[PATCH 1/2] Add -fsingle-global-definition

H.J. Lu hjl.tools@gmail.com
Sun Jun 20 23:05:43 GMT 2021


1. Generate a single global definition marker in relocatable objects.
   a. Always use GOT to access undefined data and function symbols,
      including in PIE and non-PIE.  These will avoid copy relocations
      in executables.
   b. This is compatible with existing executables and shared libraries.
2. In executable and shared library, bind symbols with the STV_PROTECTED
   visibility locally:
   a. The address of data symbol is the address of data body.
   b. For systems without function descriptor, the function pointer is
      the address of function body.
   c. The resulting shared libraries may not be incompatible with
      executables which have copy relocations on protected symbols.
3. Update asm_preferred_eh_data_format to properly select EH encoding
format with -fsingle-global-definition.
4. Add ix86_reloc_rw_mask for TARGET_ASM_RELOC_RW_MASK to avoid copy
relocation with -fsingle-global-definition.

gcc/

	PR target/35513
	PR target/100593
	* common.opt: Add -fsingle-global-definition.
	* config/i386/i386-protos.h (ix86_force_load_from_GOT_p): Add a
	bool argument.
	* config/i386/i386.c (ix86_force_load_from_GOT_p): Add a bool
	argument to indicate call operand.  Force non-call load
	from GOT for -fsingle-global-definition.
	(legitimate_pic_address_disp_p): Avoid copy relocation in PIE
	for -fsingle-global-definition.
	(ix86_print_operand): Pass true to ix86_force_load_from_GOT_p
	for call operand.
	(asm_preferred_eh_data_format): Use PC-relative format for
	-fsingle-global-definition to avoid copy relocation.  Check
	ptr_mode instead of TARGET_64BIT when selecting DW_EH_PE_sdata4.
	(ix86_binds_local_p): Don't treat protected data as extern and
	avoid copy relocation on common symbol.
	(ix86_reloc_rw_mask): New to avoid copy relocation for
	-fsingle-global-definition.
	(TARGET_ASM_RELOC_RW_MASK): New.
	* doc/invoke.texi: Document -fsingle-global-definition.

gcc/testsuite/

	PR target/35513
	PR target/100593
	* g++.dg/pr35513-1.C: New file.
	* g++.dg/pr35513-2.C: Likewise.
	* gcc.target/i386/pr35513-1.c: Likewise.
	* gcc.target/i386/pr35513-2.c: Likewise.
	* gcc.target/i386/pr35513-3.c: Likewise.
	* gcc.target/i386/pr35513-4.c: Likewise.
	* gcc.target/i386/pr35513-5.c: Likewise.
	* gcc.target/i386/pr35513-6.c: Likewise.
	* gcc.target/i386/pr35513-7.c: Likewise.
	* gcc.target/i386/pr35513-8.c: Likewise.
---
 gcc/common.opt                            |  4 ++
 gcc/config/i386/i386-protos.h             |  2 +-
 gcc/config/i386/i386.c                    | 50 +++++++++++++++------
 gcc/doc/invoke.texi                       |  8 +++-
 gcc/testsuite/g++.dg/pr35513-1.C          | 25 +++++++++++
 gcc/testsuite/g++.dg/pr35513-2.C          | 53 +++++++++++++++++++++++
 gcc/testsuite/gcc.target/i386/pr35513-1.c | 16 +++++++
 gcc/testsuite/gcc.target/i386/pr35513-2.c | 15 +++++++
 gcc/testsuite/gcc.target/i386/pr35513-3.c | 15 +++++++
 gcc/testsuite/gcc.target/i386/pr35513-4.c | 15 +++++++
 gcc/testsuite/gcc.target/i386/pr35513-5.c | 15 +++++++
 gcc/testsuite/gcc.target/i386/pr35513-6.c | 14 ++++++
 gcc/testsuite/gcc.target/i386/pr35513-7.c | 15 +++++++
 gcc/testsuite/gcc.target/i386/pr35513-8.c | 41 ++++++++++++++++++
 14 files changed, 272 insertions(+), 16 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/pr35513-1.C
 create mode 100644 gcc/testsuite/g++.dg/pr35513-2.C
 create mode 100644 gcc/testsuite/gcc.target/i386/pr35513-1.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr35513-2.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr35513-3.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr35513-4.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr35513-5.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr35513-6.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr35513-7.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr35513-8.c

