[PATCH] xtensa: add -mauto-litpools option

[PATCH] xtensa: add -mauto-litpools option

[Max Filippov]

With support from assembler this option allows compiling huge functions,
where single literal pool at the beginning of a function may not be
reachable by L32R instructions at its end.

Currently assembler --auto-litpools option cannot deal with literals
used from multiple locations separated by more than 256 KBytes of code.
Don't turn constants into literals, instead use MOVI instruction to load
them into registers and let the assembler turn them into literals as
necessary.

2015-08-11  Max Filippov  <jcmvbkbc@gmail.com>
gcc/
	* config/xtensa/constraints.md (define_constraint "Y"): New
	constraint.
	* config/xtensa/elf.h (ASM_SPEC): Add m(no-)auto-litpools.
	* config/xtensa/linux.h (ASM_SPEC): Likewise.
	* config/xtensa/predicates.md (move_operand): Match constants
	and symbols in the presence of TARGET_AUTO_LITPOOLS.
	* config/xtensa/xtensa.c (xtensa_valid_move): Don't allow
	immediate references to TLS data.
	(xtensa_emit_move_sequence): Don't force constants to memory in
	the presence of TARGET_AUTO_LITPOOLS.
	(print_operand): Add 'y' format, same as default, but capable of
	printing SF mode constants as well.
	* config/xtensa/xtensa.md (movsi_internal, movhi_internal)
	(movsf_internal): Add movi pattern that loads literal.
	(movsf, movdf): Don't force constants to memory in the presence
	of TARGET_AUTO_LITPOOLS.
	(movdf_internal): Add 'Y' constraint.
	* config/xtensa/xtensa.opt (mauto-litpools): New option.
	* doc/invoke.text (Xtensa options): Document -mauto-litpools.
---
 gcc/config/xtensa/constraints.md |  5 +++++
 gcc/config/xtensa/elf.h          |  4 +++-
 gcc/config/xtensa/linux.h        |  4 +++-
 gcc/config/xtensa/predicates.md  |  3 ++-
 gcc/config/xtensa/xtensa.c       | 19 ++++++++++++++++++-
 gcc/config/xtensa/xtensa.md      | 35 +++++++++++++++++++----------------
 gcc/config/xtensa/xtensa.opt     |  4 ++++
 gcc/doc/invoke.texi              | 19 ++++++++++++++++++-
 8 files changed, 72 insertions(+), 21 deletions(-)

diff --git a/gcc/config/xtensa/constraints.md b/gcc/config/xtensa/constraints.md
index 30f4c1f..773d4f9 100644
--- a/gcc/config/xtensa/constraints.md
+++ b/gcc/config/xtensa/constraints.md
@@ -111,6 +111,11 @@
  (and (match_code "const_int")
       (match_test "xtensa_mask_immediate (ival)")))
 
+(define_constraint "Y"
+ "A constant that can be used in relaxed MOVI instructions."
+ (and (match_code "const_int,const_double,const,symbol_ref,label_ref")
+      (match_test "TARGET_AUTO_LITPOOLS")))
+
 ;; Memory constraints.  Do not use define_memory_constraint here.  Doing so
 ;; causes reload to force some constants into the constant pool, but since
 ;; the Xtensa constant pool can only be accessed with L32R instructions, it
diff --git a/gcc/config/xtensa/elf.h b/gcc/config/xtensa/elf.h
index e59bede..12056f7 100644
--- a/gcc/config/xtensa/elf.h
+++ b/gcc/config/xtensa/elf.h
@@ -48,7 +48,9 @@ along with GCC; see the file COPYING3.  If not see
   %{mtarget-align:--target-align} \
   %{mno-target-align:--no-target-align} \
   %{mlongcalls:--longcalls} \
-  %{mno-longcalls:--no-longcalls}"
+  %{mno-longcalls:--no-longcalls} \
+  %{mauto-litpools:--auto-litpools} \
+  %{mno-auto-litpools:--no-auto-litpools}"
 
