[PATCH, rs6000] Add non-relative jump table support on Power Linux

HAO CHEN GUI guihaoc@linux.ibm.com
Mon Aug 24 07:48:43 GMT 2020


Hi,

I revised the patch according to the advice. The attachment is the 
change log and diff file. Thanks a lot.

On 20/8/2020 上午 8:14, Segher Boessenkool wrote:
> Hi!
>
> Sorry this took so long to review.  "I lost track of this patch", what
> can I say :-/
>
> On Fri, Aug 14, 2020 at 03:31:05PM +0800, HAO CHEN GUI wrote:
>> This patch adds non-relative jump table support on Power Linux. It
>> implements ASM_OUTPUT_ADDR_VEC_ELT and adds four new expansions for
>> non-relative jump table in rs6000.md. It also defines a rs6000
>> option(mrelative-jumptables). If it's set to false, the non-relative
>> jump table is picked up even PIC flag is set.
>> diff --git a/gcc/config/rs6000/linux64.h b/gcc/config/rs6000/linux64.h
>> index 34776c8421e..626f2201d96 100644
>> --- a/gcc/config/rs6000/linux64.h
>> +++ b/gcc/config/rs6000/linux64.h
>> @@ -324,7 +324,10 @@ extern int dot_symbols;
>>   
>>   /* Indicate that jump tables go in the text section.  */
>>   #undef  JUMP_TABLES_IN_TEXT_SECTION
>> -#define JUMP_TABLES_IN_TEXT_SECTION TARGET_64BIT
>> +#define JUMP_TABLES_IN_TEXT_SECTION rs6000_relative_jumptables
>> +
>> +#undef JUMP_TABLES_IN_RELRO
>> +#define JUMP_TABLES_IN_RELRO !rs6000_relative_jumptables
> The third choice is .rodata.  .data.rel.ro can be considered to be a
> sub-case of that, but not the other way around.
>
>> +extern void rs6000_output_addr_vec_elt(FILE *, int);
> (space before opening paren)
>
>> +/* Implement TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC. Return true if rs6000_relative_jumptables is set. */
> The maximum line length is 80 characters.  Two spaces after a full stop.
>
>> +/* Enable non-relative jump tables for linux ELF. */
>> +#ifdef TARGET_ELF
>> +#if !TARGET_AIX
>> +#undef rs6000_relative_jumptables
>> +#define rs6000_relative_jumptables 0
>> +#endif
>> +#endif
> AIX never is ELF, but many other things *are* ELF.  Do all of those
> handle .data.rel.ro, including do they have enough OS support for it?
>
> This also changes the default for ELF systems?  Let's not do that (in
> this patch, that is).
>
>> +/* Specify the machine mode that this machine uses
>> +   for the index in the tablejump instruction.  */
>> +#define CASE_VECTOR_MODE \
>> +  (TARGET_32BIT || rs6000_relative_jumptables ? SImode : DImode)
> #define CASE_VECTOR_MODE (rs6000_relative_jumptables ? SImode : Pmode)
>
>> +/* This is how to output an element of a case-vector
>> +   that is non-relative. */
> (no space at end of line; two spaces after full stop, also before */)
>
>> +#define ASM_OUTPUT_ADDR_VEC_ELT(FILE, VALUE) \
>> +  rs6000_output_addr_vec_elt((FILE), (VALUE))
> Space before first ( please (on the second line, on the first you
> cannot -- macro definitions are the only exception).
>
>> diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
>> index 0aa5265d199..2f28da0ea1f 100644
>> --- a/gcc/config/rs6000/rs6000.md
>> +++ b/gcc/config/rs6000/rs6000.md
>> @@ -12669,18 +12669,32 @@
>>     if (rs6000_speculate_indirect_jumps)
>>       {
>>         if (TARGET_32BIT)
