[gcc r14-5023] MATCH: first of the value replacement moving from phiopt

[gcc r14-5023] MATCH: first of the value replacement moving from phiopt

[Andrew Pinski]

https://gcc.gnu.org/g:598fdb5290dcf76ef23e993409e22f1512ff835a

commit r14-5023-g598fdb5290dcf76ef23e993409e22f1512ff835a
Author: Andrew Pinski <pinskia@gmail.com>
Date:   Thu Oct 26 15:07:53 2023 -0700

    MATCH: first of the value replacement moving from phiopt
    
    This moves a few simple patterns that are done in value replacement
    in phiopt over to match.pd. Just the simple ones which might show up
    in other code.
    
    This allows some optimizations to happen even without depending
    on sinking from happening and in some cases where phiopt is not
    invoked (cond-1.c is an example there).
    
    Changes since v1:
    * v2: Add an extra testcase to showcase improvements at -O1.
    
    Bootstrapped and tested on x86_64-linux-gnu with no regressions.
    
    gcc/ChangeLog:
    
            * match.pd: (`a == 0 ? b : b + a`,
            `a == 0 ? b : b - a`): New patterns.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.dg/tree-ssa/cond-1.c: New test.
            * gcc.dg/tree-ssa/phi-opt-value-1.c: New test.
            * gcc.dg/tree-ssa/phi-opt-value-1a.c: New test.
            * gcc.dg/tree-ssa/phi-opt-value-2.c: New test.

Diff:
---
 gcc/match.pd                                     | 14 ++++++++++++++
 gcc/testsuite/gcc.dg/tree-ssa/cond-1.c           | 17 +++++++++++++++++
 gcc/testsuite/gcc.dg/tree-ssa/phi-opt-value-1.c  | 17 +++++++++++++++++
 gcc/testsuite/gcc.dg/tree-ssa/phi-opt-value-1a.c | 19 +++++++++++++++++++
 gcc/testsuite/gcc.dg/tree-ssa/phi-opt-value-2.c  | 19 +++++++++++++++++++
 5 files changed, 86 insertions(+)

diff --git a/gcc/match.pd b/gcc/match.pd
index 7d651a6582d1..22899c51a2f9 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -4145,6 +4145,20 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
        && (INTEGRAL_TYPE_P (TREE_TYPE (@0))))
        (op (mult (convert:type @0) @2) @1))))
 
+/* ?: Value replacement. */
+/* a == 0 ? b : b + a  -> b + a */
+(for op (plus bit_ior bit_xor)
+ (simplify
+  (cond (eq @0 integer_zerop) @1 (op:c@2 @1 @0))
+   @2))
+/* a == 0 ? b : b - a  -> b - a */
+/* a == 0 ? b : b ptr+ a  -> b ptr+ a */
+/* a == 0 ? b : b shift/rotate a -> b shift/rotate a */
+(for op (lrotate rrotate lshift rshift minus pointer_plus)
+ (simplify
+  (cond (eq @0 integer_zerop) @1 (op@2 @1 @0))
+   @2))
+
 /* Simplifications of shift and rotates.  */
 
 (for rotate (lrotate rrotate)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/cond-1.c b/gcc/testsuite/gcc.dg/tree-ssa/cond-1.c
new file mode 100644
index 000000000000..478a818b2065
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/cond-1.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-optimized-raw" } */
+
+int sub(int a, int b, int c, int d) {
+  int e = (a == 0);
+  int f = !e;
+  c = b;
+  d = b - a ;
+  return ((-e & c) | (-f & d));
+}
+
+/* In the end we end up with `(a == 0) ? (b - a) : b`
+   which then can be optimized to just `(b - a)`. */
+
+/* { dg-final { scan-tree-dump-not "cond_expr," "optimized" } } */
+/* { dg-final { scan-tree-dump-not "eq_expr," "optimized" } } */
+/* { dg-final { scan-tree-dump-times "minus_expr," 1 "optimized" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-value-1.c b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-value-1.c
new file mode 100644
index 000000000000..a90de8926c67
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-value-1.c
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* Phi-OPT should be able to optimize this without sinking being invoked. */
+/* { dg-options "-O -fdump-tree-phiopt2 -fdump-tree-optimized -fno-tree-sink" } */
+
+char *f(char *a, __SIZE_TYPE__ b) {
+  char *d = a + b;
+  if (b == 0) return a;
+  return d;
+}
+int sub(int a, int b, int c) {
+  int d = a - b;
+  if (b == 0) return a;
+  return d;
+}
+
+/* { dg-final { scan-tree-dump-not "goto" "phiopt2" } } */
+/* { dg-final { scan-tree-dump-not "goto" "optimized" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-value-1a.c b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-value-1a.c
new file mode 100644
index 000000000000..b884f94ddd28
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-value-1a.c
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+[[gnu::const]]
+int constcall(int);
+
+int f(int a, int b)
+{
+  int c = b+a;
+  int t = constcall(c);
+  int d;
+  if (a == 0) d= b; else d= c;
+  return constcall(d) + t;
+}
+
+/* There should be no if statement and 2 calls to call1. */
+/* { dg-final { scan-tree-dump-not "if " "optimized" } } */
+/* { dg-final { scan-tree-dump-times "constcall " 1 "optimized" } } */
+
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-value-2.c b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-value-2.c
new file mode 100644
index 000000000000..809ccfe1479e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-value-2.c
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* Phi-OPT should be able to optimize this without sinking being invoked. */
+/* { dg-options "-O -fdump-tree-phiopt2 -fdump-tree-optimized -fno-tree-sink" } */
+
+int f(int a, int b, int c) {
+  int d = a + b;
+  if (c > 5) return c;
+  if (a == 0) return b;
+  return d;
+}
+
+unsigned rot(unsigned x, int n) {
+  const int bits = __CHAR_BIT__ * __SIZEOF_INT__;
+  int t = ((x << n) | (x >> (bits - n)));
+  return (n == 0) ? x : t;
+}
+
+/* { dg-final { scan-tree-dump-times "goto" 2 "phiopt2" } } */
+/* { dg-final { scan-tree-dump-times "goto" 2 "optimized" } } */