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* [PATCH] MIPS: Add option to pass return address location to _mcount
@ 2009-10-29  8:14 Wu Zhangjin
  2009-10-29  8:14 ` Wu Zhangjin
  2009-10-29 16:24 ` David Daney
  0 siblings, 2 replies; 9+ messages in thread
From: Wu Zhangjin @ 2009-10-29  8:14 UTC (permalink / raw)
  To: Richard Sandiford, David Daney, GCC Patches
  Cc: linux-mips, Adam Nemet, rostedt, Ralf Baechle, Nicholas Mc Guire,
	Wu Zhangjin, David Daney

From: Wu Zhangjin <wuzhangjin@gmail.com>

When we pass -pg -mmcount-ra-address, the address of the return address
relative to sp is passed in $12 to _mcount.  If the return address is not
saved, $12 will be zero. this will work as registers are never saved with an
offset of zero.  $12 is a temporary register that is not part of the ABI.

$12 is also used by libffi closure support, but its use there will not
interfere with _mcount.

2009-10-23  David Daney  <ddaney@caviumnetworks.com>

        * doc/invoke.texi (mmcount-ra-address): Document new command line option.
        * config/mips/mips.opt (config/mips/mips.opt): New option.
        * config/mips/mips-protos.h (mips_function_profiler): Declare new
        function.
        * config/mips/mips.c (struct mips_frame_info): Add ra_fp_offset member.
        (mips_for_each_saved_gpr_and_fpr): Set ra_fp_offset.
        (mips_function_profiler): Moved from FUNCTION_PROFILER, and rewritten.
        * config/mips/mips.h (FUNCTION_PROFILER): Body of macro moved to
        mips_function_profiler.

Tested-by: Wu Zhangjin <wuzhangjin@gmail.com>
Signed-off-by: David Daney <ddaney@caviumnetworks.com>
---
 gcc/config/mips/mips-protos.h                      |    1 +
 gcc/config/mips/mips.c                             |   67 +++++++++++++++++++-
 gcc/config/mips/mips.h                             |   39 +-----------
 gcc/config/mips/mips.opt                           |    4 +
 gcc/doc/invoke.texi                                |   22 ++++++-
 gcc/testsuite/gcc.target/mips/mips.exp             |    1 +
 .../gcc.target/mips/mmcount-ra-address-1.c         |    7 ++
 .../gcc.target/mips/mmcount-ra-address-2.c         |    8 +++
 .../gcc.target/mips/mmcount-ra-address-3.c         |   10 +++
 9 files changed, 119 insertions(+), 40 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/mips/mmcount-ra-address-1.c
 create mode 100644 gcc/testsuite/gcc.target/mips/mmcount-ra-address-2.c
 create mode 100644 gcc/testsuite/gcc.target/mips/mmcount-ra-address-3.c

diff --git a/gcc/config/mips/mips-protos.h b/gcc/config/mips/mips-protos.h
index 429a621..716b7ac 100644
--- a/gcc/config/mips/mips-protos.h
+++ b/gcc/config/mips/mips-protos.h
@@ -344,5 +344,6 @@ extern bool mips_eh_uses (unsigned int);
 extern bool mips_epilogue_uses (unsigned int);
 extern void mips_final_prescan_insn (rtx, rtx *, int);
 extern int mips_trampoline_code_size (void);
+extern void mips_function_profiler (FILE *);
 
 #endif /* ! GCC_MIPS_PROTOS_H */
diff --git a/gcc/config/mips/mips.c b/gcc/config/mips/mips.c
index f82091a..a1229be 100644
--- a/gcc/config/mips/mips.c
+++ b/gcc/config/mips/mips.c
@@ -319,6 +319,9 @@ struct GTY(())  mips_frame_info {
   HOST_WIDE_INT acc_sp_offset;
   HOST_WIDE_INT cop0_sp_offset;
 
+  /* Similar, but the value passed to _mcount.  */
+  HOST_WIDE_INT ra_fp_offset;
+
   /* The offset of arg_pointer_rtx from the bottom of the frame.  */
   HOST_WIDE_INT arg_pointer_offset;
 
