Re: [PATCH][IRA,LRA] Fix PR87466, all pseudos live across setjmp are spilled

[Peter Bergner <bergner at linux dot ibm dot com>]

On 10/1/18 4:25 AM, Eric Botcazou wrote:
>> Since all implementations of this hook will have to do the same, I think
>> it is better if you leave this test at the (only two) callers.  The hook
>> doesn't need an argument then, and maybe is better named something like
>> setjmp_is_normal_call?  (The original code did not test CALL_P btw).
> 
> Seconded, but I'd be even more explicit in the naming of the hook, for example 
> setjmp_preserves_nonvolatile_registers or somesuch.  (And I don't think that 
> setjmp can be considered a normal call in any case since it returns twice).

Ok, here is an updated patch that renames the hook using Eric's suggestion
and keeps the scanning of the SETJMP note in the callers of the hook like
Segher wanted.

This is currently bootstrapping right now, but ok for trunk assuming no
regressions?

Peter

gcc/
	PR rtl-optimization/87466
	* target.def (setjmp_preserves_nonvolatile_regs_p): New target hook.
	* doc/tm.texi.in (TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P): New hook.
	* doc/tm.texi: Regenerate.
	* targhooks.c (default_setjmp_preserves_nonvolatile_regs_p): Declare.
	* targhooks.h (default_setjmp_preserves_nonvolatile_regs_p): New
	function.
	* ira-lives.c (process_bb_node_lives): Use the new target hook.
	* lra-lives.c (process_bb_lives): Likewise.
	* config/rs6000/rs6000.c (TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P):
	Define.
	(rs6000_setjmp_preserves_nonvolatile_regs_p): New function.

gcc/testsuite/
	PR rtl-optimization/87466
	* gcc.target/powerpc/pr87466.c: New test.

Index: gcc/target.def
===================================================================
--- gcc/target.def	(revision 264795)
+++ gcc/target.def	(working copy)
@@ -3123,6 +3123,21 @@ In order to enforce the representation o
  int, (scalar_int_mode mode, scalar_int_mode rep_mode),
  default_mode_rep_extended)
 
+ DEFHOOK
+(setjmp_preserves_nonvolatile_regs_p,
+ "On some targets, it is assumed that the compiler will spill all pseudos\n\
+  that are live across a call to @code{setjmp}, while other targets treat\n\
+  @code{setjmp} calls as normal function calls.\n\
+  \n\
+  This hook returns false if @code{setjmp} calls do not preserve all\n\
+  non-volatile registers so that gcc that must spill all pseudos that are\n\
+  live across @code{setjmp} calls.  Define this to return true if the\n\
+  target does not need to spill all pseudos live across @code{setjmp} calls.\n\
+  The default implementation conservatively assumes all pseudos must be\n\
+  spilled across @code{setjmp} calls.",
+ bool, (void),
+ default_setjmp_preserves_nonvolatile_regs_p)
+
 /* True if MODE is valid for a pointer in __attribute__((mode("MODE"))).  */
 DEFHOOK
 (valid_pointer_mode,
Index: gcc/doc/tm.texi.in
===================================================================
--- gcc/doc/tm.texi.in	(revision 264795)
+++ gcc/doc/tm.texi.in	(working copy)
@@ -7509,6 +7509,8 @@ You need not define this macro if it wou
 
 @hook TARGET_MODE_REP_EXTENDED
 
+@hook TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P
+
 @defmac STORE_FLAG_VALUE
 A C expression describing the value returned by a comparison operator
 with an integral mode and stored by a store-flag instruction
Index: gcc/doc/tm.texi
===================================================================
--- gcc/doc/tm.texi	(revision 264795)
+++ gcc/doc/tm.texi	(working copy)
@@ -11008,6 +11008,19 @@ In order to enforce the representation o
 @code{mode}.
 @end deftypefn
 
+@deftypefn {Target Hook} bool TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P (void)
+On some targets, it is assumed that the compiler will spill all pseudos
+  that are live across a call to @code{setjmp}, while other targets treat
+  @code{setjmp} calls as normal function calls.
+  
+  This hook returns false if @code{setjmp} calls do not preserve all
+  non-volatile registers so that gcc that must spill all pseudos that are
+  live across @code{setjmp} calls.  Define this to return true if the
+  target does not need to spill all pseudos live across @code{setjmp} calls.
+  The default implementation conservatively assumes all pseudos must be
+  spilled across @code{setjmp} calls.
+@end deftypefn
+
 @defmac STORE_FLAG_VALUE
 A C expression describing the value returned by a comparison operator
 with an integral mode and stored by a store-flag instruction
Index: gcc/targhooks.c
===================================================================
--- gcc/targhooks.c	(revision 264795)
+++ gcc/targhooks.c	(working copy)
@@ -209,6 +209,14 @@ default_builtin_setjmp_frame_value (void
   return virtual_stack_vars_rtx;
 }
 
