Fix Endianess issue #162881
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Fix Endianess issue #162881
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…the first origin pointer
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@llvm/pr-subscribers-llvm-transforms @llvm/pr-subscribers-compiler-rt-sanitizer Author: None (anoopkg6) ChangesFix Endianess issue with getting shadow 4 bytes corresponding to the first origin pointer. Full diff: https://github.com/llvm/llvm-project/pull/162881.diff 1 Files Affected:
diff --git a/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
index 5ba2167859490..b4f88779b00c0 100644
--- a/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp
@@ -2187,8 +2187,14 @@ std::pair<Value *, Value *> DFSanFunction::loadShadowFast(
// and then the entire shadow for the second origin pointer (which will be
// chosen by combineOrigins() iff the least-significant half of the wide
// shadow was empty but the other half was not).
- Value *WideShadowLo = IRB.CreateShl(
- WideShadow, ConstantInt::get(WideShadowTy, WideShadowBitWidth / 2));
+ Value *WideShadowLo =
+ F->getParent()->getDataLayout().isLittleEndian()
+ ? IRB.CreateShl(
+ WideShadow,
+ ConstantInt::get(WideShadowTy, WideShadowBitWidth / 2))
+ : IRB.CreateAnd(
+ WideShadow,
+ ConstantInt::get(WideShadowTy, 0xFFFFFFFF00000000ULL));
Shadows.push_back(WideShadow);
Origins.push_back(DFS.loadNextOrigin(Pos, OriginAlign, &OriginAddr));
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Please add "[dfsan]" to the title |
thurstond
reviewed
Oct 10, 2025
| ConstantInt::get(WideShadowTy, WideShadowBitWidth / 2)) | ||
| : IRB.CreateAnd( | ||
| WideShadow, | ||
| ConstantInt::get(WideShadowTy, 0xFFFFFFFF00000000ULL)); |
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Can this be rewritten in terms of WideShadowBitWidth?
(I think it's something like (1 - (1 << (WideShadowBitWidth / 2))) << (WideShadowBitWidth / 2))
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Right way of writing this expression. Thanks.
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I don't believe we support other that little endian. So there is no point to complicate code for that. |
They are adding support for SystemZ (#162195). |
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Also, RISC-V has an exciting big-endian extension (/cc @fmayer) |
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Dfsan tests passed, which include extensive custom library functions like memcpy, memmove ... etc.
Other sanitizers - asan,lsan, tsan, ubsan - have successfully been supported on SystemZ.
Tysan, rtsan have already been tested and are in the process of pr. If some issue crops up, it will be fixed.
…________________________________
From: Vitaly Buka ***@***.***>
Sent: Friday, October 10, 2025 3:05 PM
To: llvm/llvm-project ***@***.***>
Cc: Anoop Kumar ***@***.***>; Author ***@***.***>
Subject: [EXTERNAL] Re: [llvm/llvm-project] Fix Endianess issue (PR #162881)
vitalybuka left a comment (llvm/llvm-project#162881) I don't believe we support other that little endian. So there is no point to complicate code for that. They are adding support for SystemZ (#162195). Is #162195 enough? I'd expect sanitizers
[https://avatars.githubusercontent.com/u/1531415?s=20&v=4%5Dvitalybuka left a comment (llvm/llvm-project#162881)<#162881 (comment) >
I don't believe we support other that little endian. So there is no point to complicate code for that.
They are adding support for SystemZ (#162195<#162195 >).
Is #162195<#162195 > enough?
I'd expect sanitizers does a lot of assumptions on little-endianness.
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Reply to this email directly, view it on GitHub<#162881 (comment) >, or unsubscribe<https://github.com/notifications/unsubscribe-auth/BM5K4GXOGNHB3NB43QBTZFL3XAGQBAVCNFSM6AAAAACI3L4A5CVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTGOJSGE3DENZQGM >.
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Fix Endianess issue with getting shadow 4 bytes corresponding to the first origin pointer.