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* [PATCH] Fix part of PR 110293: `A NEEQ (A NEEQ CST)` part
@ 2023-07-12 16:08 Andrew Pinski
  2023-07-13  7:38 ` Richard Biener
  0 siblings, 1 reply; 2+ messages in thread
From: Andrew Pinski @ 2023-07-12 16:08 UTC (permalink / raw)
  To: gcc-patches; +Cc: Andrew Pinski

This fixes part of PR 110293, for the outer comparison case
being `!=` or `==`.  In turn PR 110539 is able to be optimized
again as the if statement for `(a&1) == ((a & 1) != 0)` gets optimized
to `false` early enough to allow FRE/DOM to do a CSE for memory store/load.

OK? Bootstrapped and tested on x86_64-linux with no regressions.

gcc/ChangeLog:

	PR tree-optimization/110293
	PR tree-optimization/110539
	* match.pd: Expand the `x != (typeof x)(x == 0)`
	pattern to handle where the inner and outer comparsions
	are either `!=` or `==` and handle other constants
	than 0.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/pr110293-1.c: New test.
	* gcc.dg/tree-ssa/pr110539-1.c: New test.
	* gcc.dg/tree-ssa/pr110539-2.c: New test.
	* gcc.dg/tree-ssa/pr110539-3.c: New test.
	* gcc.dg/tree-ssa/pr110539-4.c: New test.
---
 gcc/match.pd                               | 39 ++++++++--
 gcc/testsuite/gcc.dg/tree-ssa/pr110293-1.c | 58 +++++++++++++++
 gcc/testsuite/gcc.dg/tree-ssa/pr110539-1.c | 12 ++++
 gcc/testsuite/gcc.dg/tree-ssa/pr110539-2.c | 12 ++++
 gcc/testsuite/gcc.dg/tree-ssa/pr110539-3.c | 75 ++++++++++++++++++++
 gcc/testsuite/gcc.dg/tree-ssa/pr110539-4.c | 82 ++++++++++++++++++++++
 6 files changed, 274 insertions(+), 4 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr110293-1.c
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr110539-1.c
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr110539-2.c
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr110539-3.c
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr110539-4.c

diff --git a/gcc/match.pd b/gcc/match.pd
index 8543f777a28..351d9285e92 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -6429,10 +6429,41 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
  (if (TYPE_UNSIGNED (TREE_TYPE (@0)))
   { constant_boolean_node (false, type); }))
 
-/* x != (typeof x)(x == 0) is always true.  */
-(simplify
- (ne:c @0 (convert (eq @0 integer_zerop)))
- { constant_boolean_node (true, type); })
+/* x != (typeof x)(x == CST) -> CST == 0 ? 1 : (CST == 1 ? (x!=0&&x!=1) : x != 0) */
+/* x != (typeof x)(x != CST) -> CST == 1 ? 1 : (CST == 0 ? (x!=0&&x!=1) : x != 1) */
+/* x == (typeof x)(x == CST) -> CST == 0 ? 0 : (CST == 1 ? (x==0||x==1) : x != 0) */
+/* x == (typeof x)(x != CST) -> CST == 1 ? 0 : (CST == 0 ? (x==0||x==1) : x != 1) */
+(for outer (ne eq)
+ (for inner (ne eq)
+  (simplify
+   (outer:c @0 (convert (inner @0 INTEGER_CST@1)))
+   (with {
+     bool cst1 = integer_onep (@1);
+     bool cst0 = integer_zerop (@1);
+     bool innereq = inner == EQ_EXPR;
+     bool outereq = outer == EQ_EXPR;
+    }
+   (switch
+    (if (innereq ? cst0 : cst1)
+     { constant_boolean_node (!outereq, type); })
+    (if (innereq ? cst1 : cst0)
+     (with {
+       tree utype = unsigned_type_for (TREE_TYPE (@0));
+       tree ucst1 = build_one_cst (utype);
+      }
+      (if (!outereq)
+       (gt (convert:utype @0) { ucst1; })
+       (le (convert:utype @0) { ucst1; })
+      )
+     )
+    )
+    (if (innereq)
+     (ne @0 { build_zero_cst (TREE_TYPE (@0)); }))
+    (ne @0 { build_one_cst (TREE_TYPE (@0)); }))
+   )
+  )
+ )
+)
 