 #undef LIB_SPEC
 #define LIB_SPEC "-lc -lsim -lc -lhandlers-sim -lhal"
diff --git a/gcc/config/xtensa/linux.h b/gcc/config/xtensa/linux.h
index 675aacf..5b0243a 100644
--- a/gcc/config/xtensa/linux.h
+++ b/gcc/config/xtensa/linux.h
@@ -42,7 +42,9 @@ along with GCC; see the file COPYING3.  If not see
   %{mtarget-align:--target-align} \
   %{mno-target-align:--no-target-align} \
   %{mlongcalls:--longcalls} \
-  %{mno-longcalls:--no-longcalls}"
+  %{mno-longcalls:--no-longcalls} \
+  %{mauto-litpools:--auto-litpools} \
+  %{mno-auto-litpools:--no-auto-litpools}"
 
 #define GLIBC_DYNAMIC_LINKER "/lib/ld.so.1"
 
diff --git a/gcc/config/xtensa/predicates.md b/gcc/config/xtensa/predicates.md
index e02209e..d7dfa11 100644
--- a/gcc/config/xtensa/predicates.md
+++ b/gcc/config/xtensa/predicates.md
@@ -142,7 +142,8 @@
 	       (match_test "GET_MODE_CLASS (mode) == MODE_INT
 			    && xtensa_simm12b (INTVAL (op))"))
 	  (and (match_code "const_int,const_double,const,symbol_ref,label_ref")
-	       (match_test "TARGET_CONST16 && CONSTANT_P (op)
+	       (match_test "(TARGET_CONST16 || TARGET_AUTO_LITPOOLS)
+			    && CONSTANT_P (op)
 			    && GET_MODE_SIZE (mode) % UNITS_PER_WORD == 0")))))
 
 ;; Accept the floating point constant 1 in the appropriate mode.
diff --git a/gcc/config/xtensa/xtensa.c b/gcc/config/xtensa/xtensa.c
index eb039ba..206ff80 100644
--- a/gcc/config/xtensa/xtensa.c
+++ b/gcc/config/xtensa/xtensa.c
@@ -501,6 +501,9 @@ xtensa_valid_move (machine_mode mode, rtx *operands)
     {
       int dst_regnum = xt_true_regnum (operands[0]);
 
+      if (xtensa_tls_referenced_p (operands[1]))
+	return FALSE;
+
       /* The stack pointer can only be assigned with a MOVSP opcode.  */
       if (dst_regnum == STACK_POINTER_REGNUM)
 	return !TARGET_WINDOWED_ABI
@@ -1069,7 +1072,7 @@ xtensa_emit_move_sequence (rtx *operands, machine_mode mode)
 	  return 1;
 	}
 
-      if (! TARGET_CONST16)
+      if (! TARGET_AUTO_LITPOOLS && ! TARGET_CONST16)
 	{
 	  src = force_const_mem (SImode, src);
 	  operands[1] = src;
@@ -2449,6 +2452,20 @@ print_operand (FILE *file, rtx x, int letter)
 	}
       break;
 
+    case 'y':
+      if (GET_CODE (x) == CONST_DOUBLE &&
+	  GET_MODE (x) == SFmode)
+	{
+	  REAL_VALUE_TYPE r;
+	  long l;
+	  REAL_VALUE_FROM_CONST_DOUBLE (r, x);
+	  REAL_VALUE_TO_TARGET_SINGLE (r, l);
+	  fprintf (file, "0x%08lx", l);
+	  break;
+	}
+
+      /* fall through */
+
     default:
       if (GET_CODE (x) == REG || GET_CODE (x) == SUBREG)
 	fprintf (file, "%s", reg_names[xt_true_regnum (x)]);
diff --git a/gcc/config/xtensa/xtensa.md b/gcc/config/xtensa/xtensa.md
index 6d84384..0e673a3 100644
--- a/gcc/config/xtensa/xtensa.md
+++ b/gcc/config/xtensa/xtensa.md
@@ -761,8 +761,8 @@
 })
 
