Re: [PATCH] phiopt: Fix up conditional_replacement [PR99305]

[Richard Biener <rguenther@suse.de>]

On March 9, 2021 4:40:22 PM GMT+01:00, Jakub Jelinek <jakub@redhat.com> wrote:
>Hi!
>
>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.
>
>Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

Ok. 

Richard. 

>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.
>
>--- gcc/tree-ssa-phiopt.c.jj	2021-01-22 11:41:38.078708425 +0100
>+++ gcc/tree-ssa-phiopt.c	2021-03-09 13:15:02.649094949 +0100
>@@ -808,14 +808,14 @@ conditional_replacement (basic_block con
>     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;
> 
>--- gcc/testsuite/g++.dg/opt/pr99305.C.jj	2021-03-09 13:39:11.040957563
>+0100
>+++ gcc/testsuite/g++.dg/opt/pr99305.C	2021-03-09 13:39:44.063589691
>+0100
>@@ -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;
>+}
>
>	Jakub