[xen master] docs/misra: document gcc-specific behavior with shifting signed integers

[patchbot@xxxxxxx]

commit 1b7dc185f8421b6ad849e88c0e9b2a81c2a99331
Author:     Stefano Stabellini <stefano.stabellini@xxxxxxx>
AuthorDate: Mon Aug 21 18:02:28 2023 -0700
Commit:     Stefano Stabellini <stefano.stabellini@xxxxxxx>
CommitDate: Wed Aug 30 18:59:52 2023 -0700

    docs/misra: document gcc-specific behavior with shifting signed integers
    
    Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 docs/misra/C-language-toolchain.rst | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/docs/misra/C-language-toolchain.rst 
b/docs/misra/C-language-toolchain.rst
index 785aed1eaf..4c4942a113 100644
--- a/docs/misra/C-language-toolchain.rst
+++ b/docs/misra/C-language-toolchain.rst
@@ -200,6 +200,15 @@ The table columns are as follows:
      - ARM64, X86_64
      - See Section "6.29 Designated Initializers" of GCC_MANUAL
 
+   * - Signed << compiler-defined behavior
+     - All architectures
+     - See Section "4.5 Integers" of GCC_MANUAL. As an extension to the
+       C language, GCC does not use the latitude given in C99 and C11
+       only to treat certain aspects of signed << as undefined.
+
+   * - Signed >> acts on negative numbers by sign extension
+     - All architectures
+     - See Section "4.5 Integers" of GCC_MANUAL.
 
 Translation Limits
 __________________
--
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