[gcc r11-7587] phiopt: Fix up conditional_replacement [PR99305]

[gcc r11-7587] phiopt: Fix up conditional_replacement [PR99305]

[Jakub Jelinek]

https://gcc.gnu.org/g:b610c30453d8e4cc88693d85a5a100d089640be5

commit r11-7587-gb610c30453d8e4cc88693d85a5a100d089640be5
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue Mar 9 19:13:11 2021 +0100

    phiopt: Fix up conditional_replacement [PR99305]
    
    Before my PR97690 changes, conditional_replacement would not set neg
    when the nonzero arg was boolean true.
    I've simplified the testing, so that it first finds the zero argument
    and then checks the other argument for all the handled cases
    (1, -1 and 1 << X, where the last case is what the patch added support for).
    But, unfortunately I've placed the integer_all_onesp test first.
    For unsigned precision 1 types such as bool integer_all_onesp, integer_onep
    and integer_pow2p can all be true and the code set neg to true in that case,
    which is undesirable.
    
    The following patch tests integer_pow2p first (which is trivially true
    for integer_onep too and tree_log2 in that case gives shift == 0)
    and only if that isn't the case, integer_all_onesp.
    
    2021-03-09  Jakub Jelinek  <jakub@redhat.com>
    
            PR tree-optimization/99305
            * tree-ssa-phiopt.c (conditional_replacement): Test integer_pow2p
            before integer_all_onesp instead of vice versa.
    
            * g++.dg/opt/pr99305.C: New test.

Diff:
---
 gcc/testsuite/g++.dg/opt/pr99305.C | 26 ++++++++++++++++++++++++++
 gcc/tree-ssa-phiopt.c              |  6 +++---
 2 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/gcc/testsuite/g++.dg/opt/pr99305.C b/gcc/testsuite/g++.dg/opt/pr99305.C
new file mode 100644
index 00000000000..8a91277e792
--- /dev/null
+++ b/gcc/testsuite/g++.dg/opt/pr99305.C
@@ -0,0 +1,26 @@
+// PR tree-optimization/99305
+// { dg-do compile }
+// { dg-options "-O3 -fno-ipa-icf -fdump-tree-optimized" }
+// { dg-final { scan-tree-dump-times " = \\\(unsigned char\\\) c_\[0-9]*\\\(D\\\);" 3 "optimized" } }
+// { dg-final { scan-tree-dump-times " = \[^\n\r]* \\+ \[0-9]*;" 3 "optimized" } }
+// { dg-final { scan-tree-dump-times " = \[^\n\r]* <= 9;" 3 "optimized" } }
+// { dg-final { scan-tree-dump-not "if \\\(c_\[0-9]*\\\(D\\\) \[!=]= 0\\\)" "optimized" } }
+// { dg-final { scan-tree-dump-not " = PHI <" "optimized" } }
+
+bool
+foo (char c)
+{
+  return c >= 48 && c <= 57;
+}
+
+bool
+bar (char c)
+{
+  return c != 0 && foo (c);
+}
+
+bool
+baz (char c)
+{
+  return c != 0 && c >= 48 && c <= 57;
+}
diff --git a/gcc/tree-ssa-phiopt.c b/gcc/tree-ssa-phiopt.c
index ddd9d531b13..aa48f447d23 100644
--- a/gcc/tree-ssa-phiopt.c
+++ b/gcc/tree-ssa-phiopt.c
@@ -808,14 +808,14 @@ conditional_replacement (basic_block cond_bb, basic_block middle_bb,
     nonzero_arg = arg0;
   else
     return false;
-  if (integer_all_onesp (nonzero_arg))
-    neg = true;
-  else if (integer_pow2p (nonzero_arg))
+  if (integer_pow2p (nonzero_arg))
     {
       shift = tree_log2 (nonzero_arg);
       if (shift && POINTER_TYPE_P (TREE_TYPE (nonzero_arg)))
 	return false;
     }
+  else if (integer_all_onesp (nonzero_arg))
+    neg = true;
   else
     return false;