Add a new option -flive-patching={inline-only-static|inline-clone}

to support live patching in GCC.

2018-11-29  qing zhao  <qing.zhao@oracle.com>

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.

From-SVN: r266627

gcc/ChangeLog

@@ -1,3 +1,16 @@
+2018-11-29  qing zhao  <qing.zhao@oracle.com>
+
+	* 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.
+
 2018-11-29  Giuliano Belinassi  <giuliano.belinassi@usp.br>
 
 	* match.pd (sinh (atanh (x))): New simplification rules.

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

@@ -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

@@ -417,6 +417,7 @@ Objective-C and Objective-C++ Dialects}.
 -fipa-bit-cp  -fipa-vrp  -fipa-pta  -fipa-profile  -fipa-pure-const @gol
 -fipa-reference  -fipa-reference-addressable @gol
 -fipa-stack-alignment  -fipa-icf  -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

@@ -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

@@ -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

@@ -702,6 +702,148 @@ default_options_optimization (struct gcc_options *opts,
 			 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.  */
+      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;
+      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.  */
@@ -1051,6 +1193,18 @@ finish_options (struct gcc_options *opts, struct gcc_options *opts_set,
   if ((opts->x_flag_sanitize & SANITIZE_KERNEL_ADDRESS) && opts->x_flag_tm)
     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);
+    }
 }
 
 #define LEFT_COLUMN	27

gcc/testsuite/ChangeLog

@@ -1,3 +1,11 @@
+2018-11-29  qing zhao  <qing.zhao@oracle.com>
+
+	* 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.
+
 2018-11-29  Giuliano Belinassi  <giuliano.belinassi@usp.br>
 
 	* gcc.dg/sinhatanh-1.c: New test.

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" } } */

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 } */

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 } */

gcc/testsuite/gcc.dg/tree-ssa/writeonly-3.c

@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-optimized -flive-patching" } */
+static struct a {int magic1,b;} a;
+volatile int magic2;
+static struct b {int a,b,c,d,e,f;} magic3;
+
+struct b foo();
+
+void
+t()
+{
+ a.magic1 = 1;
+ magic2 = 1;
+ magic3 = foo();
+}
+/* { dg-final { scan-tree-dump "magic1" "optimized"} } */
+/* { dg-final { scan-tree-dump "magic3" "optimized"} } */
+/* { dg-final { scan-tree-dump "magic2" "optimized"} } */
+/* { dg-final { scan-tree-dump "foo" "optimized"} } */
+ 

gcc/testsuite/gcc.target/i386/ipa-stack-alignment-2.c

@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-flive-patching -O" } */
+
+typedef struct {
+  long a;
+  long b[];
+} c;
+
+c *d;
+void e() { d->b[0] = 5; }
+void f() { e(); }
+
+/* { dg-final { scan-assembler "sub.*%.sp" } } */