https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111495
Sam James <sjames at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |guojiufu at gcc dot gnu.org
--- Comment #2 from Sam James <sjames at gcc dot gnu.org> ---
1aceceb1e2d6e86ce183c8cc448750fa03b6f79e is the first bad commit
commit 1aceceb1e2d6e86ce183c8cc448750fa03b6f79e
Author: Jiufu Guo <[email protected]>
Date: Mon Sep 4 10:31:04 2023 +0800
Optimize '(X - N * M) / N' to 'X / N - M' if valid
Integer expression "(X - N * M) / N" can be optimized to "X / N - M" with
the below conditions:
1. There is no wrap/overflow/underflow.
wrap/overflow/underflow breaks the arithmetic operation.
2. "X - N * M" and "X" are not of opposite sign.
Here, the operation "/" would be "trunc_div", the fractional part is
discarded. If "X - N * M" and "X" are in different signs, then trunc_div
discards the fractional parts (of /N) in different directions.
PR tree-optimization/108757
gcc/ChangeLog:
* match.pd ((X - N * M) / N): New pattern.
((X + N * M) / N): New pattern.
((X + C) div_rshift N): New pattern.
gcc/testsuite/ChangeLog:
* gcc.dg/pr108757-1.c: New test.
* gcc.dg/pr108757-2.c: New test.
* gcc.dg/pr108757.h: New test.
gcc/match.pd | 80 +++++++++++++
gcc/testsuite/gcc.dg/pr108757-1.c | 18 +++
gcc/testsuite/gcc.dg/pr108757-2.c | 19 ++++
gcc/testsuite/gcc.dg/pr108757.h | 233 ++++++++++++++++++++++++++++++++++++++
4 files changed, 350 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/pr108757-1.c
create mode 100644 gcc/testsuite/gcc.dg/pr108757-2.c
create mode 100644 gcc/testsuite/gcc.dg/pr108757.h
bisect found first bad commit
