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[wwwdocs] document zero-width field ABI changes on MIPS

Message ID bf6b80e390235055af767a380a75138883b39bb8.camel@mengyan1223.wang
State New
Headers show
Series [wwwdocs] document zero-width field ABI changes on MIPS | expand

Commit Message

Xi Ruoyao April 1, 2022, 4:32 p.m. UTC
Document PR102024 change (r12-7961 and 7962) for MIPS.  Ok for wwwdocs?


 htdocs/gcc-12/changes.html | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)
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diff --git a/htdocs/gcc-12/changes.html b/htdocs/gcc-12/changes.html
index 4e1f6b0f..a2d8156f 100644
--- a/htdocs/gcc-12/changes.html
+++ b/htdocs/gcc-12/changes.html
@@ -50,6 +50,10 @@  a work-in-progress.</p>
     (so there is a C++ ABI incompatibility, GCC 4.4 and earlier compatible
     with GCC 12 or later, incompatible with GCC 4.5 through GCC 11).
     RISC-V has changed the handling of these already starting with GCC 10.
+    As the ABI requires, MIPS takes them into account handling function
+    return values so there is a C++ ABI incompatibility with GCC 4.5
+    through 11.  For function arguments on MIPS, refer to
+    <a href="#mips_zero_width_fields">the MIPS specific entry</a>.
     GCC 12 on the above targets will report such incompatibilities as
     warnings or other diagnostics unless <code>-Wno-psabi</code> is used.
@@ -549,7 +553,18 @@  a work-in-progress.</p>
-<!-- <h3 id="mips">MIPS</h3> -->
+<h3 id="mips">MIPS</h3>
+  <li>The <a name="mips_zero_width_fields">ABI</a> passing arguments
+      containing zero-width fields (for example, C/C++ zero-width
+      bit-fields, GNU C/C++ zero-length arrays, and GNU C empty structs)
+      has changed.  Now a zero-width field will not prevent an aligned
+      64-bit floating-point field next to it from being passed through
+      FPR.  This is compatible with LLVM, but incompatible with previous
+      GCC releases. GCC 12 on MIPS will report such incompatibilities as
+      an inform unless <code>-Wno-psabi</code> is used.
+  </li>
 <!-- <h3 id="mep">MeP</h3> -->