[PATCH] Fix tree-optimization/103220: Another missing folding of (type) X op CST where type is a nop convert

apinski@marvell.com apinski@marvell.com
Sat Nov 20 06:03:02 GMT 2021


From: Andrew Pinski <apinski@marvell.com>

The problem here is that int_fits_type_p will return false if we just
change the sign of things like -2 (or 254) so we should accept the case
where we just change the sign (and not the precision) of the type.

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

	PR tree-optimization/103220

gcc/ChangeLog:

	* match.pd ((type) X bitop CST): Don't check if CST
	fits into the type if only the sign changes.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/pr103220-1.c: New test.
	* gcc.dg/tree-ssa/pr103220-2.c: New test.
	* gcc.dg/pr25530.c: Update test to check for
	4294967294 in the case -2 is not matched.
---
 gcc/match.pd                               |  3 ++-
 gcc/testsuite/gcc.dg/pr25530.c             |  2 +-
 gcc/testsuite/gcc.dg/tree-ssa/pr103220-1.c | 15 +++++++++++++++
 gcc/testsuite/gcc.dg/tree-ssa/pr103220-2.c | 16 ++++++++++++++++
 4 files changed, 34 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr103220-1.c
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr103220-2.c

diff --git a/gcc/match.pd b/gcc/match.pd
index 24a84e3b504..37c5be9e5f4 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -1607,7 +1607,8 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
   (bitop (convert@2 @0) (convert?@3 @1))
   (if (((TREE_CODE (@1) == INTEGER_CST
 	 && INTEGRAL_TYPE_P (TREE_TYPE (@0))
-	 && int_fits_type_p (@1, TREE_TYPE (@0)))
+	 && (int_fits_type_p (@1, TREE_TYPE (@0))
+	     || tree_nop_conversion_p (TREE_TYPE (@0), type)))
 	|| types_match (@0, @1))
        /* ???  This transform conflicts with fold-const.c doing
 	  Convert (T)(x & c) into (T)x & (T)c, if c is an integer
diff --git a/gcc/testsuite/gcc.dg/pr25530.c b/gcc/testsuite/gcc.dg/pr25530.c
index b846ab30140..771b36b9c29 100644
--- a/gcc/testsuite/gcc.dg/pr25530.c
+++ b/gcc/testsuite/gcc.dg/pr25530.c
@@ -8,4 +8,4 @@ f (unsigned t)
   return (t / 2) * 2;
 }
 
-/* { dg-final { scan-tree-dump "\& -2" "optimized" } } */
+/* { dg-final { scan-tree-dump "\& -2|4294967294" "optimized" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr103220-1.c b/gcc/testsuite/gcc.dg/tree-ssa/pr103220-1.c
new file mode 100644
index 00000000000..f2ef3f1d93c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr103220-1.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+unsigned char f(unsigned char a)
+{
+  signed char d = (signed char) a;
+  signed char e = d & ~1;
+  unsigned char t = e;
+  t &= ~2;
+  return t;
+}
+/* The above should reduce down to just & 252 rather than keping
+   the two &s there. */
+/* { dg-final { scan-tree-dump-times "& 252" 1 "optimized"} } */
+/* { dg-final { scan-tree-dump-times "& -2" 0 "optimized"} } */
+/* { dg-final { scan-tree-dump-times "& 253" 0 "optimized"} } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr103220-2.c b/gcc/testsuite/gcc.dg/tree-ssa/pr103220-2.c
new file mode 100644
index 00000000000..25d7412a095
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr103220-2.c
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+signed char f(unsigned char a)
+{
+  unsigned char b = a & 127;
+  signed char c = (signed char) b;
+  signed char d = (signed char) a;
+  signed char e = d & -128;
+  signed char h = c | e;
+  return h;
+}
+/* The above should reduce down to just return with a cast.
+   removing the two &s there and |'s. */
+/* { dg-final { scan-tree-dump-times "& 127" 0 "optimized"} } */
+/* { dg-final { scan-tree-dump-times "& -128" 0 "optimized"} } */
+/* { dg-final { scan-tree-dump-times "\\\| " 0 "optimized"} } */
-- 
2.17.1



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