Add uaddv4_optab, usubv4_optab

Add uaddv4_optab, usubv4_optab

[Richard Henderson]

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Toward fixing PR68385.  I'm just starting a full round of testing, but

extern void underflow(void) __attribute__((noreturn));
unsigned sub1(unsigned a, unsigned b)
{
     unsigned r = a - b;
     if (r > a) underflow();
     return r;
}

unsigned sub2(unsigned a, unsigned b)
{
     unsigned r;
     if (__builtin_sub_overflow(a, b, &r)) underflow();
     return r;
}


sub1:
	movl	%edi, %eax
	subl	%esi, %eax
	cmpl	%eax, %edi
	jb	.L7
	rep ret
...
sub2:
	movl	%edi, %eax
	subl	%esi, %eax
	jb	.L16
	rep ret
...


r~

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diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index 4c5e22a..10a004e 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -6156,6 +6156,22 @@
 		  (const_string "4")]
 	      (const_string "<MODE_SIZE>")))])
 
+(define_expand "uaddv<mode>4"
+  [(parallel [(set (reg:CCC FLAGS_REG)
+		   (compare:CCC
+		     (plus:SWI (match_dup 1) (match_dup 2))
+		     (match_dup 1)))
+	      (set (match_dup 0)
+		   (plus:SWI (match_dup 1) (match_dup 2)))])
+   (set (pc) (if_then_else
+	       (ne (reg:CCC FLAGS_REG) (const_int 0))
+	       (label_ref (match_operand 3))
+	       (pc)))]
+  ""
+{
+  ix86_fixup_binary_operands_no_copy (PLUS, <MODE>mode, operands);
+})
+
 ;; The lea patterns for modes less than 32 bits need to be matched by
 ;; several insns converted to real lea by splitters.
 
@@ -6461,6 +6477,20 @@
 		  (const_string "4")]
 	      (const_string "<MODE_SIZE>")))])
 
+(define_expand "usubv<mode>4"
+  [(parallel [(set (reg:CC FLAGS_REG)
+		   (compare:CC (match_dup 1) (match_dup 2)))
+	      (set (match_dup 0)
+		   (minus:SWI (match_dup 1) (match_dup 2)))])
+   (set (pc) (if_then_else
+	       (ltu (reg:CC FLAGS_REG) (const_int 0))
+	       (label_ref (match_operand 3))
+	       (pc)))]
+  ""
+{
+  ix86_fixup_binary_operands_no_copy (MINUS, <MODE>mode, operands);
+})
+
 (define_insn "*sub<mode>_3"
   [(set (reg FLAGS_REG)
 	(compare (match_operand:SWI 1 "nonimmediate_operand" "0,0")
diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi
index 8b2deaa..9386e62 100644
--- a/gcc/doc/md.texi
+++ b/gcc/doc/md.texi
@@ -4912,6 +4912,25 @@ address calculations.  @code{add@var{m}3} is used if
 @itemx @samp{and@var{m}3}, @samp{ior@var{m}3}, @samp{xor@var{m}3}
 Similar, for other arithmetic operations.
 
