Add a rule (T)(A) +- (T)(B) -> (T)(A +- B), which works only when (A +- B)
could be folded to a simple value. By this rule, a plusminus-mult-with-convert
expression could be handed over to the rule (A * C) +- (B * C) -> (A +- B).
Bootstrapped/regtested on x86_64-linux and aarch64-linux.
Feng
---
2020-09-15 Feng Xue <f...@os.amperecomputing.com>
gcc/
PR tree-optimization/94234
* match.pd (T)(A) +- (T)(B) -> (T)(A +- B): New simplification.
gcc/testsuite/
PR tree-optimization/94234
* gcc.dg/pr94234-3.c: New test.From f7c7483bd61fe1e3d6888f84d718fb4be4ea9e14 Mon Sep 17 00:00:00 2001
From: Feng Xue <f...@os.amperecomputing.com>
Date: Mon, 17 Aug 2020 23:00:35 +0800
Subject: [PATCH] tree-optimization/94234 - add plusminus-with-convert pattern
Add a rule (T)(A) +- (T)(B) -> (T)(A +- B), which works only when (A +- B)
could be folded to a simple value. By this rule, a plusminus-mult-with-convert
expression could be handed over to the rule (A * C) +- (B * C) -> (A +- B).
2020-09-15 Feng Xue <f...@os.amperecomputing.com>
gcc/
PR tree-optimization/94234
* match.pd (T)(A) +- (T)(B) -> (T)(A +- B): New simplification.
gcc/testsuite/
PR tree-optimization/94234
* gcc.dg/pr94234-3.c: New test.
---
gcc/match.pd | 16 ++++++++++++
gcc/testsuite/gcc.dg/pr94234-3.c | 42 ++++++++++++++++++++++++++++++++
2 files changed, 58 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/pr94234-3.c
diff --git a/gcc/match.pd b/gcc/match.pd
index 46fd880bd37..d8c59fad9c1 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -2397,6 +2397,22 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(plus (convert @0) (op @2 (convert @1))))))
#endif
+/* (T)(A) +- (T)(B) -> (T)(A +- B) only when (A +- B) could be simplified
+ to a simple value. */
+#if GIMPLE
+ (for op (plus minus)
+ (simplify
+ (op (convert @0) (convert @1))
+ (if (TREE_CODE (type) == INTEGER_TYPE
+ && TREE_CODE (TREE_TYPE (@0)) == INTEGER_TYPE
+ && TREE_CODE (TREE_TYPE (@1)) == INTEGER_TYPE
+ && TYPE_PRECISION (type) <= TYPE_PRECISION (TREE_TYPE (@0))
+ && types_match (TREE_TYPE (@0), TREE_TYPE (@1))
+ && !TYPE_OVERFLOW_TRAPS (type)
+ && !TYPE_OVERFLOW_SANITIZED (type))
+ (convert (op! @0 @1)))))
+#endif
+
/* ~A + A -> -1 */
(simplify
(plus:c (bit_not @0) @0)
diff --git a/gcc/testsuite/gcc.dg/pr94234-3.c b/gcc/testsuite/gcc.dg/pr94234-3.c
new file mode 100644
index 00000000000..9bb9b46bd96
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr94234-3.c
@@ -0,0 +1,42 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-forwprop1" } */
+
+typedef __SIZE_TYPE__ size_t;
+typedef __PTRDIFF_TYPE__ ptrdiff_t;
+
+ptrdiff_t foo1 (char *a, size_t n)
+{
+ char *b1 = a + 8 * n;
+ char *b2 = a + 8 * (n - 1);
+
+ return b1 - b2;
+}
+
+int use_ptr (char *a, char *b);
+
+ptrdiff_t foo2 (char *a, size_t n)
+{
+ char *b1 = a + 8 * (n - 1);
+ char *b2 = a + 8 * n;
+
+ use_ptr (b1, b2);
+
+ return b1 - b2;
+}
+
+int use_int (int i);
+
+unsigned goo (unsigned m_param, unsigned n_param)
+{
+ unsigned b1 = m_param * (n_param + 2);
+ unsigned b2 = m_param * (n_param + 1);
+ int r = (int)(b1) - (int)(b2);
+
+ use_int (r);
+
+ return r;
+}
+
+/* { dg-final { scan-tree-dump-times "return 8;" 1 "forwprop1" } } */
+/* { dg-final { scan-tree-dump-times "return -8;" 1 "forwprop1" } } */
+/* { dg-final { scan-tree-dump-times "return m_param" 1 "forwprop1" } } */
--
2.17.1