 (define_insn "movsi_internal"
-  [(set (match_operand:SI 0 "nonimmed_operand" "=D,D,D,D,R,R,a,q,a,W,a,a,U,*a,*A")
-	(match_operand:SI 1 "move_operand" "M,D,d,R,D,d,r,r,I,i,T,U,r,*A,*r"))]
+  [(set (match_operand:SI 0 "nonimmed_operand" "=D,D,D,D,R,R,a,q,a,a,W,a,a,U,*a,*A")
+	(match_operand:SI 1 "move_operand" "M,D,d,R,D,d,r,r,I,Y,i,T,U,r,*A,*r"))]
   "xtensa_valid_move (SImode, operands)"
   "@
    movi.n\t%0, %x1
@@ -774,15 +774,16 @@
    mov\t%0, %1
    movsp\t%0, %1
    movi\t%0, %x1
+   movi\t%0, %1
    const16\t%0, %t1\;const16\t%0, %b1
    %v1l32r\t%0, %1
    %v1l32i\t%0, %1
    %v0s32i\t%1, %0
    rsr\t%0, ACCLO
    wsr\t%1, ACCLO"
-  [(set_attr "type" "move,move,move,load,store,store,move,move,move,move,load,load,store,rsr,wsr")
+  [(set_attr "type" "move,move,move,load,store,store,move,move,move,move,move,load,load,store,rsr,wsr")
    (set_attr "mode"	"SI")
-   (set_attr "length"	"2,2,2,2,2,2,3,3,3,6,3,3,3,3,3")])
+   (set_attr "length"	"2,2,2,2,2,2,3,3,3,3,6,3,3,3,3,3")])
 
 ;; 16-bit Integer moves
 
@@ -796,21 +797,22 @@
 })
 
 (define_insn "movhi_internal"
-  [(set (match_operand:HI 0 "nonimmed_operand" "=D,D,a,a,a,U,*a,*A")
-	(match_operand:HI 1 "move_operand" "M,d,r,I,U,r,*A,*r"))]
+  [(set (match_operand:HI 0 "nonimmed_operand" "=D,D,a,a,a,a,U,*a,*A")
+	(match_operand:HI 1 "move_operand" "M,d,r,I,Y,U,r,*A,*r"))]
   "xtensa_valid_move (HImode, operands)"
   "@
    movi.n\t%0, %x1
    mov.n\t%0, %1
    mov\t%0, %1
    movi\t%0, %x1
+   movi\t%0, %1
    %v1l16ui\t%0, %1
    %v0s16i\t%1, %0
    rsr\t%0, ACCLO
    wsr\t%1, ACCLO"
-  [(set_attr "type"	"move,move,move,move,load,store,rsr,wsr")
+  [(set_attr "type"	"move,move,move,move,move,load,store,rsr,wsr")
    (set_attr "mode"	"HI")
-   (set_attr "length"	"2,2,3,3,3,3,3,3")])
+   (set_attr "length"	"2,2,3,3,3,3,3,3,3")])
 
 ;; 8-bit Integer moves
 
@@ -881,7 +883,7 @@
 	(match_operand:SF 1 "general_operand" ""))]
   ""
 {
-  if (!TARGET_CONST16 && CONSTANT_P (operands[1]))
+  if (!TARGET_CONST16 && !TARGET_AUTO_LITPOOLS && CONSTANT_P (operands[1]))
     operands[1] = force_const_mem (SFmode, operands[1]);
 
   if ((!register_operand (operands[0], SFmode)
@@ -896,8 +898,8 @@
 })
 
