[PATCH PR82439][simplify-rtx] Simplify (x | y) == x -> (y & ~x) == 0

[PATCH PR82439][simplify-rtx] Simplify (x | y) == x -> (y & ~x) == 0

[Sudakshina Das]

Hi

This patch add support for the missing transformation of (x | y) == x -> 
(y & ~x) == 0.
The transformation for (x & y) == x case already exists in 
simplify-rtx.c since 2014 as of r218503 and this patch only adds a 
couple of extra patterns for the IOR case.

Citing the example given in PR82439 :

Simple testcase (f1 should generate the same as f2):

int f1(int x, int y) { return (x | y) == x; }
int f2(int x, int y) { return (y & ~x) == 0; }

f1:
	orr	w1, w0, w1
	cmp	w1, w0
	cset	w0, eq
	ret
f2:
	bics	wzr, w1, w0
	cset	w0, eq
	ret

This benefits targets that have the BICS instruction to generate better 
code. Wilco helped me in showing that even in targets that do not have 
the BICS instruction, this is no worse and gives out 2 instructions.
For example in x86:

0000000000000000 <f1>:
    0:	09 fe                	or     %edi,%esi
    2:	31 c0                	xor    %eax,%eax
    4:	39 fe                	cmp    %edi,%esi
    6:	0f 94 c0             	sete   %al
    9:	c3                   	retq

0000000000000010 <f2>:
   10:	f7 d7                	not    %edi
   12:	31 c0                	xor    %eax,%eax
   14:	85 f7                	test   %esi,%edi
   16:	0f 94 c0             	sete   %al
   19:	c3                   	retq

Testing done: Checked for regressions on bootstrapped 
aarch64-none-linux-gnu and arm-none-linux-gnueabihf and added new test 
cases.
Is this ok for trunk?

Sudi

ChangeLog Entries:

*** gcc/ChangeLog ***

2017-01-03  Sudakshina Das  <sudi.das@arm.com>

	PR target/82439
	* simplify-rtx.c (simplify_relational_operation_1): Add
	simplifications of (x|y) == x for BICS pattern.

*** gcc/testsuite/ChangeLog ***

2017-01-03  Sudakshina Das  <sudi.das@arm.com>

	PR target/82439
	* gcc.target/aarch64/bics_5.c: New test.
	* gcc.target/arm/bics_5.c: Likewise.

Re: [PATCH PR82439][simplify-rtx] Simplify (x | y) == x -> (y & ~x) == 0

[Segher Boessenkool]

Hi!

On Wed, Jan 03, 2018 at 01:57:38PM +0000, Sudakshina Das wrote:
> This patch add support for the missing transformation of (x | y) == x -> 
> (y & ~x) == 0.

> Testing done: Checked for regressions on bootstrapped 
> aarch64-none-linux-gnu and arm-none-linux-gnueabihf and added new test 
> cases.
> Is this ok for trunk?

You forgot to include the patch :-)


Segher

Re: [PATCH PR82439][simplify-rtx] Simplify (x | y) == x -> (y & ~x) == 0

[Sudakshina Das]

[-- Attachment #1: Type: text/plain, Size: 548 bytes --]

Hi

On 03/01/18 14:38, Segher Boessenkool wrote:
> Hi!
> 
> On Wed, Jan 03, 2018 at 01:57:38PM +0000, Sudakshina Das wrote:
>> This patch add support for the missing transformation of (x | y) == x ->
>> (y & ~x) == 0.
> 
>> Testing done: Checked for regressions on bootstrapped
>> aarch64-none-linux-gnu and arm-none-linux-gnueabihf and added new test
>> cases.
>> Is this ok for trunk?
> 
> You forgot to include the patch :-)

(facepalm) This is the second time this has happened to me!
Sorry about this. Attaching now.