+@cindex @code{addv@var{m}4} instruction pattern
+@item @samp{addv@var{m}4}
+Add operand 2 and operand 1, storing the result in operand 0.  If signed
+overflow occurs during the addition, jump to the label in operand 3.
+
+@cindex @code{subv@var{m}4} instruction pattern
+@cindex @code{mulv@var{m}4} instruction pattern
+@item @samp{subv@var{m}4}, @samp{mulv@var{m}4}
+Similar, for other signed arithmetic operations.
+
+@cindex @code{uaddv@var{m}4} instruction pattern
+@item @samp{uaddv@var{m}4}
+Like @code{addv@var{m}4}, except jump on unsigned overflow.
+
+@cindex @code{usubv@var{m}4} instruction pattern
+@cindex @code{umulv@var{m}4} instruction pattern
+@item @samp{usubv@var{m}4}, @samp{umulv@var{m}4}
+Similar, for other unsigned arithmetic operations.
+
 @cindex @code{fma@var{m}4} instruction pattern
 @item @samp{fma@var{m}4}
 Multiply operand 2 and operand 1, then add operand 3, storing the
diff --git a/gcc/internal-fn.c b/gcc/internal-fn.c
index bc77bdc..b15657f 100644
--- a/gcc/internal-fn.c
+++ b/gcc/internal-fn.c
@@ -546,6 +546,33 @@ expand_addsub_overflow (location_t loc, tree_code code, tree lhs,
   /* u1 +- u2 -> ur  */
   if (uns0_p && uns1_p && unsr_p)
     {
+      insn_code icode = optab_handler (code == PLUS_EXPR ? uaddv4_optab
+                                       : usubv4_optab, mode);
+      if (icode != CODE_FOR_nothing)
+	{
+	  struct expand_operand ops[4];
+	  rtx_insn *last = get_last_insn ();
+
+	  res = gen_reg_rtx (mode);
+	  create_output_operand (&ops[0], res, mode);
+	  create_input_operand (&ops[1], op0, mode);
+	  create_input_operand (&ops[2], op1, mode);
+	  create_fixed_operand (&ops[3], do_error);
+	  if (maybe_expand_insn (icode, 4, ops))
+	    {
+	      last = get_last_insn ();
+	      if (profile_status_for_fn (cfun) != PROFILE_ABSENT
+		  && JUMP_P (last)
+		  && any_condjump_p (last)
+		  && !find_reg_note (last, REG_BR_PROB, 0))
+		add_int_reg_note (last, REG_BR_PROB, PROB_VERY_UNLIKELY);
+	      emit_jump (done_label);
+	      goto do_error_label;
+	    }
+
+	  delete_insns_since (last);
+	}
+
       /* Compute the operation.  On RTL level, the addition is always
 	 unsigned.  */
       res = expand_binop (mode, code == PLUS_EXPR ? add_optab : sub_optab,
@@ -737,92 +764,88 @@ expand_addsub_overflow (location_t loc, tree_code code, tree lhs,
   gcc_assert (!uns0_p && !uns1_p && !unsr_p);
 