diff --git a/gcc/common.opt b/gcc/common.opt
index a1353e06bdc..b1cb53bb780 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -2579,6 +2579,10 @@ fsigned-zeros
 Common Var(flag_signed_zeros) Init(1) Optimization SetByCombined
 Disable floating point optimizations that ignore the IEEE signedness of zero.
 
+fsingle-global-definition
+Common Var(flag_single_global_definition) Optimization
+Use GOT to access external symbols and make access to protected symbols local.
+
 fsingle-precision-constant
 Common Var(flag_single_precision_constant) Optimization
 Convert floating point constants to single precision constants.
diff --git a/gcc/config/i386/i386-protos.h b/gcc/config/i386/i386-protos.h
index e6ac9390777..30f75b9900b 100644
--- a/gcc/config/i386/i386-protos.h
+++ b/gcc/config/i386/i386-protos.h
@@ -77,7 +77,7 @@ extern bool ix86_expand_cmpstrn_or_cmpmem (rtx, rtx, rtx, rtx, rtx, bool);
 extern bool constant_address_p (rtx);
 extern bool legitimate_pic_operand_p (rtx);
 extern bool legitimate_pic_address_disp_p (rtx);
-extern bool ix86_force_load_from_GOT_p (rtx);
+extern bool ix86_force_load_from_GOT_p (rtx, bool = false);
 extern void print_reg (rtx, int, FILE*);
 extern void ix86_print_operand (FILE *, rtx, int);
 
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 7d0d4143bca..9878c3126d0 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -10311,13 +10311,17 @@ darwin_local_data_pic (rtx disp)
 }
 
 /* True if the function symbol operand X should be loaded from GOT.
+   If CALL_P is true, X is a call operand.
+
+   NB: -fsingle-global-definition doesn't force load from GOT for
+   call.
 
    NB: In 32-bit mode, only non-PIC is allowed in inline assembly
    statements, since a PIC register could not be available at the
    call site.  */
 
 bool
-ix86_force_load_from_GOT_p (rtx x)
+ix86_force_load_from_GOT_p (rtx x, bool call_p)
 {
   return ((TARGET_64BIT || (!flag_pic && HAVE_AS_IX86_GOT32X))
 	  && !TARGET_PECOFF && !TARGET_MACHO
@@ -10325,11 +10329,12 @@ ix86_force_load_from_GOT_p (rtx x)
 	  && ix86_cmodel != CM_LARGE
 	  && ix86_cmodel != CM_LARGE_PIC
 	  && GET_CODE (x) == SYMBOL_REF
-	  && SYMBOL_REF_FUNCTION_P (x)
-	  && (!flag_plt
-	      || (SYMBOL_REF_DECL (x)
-		  && lookup_attribute ("noplt",
-				       DECL_ATTRIBUTES (SYMBOL_REF_DECL (x)))))
+	  && ((!call_p && flag_single_global_definition)
+	      || (SYMBOL_REF_FUNCTION_P (x)
+		  && (!flag_plt
+		      || (SYMBOL_REF_DECL (x)
+			  && lookup_attribute ("noplt",
+					       DECL_ATTRIBUTES (SYMBOL_REF_DECL (x)))))))
 	  && !SYMBOL_REF_LOCAL_P (x));
 }
 