Sudi

> 
> 
> Segher
> 


[-- Attachment #2: pr82439.diff --]
[-- Type: text/x-patch, Size: 5407 bytes --]

diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index e5cfd3d..17536d0 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -5032,34 +5032,38 @@ simplify_relational_operation_1 (enum rtx_code code, machine_mode mode,
 				    simplify_gen_binary (XOR, cmp_mode,
 							 XEXP (op0, 1), op1));
 
-  /* (eq/ne (and x y) x) simplifies to (eq/ne (and (not y) x) 0), which
-     can be implemented with a BICS instruction on some targets, or
-     constant-folded if y is a constant.  */
+  /* Simplify eq/ne (and/ior x y) x/y) for targets with a BICS instruction or
+     constant folding if x/y is a constant.  */
   if ((code == EQ || code == NE)
-      && op0code == AND
-      && rtx_equal_p (XEXP (op0, 0), op1)
+      && (op0code == AND || op0code == IOR)
       && !side_effects_p (op1)
       && op1 != CONST0_RTX (cmp_mode))
     {
-      rtx not_y = simplify_gen_unary (NOT, cmp_mode, XEXP (op0, 1), cmp_mode);
-      rtx lhs = simplify_gen_binary (AND, cmp_mode, not_y, XEXP (op0, 0));
+      /* Both (eq/ne (and x y) x) and (eq/ne (ior x y) y) simplify to
+	 (eq/ne (and (not y) x) 0).  */
+      if ((op0code == AND && rtx_equal_p (XEXP (op0, 0), op1))
+	  || (op0code == IOR && rtx_equal_p (XEXP (op0, 1), op1)))
+	{
+	  rtx not_y = simplify_gen_unary (NOT, cmp_mode, XEXP (op0, 1),
+					  cmp_mode);
+	  rtx lhs = simplify_gen_binary (AND, cmp_mode, not_y, XEXP (op0, 0));
 
-      return simplify_gen_relational (code, mode, cmp_mode, lhs,
-				      CONST0_RTX (cmp_mode));
-    }
+	  return simplify_gen_relational (code, mode, cmp_mode, lhs,
+					  CONST0_RTX (cmp_mode));
+	}
 
-  /* Likewise for (eq/ne (and x y) y).  */
-  if ((code == EQ || code == NE)
-      && op0code == AND
-      && rtx_equal_p (XEXP (op0, 1), op1)
-      && !side_effects_p (op1)
-      && op1 != CONST0_RTX (cmp_mode))
-    {
-      rtx not_x = simplify_gen_unary (NOT, cmp_mode, XEXP (op0, 0), cmp_mode);
-      rtx lhs = simplify_gen_binary (AND, cmp_mode, not_x, XEXP (op0, 1));
+      /* Both (eq/ne (and x y) y) and (eq/ne (ior x y) x) simplify to
+	 (eq/ne (and (not x) y) 0).  */
+      if ((op0code == AND && rtx_equal_p (XEXP (op0, 1), op1))
+	  || (op0code == IOR && rtx_equal_p (XEXP (op0, 0), op1)))
+	{
+	  rtx not_x = simplify_gen_unary (NOT, cmp_mode, XEXP (op0, 0),
+					  cmp_mode);
+	  rtx lhs = simplify_gen_binary (AND, cmp_mode, not_x, XEXP (op0, 1));
 
-      return simplify_gen_relational (code, mode, cmp_mode, lhs,
-				      CONST0_RTX (cmp_mode));
+	  return simplify_gen_relational (code, mode, cmp_mode, lhs,
+					  CONST0_RTX (cmp_mode));
+	}
     }
 
