diff mbox series

[COMMITTED] Fold all statements in Ranger VRP.

Message ID c5836162-ee36-7054-c4f4-64223794e949@redhat.com
State Committed
Headers
Series [COMMITTED] Fold all statements in Ranger VRP. |

Commit Message

Andrew MacLeod Oct. 26, 2021, 12:03 a.m. UTC 
  This patch changes the ranger VRP pass to simplify all statements, not 
just the ones with ranges.  I believe Jeff had mentioned we were no 
longer doing this a while back.  Now we need it when running as the VRP2 
pass to satisfy the testcase: gcc.dg/wrapped-binop-simplify.c

This also requires a testcase adjustment since EVRP will now perform 
this simplification, and it causes a test looking for it in VRP1 to 
fail.  In that test, I simply disable evrp, and then add a duplicate of 
the test which then tests that EVRP also performs the optimization.

Bootstrapped on x86_64-pc-linux-gnu with no regressions. Pushed.

Andrew

Comments

Jeff Law Oct. 28, 2021, 1:38 p.m. UTC | #1 
On 10/25/2021 6:03 PM, Andrew MacLeod via Gcc-patches wrote:
> This patch changes the ranger VRP pass to simplify all statements, not 
> just the ones with ranges.  I believe Jeff had mentioned we were no 
> longer doing this a while back.  Now we need it when running as the 
> VRP2 pass to satisfy the testcase: gcc.dg/wrapped-binop-simplify.c
I did :-)   The lack of folding in [E]VRP caused a critical function in 
perl to be ever-so-slightly larger and not be inlined leading to a 
measurable performance regression in spec when compiled with gcc-11.  I 
never bothered upstreaming our internal version of this as other 
(non-VRP) changes on the trunk addressed the problem.

Jeff
Andrew MacLeod Oct. 28, 2021, 1:47 p.m. UTC | #2 
On 10/28/21 9:38 AM, Jeff Law wrote:
>
>
> On 10/25/2021 6:03 PM, Andrew MacLeod via Gcc-patches wrote:
>> This patch changes the ranger VRP pass to simplify all statements, 
>> not just the ones with ranges.  I believe Jeff had mentioned we were 
>> no longer doing this a while back.  Now we need it when running as 
>> the VRP2 pass to satisfy the testcase: gcc.dg/wrapped-binop-simplify.c
> I did :-)   The lack of folding in [E]VRP caused a critical function 
> in perl to be ever-so-slightly larger and not be inlined leading to a 
> measurable performance regression in spec when compiled with gcc-11.  
> I never bothered upstreaming our internal version of this as other 
> (non-VRP) changes on the trunk addressed the problem.
>
> Jeff
>
so does this resolve the situation then?  It should, in theory.

Andrew
Jeff Law Oct. 28, 2021, 1:48 p.m. UTC | #3 
On 10/28/2021 7:47 AM, Andrew MacLeod wrote:
> On 10/28/21 9:38 AM, Jeff Law wrote:
>>
>>
>> On 10/25/2021 6:03 PM, Andrew MacLeod via Gcc-patches wrote:
>>> This patch changes the ranger VRP pass to simplify all statements, 
>>> not just the ones with ranges.  I believe Jeff had mentioned we were 
>>> no longer doing this a while back.  Now we need it when running as 
>>> the VRP2 pass to satisfy the testcase: gcc.dg/wrapped-binop-simplify.c
>> I did :-)   The lack of folding in [E]VRP caused a critical function 
>> in perl to be ever-so-slightly larger and not be inlined leading to a 
>> measurable performance regression in spec when compiled with gcc-11.  
>> I never bothered upstreaming our internal version of this as other 
>> (non-VRP) changes on the trunk addressed the problem.
>>
>> Jeff
>>
> so does this resolve the situation then?  It should, in theory.
I would expect so.  It's quite similar to what we're doing internally 
with our gcc-11 tree.
jeff
diff mbox series

Patch

From cb153222404e2e149aa65a4b3139b09477551203 Mon Sep 17 00:00:00 2001
From: Andrew MacLeod <amacleod@redhat.com>
Date: Wed, 20 Oct 2021 13:37:29 -0400
Subject: [PATCH 1/2] Fold all statements in Ranger VRP.