@@ -10595,7 +10600,8 @@ legitimate_pic_address_disp_p (rtx disp)
 	    }
 	  else if (!SYMBOL_REF_FAR_ADDR_P (op0)
 		   && (SYMBOL_REF_LOCAL_P (op0)
-		       || (HAVE_LD_PIE_COPYRELOC
+		       || (!flag_single_global_definition
+			   && HAVE_LD_PIE_COPYRELOC
 			   && flag_pie
 			   && !SYMBOL_REF_WEAK (op0)
 			   && !SYMBOL_REF_FUNCTION_P (op0)))
@@ -13497,7 +13503,7 @@ ix86_print_operand (FILE *file, rtx x, int code)
 
       if (code == 'P')
 	{
-	  if (ix86_force_load_from_GOT_p (x))
+	  if (ix86_force_load_from_GOT_p (x, true))
 	    {
 	      /* For inline assembly statement, load function address
 		 from GOT with 'P' operand modifier to avoid PLT.  */
@@ -21895,10 +21901,10 @@ ix86_stack_protect_fail (void)
 int
 asm_preferred_eh_data_format (int code, int global)
 {
-  if (flag_pic)
+  if (flag_pic || flag_single_global_definition)
     {
       int type = DW_EH_PE_sdata8;
-      if (!TARGET_64BIT
+      if (ptr_mode == SImode
 	  || ix86_cmodel == CM_SMALL_PIC
 	  || (ix86_cmodel == CM_MEDIUM_PIC && (global || code)))
 	type = DW_EH_PE_sdata4;
@@ -22986,10 +22992,21 @@ ix86_atomic_assign_expand_fenv (tree *hold, tree *clear, tree *update)
 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)));
+  return default_binds_local_p_3 (exp, flag_shlib != 0, true,
+				  !flag_single_global_definition,
+				  (!flag_single_global_definition
+				   && (!flag_pic
+				       || (TARGET_64BIT
+					   && HAVE_LD_PIE_COPYRELOC != 0))));
+}
+
+/* If flag_pic or flag_single_global_definition is true, then neither
+   local nor global relocs should be placed in readonly memory.  */
+
+static int
+ix86_reloc_rw_mask (void)
+{
+  return (flag_pic || flag_single_global_definition) ? 3 : 0;
 }
 #endif
 
@@ -24016,6 +24033,11 @@ ix86_run_selftests (void)
 #define TARGET_GET_MULTILIB_ABI_NAME \
   ix86_get_multilib_abi_name
 
+#if !TARGET_MACHO && !TARGET_DLLIMPORT_DECL_ATTRIBUTES
+# undef TARGET_ASM_RELOC_RW_MASK
+# define TARGET_ASM_RELOC_RW_MASK ix86_reloc_rw_mask
+#endif
+
 static bool ix86_libc_has_fast_function (int fcode ATTRIBUTE_UNUSED)
 {
 #ifdef OPTION_GLIBC
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index af2ce189fae..203061e9c08 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -555,7 +555,7 @@ Objective-C and Objective-C++ Dialects}.
 -fselective-scheduling  -fselective-scheduling2 @gol
 -fsel-sched-pipelining  -fsel-sched-pipelining-outer-loops @gol
 -fsemantic-interposition  -fshrink-wrap  -fshrink-wrap-separate @gol
--fsignaling-nans @gol
+-fsignaling-nans -fsingle-global-definition @gol
 -fsingle-precision-constant  -fsplit-ivs-in-unroller  -fsplit-loops@gol
 -fsplit-paths @gol
 -fsplit-wide-types  -fsplit-wide-types-early  -fssa-backprop  -fssa-phiopt @gol
@@ -16543,6 +16543,12 @@ through the PLT for specific external functions.
 In position-dependent code, a few targets also convert calls to
 functions that are marked to not use the PLT to use the GOT instead.
 