   /* (eq/ne (bswap x) C1) simplifies to (eq/ne x C2) with C2 swapped.  */
diff --git a/gcc/testsuite/gcc.target/aarch64/bics_5.c b/gcc/testsuite/gcc.target/aarch64/bics_5.c
new file mode 100644
index 0000000..b9c2c40
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/bics_5.c
@@ -0,0 +1,86 @@
+/* { dg-do run } */
+/* { dg-options "-O2 --save-temps -fno-inline" } */
+
+extern void abort (void);
+
+int
+bics_si_test1 (int a, int b, int c)
+{
+  if ((a | b) == a)
+    return a;
+  else
+    return c;
+}
+
+int
+bics_si_test2 (int a, int b, int c)
+{
+  if ((a | b) == b)
+    return b;
+  else
+    return c;
+}
+
+typedef long long s64;
+
+s64
+bics_di_test1 (s64 a, s64 b, s64 c)
+{
+  if ((a | b) == a)
+    return a;
+  else
+    return c;
+}
+
+s64
+bics_di_test2 (s64 a, s64 b, s64 c)
+{
+  if ((a | b) == b)
+    return b;
+  else
+    return c;
+}
+
+int
+main ()
+{
+  int x;
+  s64 y;
+
+  x = bics_si_test1 (0xf00d, 0xf11f, 0);
+  if (x != 0)
+    abort ();
+
+  x = bics_si_test1 (0xf11f, 0xf00d, 0);
+  if (x != 0xf11f)
+    abort ();
+
+  x = bics_si_test2 (0xf00d, 0xf11f, 0);
+  if (x != 0xf11f)
+    abort ();
+
+  x = bics_si_test2 (0xf11f, 0xf00d, 0);
+  if (x != 0)
+    abort ();
+
+  y = bics_di_test1 (0x10001000f00dll, 0x12341000f00dll, 0ll);
+  if (y != 0)
+    abort ();
+
+  y = bics_di_test1 (0x12341000f00dll, 0x10001000f00dll, 0ll);
+  if (y != 0x12341000f00dll)
+    abort ();
+
+  y = bics_di_test2 (0x10001000f00dll, 0x12341000f00dll, 0ll);
+  if (y != 0x12341000f00dll)
+    abort ();
+
+  y = bics_di_test2 (0x12341000f00dll, 0x10001000f00dll, 0ll);
+  if (y != 0)
+    abort ();
+
+  return 0;
+}
+
+/* { dg-final { scan-assembler-times "bics\twzr, w\[0-9\]+, w\[0-9\]+" 2 } } */
+/* { dg-final { scan-assembler-times "bics\txzr, x\[0-9\]+, x\[0-9\]+" 2 } } */
diff --git a/gcc/testsuite/gcc.target/arm/bics_5.c b/gcc/testsuite/gcc.target/arm/bics_5.c
new file mode 100644
index 0000000..6f84902
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/bics_5.c
@@ -0,0 +1,46 @@
+/* { dg-do run } */
+/* { dg-options "-O2 --save-temps -fno-inline" } */
+/* { dg-require-effective-target arm32 } */
+extern void abort (void);
+int
+bics_si_test1 (int a, int b, int c)
+{
+  if ((a | b) == a)
+    return a;
+  else
+    return c;
+}
+
+int
+bics_si_test2 (int a, int b, int c)
+{
+  if ((a | b) == b)
+    return b;
+  else
+    return c;
+}
+
+int
+main ()
+{
+  int x;
+  x = bics_si_test1 (0xf00d, 0xf11f, 0);
+  if (x != 0)
+    abort ();
+
+  x = bics_si_test1 (0xf11f, 0xf00d, 0);
+  if (x != 0xf11f)
+    abort ();
+
+  x = bics_si_test2 (0xf00d, 0xf11f, 0);
+  if (x != 0xf11f)
+    abort ();
+
+  x = bics_si_test2 (0xf11f, 0xf00d, 0);
+  if (x != 0)
+    abort ();
+
+  return 0;
+}
+
+/* { dg-final { scan-assembler-times "bics\tr\[0-9\]+, r\[0-9\]+, r\[0-9\]+" 2 } } */

Re: [PATCH PR82439][simplify-rtx] Simplify (x | y) == x -> (y & ~x) == 0

[Jeff Law]

