diff mbox series

[wwwdocs] x86-64: Document ABI changes for structures with a 64-bit vector

Message ID 20210829172603.120516-1-hjl.tools@gmail.com
State New
Headers show
Series [wwwdocs] x86-64: Document ABI changes for structures with a 64-bit vector | expand

Commit Message

H.J. Lu Aug. 29, 2021, 5:26 p.m. UTC 
TYPE_MODE of record and union depends on whether vector_mode_supported_p
returns true or not.  x86-64 backend uses TYPE_MODE to decide how to pass
a parameter and return a value in a function.  64-bit integer vectors
were supported only by MMX and 64-bit float vector was supported only by
3DNOW.  GCC 10.1 enabled 64-bit integer vectors without MMX by:

commit dfa61b9ed06d71901c4c430caa89820972ad68fe
Author: H.J. Lu <hongjiu.lu@intel.com>
Date:   Wed May 15 15:02:54 2019 +0000

    i386: Allow MMX register modes in SSE registers

    In 64-bit mode, SSE2 can be used to emulate MMX instructions without
    3DNOW.  We can use SSE2 to support MMX register modes.

GCC 10.4 is changed to diagnose this ABI change with -Wpsabi.

GCC 11.1 enabled 64-bit float vector without 3DNOW by:

commit 7c355156aa20eaec7401d7c66f6a6cfbe597abc2
Author: Uros Bizjak <ubizjak@gmail.com>
Date:   Mon May 11 11:16:31 2020 +0200

    i386: Vectorize basic V2SFmode operations [PR94913]

    Enable V2SFmode vectorization and vectorize V2SFmode PLUS,
    MINUS, MULT, MIN and MAX operations using XMM registers.

GCC 11.3 is changed to diagnose this ABI change with -Wpsabi.
---
 htdocs/gcc-10/changes.html | 18 ++++++++++++++++++
 htdocs/gcc-11/changes.html | 15 +++++++++++++++
 2 files changed, 33 insertions(+)
diff mbox series

Patch

diff --git a/htdocs/gcc-10/changes.html b/htdocs/gcc-10/changes.html
index 5f386792..e3d8bed9 100644
--- a/htdocs/gcc-10/changes.html
+++ b/htdocs/gcc-10/changes.html
@@ -1155,6 +1155,24 @@  are not listed here).</p>
   via <code>-march=znver3</code>.
   </li>
 </ul>
+
+<!-- .................................................................. -->
+
+<h2 id="GCC10.4">GCC 10.4</h2>
+
+<h3>Target Specific Changes</h3>
+
+<h4>x86-64</h4>
+<ul>
+  <li>
+    <a id="x86_64_m64">The x86-64 ABI</a>
+    of passing and returning structures with a 64-bit integer vector
+    changed in GCC 10.1 when MMX is disabled.  Disabling MMX no longer
+    changes how they are passed nor returned.  This ABI change is now
+    diagnosed with <code>-Wpsabi</code>.
+  </li>
+</ul>
+
 <!-- .................................................................. -->
 
 </body>
diff --git a/htdocs/gcc-11/changes.html b/htdocs/gcc-11/changes.html
index 6dec8856..220a415c 100644
--- a/htdocs/gcc-11/changes.html
+++ b/htdocs/gcc-11/changes.html
@@ -1116,5 +1116,20 @@  are not listed here).</p>
 
 <!-- .................................................................. -->
 
+<h2><a name="11.3">GCC 11.3</a></h2>
+
+<h3>Target Specific Changes</h3>
+
+<h4>x86-64</h4>
+<ul>
+  <li>
+    <a id="x86_64_m64">The x86-64 ABI</a>
+    of passing and returning structure with a 64-bit single precision
+    vector changed in GCC 11.1 when 3DNOW is disabled.  Disabling 3DNOW
+    no longer changes how they are passed nor returned.  This ABI change
+    is now diagnosed with <code>-Wpsabi</code>.
+  </li>
+</ul>
+
 </body>
 </html>