+@item -fsingle-global-definition
+@opindex fsingle-global-definition
+Avoid copy relocation by using the GOT pointer to access external symbols
+in both position-dependent and position-independent codes.  Make access
+to protected symbols local.
+
 @item -fno-jump-tables
 @opindex fno-jump-tables
 @opindex fjump-tables
diff --git a/gcc/testsuite/g++.dg/pr35513-1.C b/gcc/testsuite/g++.dg/pr35513-1.C
new file mode 100644
index 00000000000..861cf55c103
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr35513-1.C
@@ -0,0 +1,25 @@
+// { dg-do run }
+// { dg-options "-O2 -fsingle-global-definition" }
+
+#include <iostream>
+
+class Bug
+{
+};
+
+int throw_bug()
+{
+  throw Bug();
+
+  return 0;
+}
+
+int main()
+{
+  try {
+      std::cout << throw_bug();
+  } catch (Bug bug) {
+  };
+
+  return 0;
+}
diff --git a/gcc/testsuite/g++.dg/pr35513-2.C b/gcc/testsuite/g++.dg/pr35513-2.C
new file mode 100644
index 00000000000..a58144216d5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr35513-2.C
@@ -0,0 +1,53 @@
+// { dg-do run  }
+// { dg-options "-O2 -fsingle-global-definition" }
+
+class Foo 
+{
+public:
+  Foo(int n) : n_(n) { }
+  int f() { return n_; }
+
+  int badTest();
+  int goodTest();
+
+private:
+
+  int n_;
+};
+
+int Foo::badTest()
+{
+  try {
+      throw int(99);
+  }
+
+  catch (int &i) {
+      n_ = 16;
+  }
+
+  return n_;
+}
+
+
+int Foo::goodTest()
+{
+  int	n;
+
+  try {
+      throw int(99);
+  }
+
+  catch (int &i) {
+      n = 16;
+  }
+
+  return n_;
+}
+
+int main() 
+{
+  Foo foo(5);
+  foo.goodTest();
+  foo.badTest();
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr35513-1.c b/gcc/testsuite/gcc.target/i386/pr35513-1.c
new file mode 100644
index 00000000000..ec4c8aac049
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr35513-1.c
@@ -0,0 +1,16 @@
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -fno-pic -fsingle-global-definition" } */
+
+extern void bar (void);
+extern void *p;
+
+void
+foo (void)
+{
+  p = &bar;
+}
+
+/* { dg-final { scan-assembler "mov\(l|q\)\[ \t\]*bar@GOTPCREL" { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler "movl\[ \t\]*bar@GOT," { target { ia32 && got32x_reloc } } } } */
+/* { dg-final { scan-assembler-not "mov\(l|q\)\[ \t\]*\\\$bar," { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-not "mov\(l|q\)\[ \t\]*\\\$bar," { target { ia32 && got32x_reloc } } } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr35513-2.c b/gcc/testsuite/gcc.target/i386/pr35513-2.c
new file mode 100644
index 00000000000..c5145d4d5ae
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr35513-2.c
@@ -0,0 +1,15 @@
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -fno-pic -fsingle-global-definition" } */
+
+extern int bar;
+
+int
+foo (void)
+{
+  return bar;
+}
+
+/* { dg-final { scan-assembler "mov\(l|q\)\[ \t\]*bar@GOTPCREL" { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler "movl\[ \t\]*bar@GOT," { target { ia32 && got32x_reloc } } } } */
+/* { dg-final { scan-assembler-not "mov\(l|q\)\[ \t\]*\\\$bar," { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-not "mov\(l|q\)\[ \t\]*\\\$bar," { target { ia32 && got32x_reloc } } } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr35513-3.c b/gcc/testsuite/gcc.target/i386/pr35513-3.c
new file mode 100644
index 00000000000..d0e93c84613
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr35513-3.c
@@ -0,0 +1,15 @@
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -fpie -fsingle-global-definition" } */
+
+extern int bar;
+
+int
+foo (void)
+{
+  return bar;
+}
+
+/* { dg-final { scan-assembler "mov\(l|q\)\[ \t\]*bar@GOTPCREL" { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler "movl\[ \t\]*bar@GOT" { target { ia32 && got32x_reloc } } } } */
+/* { dg-final { scan-assembler-not "mov\(l|q\)\[ \t\]*\\\$bar," { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-not "mov\(l|q\)\[ \t\]*\\\$bar," { target { ia32 && got32x_reloc } } } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr35513-4.c b/gcc/testsuite/gcc.target/i386/pr35513-4.c
