From: Jonathan Wakely <jwakely@redhat.com>
Date: Thu, 11 Oct 2018 23:21:11 +0000 (+0100)
Subject: PR libstdc++/77691 increase allocation size to at least alignment
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=49cb790a4c7be09fbb3f2e57595379d0cbbd9e54;p=gcc.git

PR libstdc++/77691 increase allocation size to at least alignment

It's not safe to assume that malloc(n) returns memory aligned to more
than n, so when relying on the guaranteed alignment of malloc ensure
that the number of bytes allocated is at least as large as the
alignment.

	PR libstdc++/77691
	* include/experimental/memory_resource (__resource_adaptor_imp): Do
	not allocate sizes smaller than alignment when relying on guaranteed
	alignment.
	* testsuite/experimental/memory_resource/new_delete_resource.cc:
	Adjust expected number of bytes allocated for alignof(max_align_t).

From-SVN: r265068
---

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 93293c0631a..35be45e4e46 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,12 @@
+2018-10-12  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/77691
+	* include/experimental/memory_resource (__resource_adaptor_imp): Do
+	not allocate sizes smaller than alignment when relying on guaranteed
+	alignment.
+	* testsuite/experimental/memory_resource/new_delete_resource.cc:
+	Adjust expected number of bytes allocated for alignof(max_align_t).
+
 2018-10-11  François Dumont  <fdumont@gcc.gnu.org>
 
 	* include/debug/forward_list
diff --git a/libstdc++-v3/include/experimental/memory_resource b/libstdc++-v3/include/experimental/memory_resource
index ccb45bfa335..fd40d2cf45b 100644
--- a/libstdc++-v3/include/experimental/memory_resource
+++ b/libstdc++-v3/include/experimental/memory_resource
@@ -421,7 +421,12 @@ namespace pmr {
       do_allocate(size_t __bytes, size_t __alignment) override
       {
 	if (__alignment <= __guaranteed_alignment<_Alloc>::value)
-	  return _M_alloc.allocate(__bytes);
+	  {
+	    if (__bytes < __alignment)
+	      __bytes = __alignment;
+	    return _M_alloc.allocate(__bytes);
+	  }
+
 
 	const _AlignMgr __mgr(__bytes, __alignment);
 	// Assume _M_alloc returns 1-byte aligned memory, so allocate enough
@@ -437,6 +442,8 @@ namespace pmr {
 	auto __ptr = static_cast<char*>(__p);
 	if (__alignment <= __guaranteed_alignment<_Alloc>::value)
 	  {
+	    if (__bytes < __alignment)
+	      __bytes = __alignment;
 	    _M_alloc.deallocate(__ptr, __bytes);
 	    return;
 	  }
diff --git a/libstdc++-v3/testsuite/experimental/memory_resource/new_delete_resource.cc b/libstdc++-v3/testsuite/experimental/memory_resource/new_delete_resource.cc
index 11667b1d138..3af3861d1a0 100644
--- a/libstdc++-v3/testsuite/experimental/memory_resource/new_delete_resource.cc
+++ b/libstdc++-v3/testsuite/experimental/memory_resource/new_delete_resource.cc
@@ -109,11 +109,13 @@ test03()
   using std::size_t;
   void* p = nullptr;
 
+  auto max = [](int n, int a) { return n > a ? n : a; };
+
   bytes_allocated = 0;
 
   memory_resource* r1 = new_delete_resource();
-  p = r1->allocate(1);
-  VERIFY( bytes_allocated == 1 );
+  p = r1->allocate(1); // uses alignment = alignof(max_align_t)
+  VERIFY( bytes_allocated <= alignof(max_align_t) );
   VERIFY( aligned<max_align_t>(p) );
   r1->deallocate(p, 1);
   VERIFY( bytes_allocated == 0 );
@@ -125,13 +127,13 @@ test03()
   VERIFY( bytes_allocated == 0 );
 
   p = r1->allocate(3, alignof(short));
-  VERIFY( bytes_allocated == 3 );
+  VERIFY( bytes_allocated == max(3, alignof(short)) );
   VERIFY( aligned<short>(p) );
   r1->deallocate(p, 3, alignof(short));
   VERIFY( bytes_allocated == 0 );
 
   p = r1->allocate(4, alignof(long));
-  VERIFY( bytes_allocated == 4 );
+  VERIFY( bytes_allocated == max(4, alignof(long)) );
   VERIFY( aligned<long>(p) );
   r1->deallocate(p, 4, alignof(long));
   VERIFY( bytes_allocated == 0 );