* [PATCH][PR tree-optimization/79578] Use operand_equal_p rather than pointer equality for base test
@ 2017-02-23 5:59 Jeff Law
2017-02-23 9:44 ` Richard Biener
0 siblings, 1 reply; 4+ messages in thread
From: Jeff Law @ 2017-02-23 5:59 UTC (permalink / raw)
To: gcc-patches
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tree-ssa-dse.c needs to verify when two writes have the same base
address. Right now it uses pointer equality. The testcase in BZ79578
shows that we should have been using operand_equal_p.
This one-liner fixes that oversight. Bootstrapped and regression tested
on x86_64-linux-gnu. Installed on the trunk.
Jeff
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commit ef506ec9114a7fe27d9ee892c17edd100f72a963
Author: law <law@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Thu Feb 23 05:47:43 2017 +0000
PR tree-optimization/79578
* tree-ssa-dse.c (clear_bytes_written_by): Use operand_equal_p
to compare base operands.
PR tree-optimization/79578
* g++.dg/tree-ssa/ssa-dse-3.C: New test.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@245675 138bc75d-0d04-0410-961f-82ee72b054a4
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 7155850..6da1d74 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2017-02-22 Jeff Law <law@redhat.com>
+
+ PR tree-optimization/79578
+ * tree-ssa-dse.c (clear_bytes_written_by): Use operand_equal_p
+ to compare base operands.
+
2017-02-22 Segher Boessenkool <segher@kernel.crashing.org>
PR target/79211
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index ea5e251..d900cc3 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2017-02-22 Jeff Law <law@redhat.com>
+
+ PR tree-optimization/79578
+ * g++.dg/tree-ssa/ssa-dse-3.C: New test.
+
2017-02-22 Sameera Deshpande <sameera.deshpande@imgtec.com>
* gcc.target/mips/msa-fp-cc.c: New test.
diff --git a/gcc/testsuite/g++.dg/tree-ssa/ssa-dse-3.C b/gcc/testsuite/g++.dg/tree-ssa/ssa-dse-3.C
new file mode 100644
index 0000000..fe8f309
--- /dev/null
+++ b/gcc/testsuite/g++.dg/tree-ssa/ssa-dse-3.C
@@ -0,0 +1,28 @@
+/* { dg-do compile } */
+/* { dg-options "-std=c++14 -O3 -fdump-tree-dse1-details" } */
+
+#include <new>
+#include <cstdint>
+
+struct A
+{
+ std::uint16_t a, b;
+};
+
+A* f(char* b) __attribute__((noinline));
+
+A* f(char* b) {
+ auto a = new(b) A{};
+ a->a = 1;
+ a->b = 2;
+ return a;
+}
+
+int main() {
+ char b[sizeof(A)] alignas(A);
+ f(b);
+}
+
+
+/* { dg-final { scan-tree-dump "Deleted dead store: " "dse1" } } */
+
diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c
index 84c0b11..a82e164 100644
--- a/gcc/tree-ssa-dse.c
+++ b/gcc/tree-ssa-dse.c
@@ -176,7 +176,7 @@ clear_bytes_written_by (sbitmap live_bytes, gimple *stmt, ao_ref *ref)
/* Verify we have the same base memory address, the write
has a known size and overlaps with REF. */
if (valid_ao_ref_for_dse (&write)
- && write.base == ref->base
+ && operand_equal_p (write.base, ref->base, 0)
&& write.size == write.max_size
&& ((write.offset < ref->offset
&& write.offset + write.size > ref->offset)
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH][PR tree-optimization/79578] Use operand_equal_p rather than pointer equality for base test
2017-02-23 5:59 [PATCH][PR tree-optimization/79578] Use operand_equal_p rather than pointer equality for base test Jeff Law
@ 2017-02-23 9:44 ` Richard Biener
2017-02-23 21:27 ` Jeff Law
0 siblings, 1 reply; 4+ messages in thread
From: Richard Biener @ 2017-02-23 9:44 UTC (permalink / raw)
To: Jeff Law; +Cc: gcc-patches
On Thu, Feb 23, 2017 at 6:49 AM, Jeff Law <law@redhat.com> wrote:
>
> tree-ssa-dse.c needs to verify when two writes have the same base address.