   /* s1 +- s2 -> sr  */
- do_signed: ;
-  enum insn_code icode;
-  icode = optab_handler (code == PLUS_EXPR ? addv4_optab : subv4_optab, mode);
-  if (icode != CODE_FOR_nothing)
-    {
-      struct expand_operand ops[4];
-      rtx_insn *last = get_last_insn ();
-
-      res = gen_reg_rtx (mode);
-      create_output_operand (&ops[0], res, mode);
-      create_input_operand (&ops[1], op0, mode);
-      create_input_operand (&ops[2], op1, mode);
-      create_fixed_operand (&ops[3], do_error);
-      if (maybe_expand_insn (icode, 4, ops))
-	{
-	  last = get_last_insn ();
-	  if (profile_status_for_fn (cfun) != PROFILE_ABSENT
-	      && JUMP_P (last)
-	      && any_condjump_p (last)
-	      && !find_reg_note (last, REG_BR_PROB, 0))
-	    add_int_reg_note (last, REG_BR_PROB, PROB_VERY_UNLIKELY);
-	  emit_jump (done_label);
-        }
-      else
-	{
-	  delete_insns_since (last);
-	  icode = CODE_FOR_nothing;
-	}
-    }
-
-  if (icode == CODE_FOR_nothing)
-    {
-      rtx_code_label *sub_check = gen_label_rtx ();
-      int pos_neg = 3;
-
-      /* Compute the operation.  On RTL level, the addition is always
-	 unsigned.  */
-      res = expand_binop (mode, code == PLUS_EXPR ? add_optab : sub_optab,
-			  op0, op1, NULL_RTX, false, OPTAB_LIB_WIDEN);
-
-      /* If we can prove one of the arguments (for MINUS_EXPR only
-	 the second operand, as subtraction is not commutative) is always
-	 non-negative or always negative, we can do just one comparison
-	 and conditional jump instead of 2 at runtime, 3 present in the
-	 emitted code.  If one of the arguments is CONST_INT, all we
-	 need is to make sure it is op1, then the first
-	 do_compare_rtx_and_jump will be just folded.  Otherwise try
-	 to use range info if available.  */
-      if (code == PLUS_EXPR && CONST_INT_P (op0))
-	std::swap (op0, op1);
-      else if (CONST_INT_P (op1))
-	;
-      else if (code == PLUS_EXPR && TREE_CODE (arg0) == SSA_NAME)
-	{
-	  pos_neg = get_range_pos_neg (arg0);
-	  if (pos_neg != 3)
-	    std::swap (op0, op1);
-	}
-      if (pos_neg == 3 && !CONST_INT_P (op1) && TREE_CODE (arg1) == SSA_NAME)
-	pos_neg = get_range_pos_neg (arg1);
-
-      /* If the op1 is negative, we have to use a different check.  */
-      if (pos_neg == 3)
-	do_compare_rtx_and_jump (op1, const0_rtx, LT, false, mode, NULL_RTX,
-				 NULL, sub_check, PROB_EVEN);
-
-      /* Compare the result of the operation with one of the operands.  */
-      if (pos_neg & 1)
-	do_compare_rtx_and_jump (res, op0, code == PLUS_EXPR ? GE : LE,
-				 false, mode, NULL_RTX, NULL, done_label,
-				 PROB_VERY_LIKELY);
-
-      /* If we get here, we have to print the error.  */
-      if (pos_neg == 3)
-	{
-	  emit_jump (do_error);
+ do_signed:
+  {
+    insn_code icode = optab_handler (code == PLUS_EXPR ? addv4_optab
+				     : subv4_optab, mode);
+    if (icode != CODE_FOR_nothing)
+      {
+	struct expand_operand ops[4];
+	rtx_insn *last = get_last_insn ();
+
+	res = gen_reg_rtx (mode);
+	create_output_operand (&ops[0], res, mode);
+	create_input_operand (&ops[1], op0, mode);
+	create_input_operand (&ops[2], op1, mode);
+	create_fixed_operand (&ops[3], do_error);
+	if (maybe_expand_insn (icode, 4, ops))
+	  {
+	    last = get_last_insn ();
+	    if (profile_status_for_fn (cfun) != PROFILE_ABSENT
+		&& JUMP_P (last)
+		&& any_condjump_p (last)
+		&& !find_reg_note (last, REG_BR_PROB, 0))
+	      add_int_reg_note (last, REG_BR_PROB, PROB_VERY_UNLIKELY);
+	    emit_jump (done_label);
+	    goto do_error_label;
+	  }
+
+	delete_insns_since (last);
+      }
+
+    rtx_code_label *sub_check = gen_label_rtx ();
+    int pos_neg = 3;
+
+    /* Compute the operation.  On RTL level, the addition is always
+       unsigned.  */
+    res = expand_binop (mode, code == PLUS_EXPR ? add_optab : sub_optab,
+			op0, op1, NULL_RTX, false, OPTAB_LIB_WIDEN);
+
+    /* If we can prove one of the arguments (for MINUS_EXPR only
+       the second operand, as subtraction is not commutative) is always
+       non-negative or always negative, we can do just one comparison
+       and conditional jump instead of 2 at runtime, 3 present in the
+       emitted code.  If one of the arguments is CONST_INT, all we
+       need is to make sure it is op1, then the first
+       do_compare_rtx_and_jump will be just folded.  Otherwise try
+       to use range info if available.  */
+    if (code == PLUS_EXPR && CONST_INT_P (op0))
+      std::swap (op0, op1);
+    else if (CONST_INT_P (op1))
+      ;
+    else if (code == PLUS_EXPR && TREE_CODE (arg0) == SSA_NAME)
+      {
+        pos_neg = get_range_pos_neg (arg0);
+        if (pos_neg != 3)
+	  std::swap (op0, op1);
+      }
+    if (pos_neg == 3 && !CONST_INT_P (op1) && TREE_CODE (arg1) == SSA_NAME)
+      pos_neg = get_range_pos_neg (arg1);
+
+    /* If the op1 is negative, we have to use a different check.  */
+    if (pos_neg == 3)
+      do_compare_rtx_and_jump (op1, const0_rtx, LT, false, mode, NULL_RTX,
+			       NULL, sub_check, PROB_EVEN);
+
+    /* Compare the result of the operation with one of the operands.  */
+    if (pos_neg & 1)
+      do_compare_rtx_and_jump (res, op0, code == PLUS_EXPR ? GE : LE,
+			       false, mode, NULL_RTX, NULL, done_label,
+			       PROB_VERY_LIKELY);
 
-	  emit_label (sub_check);
-	}
+    /* If we get here, we have to print the error.  */
+    if (pos_neg == 3)
+      {
+	emit_jump (do_error);
+	emit_label (sub_check);
+      }
 