>> -      	emit_jump_insn (gen_tablejumpsi (operands[0], operands[1]));
>> -      else
>> +        {
>> +          if (rs6000_relative_jumptables)
>> +            emit_jump_insn (gen_tablejumpsi (operands[0], operands[1]));
>> +          else
>> +      	    emit_jump_insn (gen_nonrelative_tablejumpsi (operands[0], operands[1]));
> Please fix the indent while you're at it (tabs shouldn't follow spaces).
> Oh, and line too long.
>
>> +        }
>> +      else if (rs6000_relative_jumptables)
>>   	emit_jump_insn (gen_tablejumpdi (operands[0], operands[1]));
>> +      else
>> +        emit_jump_insn (gen_nonrelative_tablejumpdi (operands[0], operands[1]));
> Please put the "relative" case on the outside, and the "32 or 64" if on
> the inside.
>
>> +(define_expand "nonrelative_tablejumpsi"
> Maybe call it "absolute_tablejumpsi"?  Not sure :-)
>
>> +   "TARGET_32BIT && rs6000_speculate_indirect_jumps && !rs6000_relative_jumptables"
> Line too long (more follow, I won't point all out, please check :-) )
>
>> + {
>> +  operands[2] = gen_reg_rtx (SImode);
>> + })
> No spaces before { and } here, those are flush left like in outer braces
> in a C function are.
>
>> +(define_expand "nonrelative_tablejumpsi_nospec"
>> +  [(set (match_dup 3)
>> +        (match_operand:SI 0 "gpc_reg_operand" "r"))
>> +   (parallel [(set (pc)
>> +                   (match_dup 3))
>> +              (use (label_ref (match_operand 1)))
>> +              (clobber (match_operand 2))])]
> Please use a leading tab instead of every 8 leading spaces.
>
>
> I'll try to be quicker at reviewing iterations of this -- there is quite
> some way to go, without me slowing things down!
>
>
> Segher
-------------- next part --------------
	* config/rs6000/linux.h (rs6000_relative_jumptables): Define.
	* config/rs6000/linux64.h (JUMP_TABLES_IN_TEXT_SECTION,
	rs6000_relative_jumptables): Define.
	* config/rs6000/rs6000-protos.h (rs6000_output_addr_vec_elt): Declare.
	* config/rs6000/rs6000.c (TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC):
	Define
	(rs6000_gen_pic_addr_diff_vec, rs6000_output_addr_vec_elt): Implement.
	* config/rs6000/rs6000.h (CASE_VECTOR_PC_RELATIVE,
	CASE_VECTOR_MODE, ASM_OUTPUT_ADDR_VEC_ELT): Define.
	* config/rs6000/rs6000.md (absolute_tablejumpsi,
	absolute_tablejumpsi_nospec, absolute_tablejumpdi,
	absolute_tablejumpdi_nospec): Add four new expansions.
	* config/rs6000/rs6000.opt (mrelative-jumptables): Add a new option and
	set rs6000_relative_jumptables to true by default.
-------------- next part --------------
diff --git a/gcc/config/rs6000/linux.h b/gcc/config/rs6000/linux.h
index b7026fcbee7..bd6c3989801 100644
--- a/gcc/config/rs6000/linux.h
+++ b/gcc/config/rs6000/linux.h
@@ -145,3 +145,7 @@
   || (TARGET_GLIBC_MAJOR == 2 && TARGET_GLIBC_MINOR >= 19)
 #define RS6000_GLIBC_ATOMIC_FENV 1
 #endif
+
+/* Disable relative jump tables for Power Linux.  */
+#undef rs6000_relative_jumptables
+#define rs6000_relative_jumptables 0
diff --git a/gcc/config/rs6000/linux64.h b/gcc/config/rs6000/linux64.h
index 34776c8421e..41051459db9 100644
--- a/gcc/config/rs6000/linux64.h
+++ b/gcc/config/rs6000/linux64.h
@@ -322,9 +322,13 @@ extern int dot_symbols;
 #define TARGET_ALIGN_NATURAL 1
 #endif
 