> Right now it uses pointer equality. The testcase in BZ79578 shows that we
> should have been using operand_equal_p.
>
> This one-liner fixes that oversight. Bootstrapped and regression tested on
> x86_64-linux-gnu. Installed on the trunk.
>
> Jeff
>
> commit ef506ec9114a7fe27d9ee892c17edd100f72a963
> Author: law <law@138bc75d-0d04-0410-961f-82ee72b054a4>
> Date: Thu Feb 23 05:47:43 2017 +0000
>
> PR tree-optimization/79578
> * tree-ssa-dse.c (clear_bytes_written_by): Use operand_equal_p
> to compare base operands.
>
> PR tree-optimization/79578
> * g++.dg/tree-ssa/ssa-dse-3.C: New test.
>
> git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@245675
> 138bc75d-0d04-0410-961f-82ee72b054a4
>
> diff --git a/gcc/ChangeLog b/gcc/ChangeLog
> index 7155850..6da1d74 100644
> --- a/gcc/ChangeLog
> +++ b/gcc/ChangeLog
> @@ -1,3 +1,9 @@
> +2017-02-22 Jeff Law <law@redhat.com>
> +
> + PR tree-optimization/79578
> + * tree-ssa-dse.c (clear_bytes_written_by): Use operand_equal_p
> + to compare base operands.
> +
> 2017-02-22 Segher Boessenkool <segher@kernel.crashing.org>
>
> PR target/79211
> diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
> index ea5e251..d900cc3 100644
> --- a/gcc/testsuite/ChangeLog
> +++ b/gcc/testsuite/ChangeLog
> @@ -1,3 +1,8 @@
> +2017-02-22 Jeff Law <law@redhat.com>
> +
> + PR tree-optimization/79578
> + * g++.dg/tree-ssa/ssa-dse-3.C: New test.
> +
> 2017-02-22 Sameera Deshpande <sameera.deshpande@imgtec.com>
>
> * gcc.target/mips/msa-fp-cc.c: New test.
> diff --git a/gcc/testsuite/g++.dg/tree-ssa/ssa-dse-3.C
> b/gcc/testsuite/g++.dg/tree-ssa/ssa-dse-3.C
> new file mode 100644
> index 0000000..fe8f309
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/tree-ssa/ssa-dse-3.C
> @@ -0,0 +1,28 @@
> +/* { dg-do compile } */
> +/* { dg-options "-std=c++14 -O3 -fdump-tree-dse1-details" } */
> +
> +#include <new>
> +#include <cstdint>
> +
> +struct A
> +{
> + std::uint16_t a, b;
> +};
> +
> +A* f(char* b) __attribute__((noinline));
> +
> +A* f(char* b) {
> + auto a = new(b) A{};
> + a->a = 1;
> + a->b = 2;
> + return a;
> +}
> +
> +int main() {
> + char b[sizeof(A)] alignas(A);
> + f(b);
> +}
> +
> +
> +/* { dg-final { scan-tree-dump "Deleted dead store: " "dse1" } } */
> +
> diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c
> index 84c0b11..a82e164 100644
> --- a/gcc/tree-ssa-dse.c
> +++ b/gcc/tree-ssa-dse.c
> @@ -176,7 +176,7 @@ clear_bytes_written_by (sbitmap live_bytes, gimple
> *stmt, ao_ref *ref)
> /* Verify we have the same base memory address, the write
> has a known size and overlaps with REF. */
> if (valid_ao_ref_for_dse (&write)
> - && write.base == ref->base
> + && operand_equal_p (write.base, ref->base, 0)
As you've identified size and offset match you are really interested
in comparing the base addresses and thus should use OEP_ADDRESS_OF.
