diff mbox

Add -Wdisabled-optimization to loop prefetching pass (PR, tree-optimization/79803).

Message ID 1353c891-50d9-5965-f989-da8724fae246@suse.cz
State New
Headers show

Commit Message

Martin Liška March 2, 2017, 5:48 p.m. UTC 
Hello.

I've just followed Richi's advises in the PR.

Patch can bootstrap on ppc64le-redhat-linux and survives regression tests.

Ready to be installed?
Martin

Comments

Richard Biener March 3, 2017, 10:57 a.m. UTC | #1 
On Thu, Mar 2, 2017 at 6:48 PM, Martin Liška <mliska@suse.cz> wrote:
> Hello.
>
> I've just followed Richi's advises in the PR.
>
> Patch can bootstrap on ppc64le-redhat-linux and survives regression tests.
>
> Ready to be installed?

I think the check tests for power-of two, not even.  Also you should mention
this is a --param, otherwise people might think their CPU is broken ;)

Ok otherwise.

Thanks,
Richard.

> Martin
Richard Biener March 3, 2017, 10:57 a.m. UTC | #2 
On Fri, Mar 3, 2017 at 11:57 AM, Richard Biener
<richard.guenther@gmail.com> wrote:
> On Thu, Mar 2, 2017 at 6:48 PM, Martin Liška <mliska@suse.cz> wrote:
>> Hello.
>>
>> I've just followed Richi's advises in the PR.
>>
>> Patch can bootstrap on ppc64le-redhat-linux and survives regression tests.
>>
>> Ready to be installed?
>
> I think the check tests for power-of two, not even.  Also you should mention
> this is a --param, otherwise people might think their CPU is broken ;)
>
> Ok otherwise.

Oh, and maybe only warn once, not for each function...

>
> Thanks,
> Richard.
>
>> Martin
diff mbox

Patch

From 9a850909d00e2b63961167665d48f7ebbb99ac84 Mon Sep 17 00:00:00 2001
From: marxin <mliska@suse.cz>
Date: Thu, 2 Mar 2017 13:34:55 +0100
Subject: [PATCH] Add -Wdisabled-optimization to loop prefetching pass (PR
 tree-optimization/79803).

gcc/ChangeLog:

2017-03-02  Martin Liska  <mliska@suse.cz>

	PR tree-optimization/79803
	* tree-ssa-loop-prefetch.c (tree_ssa_prefetch_arrays): Remove
	assert.
	(pass_loop_prefetch::execute): Disabled optimization if an
	assumption about L1 cache size is not met.

gcc/testsuite/ChangeLog:

2017-03-02  Martin Liska  <mliska@suse.cz>

	PR tree-optimization/79803
	* gcc.dg/tree-ssa/pr79803.c: New test.
---
 gcc/testsuite/gcc.dg/tree-ssa/pr79803.c | 39 +++++++++++++++++++++++++++++++++
 gcc/tree-ssa-loop-prefetch.c            | 13 +++++++----
 2 files changed, 48 insertions(+), 4 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr79803.c

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr79803.c b/gcc/testsuite/gcc.dg/tree-ssa/pr79803.c
new file mode 100644
index 00000000000..e43a40739d5
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr79803.c
@@ -0,0 +1,39 @@ 
+/* { dg-do compile { target { x86_64-*-* } } } */
+/* { dg-options "-march=opteron-sse3 -Ofast --param l1-cache-line-size=3 -Wdisabled-optimization" } */
+/* { dg-require-effective-target indirect_jumps } */
+
+#include <setjmp.h>
+
+extern void abort (void);
+
+jmp_buf buf;
+
+void raise0(void)
+{
+  __builtin_longjmp (buf, 1);
+}
+
+int execute(int cmd) /* { dg-warning "'l1-cache-size' is not an even number 3" } */
+{
+  int last = 0;
+
+  if (__builtin_setjmp (buf) == 0)
+    while (1)
+      {
+	last = 1;
+	raise0 ();
+      }
+
+  if (last == 0)
+    return 0;
+  else
+    return cmd;
+}
+
+int main(void)
+{
+  if (execute (1) == 0)
+    abort ();
+
+  return 0;
+}
diff --git a/gcc/tree-ssa-loop-prefetch.c b/gcc/tree-ssa-loop-prefetch.c
index 54cd9421998..2cdf210308b 100644
--- a/gcc/tree-ssa-loop-prefetch.c
+++ b/gcc/tree-ssa-loop-prefetch.c
@@ -47,6 +47,7 @@  along with GCC; see the file COPYING3.  If not see
 #include "langhooks.h"
 #include "tree-inline.h"
 #include "tree-data-ref.h"
+#include "diagnostic-core.h"
 
 /* This pass inserts prefetch instructions to optimize cache usage during
    accesses to arrays in loops.  It processes loops sequentially and:
@@ -1977,10 +1978,6 @@  tree_ssa_prefetch_arrays (void)
       set_builtin_decl (BUILT_IN_PREFETCH, decl, false);
     }
 
-  /* We assume that size of cache line is a power of two, so verify this
-     here.  */
-  gcc_assert ((PREFETCH_BLOCK & (PREFETCH_BLOCK - 1)) == 0);
-
   FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
     {
       if (dump_file && (dump_flags & TDF_DETAILS))
@@ -2038,6 +2035,14 @@  pass_loop_prefetch::execute (function *fun)
   if (number_of_loops (fun) <= 1)
     return 0;
 
+  if ((PREFETCH_BLOCK & (PREFETCH_BLOCK - 1)) != 0)
+    {
+      warning (OPT_Wdisabled_optimization,
+	       "%<l1-cache-size%> is not an even number %d",
+	       PREFETCH_BLOCK);
+      return 0;
+    }
+
   return tree_ssa_prefetch_arrays ();
 }
 
-- 
2.11.1