-      /* We have k = a + b for b < 0 here.  k <= a must hold.  */
-      if (pos_neg & 2)
-	do_compare_rtx_and_jump (res, op0, code == PLUS_EXPR ? LE : GE,
-				 false, mode, NULL_RTX, NULL, done_label,
-				 PROB_VERY_LIKELY);
-    }
+    /* We have k = a + b for b < 0 here.  k <= a must hold.  */
+    if (pos_neg & 2)
+      do_compare_rtx_and_jump (res, op0, code == PLUS_EXPR ? LE : GE,
+			       false, mode, NULL_RTX, NULL, done_label,
+			       PROB_VERY_LIKELY);
+  }
 
  do_error_label:
   emit_label (do_error);
diff --git a/gcc/optabs.def b/gcc/optabs.def
index 0ca2333..c141a3c 100644
--- a/gcc/optabs.def
+++ b/gcc/optabs.def
@@ -197,6 +197,8 @@ OPTAB_D (ctrap_optab, "ctrap$a4")
 OPTAB_D (addv4_optab, "addv$I$a4")
 OPTAB_D (subv4_optab, "subv$I$a4")
 OPTAB_D (mulv4_optab, "mulv$I$a4")
+OPTAB_D (uaddv4_optab, "uaddv$I$a4")
+OPTAB_D (usubv4_optab, "usubv$I$a4")
 OPTAB_D (umulv4_optab, "umulv$I$a4")
 OPTAB_D (negv3_optab, "negv$I$a3")
 OPTAB_D (addptr3_optab, "addptr$a3")

Re: Add uaddv4_optab, usubv4_optab

[Jakub Jelinek]

On Fri, Nov 20, 2015 at 11:27:48AM +0100, Richard Henderson wrote:
> Toward fixing PR68385.  I'm just starting a full round of testing, but
> 
> extern void underflow(void) __attribute__((noreturn));
> unsigned sub1(unsigned a, unsigned b)
> {
>     unsigned r = a - b;
>     if (r > a) underflow();
>     return r;
> }
> 
> unsigned sub2(unsigned a, unsigned b)
> {
>     unsigned r;
>     if (__builtin_sub_overflow(a, b, &r)) underflow();
>     return r;
> }
> 
> 
> sub1:
> 	movl	%edi, %eax
> 	subl	%esi, %eax
> 	cmpl	%eax, %edi
> 	jb	.L7
> 	rep ret
> ...
> sub2:
> 	movl	%edi, %eax
> 	subl	%esi, %eax
> 	jb	.L16
> 	rep ret
> ...

That looks good.

> --- a/gcc/config/i386/i386.md
> +++ b/gcc/config/i386/i386.md
> @@ -6156,6 +6156,22 @@
>  		  (const_string "4")]
>  	      (const_string "<MODE_SIZE>")))])
>  
> +(define_expand "uaddv<mode>4"
> +  [(parallel [(set (reg:CCC FLAGS_REG)
> +		   (compare:CCC
> +		     (plus:SWI (match_dup 1) (match_dup 2))
> +		     (match_dup 1)))
> +	      (set (match_dup 0)
> +		   (plus:SWI (match_dup 1) (match_dup 2)))])
> +   (set (pc) (if_then_else
> +	       (ne (reg:CCC FLAGS_REG) (const_int 0))
> +	       (label_ref (match_operand 3))
> +	       (pc)))]
> +  ""
> +{
> +  ix86_fixup_binary_operands_no_copy (PLUS, <MODE>mode, operands);
> +})

Do we need this one on i?86?  I'm not against adding it to optabs, so that
other targets have a way to improve that, but doesn't combine handle this
case on i?86 already well?
I've been thinking of only transforming the above sub1 code (in forwprop, as
richi suggested) to sub2 internal call + REALPART/IMAGPART extraction if
the corresponding optab exists.

> +
>  ;; The lea patterns for modes less than 32 bits need to be matched by
>  ;; several insns converted to real lea by splitters.
>  
> @@ -6461,6 +6477,20 @@
>  		  (const_string "4")]
>  	      (const_string "<MODE_SIZE>")))])
>  
> +(define_expand "usubv<mode>4"
> +  [(parallel [(set (reg:CC FLAGS_REG)
> +		   (compare:CC (match_dup 1) (match_dup 2)))
> +	      (set (match_dup 0)
> +		   (minus:SWI (match_dup 1) (match_dup 2)))])
> +   (set (pc) (if_then_else
> +	       (ltu (reg:CC FLAGS_REG) (const_int 0))
> +	       (label_ref (match_operand 3))
> +	       (pc)))]

If this works, it will be nice, I thought we'll need a new CC*mode.