 (for cmp (unordered ordered unlt unle ungt unge uneq ltgt)
  /* If the second operand is NaN, the result is constant.  */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr110293-1.c b/gcc/testsuite/gcc.dg/tree-ssa/pr110293-1.c
new file mode 100644
index 00000000000..24aea1a2d03
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr110293-1.c
@@ -0,0 +1,58 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-optimized-raw" } */
+
+_Bool eqeq0(unsigned x)
+{
+  return x == (x == 0);
+}
+_Bool eqeq1(unsigned x)
+{
+  return x == (x == 1);
+}
+_Bool eqeq2(unsigned x)
+{
+  return x == (x == 2);
+}
+
+_Bool neeq0(unsigned x)
+{
+  return x != (x == 0);
+}
+_Bool neeq1(unsigned x)
+{
+  return x != (x == 1);
+}
+_Bool neeq2(unsigned x)
+{
+  return x != (x == 2);
+}
+
+_Bool eqne0(unsigned x)
+{
+  return x == (x != 0);
+}
+_Bool eqne1(unsigned x)
+{
+  return x == (x != 1);
+}
+_Bool eqne2(unsigned x)
+{
+  return x == (x != 2);
+}
+
+_Bool nene0(unsigned x)
+{
+  return x != (x != 0);
+}
+_Bool nene1(unsigned x)
+{
+  return x != (x != 1);
+}
+_Bool nene2(unsigned x)
+{
+  return x != (x != 2);
+}
+
+/* All of these functions should have removed the inner most comparison which
+   means all of the conversions from bool to unsigned should have been removed too. */
+/* { dg-final { scan-tree-dump-not "nop_expr," "optimized"} } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr110539-1.c b/gcc/testsuite/gcc.dg/tree-ssa/pr110539-1.c
new file mode 100644
index 00000000000..6ba864cdd13
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr110539-1.c
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-optimized" } */
+int f(int a)
+{
+        int b = a & 1;
+        int c = b != 0;
+        return c == b;
+}
+
+/* This should be optimized to just return 1; */
+/* { dg-final { scan-tree-dump-not " == " "optimized"} } */
+/* { dg-final { scan-tree-dump "return 1;" "optimized"} } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr110539-2.c b/gcc/testsuite/gcc.dg/tree-ssa/pr110539-2.c
new file mode 100644
index 00000000000..17874d349ef
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr110539-2.c
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-optimized" } */
+int f(int a)
+{
+        int b = a & 1;
+        int c = b == 0;
+        return c == b;
+}
+
+/* This should be optimized to just return 0; */
+/* { dg-final { scan-tree-dump-not " == " "optimized"} } */
+/* { dg-final { scan-tree-dump "return 0;" "optimized"} } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr110539-3.c b/gcc/testsuite/gcc.dg/tree-ssa/pr110539-3.c
new file mode 100644
index 00000000000..e2bd4dfb45d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr110539-3.c
@@ -0,0 +1,75 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+void foo(void);
+static int a, c = 1;
+static short b;
+static int *d = &c, *e = &a;
+static int **f = &d;
+void __assert_fail() __attribute__((__noreturn__));
+static void g(short h) {
+    if (*d)
+        ;
+    else {
+        if (e) __assert_fail();
+        if (a) {
+            __builtin_unreachable();
+        } else
+            __assert_fail();
+    }
+    if ((((0, 0) || h) == h) + b) *f = 0;
+}
+int main() {
+    int i = 0 != 10 & a;
+    g(i);
+    *e = 9;
+    e = 0;
+    if (d == 0)
+        ;
+    else
+        foo();
+    ;
+}
+/* The call to foo should be optimized away. */
