[gcc r12-2138] match.pd: Relax rule to include POLY_INT_CSTs

[gcc r12-2138] match.pd: Relax rule to include POLY_INT_CSTs

[Richard Sandiford]

https://gcc.gnu.org/g:298b0db76dfcc82427d987fbbd239afcb0c3dbfd

commit r12-2138-g298b0db76dfcc82427d987fbbd239afcb0c3dbfd
Author: Richard Sandiford <richard.sandiford@arm.com>
Date:   Thu Jul 8 12:49:44 2021 +0100

    match.pd: Relax rule to include POLY_INT_CSTs
    
    match.pd has a rule to simplify an extension, operation and truncation
    back to the original type:
    
     (simplify
       (convert (op:s@0 (convert1?@3 @1) (convert2?@4 @2)))
    
    Currently it handles cases in which @2 is an INTEGER_CST, but it
    also works for POLY_INT_CSTs.[*]
    
    For INTEGER_CST it doesn't matter whether we test @2 or @4,
    but for POLY_INT_CST it is possible to have unfolded (convert …)s.
    
    Originally I saw this leading to some bad ivopts decisions, because
    we weren't folding away redundancies from candidate iv expressions.
    It's also possible to test the fold directly using the SVE ACLE.
    
    [*] Not all INTEGER_CST rules work for POLY_INT_CSTs, since extensions
        don't necessarily distribute over the internals of the POLY_INT_CST.
        But in this case that isn't an issue.
    
    gcc/
            * match.pd: Simplify an extend-operate-truncate sequence involving
            a POLY_INT_CST.
    
    gcc/testsuite/
            * gcc.target/aarch64/sve/acle/general/cntb_1.c: New test.

Diff:
---
 gcc/match.pd                                               |  2 +-
 gcc/testsuite/gcc.target/aarch64/sve/acle/general/cntb_1.c | 14 ++++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/gcc/match.pd b/gcc/match.pd
index 334e8cc0496..30680d488ab 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -6175,7 +6175,7 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 	&& (types_match (@1, @2)
 	    /* Or the second operand is const integer or converted const
 	       integer from valueize.  */
-	    || TREE_CODE (@2) == INTEGER_CST))
+	    || poly_int_tree_p (@4)))
      (if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (@1)))
        (op @1 (convert @2))
        (with { tree utype = unsigned_type_for (TREE_TYPE (@1)); }
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/acle/general/cntb_1.c b/gcc/testsuite/gcc.target/aarch64/sve/acle/general/cntb_1.c
new file mode 100644
index 00000000000..b43fcf0ed6d
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/sve/acle/general/cntb_1.c
@@ -0,0 +1,14 @@
+/* { dg-options "-O -fdump-tree-optimized" } */
+
+#include <arm_sve.h>
+
+unsigned int
+foo (unsigned int x)
+{
+  unsigned long tmp = x;
+  tmp += svcntb ();
+  x = tmp;
+  return x - svcntb ();
+}
+
+/* { dg-final { scan-tree-dump-not { POLY_INT_CST } optimized } } */