[SDAG] Honor signed arguments in floating point libcalls #109134
Conversation
|
Thank you for submitting a Pull Request (PR) to the LLVM Project! This PR will be automatically labeled and the relevant teams will be notified. If you wish to, you can add reviewers by using the "Reviewers" section on this page. If this is not working for you, it is probably because you do not have write permissions for the repository. In which case you can instead tag reviewers by name in a comment by using If you have received no comments on your PR for a week, you can request a review by "ping"ing the PR by adding a comment “Ping”. The common courtesy "ping" rate is once a week. Please remember that you are asking for valuable time from other developers. If you have further questions, they may be answered by the LLVM GitHub User Guide. You can also ask questions in a comment on this PR, on the LLVM Discord or on the forums. |
|
@llvm/pr-subscribers-backend-x86 @llvm/pr-subscribers-llvm-selectiondag Author: Timothy Pearson (tpearson-ssc) ChangesIn ExpandFPLibCall, an assumption is made that all floating point libcalls that take integer arguments use unsigned integers. In the case of ldexp and frexp, this assumption is incorrect, leading to miscompilation and subsequent target-dependent incorrect operation. Indicate that ldexp and frexp utilize signed arguments in ExpandFPLibCall. Fixes #108904 Full diff: https://github.com/llvm/llvm-project/pull/109134.diff 1 Files Affected:
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index f5fbc01cd95e96..b6c1b340909cf7 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -2205,7 +2205,26 @@ void SelectionDAGLegalize::ExpandFPLibCall(SDNode* Node,
Results.push_back(Tmp.first);
Results.push_back(Tmp.second);
} else {
- SDValue Tmp = ExpandLibCall(LC, Node, false).first;
+ bool isSignedArgument;
+ switch (LC) {
+ case RTLIB::LDEXP_F32:
+ case RTLIB::LDEXP_F64:
+ case RTLIB::LDEXP_F80:
+ case RTLIB::LDEXP_F128:
+ case RTLIB::LDEXP_PPCF128:
+ isSignedArgument = true;
+ break;
+ case RTLIB::FREXP_F32:
+ case RTLIB::FREXP_F64:
+ case RTLIB::FREXP_F80:
+ case RTLIB::FREXP_F128:
+ case RTLIB::FREXP_PPCF128:
+ isSignedArgument = true;
+ break;
+ default:
+ isSignedArgument = false;
+ }
+ SDValue Tmp = ExpandLibCall(LC, Node, isSignedArgument).first;
Results.push_back(Tmp);
}
}
|
Will do later today. Just wanted to see if there was initial agreement on this overall approach being sufficient. |
|
It looks like a number of existing tests fails: You should update these as well, likely by rerunning update_llc_test_checks.py on them. |
|
@lei137 Any thoughts on this PR? Looking for a second approval so we can get this merged -- we're having to carry this patch downstream in our Chromium repositories to get a working browser. Thanks! |
|
@bogner Since this touches |
In ExpandFPLibCall, an assumption is made that all floating point libcalls that take integer arguments use unsigned integers. In the case of ldexp, this assumption is incorrect, leading to miscompilation and subsequent target- dependent incorrect operation. Indicate that ldexp utilizes signed arguments in ExpandFPLibCall. Fixes #108904 Signed-off-by: Timothy Pearson <[email protected]>
|
@tpearson-ssc Congratulations on having your first Pull Request (PR) merged into the LLVM Project! Your changes will be combined with recent changes from other authors, then tested by our build bots. If there is a problem with a build, you may receive a report in an email or a comment on this PR. Please check whether problems have been caused by your change specifically, as the builds can include changes from many authors. It is not uncommon for your change to be included in a build that fails due to someone else's changes, or infrastructure issues. How to do this, and the rest of the post-merge process, is covered in detail here. If your change does cause a problem, it may be reverted, or you can revert it yourself. This is a normal part of LLVM development. You can fix your changes and open a new PR to merge them again. If you don't get any reports, no action is required from you. Your changes are working as expected, well done! |
In ExpandFPLibCall, an assumption is made that all floating point libcalls that take integer arguments use unsigned integers. In the case of ldexp and frexp, this assumption is incorrect, leading to miscompilation and subsequent target-dependent incorrect operation. Indicate that ldexp and frexp utilize signed arguments in ExpandFPLibCall. Fixes llvm#108904 Signed-off-by: Timothy Pearson <[email protected]> (cherry picked from commit 90c1474)
In ExpandFPLibCall, an assumption is made that all floating point libcalls that take integer arguments use unsigned integers. In the case of ldexp and frexp, this assumption is incorrect, leading to miscompilation and subsequent target-dependent incorrect operation. Indicate that ldexp and frexp utilize signed arguments in ExpandFPLibCall. Fixes llvm#108904 Signed-off-by: Timothy Pearson <[email protected]> (cherry picked from commit 90c1474)
In ExpandFPLibCall, an assumption is made that all floating point libcalls that take integer arguments use unsigned integers. In the case of ldexp and frexp, this assumption is incorrect, leading to miscompilation and subsequent target-dependent incorrect operation.
Indicate that ldexp and frexp utilize signed arguments in ExpandFPLibCall.
Fixes #108904