phi-opt: Improve factor heurstic with constants and conversions from bool [PR116890]

Take:
```
  if (t_3(D) != 0)
    goto <bb 3>;
  else
    goto <bb 4>;

  <bb 3>
  _8 = c_4(D) != 0;
  _9 = (int) _8;

  <bb 4>
  # e_2 = PHI <_9(3), 0(2)>
```

We should factor out the conversion here as that will allow a simplfication to
`(t_3 != 0) & (c_4 != 0)`. Unlike most other types; `a ? b : CST` will simplify
for boolean result type to either `a | b` or `a & b` so allowing this conversion
for all operations will be always profitable.

Bootstrapped and tested on x86_64-linux-gnu with no regressions.

Note on the phi-opt-7.c testcase change, we are now able to optimize this
and remove the if due to the factoring out now so this is an improvement.

	PR tree-optimization/116890

gcc/ChangeLog:

	* tree-ssa-phiopt.cc (factor_out_conditional_operation): Conversions
	from bool is also should be considered as wanting to happen.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/phi-opt-7.c: Update testcase for no ifs left.
	* gcc.dg/tree-ssa/phi-opt-42.c: New test.
	* gcc.dg/tree-ssa/phi-opt-43.c: New test.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-42.c b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-42.c
new file mode 100644 (file)
index 0000000..6255694
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-42.c
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-optimized" } */
+
+/* PR tree-optimization/116890 */
+
+int f(int a, int b, int c)
+{
+  int x;
+  if (c) x = a == 0;
+  else x = 0;
+  return x;
+}
+
+
+/* The if should have been removed as the the conversion from bool to int should have been factored out.  */
+/* { dg-final { scan-tree-dump-not "if" "optimized" }  }*/
+/* { dg-final { scan-tree-dump-times "\[^\r\n\]*_\[0-9\]* = a_\[0-9\]*.D. == 0" 1 "optimized"  } } */
+/* { dg-final { scan-tree-dump-times "\[^\r\n\]*_\[0-9\]* = c_\[0-9\]*.D. != 0" 1 "optimized"  } } */
+

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-43.c b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-43.c
new file mode 100644 (file)
index 0000000..1d16f28
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-43.c
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-optimized" } */
+
+/* PR tree-optimization/116890 */
+
+int f(_Bool a, _Bool b, int c)
+{
+  int x;
+  if (c) x = a & b;
+  else x = 0;
+  return x;
+}
+
+
+/* The if should have been removed as the the conversion from bool to int should have been factored out.  */
+/* { dg-final { scan-tree-dump-not "if" "optimized" }  }*/
+/* { dg-final { scan-tree-dump-times "\[^\r\n\]*_\[0-9\]* = a_\[0-9\]*.D. & b_\[0-9\]*.D." 1 "optimized"  } } */
+/* { dg-final { scan-tree-dump-times "\[^\r\n\]*_\[0-9\]* = c_\[0-9\]*.D. != 0" 1 "optimized"  } } */
+

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-7.c b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-7.c
index 51e1f6dfa75526200e7ec90411d903971e8ad32e..3ee43e55692ec0c238f63c7e7ef8409864443a1b 100644 (file)
--- a/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-7.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/phi-opt-7.c
@@ -15,8 +15,8 @@ int f(int t, int c)
   return g(d,e);
 }
 
-/* There should be one ifs as one of them should be changed into
-   a conditional and the other should be there still.  */
-/* { dg-final { scan-tree-dump-times "if" 1 "optimized" }  }*/
+/* There should be no ifs as this is converted into `(t != 0) & (c != 0)`.
+/* { dg-final { scan-tree-dump-not "if" "optimized" }  }*/
 /* { dg-final { scan-tree-dump-times "\[^\r\n\]*_\[0-9\]* = c_\[0-9\]*.D. != 0" 1 "optimized"  } } */
+/* { dg-final { scan-tree-dump-times "\[^\r\n\]*_\[0-9\]* = t_\[0-9\]*.D. != 0" 1 "optimized"  } } */
 

diff --git a/gcc/tree-ssa-phiopt.cc b/gcc/tree-ssa-phiopt.cc
index d43832b390babc133835d06a6029045127817f36..bd7f9607eb9a37f773a0e4fa3f57e5fa9679f19b 100644 (file)
--- a/gcc/tree-ssa-phiopt.cc
+++ b/gcc/tree-ssa-phiopt.cc
@@ -345,9 +345,17 @@ factor_out_conditional_operation (edge e0, edge e1, gphi *phi,
              if (gassign *assign = dyn_cast <gassign *> (stmt))
                {
                  tree lhs = gimple_assign_lhs (assign);
+                 tree lhst = TREE_TYPE (lhs);
                  enum tree_code ass_code
                    = gimple_assign_rhs_code (assign);
-                 if (ass_code != MAX_EXPR && ass_code != MIN_EXPR)
+                 if (ass_code != MAX_EXPR && ass_code != MIN_EXPR
+                     /* Conversions from boolean like types is ok
+                        as `a?1:b` and `a?0:b` will always simplify
+                        to `a & b` or `a | b`.
+                        See PR 116890.  */
+                     && !(INTEGRAL_TYPE_P (lhst)
+                          && TYPE_UNSIGNED (lhst)
+                          && TYPE_PRECISION (lhst) == 1))
                    return NULL;
                  if (lhs != gimple_assign_rhs1 (arg0_def_stmt))
                    return NULL;