Re: [PATCH] fold a * (a > 0 ? 1 : -1) to abs(a) and related optimizations

[Andrew Pinski <pinskia@gmail.com>]

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Forgot the patch

On Fri, Jun 23, 2017 at 8:59 PM, Andrew Pinski <pinskia@gmail.com> wrote:
> Hi,
>   I saw this on llvm's review site (https://reviews.llvm.org/D34579)
> and I thought why not add it to GCC.  I expanded more than what was
> done on the LLVM patch.
>
> I added the following optimizations:
> Transform X * (X > 0 ? 1 : -1) into ABS(X).
> Transform X * (X >= 0 ? 1 : -1) into ABS(X).
> Transform X * (X > 0.0 ? 1.0 : -1.0) into ABS(X).
> Transform X * (X >= 0.0 ? 1.0 : -1.0) into ABS(X).
> Transform X * (X > 0 ? -1 : 1) into -ABS(X).
> Transform X * (X >= 0 ? -1 : 1) into -ABS(X).
> Transform X * (X > 0.0 ? -1.0 : 1.0) into -ABS(X).
> Transform X * (X >= 0.0 ? -1.0 : 1.0) into -ABS(X).
> Transform X * (X < 0 ? 1 : -1) into -ABS(X).
> Transform X * (X <= 0 ? 1 : -1) into -ABS(X).
> Transform X * (X < 0.0 ? 1.0 : -1.0) into -ABS(X).
> Transform X * (X <= 0.0 ? 1.0 : -1.0) into -ABS(X).
> Transform X * (X < 0 ? -1 : 1) into ABS(X).
> Transform X * (X <= 0 ? -1 : 1) into ABS(X).
> Transform X * (X < 0.0 ? -1.0 : 1.0) into ABS(X).
> Transform X * (X <= 0.0 ? -1.0 : 1.0) into ABS(X).
>
> The floating points ones only happen when not honoring SNANS and not
> honoring signed zeros.
>
> OK?  Bootstrapped and tested on aarch64-linux-gnu with no regressions.
>
> Thanks,
> Andrew Pinski
>
> ChangeLog:
> * match.pd ( X * (X >/>=/</<= 0 ? 1 : -1)): New patterns.
>
> Testsuite/ChangeLog:
> * testsuite/gcc.dg/tree-ssa/mult-abs-1.c: New testcase.
> * testsuite/gcc.dg/tree-ssa/mult-abs-2.c: New testcase.

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Index: match.pd
===================================================================
--- match.pd	(revision 249613)
+++ match.pd	(working copy)
@@ -155,6 +155,55 @@
            || !COMPLEX_FLOAT_TYPE_P (type)))
    (negate @0)))
 