Until now, ranger VRP has only simplified statements with ranges.  This patch
enables us to fold all statements.

	gcc/
	* tree-vrp.c (rvrp_folder::fold_stmt): If simplification fails, try
	to fold anyway.

	gcc/testsuite/
	* gcc.dg/tree-ssa/vrp98.c: Disable evrp for vrp1 test.
	* gcc.dg/tree-ssa/vrp98-1.c: New. Test for folding in evrp.
---
 gcc/testsuite/gcc.dg/tree-ssa/vrp98-1.c | 41 +++++++++++++++++++++++++
 gcc/testsuite/gcc.dg/tree-ssa/vrp98.c   |  2 +-
 gcc/tree-vrp.c                          |  5 ++-
 3 files changed, 46 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/vrp98-1.c

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp98-1.c b/gcc/testsuite/gcc.dg/tree-ssa/vrp98-1.c
new file mode 100644
index 00000000000..daa3f073b92
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp98-1.c
@@ -0,0 +1,41 @@ 
+/* { dg-do compile } */
+/* { dg-require-effective-target int128 } */
+/* { dg-options "-Os -fdump-tree-evrp-details" } */
+
+#include <stdint.h>
+#include <limits.h>
+
+typedef unsigned int word __attribute__((mode(word)));
+typedef unsigned __int128 bigger_than_word;
+
+int
+foo (bigger_than_word a, word b, uint8_t c)
+{
+  /* Must fold use of t1 into use of b, as b is no wider than word_mode. */
+  const uint8_t t1 = b % UCHAR_MAX;
+
+  /* Must NOT fold use of t2 into use of a, as a is wider than word_mode. */
+  const uint8_t t2 = a % UCHAR_MAX;
+
+  /* Must fold use of t3 into use of c, as c is narrower than t3. */
+  const uint32_t t3 = (const uint32_t)(c >> 1);
+
+  uint16_t ret = 0;
+
+  if (t1 == 1)
+    ret = 20;
+  else if (t2 == 2)
+    ret = 30;
+  else if (t3 == 3)
+    ret = 40;
+  /* Th extra condition below is necessary to prevent a prior pass from
+     folding away the cast. Ignored in scan-tree-dump. */
+  else if (t3 == 4)
+    ret = 50;
+
+  return ret;
+}
+
+/* { dg-final { scan-tree-dump "Folded into: if \\(_\[0-9\]+ == 1\\)" "evrp" } } */
+/* { dg-final { scan-tree-dump-not "Folded into: if \\(_\[0-9\]+ == 2\\)" "evrp" } } */
+/* { dg-final { scan-tree-dump "Folded into: if \\(_\[0-9\]+ == 3\\)" "evrp" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp98.c b/gcc/testsuite/gcc.dg/tree-ssa/vrp98.c
index 982f091080c..78d3bbaf499 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/vrp98.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp98.c
@@ -1,6 +1,6 @@ 
 /* { dg-do compile } */
 /* { dg-require-effective-target int128 } */
-/* { dg-options "-Os -fdump-tree-vrp1-details" } */
+/* { dg-options "-Os -fdisable-tree-evrp -fdump-tree-vrp1-details" } */
 
 #include <stdint.h>
 #include <limits.h>
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index ba7a4efc7c6..a948c524098 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -50,6 +50,7 @@  along with GCC; see the file COPYING3.  If not see
 #include "gimple-range.h"
 #include "gimple-range-path.h"
 #include "value-pointer-equiv.h"
+#include "gimple-fold.h"
 
 /* Set of SSA names found live during the RPO traversal of the function
    for still active basic-blocks.  */
@@ -4381,7 +4382,9 @@  public:
 
   bool fold_stmt (gimple_stmt_iterator *gsi) OVERRIDE
   {
-    return m_simplifier.simplify (gsi);
+    if (m_simplifier.simplify (gsi))
+      return true;
+    return ::fold_stmt (gsi, follow_single_use_edges);
   }
 
 private:
-- 
2.17.2