[SDAG] Honor signed arguments in floating point libcalls #109134
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@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);
}
}
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Will do later today. Just wanted to see if there was initial agreement on this overall approach being sufficient. |
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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. |
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@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! |
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 llvm#108904 Signed-off-by: Timothy Pearson <[email protected]>
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@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 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