+/* The missed optimization at -O2 here was:
+        int b = a & 1;
+        int c = b != 0;
+        int d = c == b;
+  not being optimized to 1 early enough, it is done in vrp2 but
+  that is too late.
+  In phiopt2 we got:
+    _17 = i_7 != 0;
+    _12 = (int) _17;
+    if (i_7 == _12)
+      goto <bb 9>; [50.00%]
+    else
+      goto <bb 10>; [50.00%]
+
+    <bb 9> [local count: 268435456]:
+    d = 0B;
+
+    <bb 10> [local count: 536870913]:
+    e.1_3 = e;
+    *e.1_3 = 9;
+    e = 0B;
+    d.2_4 = d;
+    if (d.2_4 == 0B)
+
+  The first if is not optimized before, until vrp2 which is
+  too late as there are no passes which will then find the
+  load of d in `d.2_4 = d;` was `0B` after vrp2.
+
+  Now in forwprop3 (after phiopt2), we optimize:
+    _17 = i_7 != 0;
+    _12 = (int) _17;
+    if (i_7 == _12)
+  into just:
+    _t = (unsigned)i_7;
+    if (_t <= 1)
+
+  And then during ccp3, that is optimized away and that is optimized
+  early enough now that the load `d.2_4 = d;` is optimizd to just
+ `d.2_4 = 0B;`
+ */
+
+/* { dg-final { scan-tree-dump-not "foo \\(\\)" "optimized"} } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr110539-4.c b/gcc/testsuite/gcc.dg/tree-ssa/pr110539-4.c
new file mode 100644
index 00000000000..2c03dcc87fa
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr110539-4.c
@@ -0,0 +1,82 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fstrict-aliasing -fdump-tree-optimized" } */
+
+/* This is a small variant of pr110539-3.c using -O1 -fstrict-aliasing
+   rather than -O2. Just to show VRP and PRE is not needed to optimize
+   the call to foo away. */
+
+
+void foo(void);
+static int a, c = 1;
+static short b;
+static int *d = &c, *e = &a;
+static int **f = &d;
+void __assert_fail() __attribute__((__noreturn__));
+static void g(int h) {
+    if (*d)
+        ;
+    else {
+        if (e) __assert_fail();
+        if (a) {
+            __builtin_unreachable();
+        } else
+            __assert_fail();
+    }
+    if (((h!=0) == h) + b) *f = 0;
+}
+
+int main() {
+    int i = 0 != 10 & a;
+    g(i);
+    *e = 9;
+    e = 0;
+    if (d == 0)
+        ;
+    else
+        foo();
+    ;
+}
+
+/* The call to foo should be optimized away. */
+/* The missed optimization at -O1 here was:
+        int b = a & 1;
+        int c = b != 0;
+        int d = c == b;
+  not being optimized to 1 early enough, it is done in vrp2 but
+  that is too late.
+  In phiopt2 we got:
+    _17 = i_7 != 0;
+    _12 = (int) _17;
+    if (i_7 == _12)
+      goto <bb 9>; [50.00%]
+    else
+      goto <bb 10>; [50.00%]
+
+    <bb 9> [local count: 268435456]:
+    d = 0B;
+
+    <bb 10> [local count: 536870913]:
+    e.1_3 = e;
+    *e.1_3 = 9;
+    e = 0B;
+    d.2_4 = d;
+    if (d.2_4 == 0B)
+
+  The first if is not optimized before, until vrp2 which is
+  too late as there are no passes which will then find the
+  load of d in `d.2_4 = d;` was `0B` after vrp2.
+
+  Now in forwprop3 (after phiopt2), we optimize:
+    _17 = i_7 != 0;
+    _12 = (int) _17;
+    if (i_7 == _12)
+  into just:
+    _t = (unsigned)i_7;
+    if (_t <= 1)
+
+  And then during ccp3, that is optimized away and that is optimized
+  early enough now that the load `d.2_4 = d;` is optimizd to just
+ `d.2_4 = 0B;`
+ */
+
+/* { dg-final { scan-tree-dump-not "foo \\(\\)" "optimized"} } */
-- 
2.31.1


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