@@ -9619,6 +9622,9 @@ mips_for_each_saved_gpr_and_fpr (HOST_WIDE_INT sp_offset,
   for (regno = GP_REG_LAST; regno >= GP_REG_FIRST; regno--)
     if (BITSET_P (cfun->machine->frame.mask, regno - GP_REG_FIRST))
       {
+	/* Record the ra offset for use by mips_function_profiler.  */
+	if (crtl->profile && regno == RETURN_ADDR_REGNUM)
+	  cfun->machine->frame.ra_fp_offset = offset + sp_offset;
 	mips_save_restore_reg (word_mode, regno, offset, fn);
 	offset -= UNITS_PER_WORD;
       }
@@ -16091,7 +16097,66 @@ mips_trampoline_init (rtx m_tramp, tree fndecl, rtx chain_value)
   emit_insn (gen_add3_insn (end_addr, addr, GEN_INT (TRAMPOLINE_SIZE)));
   emit_insn (gen_clear_cache (addr, end_addr));
 }
-\f
+
+/* Implement FUNCTION_PROFILER.  */
+
+void mips_function_profiler (FILE *file)
+{
+  if (TARGET_MIPS16)
+    sorry ("mips16 function profiling");
+  if (TARGET_LONG_CALLS)
+    {
+      /* For TARGET_LONG_CALLS use $3 for the address of _mcount.  */
+      if (Pmode == DImode)
+	fprintf (file, "\tdla\t%s,_mcount\n", reg_names[3]);
+      else
+	fprintf (file, "\tla\t%s,_mcount\n", reg_names[3]);
+    }
+  mips_push_asm_switch (&mips_noat);
+  fprintf (file, "\tmove\t%s,%s\t\t# save current return address\n",
+	   reg_names[AT_REGNUM], reg_names[RETURN_ADDR_REGNUM]);
+  /* _mcount treats $2 as the static chain register.  */
+  if (cfun->static_chain_decl != NULL)
+    fprintf (file, "\tmove\t%s,%s\n", reg_names[2],
+	     reg_names[STATIC_CHAIN_REGNUM]);
+  if (TARGET_MCOUNT_RA_ADDRESS)
+    {
+      /* If TARGET_MCOUNT_RA_ADDRESS load $12 with the address of the ra
+       * save location.  */
+      if (cfun->machine->frame.ra_fp_offset == 0)
+	/* ra not saved, pass zero.  */
+	fprintf (file, "\tmove\t%s,%s\n",
+		 reg_names[12], reg_names[0]);
+      else if (SMALL_OPERAND (cfun->machine->frame.ra_fp_offset))
+	fprintf (file,
+		 "\t%s\t%s,%s," HOST_WIDE_INT_PRINT_DEC "\n",
+		 Pmode == DImode ? "daddiu" : "addiu", reg_names[12],
+		 reg_names[STACK_POINTER_REGNUM],
+		 cfun->machine->frame.ra_fp_offset);
+      else
+	fprintf (file, "\t%s\t%s," HOST_WIDE_INT_PRINT_DEC "(%s)",
+                 Pmode == DImode ? "dla" : "la", reg_names[12],
+                 cfun->machine->frame.ra_fp_offset,
+                 reg_names[STACK_POINTER_REGNUM]);
+    }
+  if (!TARGET_NEWABI)
+      fprintf (file,
+	       "\t%s\t%s,%s,%d\t\t# _mcount pops 2 words from  stack\n",
+	       TARGET_64BIT ? "dsubu" : "subu",
+	       reg_names[STACK_POINTER_REGNUM],
+	       reg_names[STACK_POINTER_REGNUM],
+	       Pmode == DImode ? 16 : 8);
+  if (TARGET_LONG_CALLS)
+    fprintf (file, "\tjalr\t%s\n", reg_names[3]);
+  else
+    fprintf (file, "\tjal\t_mcount\n");
+  mips_pop_asm_switch (&mips_noat);
+  /* _mcount treats $2 as the static chain register.  */
+  if (cfun->static_chain_decl != NULL)
+    fprintf (file, "\tmove\t%s,%s\n", reg_names[STATIC_CHAIN_REGNUM],
+	     reg_names[2]);
+}
+
 /* Initialize the GCC target structure.  */
 #undef TARGET_ASM_ALIGNED_HI_OP
 #define TARGET_ASM_ALIGNED_HI_OP "\t.half\t"
diff --git a/gcc/config/mips/mips.h b/gcc/config/mips/mips.h
index 50bc4ea..2829708 100644
--- a/gcc/config/mips/mips.h
+++ b/gcc/config/mips/mips.h
@@ -2372,44 +2372,7 @@ typedef struct mips_args {
 /* Output assembler code to FILE to increment profiler label # LABELNO
    for profiling a function entry.  */
 