+(for cmp (gt ge)
+ /* Transform X * (X > 0 ? 1 : -1) into ABS(X). */
+ /* Transform X * (X >= 0 ? 1 : -1) into ABS(X). */
+ (simplify
+  (mult:c @0 (cond (cmp @0 integer_zerop) integer_onep integer_all_onesp))
+  (abs @0))
+ /* Transform X * (X > 0.0 ? 1.0 : -1.0) into ABS(X). */
+ /* Transform X * (X >= 0.0 ? 1.0 : -1.0) into ABS(X). */
+ (simplify
+  (mult:c @0 (cond (cmp @0 real_zerop) real_onep real_minus_onep))
+  (if (!HONOR_SNANS (type) && !HONOR_SIGNED_ZEROS (type))
+   (abs @0)))
+ /* Transform X * (X > 0 ? -1 : 1) into -ABS(X). */
+ /* Transform X * (X >= 0 ? -1 : 1) into -ABS(X). */
+ (simplify
+  (mult:c @0 (cond (cmp @0 integer_zerop) integer_all_onesp integer_onep))
+  (negate (abs @0)))
+ /* Transform X * (X > 0.0 ? -1.0 : 1.0) into -ABS(X). */
+ /* Transform X * (X >= 0.0 ? -1.0 : 1.0) into -ABS(X). */
+ (simplify
+  (mult:c @0 (cond (cmp @0 real_zerop) real_minus_onep real_onep))
+  (if (!HONOR_SNANS (type) && !HONOR_SIGNED_ZEROS (type))
+   (negate (abs @0)))))
+
+(for cmp (lt le)
+ /* Transform X * (X < 0 ? 1 : -1) into -ABS(X). */
+ /* Transform X * (X <= 0 ? 1 : -1) into -ABS(X). */
+ (simplify
+  (mult:c @0 (cond (cmp @0 integer_zerop) integer_onep integer_all_onesp))
+  (negate (abs @0)))
+ /* Transform X * (X < 0.0 ? 1.0 : -1.0) into -ABS(X). */
+ /* Transform X * (X <= 0.0 ? 1.0 : -1.0) into -ABS(X). */
+ (simplify
+  (mult:c @0 (cond (cmp @0 real_zerop) real_onep real_minus_onep))
+  (if (!HONOR_SNANS (type) && !HONOR_SIGNED_ZEROS (type))
+   (negate (abs @0))))
+ /* Transform X * (X < 0 ? -1 : 1) into ABS(X). */
+ /* Transform X * (X <= 0 ? -1 : 1) into ABS(X). */
+ (simplify
+  (mult:c @0 (cond (cmp @0 integer_zerop) integer_all_onesp integer_onep))
+  (abs @0))
+ /* Transform X * (X < 0.0 ? -1.0 : 1.0) into ABS(X). */
+ /* Transform X * (X <= 0.0 ? -1.0 : 1.0) into ABS(X). */
+ (simplify
+  (mult:c @0 (cond (cmp @0 real_zerop) real_minus_onep real_onep))
+  (if (!HONOR_SNANS (type) && !HONOR_SIGNED_ZEROS (type))
+   (abs @0))))
+
+
 /* X * 1, X / 1 -> X.  */
 (for op (mult trunc_div ceil_div floor_div round_div exact_div)
   (simplify
Index: testsuite/gcc.dg/tree-ssa/mult-abs-1.c
===================================================================
--- testsuite/gcc.dg/tree-ssa/mult-abs-1.c	(nonexistent)
+++ testsuite/gcc.dg/tree-ssa/mult-abs-1.c	(working copy)
@@ -0,0 +1,35 @@
+/* { dg-options "-O2 -fdump-tree-gimple" } */
+/* { dg-do compile } */
+int f(int x)
+{
+  return x * (x > 0 ? -1 : 1);
+}
+int f1(int x)
+{
+  return x * (x > 0 ? 1 : -1);
+}
+int g(int x)
+{
+  return x * (x >= 0 ? -1 : 1);
+}
+int g1(int x)
+{
+  return x * (x >= 0 ? 1 : -1);
+}
+int h(int x)
+{
+  return x * (x < 0 ? -1 : 1);
+}
+int h1(int x)
+{
+  return x * (x < 0 ? 1 : -1);
+}
+int i(int x)
+{
+  return x * (x <= 0 ? -1 : 1);
+}
+int i1(int x)
+{
+  return x * (x <= 0 ? 1 : -1);
+}
+/* { dg-final { scan-tree-dump-times "ABS" 8 "gimple"} } */
Index: testsuite/gcc.dg/tree-ssa/mult-abs-2.c
===================================================================
--- testsuite/gcc.dg/tree-ssa/mult-abs-2.c	(nonexistent)
+++ testsuite/gcc.dg/tree-ssa/mult-abs-2.c	(working copy)
@@ -0,0 +1,35 @@
+/* { dg-options "-O2 -ffast-math -fdump-tree-gimple" } */
+/* { dg-do compile } */
+float f(float x)
+{
+  return x * (x > 0.f ? -1.f : 1.f);
+}
+float f1(float x)
+{
+  return x * (x > 0.f ? 1.f : -1.f);
+}
+float g(float x)
+{
+  return x * (x >= 0.f ? -1.f : 1.f);
+}
+float g1(float x)
+{
+  return x * (x >= 0.f ? 1.f : -1.f);
+}
+float h(float x)
+{
+  return x * (x < 0.f ? -1.f : 1.f);
+}
+float h1(float x)
+{
+  return x * (x < 0.f ? 1.f : -1.f);
+}
+float i(float x)
+{
+  return x * (x <= 0.f ? -1.f : 1.f);
+}
+float i1(float x)
+{
+  return x * (x <= 0.f ? 1.f : -1.f);
+}
+/* { dg-final { scan-tree-dump-times "ABS" 8 "gimple"} } */