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

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

From: Stefano Stabellini <stefano.stabellini@xxxxxxx>

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
---
Changes in v2:
- use "shift" instead of << or >>
- use All Architectures (I haven't changed all the other instances of
x86/arm in the file yet)
---
 docs/misra/C-language-toolchain.rst | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/docs/misra/C-language-toolchain.rst 
b/docs/misra/C-language-toolchain.rst
index 785aed1eaf..f5ca7bd2c8 100644
--- a/docs/misra/C-language-toolchain.rst
+++ b/docs/misra/C-language-toolchain.rst
@@ -200,6 +200,12 @@ The table columns are as follows:
      - ARM64, X86_64
      - See Section "6.29 Designated Initializers" of GCC_MANUAL
 
+   * - Signed shift acts on negative numbers by sign extension
+     - 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 shift as undefined.
+
 
 Translation Limits
 __________________
-- 
2.25.1