RE: [PATCH] [PHIOPT] Add A ? B + CST : B match and simplify optimizations

[Zhongyunde <zhongyunde@huawei.com>]

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> -----Original Message-----
> From: Andrew Pinski [mailto:pinskia@gcc.gnu.org]
> Sent: Saturday, November 5, 2022 2:34 PM
> To: Zhongyunde <zhongyunde@huawei.com>
> Cc: hongtao.liu@intel.com; gcc-patches@gcc.gnu.org; Zhangwen(Esan)
> <zwzhangwen.zhang@huawei.com>; Weiwei (weiwei, Compiler)
> <weiwei64@huawei.com>; zhong_1985624@163.com
> Subject: Re: [PATCH] [PHIOPT] Add A ? B + CST : B match and simplify
> optimizations
> 
> On Fri, Nov 4, 2022 at 11:17 PM Zhongyunde <zhongyunde@huawei.com>
> wrote:
> >
> > hi,
> >   This patch is try to fix the issue
> > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107190,
> > would you like to give me some suggestion, thanks.
> 
> This seems like a "simplified" version of
> https://gcc.gnu.org/pipermail/gcc-patches/2021-November/584411.html
> which just handles power of 2 constants where we know the cond will be
> removed.
> We could do even more "simplified" of 1 if needed really.
> What is the IR before PHI-OPT? Is it just + 1?

Thanks for your attention. It is + 4294967296 before PHI-OPT  (See detail https://gcc.godbolt.org/z/6zEc6ja1z)
So we should keep matching the power of 2 constants ?

> Also your pattern can be simplified to use integer_pow2p in the match part
> instead of INTEGER_CST.
> 
Apply your comment, thanks

> Thanks,
> Andrew



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From 1dfbda734390d8398a12a455028149b058076a51 Mon Sep 17 00:00:00 2001
From: zhongyunde <zhongyunde@huawei.com>
Date: Sat, 5 Nov 2022 13:22:33 +0800
Subject: [PATCH] [PHIOPT] Add A ? B op CST : B match and simplify
 optimizations

    Refer to commit b6bdd7a4, use pattern match to simple
    A ? B op CST : B (where CST is power of 2) simplifications.
    Fixes https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107190

    gcc/
            * match.pd (A ? B op CST : B): Add simplifcations for A ? B op POW2 : B

    gcc/testsuite/
            * gcc.dg/pr107190.c: New test.
---
 gcc/match.pd                    | 21 +++++++++++++++++++++
 gcc/testsuite/gcc.dg/pr107190.c | 27 +++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/pr107190.c

diff --git a/gcc/match.pd b/gcc/match.pd
index 194ba8f5188..7ff393f371f 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -4503,6 +4503,27 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
       && INTEGRAL_TYPE_P (TREE_TYPE (@0)))
   (cond @1 (convert @2) (convert @3))))
 
+#if GIMPLE
+(if (canonicalize_math_p ())
+/* These patterns are mostly used by PHIOPT to move some operations outside of
+   the if statements. They should be done late because it gives jump threading
+   and few other passes to reduce what is going on.  */
+/* a ? x op C : x -> x op << log2(C) when C is power of 2. */
+ (for op (plus minus bit_ior bit_xor lshift rshift lrotate rrotate)
+  (simplify
+   (cond @0 (op:s @1 integer_pow2p@2) @1)
+    /* powerof2cst */
+   (if (INTEGRAL_TYPE_P (type))
+    (with {
+      tree shift = build_int_cst (integer_type_node, tree_log2 (@2));
+     }
+     (op @1 (lshift (convert (convert:boolean_type_node @0)) { shift; })))
+   )
+  )
+ )
+)
+#endif
+
 /* Simplification moved from fold_cond_expr_with_comparison.  It may also
    be extended.  */
 /* This pattern implements two kinds simplification:
diff --git a/gcc/testsuite/gcc.dg/pr107190.c b/gcc/testsuite/gcc.dg/pr107190.c
new file mode 100644
index 00000000000..235b2761a02
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr107190.c
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fexpensive-optimizations -fdump-tree-phiopt2-details" } */
+
+#  define BN_BITS4        32
+#  define BN_MASK2        (0xffffffffffffffffL)
+#  define BN_MASK2l       (0xffffffffL)
+#  define BN_MASK2h       (0xffffffff00000000L)
+#  define BN_MASK2h1      (0xffffffff80000000L)
+#  define LBITS(a)        ((a)&BN_MASK2l)
+#  define HBITS(a)        (((a)>>BN_BITS4)&BN_MASK2l)
+#  define L2HBITS(a)      (((a)<<BN_BITS4)&BN_MASK2)
+
+unsigned int test_m(unsigned long in0, unsigned long in1) {
+    unsigned long m, m1, lt, ht, bl, bh;
+    lt = LBITS(in0);
+    ht = HBITS(in0);
+    bl = LBITS(in1);
+    bh = HBITS(in1);
+    m  = bh * lt;
+    m1 = bl * ht;
+    ht = bh * ht;
+    m  = (m + m1) & BN_MASK2;
+    if (m < m1) ht += L2HBITS((unsigned long)1);
+    return ht + m;
+}
+
+/* { dg-final { scan-tree-dump "COND_EXPR in block 2 and PHI in block 4 converted to straightline code" "phiopt2" } } */
-- 
2.19.1