 (define_insn "movsf_internal"
-  [(set (match_operand:SF 0 "nonimmed_operand" "=f,f,U,D,D,R,a,f,a,W,a,a,U")
-	(match_operand:SF 1 "move_operand" "f,U,f,d,R,d,r,r,f,iF,T,U,r"))]
+  [(set (match_operand:SF 0 "nonimmed_operand" "=f,f,U,D,D,R,a,f,a,a,W,a,a,U")
+	(match_operand:SF 1 "move_operand" "f,U,f,d,R,d,r,r,f,Y,iF,T,U,r"))]
   "((register_operand (operands[0], SFmode)
      || register_operand (operands[1], SFmode))
     && !(FP_REG_P (xt_true_regnum (operands[0]))
@@ -912,13 +914,14 @@
    mov\t%0, %1
    wfr\t%0, %1
    rfr\t%0, %1
+   movi\t%0, %y1
    const16\t%0, %t1\;const16\t%0, %b1
    %v1l32r\t%0, %1
    %v1l32i\t%0, %1
    %v0s32i\t%1, %0"
-  [(set_attr "type"	"farith,fload,fstore,move,load,store,move,farith,farith,move,load,load,store")
+  [(set_attr "type"	"farith,fload,fstore,move,load,store,move,farith,farith,move,move,load,load,store")
    (set_attr "mode"	"SF")
-   (set_attr "length"	"3,3,3,2,2,2,3,3,3,6,3,3,3")])
+   (set_attr "length"	"3,3,3,2,2,2,3,3,3,3,6,3,3,3")])
 
 (define_insn "*lsiu"
   [(set (match_operand:SF 0 "register_operand" "=f")
@@ -991,7 +994,7 @@
 	(match_operand:DF 1 "general_operand" ""))]
   ""
 {
-  if (CONSTANT_P (operands[1]) && !TARGET_CONST16)
+  if (CONSTANT_P (operands[1]) && !TARGET_CONST16 && !TARGET_AUTO_LITPOOLS)
     operands[1] = force_const_mem (DFmode, operands[1]);
 
   if (!register_operand (operands[0], DFmode)
@@ -1002,8 +1005,8 @@
 })
 
 (define_insn_and_split "movdf_internal"
-  [(set (match_operand:DF 0 "nonimmed_operand" "=a,W,a,a,U")
-	(match_operand:DF 1 "move_operand" "r,iF,T,U,r"))]
+  [(set (match_operand:DF 0 "nonimmed_operand" "=a,a,W,a,a,U")
+	(match_operand:DF 1 "move_operand" "r,Y,iF,T,U,r"))]
   "register_operand (operands[0], DFmode)
    || register_operand (operands[1], DFmode)"
   "#"
diff --git a/gcc/config/xtensa/xtensa.opt b/gcc/config/xtensa/xtensa.opt
index 2fd6cee..21c6e96 100644
--- a/gcc/config/xtensa/xtensa.opt
+++ b/gcc/config/xtensa/xtensa.opt
@@ -38,6 +38,10 @@ mtext-section-literals
 Target
 Intersperse literal pools with code in the text section
 
+mauto-litpools
+Target Report Mask(AUTO_LITPOOLS)
+Relax literals in assembler and place them automatically in the text section
+
 mserialize-volatile
 Target Report Mask(SERIALIZE_VOLATILE)
 -mno-serialize-volatile	Do not serialize volatile memory references with MEMW instructions
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index f84a199..994c3b4 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -1106,6 +1106,7 @@ See RS/6000 and PowerPC Options.
 -mforce-no-pic @gol
 -mserialize-volatile  -mno-serialize-volatile @gol
 -mtext-section-literals  -mno-text-section-literals @gol
+-mauto-litpools  -mno-auto-litpools @gol
 -mtarget-align  -mno-target-align @gol
 -mlongcalls  -mno-longcalls}
 