+/* The default implementation of TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P.  */
+
+bool
+default_setjmp_preserves_nonvolatile_regs_p (void)
+{
+  return false;
+}
+
 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns false.  */
 
 bool
Index: gcc/targhooks.h
===================================================================
--- gcc/targhooks.h	(revision 264795)
+++ gcc/targhooks.h	(working copy)
@@ -42,6 +42,7 @@ extern bool default_return_in_memory (co
 extern rtx default_expand_builtin_saveregs (void);
 extern void default_setup_incoming_varargs (cumulative_args_t, machine_mode, tree, int *, int);
 extern rtx default_builtin_setjmp_frame_value (void);
+extern bool default_setjmp_preserves_nonvolatile_regs_p (void);
 extern bool default_pretend_outgoing_varargs_named (cumulative_args_t);
 
 extern scalar_int_mode default_eh_return_filter_mode (void);
Index: gcc/ira-lives.c
===================================================================
--- gcc/ira-lives.c	(revision 264795)
+++ gcc/ira-lives.c	(working copy)
@@ -1207,8 +1207,9 @@ process_bb_node_lives (ira_loop_tree_nod
 		     call, if this function receives a nonlocal
 		     goto.  */
 		  if (cfun->has_nonlocal_label
-		      || find_reg_note (insn, REG_SETJMP,
-					NULL_RTX) != NULL_RTX)
+		      || (!targetm.setjmp_preserves_nonvolatile_regs_p ()
+			  && (find_reg_note (insn, REG_SETJMP, NULL_RTX)
+			      != NULL_RTX)))
 		    {
 		      SET_HARD_REG_SET (OBJECT_CONFLICT_HARD_REGS (obj));
 		      SET_HARD_REG_SET (OBJECT_TOTAL_CONFLICT_HARD_REGS (obj));
Index: gcc/lra-lives.c
===================================================================
--- gcc/lra-lives.c	(revision 264795)
+++ gcc/lra-lives.c	(working copy)
@@ -895,8 +895,9 @@ process_bb_lives (basic_block bb, int &c
 	  sparseset_ior (pseudos_live_through_calls,
 			 pseudos_live_through_calls, pseudos_live);
 	  if (cfun->has_nonlocal_label
-	      || find_reg_note (curr_insn, REG_SETJMP,
-				NULL_RTX) != NULL_RTX)
+	      || (!targetm.setjmp_preserves_nonvolatile_regs_p ()
+		  && (find_reg_note (curr_insn, REG_SETJMP, NULL_RTX)
+		      != NULL_RTX)))
 	    sparseset_ior (pseudos_live_through_setjumps,
 			   pseudos_live_through_setjumps, pseudos_live);
 	}
Index: gcc/config/rs6000/rs6000.c
===================================================================
--- gcc/config/rs6000/rs6000.c	(revision 264795)
+++ gcc/config/rs6000/rs6000.c	(working copy)
@@ -1978,6 +1978,10 @@ static const struct attribute_spec rs600
 #undef TARGET_ASM_GLOBALIZE_DECL_NAME
 #define TARGET_ASM_GLOBALIZE_DECL_NAME rs6000_globalize_decl_name
 #endif
+
+#undef TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P
+#define TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P \
+  rs6000_setjmp_preserves_nonvolatile_regs_p
 
 
 /* Processor table.  */
@@ -38872,6 +38876,14 @@ rs6000_starting_frame_offset (void)
     return 0;
   return RS6000_STARTING_FRAME_OFFSET;
 }
+
+/* Implement TARGET_SETJMP_PRESERVES_NONVOLATILE_REGS_P.  */
+
+static bool
+rs6000_setjmp_preserves_nonvolatile_regs_p (void)
+{
+  return true;
+}
 
 
 /* Create an alias for a mangled name where we have changed the mangling (in
Index: gcc/testsuite/gcc.target/powerpc/pr87466.c
===================================================================
--- gcc/testsuite/gcc.target/powerpc/pr87466.c	(nonexistent)
+++ gcc/testsuite/gcc.target/powerpc/pr87466.c	(working copy)
@@ -0,0 +1,19 @@
+/* { dg-do compile { target powerpc*-*-* } } */
+/* { dg-options "-O2" } */
+
+#include <stdlib.h>
+#include <setjmp.h>
+
+extern void foo (jmp_buf);
+
+long
+c (long var)
+{
+  jmp_buf env;
+  if (setjmp(env) != 0)
+    abort();
+  foo (env);
+  return var;
+}
+
+/* { dg-final { scan-assembler {\mmr\M} } } */