+/* Disable relative jump tables for Power Linux64.  */
+#undef rs6000_relative_jumptables
+#define rs6000_relative_jumptables 0
+
 /* Indicate that jump tables go in the text section.  */
 #undef  JUMP_TABLES_IN_TEXT_SECTION
-#define JUMP_TABLES_IN_TEXT_SECTION TARGET_64BIT
+#define JUMP_TABLES_IN_TEXT_SECTION rs6000_relative_jumptables
 
 /* The linux ppc64 ABI isn't explicit on whether aggregates smaller
    than a doubleword should be padded upward or downward.  You could
diff --git a/gcc/config/rs6000/rs6000-protos.h b/gcc/config/rs6000/rs6000-protos.h
index 5508484ba19..62564dd67f2 100644
--- a/gcc/config/rs6000/rs6000-protos.h
+++ b/gcc/config/rs6000/rs6000-protos.h
@@ -155,6 +155,8 @@ extern void rs6000_split_logical (rtx [], enum rtx_code, bool, bool, bool);
 extern bool rs6000_pcrel_p (struct function *);
 extern bool rs6000_fndecl_pcrel_p (const_tree);
 
+extern void rs6000_output_addr_vec_elt (FILE *, int);
+
 /* Different PowerPC instruction formats that are used by GCC.  There are
    various other instruction formats used by the PowerPC hardware, but these
    formats are not currently used by GCC.  */
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 58f5d780603..94d1e650b94 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -1369,6 +1369,9 @@ static const struct attribute_spec rs6000_attribute_table[] =
 #undef TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA
 #define TARGET_ASM_OUTPUT_ADDR_CONST_EXTRA rs6000_output_addr_const_extra
 
+#undef  TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC
+#define TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC rs6000_gen_pic_addr_diff_vec
+
 #undef TARGET_LEGITIMIZE_ADDRESS
 #define TARGET_LEGITIMIZE_ADDRESS rs6000_legitimize_address
 
@@ -26494,6 +26497,27 @@ rs6000_cannot_substitute_mem_equiv_p (rtx mem)
   return false;
 }
 
+/* Implement TARGET_ASM_GENERATE_PIC_ADDR_DIFF_VEC.
+   Return true if rs6000_relative_jumptables is set.  */
+
+static bool
+rs6000_gen_pic_addr_diff_vec (void)
+{
+  return rs6000_relative_jumptables;
+}
+
+void
+rs6000_output_addr_vec_elt (FILE *file, int value)
+{
+  const char *directive = TARGET_64BIT ? DOUBLE_INT_ASM_OP : "\t.long\t";
+  char buf[100];
+
+  fprintf (file, "%s", directive);
+  ASM_GENERATE_INTERNAL_LABEL (buf, "L", value);
+  assemble_name (file, buf);
+  fprintf (file, "\n");
+}
+
 struct gcc_target targetm = TARGET_INITIALIZER;
 
 #include "gt-rs6000.h"
diff --git a/gcc/config/rs6000/rs6000.h b/gcc/config/rs6000/rs6000.h
index 1209a33173e..d96d22590d7 100644
--- a/gcc/config/rs6000/rs6000.h
+++ b/gcc/config/rs6000/rs6000.h
@@ -1752,15 +1752,16 @@ typedef struct rs6000_args
 
 /* #define LEGITIMATE_PIC_OPERAND_P (X) */
 

-/* Specify the machine mode that this machine uses
-   for the index in the tablejump instruction.  */
-#define CASE_VECTOR_MODE SImode
-
 /* Define as C expression which evaluates to nonzero if the tablejump
    instruction expects the table to contain offsets from the address of the
    table.
    Do not define this if the table should contain absolute addresses.  */
-#define CASE_VECTOR_PC_RELATIVE 1
+#define CASE_VECTOR_PC_RELATIVE 0
+
+/* Specify the machine mode that this machine uses
+   for the index in the tablejump instruction.  */
+#define CASE_VECTOR_MODE \
+  (TARGET_32BIT || rs6000_relative_jumptables ? SImode : DImode)
 
 /* Define this as 1 if `char' should by default be signed; else as 0.  */
 #define DEFAULT_SIGNED_CHAR 0
@@ -2190,6 +2191,11 @@ extern char rs6000_reg_names[][8];	/* register names (0 vs. %r0).  */
        putc ('\n', FILE);				\
      } while (0)
 