@@ -23242,7 +23243,23 @@ pools from separate object files to remove redundant literals and
 improve code size.  With @option{-mtext-section-literals}, the literals
 are interspersed in the text section in order to keep them as close as
 possible to their references.  This may be necessary for large assembly
-files.
+files.  Literals for each function are placed right before that function.
+
+@item -mauto-litpools
+@itemx -mno-auto-litpools
+@opindex mauto-litpools
+@opindex mno-auto-litpools
+These options control the treatment of literal pools.  The default is
+@option{-mno-auto-litpools}, which places literals in a separate
+section in the output file unless @option{-mtext-section-literals} is
+used.  With @option{-mauto-litpools} the literals are interspersed in
+the text section by the assembler.  Compiler does not produce explicit
+@code{.literal} directives and loads literals into registers with
+@code{MOVI} instructions instead of @code{L32R} to let the assembler
+do relaxation and place literals as necessary.  This option allows
+assembler to create several literal pools per function and assemble
+very big functions, which may not be possible with
+@option{-mtext-section-literals}.
 
 @item -mtarget-align
 @itemx -mno-target-align
-- 
1.8.1.4

Re: [PATCH] xtensa: add -mauto-litpools option

[augustine.sterling]

On Tue, Aug 11, 2015 at 6:09 PM, Max Filippov <jcmvbkbc@gmail.com> wrote:
> With support from assembler this option allows compiling huge functions,
> where single literal pool at the beginning of a function may not be
> reachable by L32R instructions at its end.
>
> Currently assembler --auto-litpools option cannot deal with literals
> used from multiple locations separated by more than 256 KBytes of code.
> Don't turn constants into literals, instead use MOVI instruction to load
> them into registers and let the assembler turn them into literals as
> necessary.
>
> 2015-08-11  Max Filippov  <jcmvbkbc@gmail.com>
> gcc/
>         * config/xtensa/constraints.md (define_constraint "Y"): New
>         constraint.
>         * config/xtensa/elf.h (ASM_SPEC): Add m(no-)auto-litpools.
>         * config/xtensa/linux.h (ASM_SPEC): Likewise.
>         * config/xtensa/predicates.md (move_operand): Match constants
>         and symbols in the presence of TARGET_AUTO_LITPOOLS.
>         * config/xtensa/xtensa.c (xtensa_valid_move): Don't allow
>         immediate references to TLS data.
>         (xtensa_emit_move_sequence): Don't force constants to memory in
>         the presence of TARGET_AUTO_LITPOOLS.
>         (print_operand): Add 'y' format, same as default, but capable of
>         printing SF mode constants as well.
>         * config/xtensa/xtensa.md (movsi_internal, movhi_internal)
>         (movsf_internal): Add movi pattern that loads literal.
>         (movsf, movdf): Don't force constants to memory in the presence
>         of TARGET_AUTO_LITPOOLS.
>         (movdf_internal): Add 'Y' constraint.
>         * config/xtensa/xtensa.opt (mauto-litpools): New option.
>         * doc/invoke.text (Xtensa options): Document -mauto-litpools.

If this is OK with the linux people, it is OK with me. As I recall,
they used to have a need to keep literals in page-level groups, but my
memory is hazy.

Re: [PATCH] xtensa: add -mauto-litpools option

[Max Filippov]

On Wed, Aug 12, 2015 at 7:35 PM, augustine.sterling@gmail.com
<augustine.sterling@gmail.com> wrote:
> On Tue, Aug 11, 2015 at 6:09 PM, Max Filippov <jcmvbkbc@gmail.com> wrote:
>> With support from assembler this option allows compiling huge functions,
>> where single literal pool at the beginning of a function may not be
>> reachable by L32R instructions at its end.
>>
>> Currently assembler --auto-litpools option cannot deal with literals
>> used from multiple locations separated by more than 256 KBytes of code.
>> Don't turn constants into literals, instead use MOVI instruction to load
>> them into registers and let the assembler turn them into literals as
>> necessary.
>
> If this is OK with the linux people, it is OK with me. As I recall,
> they used to have a need to keep literals in page-level groups, but my
> memory is hazy.

Text-section-literals remain available, and without auto-litpools option
code generation doesn't change at all. Even with auto-litpools option
literals will tend to pool at the beginning of functions, so code generation
shouldn't change much.

I've applied the patch to trunk.

-- 
Thanks.
-- Max