After discussion (https://gcc.gnu.org/ml/gcc-patches/2016-09/msg00718.html)
here is the latest version of the strchr patch. This uses a gimple statement
for
the pointer addition so the gsi_prev always points at the strlen call.
Optimize strchr (s, 0) to s + strlen (s). strchr (s, 0) appears a common
idiom for finding the end of a string, however it is not a very efficient
way of doing so. Strlen is a much simpler operation which is significantly
faster (eg. on x86 strlen is 50% faster for strings of 8 bytes and about
twice as fast as strchr on strings of 1KB).
OK for commit?
ChangeLog:
2016-09-23 Wilco Dijkstra <wdijk...@arm.com>
gcc/
* gcc/gimple-fold.c (gimple_fold_builtin_strchr):
New function to optimize strchr (s, 0) to strlen.
(gimple_fold_builtin): Add BUILT_IN_STRCHR case.
testsuite/
* gcc/testsuite/gcc.dg/strlenopt-20.c: Update test.
* gcc/testsuite/gcc.dg/strlenopt-21.c: Likewise.
* gcc/testsuite/gcc.dg/strlenopt-22.c: Likewise.
* gcc/testsuite/gcc.dg/strlenopt-22g.c: Likewise.
* gcc/testsuite/gcc.dg/strlenopt-26.c: Likewise.
* gcc/testsuite/gcc.dg/strlenopt-5.c: Likewise.
* gcc/testsuite/gcc.dg/strlenopt-7.c: Likewise.
* gcc/testsuite/gcc.dg/strlenopt-9.c: Likewise.
--
diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c
index
addabb745efc73465f313d1d591aea383f7f4a13..ddf4cf0ae68ef6708377fdb1a2b45575d90da799
100644
--- a/gcc/gimple-fold.c
+++ b/gcc/gimple-fold.c
@@ -1457,6 +1457,55 @@ gimple_fold_builtin_strncpy (gimple_stmt_iterator *gsi,
return true;
}
+/* Simplify strchr (str, 0) into str + strlen (str).
+ In general strlen is significantly faster than strchr
+ due to being a simpler operation. */
+static bool
+gimple_fold_builtin_strchr (gimple_stmt_iterator *gsi)
+{
+ gimple *stmt = gsi_stmt (*gsi);
+ tree str = gimple_call_arg (stmt, 0);
+ tree c = gimple_call_arg (stmt, 1);
+ location_t loc = gimple_location (stmt);
+
+ if (optimize_function_for_size_p (cfun))
+ return false;
+
+ if (!integer_zerop (c) || !gimple_call_lhs (stmt))
+ return false;
+
+ tree len;
+ tree strlen_fn = builtin_decl_implicit (BUILT_IN_STRLEN);
+
+ if (!strlen_fn)
+ return false;
+
+ /* Create newstr = strlen (str). */
+ gimple_seq stmts = NULL;
+ gimple *new_stmt = gimple_build_call (strlen_fn, 1, str);
+ gimple_set_location (new_stmt, loc);
+ if (gimple_in_ssa_p (cfun))
+ len = make_ssa_name (size_type_node);
+ else
+ len = create_tmp_reg (size_type_node);
+ gimple_call_set_lhs (new_stmt, len);
+ gimple_seq_add_stmt_without_update (&stmts, new_stmt);
+
+ /* Create (str p+ strlen (str)). */
+ new_stmt = gimple_build_assign (gimple_call_lhs (stmt),
+ POINTER_PLUS_EXPR, str, len);
+ gimple_seq_add_stmt_without_update (&stmts, new_stmt);
+ gsi_replace_with_seq_vops (gsi, stmts);
+ /* gsi now points at the assignment to the lhs, get a
+ stmt iterator to the strlen.
+ ??? We can't use gsi_for_stmt as that doesn't work when the
+ CFG isn't built yet. */
+ gimple_stmt_iterator gsi2 = *gsi;
+ gsi_prev (&gsi2);
+ fold_stmt (&gsi2);
+ return true;
+}
+
/* Simplify a call to the strcat builtin. DST and SRC are the arguments
to the call.