Richard.
> && write.size == write.max_size
> && ((write.offset < ref->offset
> && write.offset + write.size > ref->offset)
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH][PR tree-optimization/79578] Use operand_equal_p rather than pointer equality for base test
2017-02-23 9:44 ` Richard Biener
@ 2017-02-23 21:27 ` Jeff Law
2017-02-24 10:05 ` Richard Biener
0 siblings, 1 reply; 4+ messages in thread
From: Jeff Law @ 2017-02-23 21:27 UTC (permalink / raw)
To: Richard Biener; +Cc: gcc-patches
On 02/23/2017 02:02 AM, Richard Biener wrote:
>> diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c
>> index 84c0b11..a82e164 100644
>> --- a/gcc/tree-ssa-dse.c
>> +++ b/gcc/tree-ssa-dse.c
>> @@ -176,7 +176,7 @@ clear_bytes_written_by (sbitmap live_bytes, gimple
>> *stmt, ao_ref *ref)
>> /* Verify we have the same base memory address, the write
>> has a known size and overlaps with REF. */
>> if (valid_ao_ref_for_dse (&write)
>> - && write.base == ref->base
>> + && operand_equal_p (write.base, ref->base, 0)
>
> As you've identified size and offset match you are really interested
> in comparing the base addresses and thus should use OEP_ADDRESS_OF.
I pondered that, but (perhaps incorrectly) thought that OEP_ADDRESS_OF
was an optimization and that a more simple o_e_p with no flags was safer.
I'm happy to change it, particularly if it's a correctness issue (in
which case I think we've designed a horrible API for o_e_p, but such is
life). In fact, I've already bootstrapped and regression tested that
change.
jeff
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH][PR tree-optimization/79578] Use operand_equal_p rather than pointer equality for base test
2017-02-23 21:27 ` Jeff Law
@ 2017-02-24 10:05 ` Richard Biener
0 siblings, 0 replies; 4+ messages in thread
From: Richard Biener @ 2017-02-24 10:05 UTC (permalink / raw)
To: Jeff Law; +Cc: gcc-patches
On Thu, Feb 23, 2017 at 10:06 PM, Jeff Law <law@redhat.com> wrote:
> On 02/23/2017 02:02 AM, Richard Biener wrote:
>
>>> diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c
>>> index 84c0b11..a82e164 100644
>>> --- a/gcc/tree-ssa-dse.c
>>> +++ b/gcc/tree-ssa-dse.c
>>> @@ -176,7 +176,7 @@ clear_bytes_written_by (sbitmap live_bytes, gimple
>>> *stmt, ao_ref *ref)
>>> /* Verify we have the same base memory address, the write
>>> has a known size and overlaps with REF. */
>>> if (valid_ao_ref_for_dse (&write)
>>> - && write.base == ref->base
>>> + && operand_equal_p (write.base, ref->base, 0)
>>
>>
>> As you've identified size and offset match you are really interested
>> in comparing the base addresses and thus should use OEP_ADDRESS_OF.
>
> I pondered that, but (perhaps incorrectly) thought that OEP_ADDRESS_OF was
> an optimization and that a more simple o_e_p with no flags was safer.
>
> I'm happy to change it, particularly if it's a correctness issue (in which
> case I think we've designed a horrible API for o_e_p, but such is life). In
> fact, I've already bootstrapped and regression tested that change.
It's indeed an optimization to use OEP_ADDRESS_OF and 0 is more conservative.
Richard.
> jeff
>
^ permalink raw reply [flat|nested] 4+ messages in thread
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2017-02-23 5:59 [PATCH][PR tree-optimization/79578] Use operand_equal_p rather than pointer equality for base test Jeff Law
2017-02-23 9:44 ` Richard Biener
2017-02-23 21:27 ` Jeff Law
2017-02-24 10:05 ` Richard Biener
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