FYI, I'm putting in this follow-up tweak to the GNAT manual.
Implied compares in Ada Harded Conditionals documentation
From: Alexandre Oliva <ol...@adacore.com>
Improve the wording on optimizations that prevent compare hardening,
so as to also cover cases in which explicit compares get combined into
operations with implied compares.
for gcc/ada/ChangeLog
* doc/gnat_rm/security_hardening_features.rst: Mention
optimization to operations with implied compares.
---
.../doc/gnat_rm/security_hardening_features.rst | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/gcc/ada/doc/gnat_rm/security_hardening_features.rst
b/gcc/ada/doc/gnat_rm/security_hardening_features.rst
index 52240d7e3dd54..cf76938d91d13 100644
--- a/gcc/ada/doc/gnat_rm/security_hardening_features.rst
+++ b/gcc/ada/doc/gnat_rm/security_hardening_features.rst
@@ -112,14 +112,15 @@ long after boolean expressions are decomposed into
separate compares,
each one turned into either a conditional branch or a compare whose
result is stored in a boolean variable or temporary. Compiler
optimizations, if enabled, may also turn conditional branches into
-stored compares, and vice-versa. Conditionals may also be optimized
+stored compares, and vice-versa, or into operations with implied
+conditionals (e.g. MIN and MAX). Conditionals may also be optimized
out entirely, if their value can be determined at compile time, and
occasionally multiple compares can be combined into one.
It is thus difficult to predict which of these two options will affect
a specific compare operation expressed in source code. Using both
-options ensures that every compare that is not optimized out will be
-hardened.
+options ensures that every compare that is neither optimized out nor
+optimized into implied conditionals will be hardened.
The addition of reversed compares can be observed by enabling the dump
files of the corresponding passes, through command line options
--
Alexandre Oliva, happy hacker https://FSFLA.org/blogs/lxo/
Free Software Activist GNU Toolchain Engineer
Disinformation flourishes because many people care deeply about injustice
but very few check the facts. Ask me about <https://stallmansupport.org>