+/* This is how to output an element of a case-vector
+   that is non-relative.  */
+#define ASM_OUTPUT_ADDR_VEC_ELT(FILE, VALUE) \
+  rs6000_output_addr_vec_elt ((FILE), (VALUE))
+
 /* This is how to output an assembler line
    that says to advance the location counter
    to a multiple of 2**LOG bytes.  */
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index 0aa5265d199..868609641a6 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -12668,19 +12668,35 @@
 {
   if (rs6000_speculate_indirect_jumps)
     {
-      if (TARGET_32BIT)
-      	emit_jump_insn (gen_tablejumpsi (operands[0], operands[1]));
+      if (rs6000_relative_jumptables)
+	{
+	  if (TARGET_32BIT)
+	    emit_jump_insn (gen_tablejumpsi (operands[0], operands[1]));
+	  else
+	    emit_jump_insn (gen_tablejumpdi (operands[0], operands[1]));
+	}
+      else if (TARGET_32BIT)
+	emit_jump_insn (gen_absolute_tablejumpsi (operands[0], operands[1]));
       else
-	emit_jump_insn (gen_tablejumpdi (operands[0], operands[1]));
+	emit_jump_insn (gen_absolute_tablejumpdi (operands[0], operands[1]));
     }
   else
     {
       rtx ccreg = gen_reg_rtx (CCmode);
       rtx jump;
-      if (TARGET_32BIT)
-	jump = gen_tablejumpsi_nospec (operands[0], operands[1], ccreg);
+      if (rs6000_relative_jumptables)
+	{
+	  if (TARGET_32BIT)
+	    jump = gen_tablejumpsi_nospec (operands[0], operands[1], ccreg);
+	  else
+	    jump = gen_tablejumpdi_nospec (operands[0], operands[1], ccreg);
+	}
+      else if (TARGET_32BIT)
+	jump = gen_absolute_tablejumpsi_nospec (operands[0], operands[1],
+						ccreg);
       else
-	jump = gen_tablejumpdi_nospec (operands[0], operands[1], ccreg);
+	jump = gen_absolute_tablejumpdi_nospec (operands[0], operands[1],
+						ccreg);
       emit_jump_insn (jump);
     }
   DONE;
@@ -12693,13 +12709,26 @@
    (parallel [(set (pc)
 		   (match_dup 3))
 	      (use (label_ref (match_operand 1)))])]
-  "TARGET_32BIT && rs6000_speculate_indirect_jumps"
+  "TARGET_32BIT && rs6000_speculate_indirect_jumps
+   && rs6000_relative_jumptables"
 {
   operands[0] = force_reg (SImode, operands[0]);
   operands[2] = force_reg (SImode, gen_rtx_LABEL_REF (SImode, operands[1]));
   operands[3] = gen_reg_rtx (SImode);
 })
 
+(define_expand "absolute_tablejumpsi"
+  [(set (match_dup 2)
+	(match_operand:SI 0 "gpc_reg_operand" "r"))
+   (parallel [(set (pc)
+		   (match_dup 2))
+	      (use (label_ref (match_operand 1)))])]
+   "TARGET_32BIT && rs6000_speculate_indirect_jumps
+    && !rs6000_relative_jumptables"
+{
+  operands[2] = gen_reg_rtx (SImode);
+})
+
 (define_expand "tablejumpsi_nospec"
   [(set (match_dup 4)
 	(plus:SI (match_operand:SI 0)
@@ -12708,32 +12737,59 @@
 		   (match_dup 4))
 	      (use (label_ref (match_operand 1)))
 	      (clobber (match_operand 2))])]
-  "TARGET_32BIT && !rs6000_speculate_indirect_jumps"
+  "TARGET_32BIT && !rs6000_speculate_indirect_jumps
+   && rs6000_relative_jumptables"
 {
   operands[0] = force_reg (SImode, operands[0]);
   operands[3] = force_reg (SImode, gen_rtx_LABEL_REF (SImode, operands[1]));
   operands[4] = gen_reg_rtx (SImode);
 })
 