@@ -2898,6 +2947,8 @@ gimple_fold_builtin (gimple_stmt_iterator *gsi)
gimple_call_arg (stmt, 1));
case BUILT_IN_STRNCAT:
return gimple_fold_builtin_strncat (gsi);
+ case BUILT_IN_STRCHR:
+ return gimple_fold_builtin_strchr (gsi);
case BUILT_IN_FPUTS:
return gimple_fold_builtin_fputs (gsi, gimple_call_arg (stmt, 0),
gimple_call_arg (stmt, 1), false);
diff --git a/gcc/testsuite/gcc.dg/strlenopt-20.c
b/gcc/testsuite/gcc.dg/strlenopt-20.c
index
a83e845c26d88e5acdcabf142f7b319136663488..7b483eaeac1aa47278111a92148a16f00b2aaa2d
100644
--- a/gcc/testsuite/gcc.dg/strlenopt-20.c
+++ b/gcc/testsuite/gcc.dg/strlenopt-20.c
@@ -86,9 +86,9 @@ main ()
return 0;
}
-/* { dg-final { scan-tree-dump-times "strlen \\(" 1 "strlen" } } */
+/* { dg-final { scan-tree-dump-times "strlen \\(" 2 "strlen" } } */
/* { dg-final { scan-tree-dump-times "memcpy \\(" 4 "strlen" } } */
/* { dg-final { scan-tree-dump-times "strcpy \\(" 0 "strlen" } } */
/* { dg-final { scan-tree-dump-times "strcat \\(" 0 "strlen" } } */
-/* { dg-final { scan-tree-dump-times "strchr \\(" 1 "strlen" } } */
+/* { dg-final { scan-tree-dump-times "strchr \\(" 0 "strlen" } } */
/* { dg-final { scan-tree-dump-times "stpcpy \\(" 0 "strlen" } } */
diff --git a/gcc/testsuite/gcc.dg/strlenopt-21.c
b/gcc/testsuite/gcc.dg/strlenopt-21.c
index
e22fa9fca9ba14354db2cd5f602283b64bd8dcac..05b85a49dde0a7f5d269174fd4269e40be910dbd
100644
--- a/gcc/testsuite/gcc.dg/strlenopt-21.c
+++ b/gcc/testsuite/gcc.dg/strlenopt-21.c
@@ -57,9 +57,9 @@ main ()
return 0;
}
-/* { dg-final { scan-tree-dump-times "strlen \\(" 1 "strlen" } } */
+/* { dg-final { scan-tree-dump-times "strlen \\(" 2 "strlen" } } */
/* { dg-final { scan-tree-dump-times "memcpy \\(" 3 "strlen" } } */
/* { dg-final { scan-tree-dump-times "strcpy \\(" 0 "strlen" } } */
/* { dg-final { scan-tree-dump-times "strcat \\(" 0 "strlen" } } */
-/* { dg-final { scan-tree-dump-times "strchr \\(" 1 "strlen" } } */
+/* { dg-final { scan-tree-dump-times "strchr \\(" 0 "strlen" } } */
/* { dg-final { scan-tree-dump-times "stpcpy \\(" 0 "strlen" } } */
diff --git a/gcc/testsuite/gcc.dg/strlenopt-22.c
b/gcc/testsuite/gcc.dg/strlenopt-22.c
index
aa55f5ebd6a2d4803ee9a7fd60fc538d86f47124..b4ef772f0e59252f10a5419ede6837b3c8ca8265
100644
--- a/gcc/testsuite/gcc.dg/strlenopt-22.c
+++ b/gcc/testsuite/gcc.dg/strlenopt-22.c
@@ -31,9 +31,9 @@ main ()
return 0;
}
-/* { dg-final { scan-tree-dump-times "strlen \\(" 3 "strlen" } } */
+/* { dg-final { scan-tree-dump-times "strlen \\(" 4 "strlen" } } */
/* { dg-final { scan-tree-dump-times "memcpy \\(" 1 "strlen" } } */
/* { dg-final { scan-tree-dump-times "strcpy \\(" 1 "strlen" } } */
/* { dg-final { scan-tree-dump-times "strcat \\(" 0 "strlen" } } */
-/* { dg-final { scan-tree-dump-times "strchr \\(" 1 "strlen" } } */
+/* { dg-final { scan-tree-dump-times "strchr \\(" 0 "strlen" } } */
/* { dg-final { scan-tree-dump-times "stpcpy \\(" 0 "strlen" } } */
diff --git a/gcc/testsuite/gcc.dg/strlenopt-22g.c
b/gcc/testsuite/gcc.dg/strlenopt-22g.c
index
3e2f8c4633939a0b5ff667fb3671e11cde8fe6ed..9c5d020588f3f338a9acf51d36facfea55810760
100644
--- a/gcc/testsuite/gcc.dg/strlenopt-22g.c
+++ b/gcc/testsuite/gcc.dg/strlenopt-22g.c
@@ -5,9 +5,9 @@
#define USE_GNU
#include "strlenopt-22.c"
-/* { dg-final { scan-tree-dump-times "strlen \\(" 0 "strlen" } } */
+/* { dg-final { scan-tree-dump-times "strlen \\(" 1 "strlen" } } */
/* { dg-final { scan-tree-dump-times "memcpy \\(" 1 "strlen" } } */
/* { dg-final { scan-tree-dump-times "strcpy \\(" 0 "strlen" } } */
