_local_p_3. (default_binds_local_p_1): Pass false to default_binds_local_p_3. * config/i386/i386.c (ix86_binds_local_p): New. (TARGET_BINDS_LOCAL_P): Replace default_binds_local_p_2 with ix86_binds_local_p. gcc/testsuite/ PR target/65780 * gcc.dg/pr65780-1.c: New test. * gcc.dg/pr65780-2.c: Likewise. * gcc.target/i386/pr32219-9.c: Likewise. * gcc.target/i386/pr32219-1.c (xxx): Make it initialized common symbol. * gcc.target/i386/pr64317.c (c): Initialize. From-SVN: r222184 --- gcc/ChangeLog | 14 +++++++++ gcc/config/i386/i386.c | 15 +++++++++- gcc/output.h | 1 + gcc/testsuite/ChangeLog | 10 +++++++ gcc/testsuite/gcc.dg/pr65780-1.c | 12 ++++++++ gcc/testsuite/gcc.dg/pr65780-2.c | 13 +++++++++ gcc/testsuite/gcc.target/i386/pr32219-1.c | 3 +- gcc/testsuite/gcc.target/i386/pr32219-9.c | 15 ++++++++++ gcc/testsuite/gcc.target/i386/pr64317.c | 2 +- gcc/varasm.c | 35 +++++++++++++++-------- 10 files changed, 105 insertions(+), 15 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/pr65780-1.c create mode 100644 gcc/testsuite/gcc.dg/pr65780-2.c create mode 100644 gcc/testsuite/gcc.target/i386/pr32219-9.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 008e36ab5ee..71c692e91a0 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,17 @@ +2015-04-17 H.J. Lu + + PR target/65780 + * output.h (default_binds_local_p_3): New. + * varasm.c (default_binds_local_p_3): Make it public. Take an + argument to indicate if common symbol may be local. If common + symbol may be local, treat non-external variable as defined + locally. + (default_binds_local_p_2): Pass !flag_pic to default_binds_local_p_3. + (default_binds_local_p_1): Pass false to default_binds_local_p_3. + * config/i386/i386.c (ix86_binds_local_p): New. + (TARGET_BINDS_LOCAL_P): Replace default_binds_local_p_2 with + ix86_binds_local_p. + 2015-04-17 Jakub Jelinek PR debug/65771 diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c index 1f20ff394c8..72e6bc27f62 100644 --- a/gcc/config/i386/i386.c +++ b/gcc/config/i386/i386.c @@ -51793,6 +51793,19 @@ ix86_initialize_bounds (tree var, tree lb, tree ub, tree *stmts) return 2; } +/* For i386, common symbol is local only for non-PIE binaries. For + x86-64, common symbol is local only for non-PIE binaries or linker + supports copy reloc in PIE binaries. */ + +static bool +ix86_binds_local_p (const_tree exp) +{ + return default_binds_local_p_3 (exp, flag_shlib != 0, true, true, + (!flag_pic + || (TARGET_64BIT + && HAVE_LD_PIE_COPYRELOC != 0))); +} + /* Initialize the GCC target structure. */ #undef TARGET_RETURN_IN_MEMORY #define TARGET_RETURN_IN_MEMORY ix86_return_in_memory @@ -51927,7 +51940,7 @@ ix86_initialize_bounds (tree var, tree lb, tree ub, tree *stmts) #define TARGET_BINDS_LOCAL_P darwin_binds_local_p #else #undef TARGET_BINDS_LOCAL_P -#define TARGET_BINDS_LOCAL_P default_binds_local_p_2 +#define TARGET_BINDS_LOCAL_P ix86_binds_local_p #endif #if TARGET_DLLIMPORT_DECL_ATTRIBUTES #undef TARGET_BINDS_LOCAL_P diff --git a/gcc/output.h b/gcc/output.h index 53e47d03b3a..81d2ad29a83 100644 --- a/gcc/output.h +++ b/gcc/output.h @@ -587,6 +587,7 @@ extern bool default_use_anchors_for_symbol_p (const_rtx); extern bool default_binds_local_p (const_tree); extern bool default_binds_local_p_1 (const_tree, int); extern bool default_binds_local_p_2 (const_tree); +extern bool default_binds_local_p_3 (const_tree, bool, bool, bool, bool); extern void default_globalize_label (FILE *, const char *); extern void default_globalize_decl_name (FILE *, tree); extern void default_emit_unwind_label (FILE *, tree, int, int); diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index e7b30489c7f..c6bd2eda4b6 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,13 @@ +2015-04-17 H.J. Lu + + PR target/65780 + * gcc.dg/pr65780-1.c: New test. + * gcc.dg/pr65780-2.c: Likewise. + * gcc.target/i386/pr32219-9.c: Likewise. + * gcc.target/i386/pr32219-1.c (xxx): Make it initialized common + symbol. + * gcc.target/i386/pr64317.c (c): Initialize. + 2015-04-17 H.J. Lu PR target/65612 diff --git a/gcc/testsuite/gcc.dg/pr65780-1.c b/gcc/testsuite/gcc.dg/pr65780-1.c new file mode 100644 index 00000000000..b586211b649 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr65780-1.c @@ -0,0 +1,12 @@ +/* PR target/65780 */ +/* { dg-do link { target *-*-linux* *-*-gnu* } } */ +/* { dg-options "-O2" } */ + +int optopt; + +int +main () +{ + optopt = 4; + return 0; +} diff --git a/gcc/testsuite/gcc.dg/pr65780-2.c b/gcc/testsuite/gcc.dg/pr65780-2.c new file mode 100644 index 00000000000..bff33237cf5 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr65780-2.c @@ -0,0 +1,13 @@ +/* PR target/65780 */ +/* { dg-do link { target *-*-linux* *-*-gnu* } } */ +/* { dg-require-effective-target pie } */ +/* { dg-options "-O2 -fpie" } */ + +int optopt; + +int +main () +{ + optopt = 4; + return 0; +} diff --git a/gcc/testsuite/gcc.target/i386/pr32219-1.c b/gcc/testsuite/gcc.target/i386/pr32219-1.c index 5bd80a0cd47..2622f663059 100644 --- a/gcc/testsuite/gcc.target/i386/pr32219-1.c +++ b/gcc/testsuite/gcc.target/i386/pr32219-1.c @@ -1,7 +1,8 @@ /* { dg-do compile { target *-*-linux* } } */ /* { dg-options "-O2 -fpie" } */ -/* Common symbol with -fpie. */ +/* Initialized common symbol with -fpie. */ +int xxx = 5; int xxx; int diff --git a/gcc/testsuite/gcc.target/i386/pr32219-9.c b/gcc/testsuite/gcc.target/i386/pr32219-9.c new file mode 100644 index 00000000000..8c218266359 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr32219-9.c @@ -0,0 +1,15 @@ +/* { dg-do compile { target *-*-linux* } } */ +/* { dg-require-effective-target pie_copyreloc } */ +/* { dg-options "-O2 -fpie" } */ + +/* Uninitialized common symbol with -fpie. */ +int xxx; + +int +foo () +{ + return xxx; +} + +/* { dg-final { scan-assembler "movl\[ \t\]xxx\\(%rip\\), %eax" { target { ! ia32 } } } } */ +/* { dg-final { scan-assembler-not "xxx@GOTPCREL" { target { ! ia32 } } } } */ diff --git a/gcc/testsuite/gcc.target/i386/pr64317.c b/gcc/testsuite/gcc.target/i386/pr64317.c index 32969fc689a..8cac6ddb25d 100644 --- a/gcc/testsuite/gcc.target/i386/pr64317.c +++ b/gcc/testsuite/gcc.target/i386/pr64317.c @@ -3,7 +3,7 @@ /* { dg-final { scan-assembler "addl\[ \\t\]+\[$\]_GLOBAL_OFFSET_TABLE_, %ebx" } } */ /* { dg-final { scan-assembler "movl\[ \\t\]+c@GOTOFF\[(\]%ebx\[)\]" } } */ /* { dg-final { scan-assembler-not "movl\[ \\t\]+\[0-9]+\[(\]%esp\[)\], %ebx" } } */ -long c; +long c = 1; int bar(); diff --git a/gcc/varasm.c b/gcc/varasm.c index e644b1daa7e..e8d996cb1e3 100644 --- a/gcc/varasm.c +++ b/gcc/varasm.c @@ -6809,9 +6809,13 @@ resolution_local_p (enum ld_plugin_symbol_resolution resolution) || resolution == LDPR_RESOLVED_EXEC); } -static bool +/* COMMON_LOCAL_P is true means that the linker can guarantee that an + uninitialized common symbol in the executable will still be defined + (through COPY relocation) in the executable. */ + +bool default_binds_local_p_3 (const_tree exp, bool shlib, bool weak_dominate, - bool extern_protected_data) + bool extern_protected_data, bool common_local_p) { /* A non-decl is an entry in the constant pool. */ if (!DECL_P (exp)) @@ -6836,7 +6840,16 @@ default_binds_local_p_3 (const_tree exp, bool shlib, bool weak_dominate, because dynamic linking might overwrite symbols in shared libraries. */ bool resolved_locally = false; - bool defined_locally = !DECL_EXTERNAL (exp); + + bool uninited_common = (DECL_COMMON (exp) + && (DECL_INITIAL (exp) == NULL + || (!in_lto_p + && DECL_INITIAL (exp) == error_mark_node))); + + /* A non-external variable is defined locally only if it isn't + uninitialized COMMON variable or common_local_p is true. */ + bool defined_locally = (!DECL_EXTERNAL (exp) + && (!uninited_common || common_local_p)); if (symtab_node *node = symtab_node::get (exp)) { if (node->in_other_partition) @@ -6878,10 +6891,7 @@ default_binds_local_p_3 (const_tree exp, bool shlib, bool weak_dominate, /* Uninitialized COMMON variable may be unified with symbols resolved from other modules. */ - if (DECL_COMMON (exp) - && !resolved_locally - && (DECL_INITIAL (exp) == NULL - || (!in_lto_p && DECL_INITIAL (exp) == error_mark_node))) + if (uninited_common && !resolved_locally) return false; /* Otherwise we're left with initialized (or non-common) global data @@ -6895,21 +6905,22 @@ default_binds_local_p_3 (const_tree exp, bool shlib, bool weak_dominate, bool default_binds_local_p (const_tree exp) { - return default_binds_local_p_3 (exp, flag_shlib != 0, true, false); + return default_binds_local_p_3 (exp, flag_shlib != 0, true, false, false); } -/* Similar to default_binds_local_p, but protected data may be - external. */ +/* Similar to default_binds_local_p, but common symbol may be local. */ + bool default_binds_local_p_2 (const_tree exp) { - return default_binds_local_p_3 (exp, flag_shlib != 0, true, true); + return default_binds_local_p_3 (exp, flag_shlib != 0, true, false, + !flag_pic); } bool default_binds_local_p_1 (const_tree exp, int shlib) { - return default_binds_local_p_3 (exp, shlib != 0, false, false); + return default_binds_local_p_3 (exp, shlib != 0, false, false, false); } /* Return true when references to DECL must bind to current definition in -- 2.30.2