On 01/03/2018 06:57 AM, Sudakshina Das wrote:
> Hi
> 
> This patch add support for the missing transformation of (x | y) == x ->
> (y & ~x) == 0.
> The transformation for (x & y) == x case already exists in
> simplify-rtx.c since 2014 as of r218503 and this patch only adds a
> couple of extra patterns for the IOR case.
> 
> Citing the example given in PR82439 :
> 
> Simple testcase (f1 should generate the same as f2):
> 
> int f1(int x, int y) { return (x | y) == x; }
> int f2(int x, int y) { return (y & ~x) == 0; }
> 
> f1:
>     orr    w1, w0, w1
>     cmp    w1, w0
>     cset    w0, eq
>     ret
> f2:
>     bics    wzr, w1, w0
>     cset    w0, eq
>     ret
> 
> This benefits targets that have the BICS instruction to generate better
> code. Wilco helped me in showing that even in targets that do not have
> the BICS instruction, this is no worse and gives out 2 instructions.
> For example in x86:
> 
> 0000000000000000 <f1>:
>    0:    09 fe                    or     %edi,%esi
>    2:    31 c0                    xor    %eax,%eax
>    4:    39 fe                    cmp    %edi,%esi
>    6:    0f 94 c0                 sete   %al
>    9:    c3                       retq
> 
> 0000000000000010 <f2>:
>   10:    f7 d7                    not    %edi
>   12:    31 c0                    xor    %eax,%eax
>   14:    85 f7                    test   %esi,%edi
>   16:    0f 94 c0                 sete   %al
>   19:    c3                       retq
> 
> Testing done: Checked for regressions on bootstrapped
> aarch64-none-linux-gnu and arm-none-linux-gnueabihf and added new test
> cases.
> Is this ok for trunk?
> 
> Sudi
> 
> ChangeLog Entries:
> 
> *** gcc/ChangeLog ***
> 
> 2017-01-03  Sudakshina Das  <sudi.das@arm.com>
> 
>     PR target/82439
>     * simplify-rtx.c (simplify_relational_operation_1): Add
>     simplifications of (x|y) == x for BICS pattern.
> 
> *** gcc/testsuite/ChangeLog ***
> 
> 2017-01-03  Sudakshina Das  <sudi.das@arm.com>
> 
>     PR target/82439
>     * gcc.target/aarch64/bics_5.c: New test.
>     * gcc.target/arm/bics_5.c: Likewise.
OK.
jeff

Re: [PATCH PR82439][simplify-rtx] Simplify (x | y) == x -> (y & ~x) == 0

[Sudakshina Das]

Hi Jeff

On 04/01/18 18:30, Jeff Law wrote:
> On 01/03/2018 06:57 AM, Sudakshina Das wrote:
>> Hi
>>
>> This patch add support for the missing transformation of (x | y) == x ->
>> (y & ~x) == 0.
>> The transformation for (x & y) == x case already exists in
>> simplify-rtx.c since 2014 as of r218503 and this patch only adds a
>> couple of extra patterns for the IOR case.
>>
>> Citing the example given in PR82439 :
>>
>> Simple testcase (f1 should generate the same as f2):
>>
>> int f1(int x, int y) { return (x | y) == x; }
>> int f2(int x, int y) { return (y & ~x) == 0; }
>>
>> f1:
>>      orr    w1, w0, w1
>>      cmp    w1, w0
>>      cset    w0, eq
>>      ret
>> f2:
>>      bics    wzr, w1, w0
>>      cset    w0, eq
>>      ret
>>
>> This benefits targets that have the BICS instruction to generate better
>> code. Wilco helped me in showing that even in targets that do not have
>> the BICS instruction, this is no worse and gives out 2 instructions.
>> For example in x86:
>>
>> 0000000000000000 <f1>:
>>     0:    09 fe                    or     %edi,%esi
>>     2:    31 c0                    xor    %eax,%eax
>>     4:    39 fe                    cmp    %edi,%esi
>>     6:    0f 94 c0                 sete   %al
>>     9:    c3                       retq
>>
>> 0000000000000010 <f2>:
>>    10:    f7 d7                    not    %edi
>>    12:    31 c0                    xor    %eax,%eax
>>    14:    85 f7                    test   %esi,%edi
>>    16:    0f 94 c0                 sete   %al
>>    19:    c3                       retq
>>
>> Testing done: Checked for regressions on bootstrapped
>> aarch64-none-linux-gnu and arm-none-linux-gnueabihf and added new test
>> cases.
>> Is this ok for trunk?
>>
>> Sudi
>>
>> ChangeLog Entries:
>>
>> *** gcc/ChangeLog ***
>>
>> 2017-01-03  Sudakshina Das  <sudi.das@arm.com>
>>
>>      PR target/82439
>>      * simplify-rtx.c (simplify_relational_operation_1): Add
>>      simplifications of (x|y) == x for BICS pattern.
>>
>> *** gcc/testsuite/ChangeLog ***
>>
>> 2017-01-03  Sudakshina Das  <sudi.das@arm.com>
>>
>>      PR target/82439
>>      * gcc.target/aarch64/bics_5.c: New test.
>>      * gcc.target/arm/bics_5.c: Likewise.
> OK.

Thanks! Committed as r256275.

Sudi

> jeff
>