> --- a/gcc/doc/md.texi
> +++ b/gcc/doc/md.texi
> @@ -4912,6 +4912,25 @@ address calculations.  @code{add@var{m}3} is used if
>  @itemx @samp{and@var{m}3}, @samp{ior@var{m}3}, @samp{xor@var{m}3}
>  Similar, for other arithmetic operations.
>  
> +@cindex @code{addv@var{m}4} instruction pattern
> +@item @samp{addv@var{m}4}
> +Add operand 2 and operand 1, storing the result in operand 0.  If signed
> +overflow occurs during the addition, jump to the label in operand 3.
> +
> +@cindex @code{subv@var{m}4} instruction pattern
> +@cindex @code{mulv@var{m}4} instruction pattern
> +@item @samp{subv@var{m}4}, @samp{mulv@var{m}4}
> +Similar, for other signed arithmetic operations.
> +
> +@cindex @code{uaddv@var{m}4} instruction pattern
> +@item @samp{uaddv@var{m}4}
> +Like @code{addv@var{m}4}, except jump on unsigned overflow.
> +
> +@cindex @code{usubv@var{m}4} instruction pattern
> +@cindex @code{umulv@var{m}4} instruction pattern
> +@item @samp{usubv@var{m}4}, @samp{umulv@var{m}4}
> +Similar, for other unsigned arithmetic operations.

Eric has just submitted a documentation path that documented the
{add,sub,mul,umul}v<mode>4 and negv<mode>3 patterns, so this should be
applied on top of that.

	Jakub

Re: Add uaddv4_optab, usubv4_optab

[Eric Botcazou]

> Eric has just submitted a documentation path that documented the
> {add,sub,mul,umul}v<mode>4 and negv<mode>3 patterns, so this should be
> applied on top of that.

OK, I'm going to apply it, thanks.  Note that the comment at the beginning 
of expand_addsub_overflow describing the overall strategy ought to be adjusted 
if new patterns for the jump on carry are added.

-- 
Eric Botcazou

Re: Add uaddv4_optab, usubv4_optab

[Richard Henderson]

On 11/20/2015 11:56 AM, Eric Botcazou wrote:
>> Eric has just submitted a documentation path that documented the
>> {add,sub,mul,umul}v<mode>4 and negv<mode>3 patterns, so this should be
>> applied on top of that.
>
> OK, I'm going to apply it, thanks.

Thanks.

> Note that the comment at the beginning
> of expand_addsub_overflow describing the overall strategy ought to be adjusted
> if new patterns for the jump on carry are added.

Ok, I'll do that.


r~

Re: Add uaddv4_optab, usubv4_optab

[Richard Henderson]

On 11/20/2015 11:43 AM, Jakub Jelinek wrote:
>> +(define_expand "uaddv<mode>4"
>> +  [(parallel [(set (reg:CCC FLAGS_REG)
>> +		   (compare:CCC
>> +		     (plus:SWI (match_dup 1) (match_dup 2))
>> +		     (match_dup 1)))
>> +	      (set (match_dup 0)
>> +		   (plus:SWI (match_dup 1) (match_dup 2)))])
>> +   (set (pc) (if_then_else
>> +	       (ne (reg:CCC FLAGS_REG) (const_int 0))
>> +	       (label_ref (match_operand 3))
>> +	       (pc)))]
>> +  ""
>> +{
>> +  ix86_fixup_binary_operands_no_copy (PLUS, <MODE>mode, operands);
>> +})
>
> Do we need this one on i?86?  I'm not against adding it to optabs, so that
> other targets have a way to improve that, but doesn't combine handle this
> case on i?86 already well?

Perhaps combine can do the job, but in my option it's better to have the optab 
than not.  Especially when it's so easy to add in this case.

>> +(define_expand "usubv<mode>4"
>> +  [(parallel [(set (reg:CC FLAGS_REG)
>> +		   (compare:CC (match_dup 1) (match_dup 2)))
>> +	      (set (match_dup 0)
>> +		   (minus:SWI (match_dup 1) (match_dup 2)))])
>> +   (set (pc) (if_then_else
>> +	       (ltu (reg:CC FLAGS_REG) (const_int 0))
>> +	       (label_ref (match_operand 3))
>> +	       (pc)))]
>
> If this works, it will be nice, I thought we'll need a new CC*mode.

No, we just need to re-use the existing insn that performs the low half of a 
double-word subtraction operation.

> Eric has just submitted a documentation path that documented the
> {add,sub,mul,umul}v<mode>4 and negv<mode>3 patterns, so this should be
> applied on top of that.

Ok, I'll look out for that.


r~

Re: Add uaddv4_optab, usubv4_optab

[Eric Botcazou]

> Toward fixing PR68385.  I'm just starting a full round of testing, but

Do you mind if I install my doc patch?  It's slightly more thorough.

-- 
Eric Botcazou