+(define_expand "absolute_tablejumpsi_nospec"
+  [(set (match_dup 3)
+	(match_operand:SI 0 "gpc_reg_operand" "r"))
+   (parallel [(set (pc)
+		   (match_dup 3))
+	      (use (label_ref (match_operand 1)))
+	      (clobber (match_operand 2))])]
+  "TARGET_32BIT && !rs6000_speculate_indirect_jumps
+   && !rs6000_relative_jumptables"
+{
+  operands[3] = gen_reg_rtx (SImode);
+})
+
 (define_expand "tablejumpdi"
   [(set (match_dup 4)
-        (sign_extend:DI (match_operand:SI 0 "lwa_operand")))
+	(sign_extend:DI (match_operand:SI 0 "lwa_operand")))
    (set (match_dup 3)
 	(plus:DI (match_dup 4)
 		 (match_dup 2)))
    (parallel [(set (pc)
 		   (match_dup 3))
 	      (use (label_ref (match_operand 1)))])]
-  "TARGET_64BIT && rs6000_speculate_indirect_jumps"
+  "TARGET_64BIT && rs6000_speculate_indirect_jumps
+   && rs6000_relative_jumptables"
 {
   operands[2] = force_reg (DImode, gen_rtx_LABEL_REF (DImode, operands[1]));
   operands[3] = gen_reg_rtx (DImode);
   operands[4] = gen_reg_rtx (DImode);
 })
 
+(define_expand "absolute_tablejumpdi"
+  [(set (match_dup 2)
+	(match_operand:DI 0 "gpc_reg_operand" "r"))
+   (parallel [(set (pc)
+		   (match_dup 2))
+	      (use (label_ref (match_operand 1)))])]
+   "TARGET_64BIT && rs6000_speculate_indirect_jumps
+    && !rs6000_relative_jumptables"
+{
+  operands[2] = gen_reg_rtx (DImode);
+})
+
 (define_expand "tablejumpdi_nospec"
   [(set (match_dup 5)
-        (sign_extend:DI (match_operand:SI 0 "lwa_operand")))
+	(sign_extend:DI (match_operand:SI 0 "lwa_operand")))
    (set (match_dup 4)
 	(plus:DI (match_dup 5)
 		 (match_dup 3)))
@@ -12741,13 +12797,27 @@
 		   (match_dup 4))
 	      (use (label_ref (match_operand 1)))
 	      (clobber (match_operand 2))])]
-  "TARGET_64BIT && !rs6000_speculate_indirect_jumps"
+  "TARGET_64BIT && !rs6000_speculate_indirect_jumps
+   && rs6000_relative_jumptables"
 {
   operands[3] = force_reg (DImode, gen_rtx_LABEL_REF (DImode, operands[1]));
   operands[4] = gen_reg_rtx (DImode);
   operands[5] = gen_reg_rtx (DImode);
 })
 
+(define_expand "absolute_tablejumpdi_nospec"
+  [(set (match_dup 3)
+	(match_operand:DI 0 "gpc_reg_operand" "r"))
+   (parallel [(set (pc)
+		   (match_dup 3))
+	      (use (label_ref (match_operand 1)))
+	      (clobber (match_operand 2))])]
+  "TARGET_64BIT && !rs6000_speculate_indirect_jumps
+   && !rs6000_relative_jumptables"
+{
+  operands[3] = gen_reg_rtx (DImode);
+})
+
 (define_insn "*tablejump<mode>_internal1"
   [(set (pc)
 	(match_operand:P 0 "register_operand" "c,*l"))
diff --git a/gcc/config/rs6000/rs6000.opt b/gcc/config/rs6000/rs6000.opt
index f95b8279270..7cf8bdb1faa 100644
--- a/gcc/config/rs6000/rs6000.opt
+++ b/gcc/config/rs6000/rs6000.opt
@@ -578,3 +578,6 @@ Generate (do not generate) prefixed memory instructions.
 mpcrel
 Target Report Mask(PCREL) Var(rs6000_isa_flags)
 Generate (do not generate) pc-relative memory addressing.
+
+mrelative-jumptables
+Target Undocumented Var(rs6000_relative_jumptables) Init(1) Save
diff --git a/gcc/config/s390/s390.c b/gcc/config/s390/s390.c


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