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Re: [PATCH] libstdc++-v3: Have aligned_alloc() on Newlib

On 13/08/18 13:04 +0100, Jonathan Wakely wrote:
On 13/08/18 12:55 +0100, Szabolcs Nagy wrote:
On 09/08/18 10:08, Jonathan Wakely wrote:
On 09/08/18 06:56 +0200, Sebastian Huber wrote:
On 08/08/18 16:33, Jonathan Wakely wrote:
On 08/08/18 16:22 +0200, Ulrich Weigand wrote:
Jonathan Wakely wrote:

Aha, so newlib was using memalign previously:

@@ -53,20 +54,24 @@ aligned_alloc (std::size_t al, std::size_t sz)
 extern "C" void *memalign(std::size_t boundary, std::size_t size);
-#define aligned_alloc memalign

Yes, exactly ... this commit introduced the regression.

OK, I've regressed the branches then - I'll fix that.

This should fix it. I'll finish testing and commit it.

Sebastian, your patch to define HAVE_ALIGNED_ALLOC is OK for
gcc-7-branch and gcc-8-branch, because changing newlib from using
memalign to aligned_alloc is safe.

Should I check in my patch in addition to your patch?

Yes please, on trunk and 7 and 8. It's better to use the standard
aligned_alloc if available.

but the newlib aligned_alloc is broken on baremetal targets,
it is implemented using posix_memalign which is not provided
by the newlib malloc implementation (except on cygwin)

Ouch, OK, let's revert it. Using memalign is fine.

The original problem that I think Sebastian was trying to solve should
be fixed by r263409 anyway (and was backported to all branches).

I've committed this to trunk and will do so on the branches too.

commit 6fe6d2c2256a73bca9ca3754761bd724b654db13
Author: Jonathan Wakely <>
Date:   Mon Aug 13 14:05:46 2018 +0100

    Revert "libstdc++-v3: Have aligned_alloc() on Newlib"
    This reverts commit r263461 / 2e920cd849b3cf0a72df4f172e27676a3e70b73f
    because aligned_alloc is not defined for baremetal newlib targets, see
    2018-08-10  Sebastian Huber  <>
            PR target/85904
            * Define HAVE_ALIGNED_ALLOC if building for
            * configure: Regenerate.

diff --git a/libstdc++-v3/ b/libstdc++-v3/
index e15228dde5e..332af3706d3 100644
--- a/libstdc++-v3/
+++ b/libstdc++-v3/
@@ -330,7 +330,6 @@ else

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