-#define FUNCTION_PROFILER(FILE, LABELNO)				\
-{									\
-  if (TARGET_MIPS16)							\
-    sorry ("mips16 function profiling");				\
-  if (TARGET_LONG_CALLS)						\
-    {									\
-      /*  For TARGET_LONG_CALLS use $3 for the address of _mcount.  */	\
-      if (Pmode == DImode)						\
-	fprintf (FILE, "\tdla\t%s,_mcount\n", reg_names[GP_REG_FIRST + 3]); \
-      else								\
-	fprintf (FILE, "\tla\t%s,_mcount\n", reg_names[GP_REG_FIRST + 3]); \
-    }									\
-  mips_push_asm_switch (&mips_noat);					\
-  fprintf (FILE, "\tmove\t%s,%s\t\t# save current return address\n",	\
-	   reg_names[AT_REGNUM], reg_names[RETURN_ADDR_REGNUM]);	\
-  /* _mcount treats $2 as the static chain register.  */		\
-  if (cfun->static_chain_decl != NULL)					\
-    fprintf (FILE, "\tmove\t%s,%s\n", reg_names[2],			\
-	     reg_names[STATIC_CHAIN_REGNUM]);				\
-  if (!TARGET_NEWABI)							\
-    {									\
-      fprintf (FILE,							\
-	       "\t%s\t%s,%s,%d\t\t# _mcount pops 2 words from  stack\n", \
-	       TARGET_64BIT ? "dsubu" : "subu",				\
-	       reg_names[STACK_POINTER_REGNUM],				\
-	       reg_names[STACK_POINTER_REGNUM],				\
-	       Pmode == DImode ? 16 : 8);				\
-    }									\
-  if (TARGET_LONG_CALLS)						\
-    fprintf (FILE, "\tjalr\t%s\n", reg_names[GP_REG_FIRST + 3]);	\
-  else									\
-    fprintf (FILE, "\tjal\t_mcount\n");					\
-  mips_pop_asm_switch (&mips_noat);					\
-  /* _mcount treats $2 as the static chain register.  */		\
-  if (cfun->static_chain_decl != NULL)					\
-    fprintf (FILE, "\tmove\t%s,%s\n", reg_names[STATIC_CHAIN_REGNUM],	\
-	     reg_names[2]);						\
-}
+#define FUNCTION_PROFILER(FILE, LABELNO) mips_function_profiler ((FILE))
 
 /* The profiler preserves all interesting registers, including $31.  */
 #define MIPS_SAVE_REG_FOR_PROFILING_P(REGNO) false
diff --git a/gcc/config/mips/mips.opt b/gcc/config/mips/mips.opt
index 8462e46..188d5e1 100644
--- a/gcc/config/mips/mips.opt
+++ b/gcc/config/mips/mips.opt
@@ -208,6 +208,10 @@ mlong64
 Target Report RejectNegative Mask(LONG64)
 Use a 64-bit long type
 
+mmcount-ra-address
+Target Report Var(TARGET_MCOUNT_RA_ADDRESS)
+Pass the address of the ra save location to _mcount in $12
+
 mmemcpy
 Target Report Mask(MEMCPY)
 Don't optimize block moves
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 4a9ffbf..0e1490e 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -709,7 +709,7 @@ Objective-C and Objective-C++ Dialects}.
 -mbranch-cost=@var{num}  -mbranch-likely  -mno-branch-likely @gol
 -mfp-exceptions -mno-fp-exceptions @gol
 -mvr4130-align -mno-vr4130-align -msynci -mno-synci @gol
--mrelax-pic-calls -mno-relax-pic-calls}
+-mrelax-pic-calls -mno-relax-pic-calls -mmcount-ra-address}
 