new file mode 100644
index 00000000000..fffb7d878a8
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr35513-4.c
@@ -0,0 +1,15 @@
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -fplt -fno-pic -fsingle-global-definition" } */
+
+extern void foo (void);
+
+int
+bar (void)
+{
+  foo ();
+  return 0;
+}
+
+/* { dg-final { scan-assembler "call\[ \t\]*foo" } } */
+/* { dg-final { scan-assembler-not "foo@GOTPCREL" { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-not "foo@GOT" { target ia32 } } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr35513-5.c b/gcc/testsuite/gcc.target/i386/pr35513-5.c
new file mode 100644
index 00000000000..a107611a104
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr35513-5.c
@@ -0,0 +1,15 @@
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -fplt -fpic -fsingle-global-definition" } */
+
+extern void foo (void);
+
+int
+bar (void)
+{
+  foo ();
+  return 0;
+}
+
+/* { dg-final { scan-assembler "call\[ \t\]*foo@PLT" } } */
+/* { dg-final { scan-assembler-not "foo@GOTPCREL" { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-not "foo@GOT" { target ia32 } } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr35513-6.c b/gcc/testsuite/gcc.target/i386/pr35513-6.c
new file mode 100644
index 00000000000..164899a96d0
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr35513-6.c
@@ -0,0 +1,14 @@
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -fplt -fno-pic -fsingle-global-definition" } */
+
+extern void foo (void);
+
+void
+bar (void)
+{
+  foo ();
+}
+
+/* { dg-final { scan-assembler "jmp\[ \t\]*foo" } } */
+/* { dg-final { scan-assembler-not "foo@GOTPCREL" { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-not "foo@GOT" { target ia32 } } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr35513-7.c b/gcc/testsuite/gcc.target/i386/pr35513-7.c
new file mode 100644
index 00000000000..5c6419368e7
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr35513-7.c
@@ -0,0 +1,15 @@
+/* { dg-do compile { target *-*-linux* } } */
+/* { dg-options "-O2 -fplt -fpic -fsingle-global-definition" } */
+
+extern void foo (void);
+
+void
+bar (void)
+{
+  foo ();
+}
+
+/* { dg-final { scan-assembler "jmp\[ \t\]*foo@PLT" { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler "call\[ \t\]*foo@PLT" { target ia32 } } } */
+/* { dg-final { scan-assembler-not "foo@GOTPCREL" { target { ! ia32 } } } } */
+/* { dg-final { scan-assembler-not "foo@GOT" { target ia32 } } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr35513-8.c b/gcc/testsuite/gcc.target/i386/pr35513-8.c
new file mode 100644
index 00000000000..c0fef079d73
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr35513-8.c
@@ -0,0 +1,41 @@
+/* { dg-do assemble { target { *-*-linux* && { ! ia32 } } } } */
+/* { dg-require-effective-target maybe_x32 } */
+/* { dg-options "-mx32 -O2 -fno-pic -fexceptions -fasynchronous-unwind-tables -fsingle-global-definition" } */
+
+extern int foo (int);
+extern void exit (int __status) __attribute__ ((__nothrow__ )) __attribute__ ((__noreturn__));
+struct __pthread_cleanup_frame
+{
+  void (*__cancel_routine) (void *);
+  void *__cancel_arg;
+  int __do_it;
+  int __cancel_type;
+};
+extern __inline void
+__pthread_cleanup_routine (struct __pthread_cleanup_frame *__frame)
+{
+  if (__frame->__do_it)
+    __frame->__cancel_routine (__frame->__cancel_arg);
+}
+static int cl_called;
+
+static void
+cl (void *arg)
+{
+  ++cl_called;
+}
+
+
+void *
+tf_usleep (void *arg)
+{
+
+  do { struct __pthread_cleanup_frame __clframe __attribute__ ((__cleanup__ (__pthread_cleanup_routine))) = { .__cancel_routine = (cl), .__cancel_arg = (
+																			 ((void *)0)), .__do_it = 1 };;
+
+    foo (arg == ((void *)0) ? (0x7fffffffL * 2UL + 1UL) : 0);
+
+    __clframe.__do_it = (0); } while (0);
+
+  exit (1);
+}
-- 
2.31.1



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