Re: [PATCH] libstdc++: Handle non-integral sizes in std::uninitialized_fill_n

[Jonathan Wakely via Gcc-patches]

On 17/06/20 21:10 +0100, Jonathan Wakely wrote:

On 17/06/20 20:55 +0100, Jonathan Wakely wrote:

+struct Value
+{
+  int value = 0x1234;
+};

Oops, I modified this test, and it no longer tests the right code.
This type isn't trivial, so doesn't use the fill_n optimization
anyway. I'll fix the test.

Here's the fix. Tested x86_64-linux, committed to master.



commit 94b94c0bb1ca52f2b6912852cb40240efe72e82b
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Wed Jun 17 21:23:35 2020 +0100

    libstdc++: Fix tests for uninitialized_value_construct_n
    
    In my recent r11-1460 commit the tests had been "improved" before
    commit, and no longer exercised the code paths changed by the patch.
    
    This restores what I originally tested, so that the tests fail before
    the r11-1460 change and pass after it.
    
            * testsuite/20_util/specialized_algorithms/uninitialized_default_n/sizes.cc:
            Replace Value type with int so trivial code path is used.
            * testsuite/20_util/specialized_algorithms/uninitialized_value_construct_n/sizes.cc:
            Likewise.

diff --git a/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_default_n/sizes.cc b/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_default_n/sizes.cc
index 1bb4c6a9fb1..6842c76df07 100644
--- a/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_default_n/sizes.cc
+++ b/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_default_n/sizes.cc
@@ -18,25 +18,14 @@
 // { dg-do run { target c++11 } }
 
 #include <memory>
-#include <algorithm>
 #include <testsuite_hooks.h>
 
-struct Value
-{
-  int value = 0x1234;
-};
-
 void
 test01()
 {
-  alignas(Value) unsigned char buf[3 * sizeof(Value) + 1];
-  std::fill(std::begin(buf), std::end(buf), 0xff);
-  const auto p = reinterpret_cast<Value*>(buf);
-  std::__uninitialized_default_n(p, 2.0001);
-  VERIFY( p[0].value == 0x1234 );
-  VERIFY( p[1].value == 0x1234 );
-  VERIFY( p[2].value == 0x1234 );
-  VERIFY( *std::prev(std::end(buf)) == 0xff );
+  int i[3];
+  auto j = std::__uninitialized_default_n(i, 2.0001);
+  VERIFY( j == (i + 3) );
 }
 
 void
@@ -52,16 +41,10 @@ test02()
     int operator>(void*) { return value != 0; }
   };
 
-  alignas(Value) unsigned char buf[4 * sizeof(Value) + 1];
-  std::fill(std::begin(buf), std::end(buf), 0xff);
-  const auto p = reinterpret_cast<Value*>(buf);
+  int i[3];
   Size n = {4};
-  std::__uninitialized_default_n(p, n);
-  VERIFY( p[0].value == 0x1234 );
-  VERIFY( p[1].value == 0x1234 );
-  VERIFY( p[2].value == 0x1234 );
-  VERIFY( p[3].value == 0x1234 );
-  VERIFY( *std::prev(std::end(buf)) == 0xff );
+  auto j = std::__uninitialized_default_n(i, n);
+  VERIFY( j == (i + 4) );
 }
 
 int
diff --git a/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_value_construct_n/sizes.cc b/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_value_construct_n/sizes.cc
index e822b198928..7ad55e01157 100644
--- a/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_value_construct_n/sizes.cc
+++ b/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_value_construct_n/sizes.cc
@@ -19,25 +19,14 @@
 // { dg-do run { target c++17 } }
 
 #include <memory>
-#include <algorithm>
 #include <testsuite_hooks.h>
 
-struct Value
-{
-  int value = 0x1234;
-};
-
 void
 test01()
 {
-  alignas(Value) unsigned char buf[3 * sizeof(Value) + 1];
-  std::fill(std::begin(buf), std::end(buf), 0xff);
-  const auto p = reinterpret_cast<Value*>(buf);
-  std::uninitialized_value_construct_n(p, 2.0001);
-  VERIFY( p[0].value == 0x1234 );
-  VERIFY( p[1].value == 0x1234 );
-  VERIFY( p[2].value == 0x1234 );
-  VERIFY( *std::prev(std::end(buf)) == 0xff );
+  int i[3];
+  auto j = std::uninitialized_value_construct_n(i, 2.0001);
+  VERIFY( j == (i + 3) );
 }
 
 void
@@ -53,16 +42,10 @@ test02()
     int operator>(void*) { return value != 0; }
   };
 
-  alignas(Value) unsigned char buf[4 * sizeof(Value) + 1];
-  std::fill(std::begin(buf), std::end(buf), 0xff);
-  const auto p = reinterpret_cast<Value*>(buf);
+  int i[3];
   Size n = {4};
-  std::uninitialized_value_construct_n(p, n);
-  VERIFY( p[0].value == 0x1234 );
-  VERIFY( p[1].value == 0x1234 );
-  VERIFY( p[2].value == 0x1234 );
-  VERIFY( p[3].value == 0x1234 );
-  VERIFY( *std::prev(std::end(buf)) == 0xff );
+  auto j = std::__uninitialized_default_n(i, n);
+  VERIFY( j == (i + 4) );
 }
 
 int