 @emph{MMIX Options}
 @gccoptlist{-mlibfuncs  -mno-libfuncs  -mepsilon  -mno-epsilon  -mabi=gnu @gol
@@ -14207,6 +14207,26 @@ an assembler and a linker that supports the @code{.reloc} assembly
 directive and @code{-mexplicit-relocs} is in effect.  With
 @code{-mno-explicit-relocs}, this optimization can be performed by the
 assembler and the linker alone without help from the compiler.
+
+@item -mmcount-ra-address
+@itemx -mno-mcount-ra-address
+@opindex mmcount-ra-address
+@opindex mno-mcount-ra-address
+Allow (do not allow) @code{_mcount} to modify the calling function's
+return address.  When enabled, this option extends the usual @code{_mcount}
+interface with a new @var{ra-address} parameter, which has type
+@code{intptr_t *} and is passed in register @code{$12}.  @code{_mcount}
+can then modify the return address by doing both of the following:
+@itemize
+@item
+Returning the new address in register @code{$31}.
+@item
+Storing the new address in @code{*@var{ra-address}},
+if @var{ra-address} is nonnull.
+@end itemize
+
+The default is @option{-mno-mcount-ra-address}.
+
 @end table
 
 @node MMIX Options
diff --git a/gcc/testsuite/gcc.target/mips/mips.exp b/gcc/testsuite/gcc.target/mips/mips.exp
index aef473f..02e031c 100644
--- a/gcc/testsuite/gcc.target/mips/mips.exp
+++ b/gcc/testsuite/gcc.target/mips/mips.exp
@@ -263,6 +263,7 @@ foreach option {
     sym32
     synci
     relax-pic-calls
+    mcount-ra-address
 } {
     lappend mips_option_groups $option "-m(no-|)$option"
 }
diff --git a/gcc/testsuite/gcc.target/mips/mmcount-ra-address-1.c b/gcc/testsuite/gcc.target/mips/mmcount-ra-address-1.c
new file mode 100644
index 0000000..2af802d
--- /dev/null
+++ b/gcc/testsuite/gcc.target/mips/mmcount-ra-address-1.c
@@ -0,0 +1,7 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -pg -mmcount-ra-address -march=mips64 -mabi=64 -mno-abicalls -msym32" } */
+/* { dg-final { scan-assembler "\tmove\t\\\$12,\\\$0" } } */
+int bazl(int i)
+{
+  return i + 2;
+}
diff --git a/gcc/testsuite/gcc.target/mips/mmcount-ra-address-2.c b/gcc/testsuite/gcc.target/mips/mmcount-ra-address-2.c
new file mode 100644
index 0000000..d1935c8
--- /dev/null
+++ b/gcc/testsuite/gcc.target/mips/mmcount-ra-address-2.c
@@ -0,0 +1,8 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -pg -mmcount-ra-address -march=mips64 -mabi=64 -mno-abicalls -msym32" } */
+/* { dg-final { scan-assembler "\tdaddiu\t\\\$12,\\\$sp,8" } } */
+int foo (int);
+int bar (int i)
+{
+  return foo (i) + 2;
+}
diff --git a/gcc/testsuite/gcc.target/mips/mmcount-ra-address-3.c b/gcc/testsuite/gcc.target/mips/mmcount-ra-address-3.c
new file mode 100644
index 0000000..0798e04
--- /dev/null
+++ b/gcc/testsuite/gcc.target/mips/mmcount-ra-address-3.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -pg -mmcount-ra-address -march=mips64 -mabi=64 -mno-abicalls -msym32" } */
+/* { dg-final { scan-assembler "\tdli\t\\\$12,200008" } } */
+/* { dg-final { scan-assembler "\tdaddu\t\\\$12,\\\$12,\\\$sp" } } */
+int foo (int *);
+int bar(int i)
+{
+  int big[50000];
+  return foo (big) + 2;
+}
-- 
1.6.2.1