/* { dg-final { scan-tree-dump-times "strcat \\(" 0 "strlen" } } */
-/* { dg-final { scan-tree-dump-times "strchr \\(" 1 "strlen" } } */
+/* { dg-final { scan-tree-dump-times "strchr \\(" 0 "strlen" } } */
/* { dg-final { scan-tree-dump-times "stpcpy \\(" 1 "strlen" } } */
diff --git a/gcc/testsuite/gcc.dg/strlenopt-26.c
b/gcc/testsuite/gcc.dg/strlenopt-26.c
index
4bd54bef540806ca90d2b9bcfc33eb531991c967..da2f465a5b5003fa5dca05f3a6ee00e97b98b5dd
100644
--- a/gcc/testsuite/gcc.dg/strlenopt-26.c
+++ b/gcc/testsuite/gcc.dg/strlenopt-26.c
@@ -21,4 +21,5 @@ main (void)
return 0;
}
-/* { dg-final { scan-tree-dump-times "strlen \\(" 1 "strlen" } } */
+/* { dg-final { scan-tree-dump-times "strlen \\(" 2 "strlen" } } */
+/* { dg-final { scan-tree-dump-times "strchr \\(" 0 "strlen" } } */
diff --git a/gcc/testsuite/gcc.dg/strlenopt-5.c
b/gcc/testsuite/gcc.dg/strlenopt-5.c
index
1b006a93045599a75bdb10a39e86ffa59b475c83..a24aea44e8b00ff7b35a907aaa941b4c509642c4
100644
--- a/gcc/testsuite/gcc.dg/strlenopt-5.c
+++ b/gcc/testsuite/gcc.dg/strlenopt-5.c
@@ -48,9 +48,9 @@ main ()
return 0;
}
-/* { dg-final { scan-tree-dump-times "strlen \\(" 0 "strlen" } } */
+/* { dg-final { scan-tree-dump-times "strlen \\(" 2 "strlen" } } */
/* { dg-final { scan-tree-dump-times "memcpy \\(" 2 "strlen" } } */
/* { dg-final { scan-tree-dump-times "strcpy \\(" 1 "strlen" } } */
/* { dg-final { scan-tree-dump-times "strcat \\(" 0 "strlen" } } */
-/* { dg-final { scan-tree-dump-times "strchr \\(" 2 "strlen" } } */
+/* { dg-final { scan-tree-dump-times "strchr \\(" 0 "strlen" } } */
/* { dg-final { scan-tree-dump-times "stpcpy \\(" 0 "strlen" } } */
diff --git a/gcc/testsuite/gcc.dg/strlenopt-7.c
b/gcc/testsuite/gcc.dg/strlenopt-7.c
index
3ae1e2cb3f0d08c8b05107c4e65b67bdb39cf7ab..aa53d7e75254dfe56c93172afc49f95e5b7901e6
100644
--- a/gcc/testsuite/gcc.dg/strlenopt-7.c
+++ b/gcc/testsuite/gcc.dg/strlenopt-7.c
@@ -40,11 +40,11 @@ main ()
return 0;
}
-/* { dg-final { scan-tree-dump-times "strlen \\(" 0 "strlen" } } */
+/* { dg-final { scan-tree-dump-times "strlen \\(" 1 "strlen" } } */
/* { dg-final { scan-tree-dump-times "memcpy \\(" 2 "strlen" } } */
/* { dg-final { scan-tree-dump-times "strcpy \\(" 0 "strlen" } } */
/* { dg-final { scan-tree-dump-times "strcat \\(" 0 "strlen" } } */
-/* { dg-final { scan-tree-dump-times "strchr \\(" 1 "strlen" } } */
+/* { dg-final { scan-tree-dump-times "strchr \\(" 0 "strlen" } } */
/* { dg-final { scan-tree-dump-times "stpcpy \\(" 0 "strlen" } } */
/* { dg-final { scan-tree-dump-times "\\*r_\[0-9\]* = 0;" 1 "strlen" } } */
/* { dg-final { scan-tree-dump-times "return 3;" 1 "optimized" } } */
diff --git a/gcc/testsuite/gcc.dg/strlenopt-9.c
b/gcc/testsuite/gcc.dg/strlenopt-9.c
index
f78defe6287cee9e9ed4779c70675e91c6541d40..e8ff1023d71268e2067993189d5f62eab37a16e5
100644
--- a/gcc/testsuite/gcc.dg/strlenopt-9.c
+++ b/gcc/testsuite/gcc.dg/strlenopt-9.c
@@ -98,10 +98,10 @@ main ()
return 0;
}
-/* { dg-final { scan-tree-dump-times "strlen \\(" 3 "strlen" } } */
+/* { dg-final { scan-tree-dump-times "strlen \\(" 5 "strlen" } } */
/* { dg-final { scan-tree-dump-times "memcpy \\(" 6 "strlen" } } */
/* { dg-final { scan-tree-dump-times "strcpy \\(" 1 "strlen" } } */
/* { dg-final { scan-tree-dump-times "strcat \\(" 0 "strlen" } } */
-/* { dg-final { scan-tree-dump-times "strchr \\(" 3 "strlen" } } */
+/* { dg-final { scan-tree-dump-times "strchr \\(" 0 "strlen" } } */
/* { dg-final { scan-tree-dump-times "stpcpy \\(" 0 "strlen" } } */
/* { dg-final { scan-tree-dump-times "return 4;" 1 "optimized" } } */