^ permalink raw reply related	[flat|nested] 9+ messages in thread
* [PATCH -v4 1/9] tracing: convert trace_clock_local() as weak function
@ 2009-10-21 14:34 Wu Zhangjin
  2009-10-21 14:34 ` [PATCH -v4 2/9] MIPS: add mips_timecounter_read() to get high precision timestamp Wu Zhangjin
  0 siblings, 1 reply; 9+ messages in thread
From: Wu Zhangjin @ 2009-10-21 14:34 UTC (permalink / raw)
  To: linux-kernel, linux-mips
  Cc: Wu Zhangjin, Thomas Gleixner, Ralf Baechle, Nicholas Mc Guire,
	Steven Rostedt

trace_clock_local() is based on the arch-specific sched_clock(), in X86,
it is tsc(64bit) based, which can give very high precision(about 1ns
with 1GHz). but in MIPS, the sched_clock() is jiffies based, which can
give only 10ms precison with 1000 HZ. which is not enough for tracing,
especially for Real Time system.

so, we need to implement a MIPS specific sched_clock() to get higher
precision. There is a tsc like clock counter register in MIPS, whose
frequency is half of the processor, so, if the cpu frequency is 800MHz,
the time precision reaches 2.5ns, which is very good for tracing, even
for Real Time system.

but 'Cause it is only 32bit long, which will rollover quickly, so, such
a sched_clock() will bring with extra load, which is not good for the
whole system. so, we only need to implement a arch-specific
trace_clock_local() for tracing. as a preparation, we convert it as a
weak function.

The MIPS specific trace_clock_local() is coming in the next two patches.

Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
---
 kernel/trace/trace_clock.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/trace/trace_clock.c b/kernel/trace/trace_clock.c
index 20c5f92..06b8cd2 100644
--- a/kernel/trace/trace_clock.c
+++ b/kernel/trace/trace_clock.c
@@ -26,7 +26,7 @@
  * Useful for tracing that does not cross to other CPUs nor
  * does it go through idle events.
  */
-u64 notrace trace_clock_local(void)
+u64 __weak notrace trace_clock_local(void)
 {
 	unsigned long flags;
 	u64 clock;
-- 
1.6.2.1

^ permalink raw reply related	[flat|nested] 9+ messages in thread
end of thread, other threads:[~2009-10-29 18:11 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2009-10-29  8:14 [PATCH] MIPS: Add option to pass return address location to _mcount Wu Zhangjin
2009-10-29  8:14 ` Wu Zhangjin
2009-10-29 16:24 ` David Daney
  -- strict thread matches above, loose matches on Subject: below --
2009-10-21 14:34 [PATCH -v4 1/9] tracing: convert trace_clock_local() as weak function Wu Zhangjin
2009-10-21 14:34 ` [PATCH -v4 2/9] MIPS: add mips_timecounter_read() to get high precision timestamp Wu Zhangjin
2009-10-21 14:34   ` [PATCH -v4 3/9] tracing: add MIPS specific trace_clock_local() Wu Zhangjin
2009-10-21 14:34     ` [PATCH -v4 4/9] tracing: add static function tracer support for MIPS Wu Zhangjin
2009-10-21 15:24       ` Steven Rostedt
2009-10-22 17:47         ` Wu Zhangjin
2009-10-22 18:34           ` David Daney
2009-10-22 22:17             ` Richard Sandiford
2009-10-23 22:48               ` [PATCH] MIPS: Add option to pass return address location to _mcount. Was: " David Daney
2009-10-24  9:12                 ` Richard Sandiford
2009-10-26 19:08                   ` [PATCH] MIPS: Add option to pass return address location to _mcount David Daney
2009-10-27  1:04                     ` Wu Zhangjin
2009-10-27 21:20                     ` Richard Sandiford
2009-10-29  6:44                       ` Wu Zhangjin
2009-10-29 16:32                         ` David Daney
2009-10-29 18:11                       ` David Daney

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