[llvm] r362286 - [RuntimeDyld] fix too-small-bitmask error

Nick Desaulniers via llvm-commits llvm-commits at lists.llvm.org
Fri May 31 21:51:26 PDT 2019

Author: nickdesaulniers
Date: Fri May 31 21:51:26 2019
New Revision: 362286

URL: http://llvm.org/viewvc/llvm-project?rev=362286&view=rev
[RuntimeDyld] fix too-small-bitmask error

This was flagged in https://www.viva64.com/en/b/0629/ under "Snippet No.

It seems that this statement is doing the standard bitwise trick for
adjusting a value to have a specific alignment.

The issue is that getStubAlignment() returns an unsigned, while DataSize
is declared a uint64_t. The right hand side of the expression is not
extended to 64b before bitwise negation, resulting in the top half of
the mask being 0s, which is not correct for realignment.

Reviewers: lhames, MaskRay

Reviewed By: MaskRay

Subscribers: RKSimon, MaskRay, hiraditya, llvm-commits, srhines

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62227


Modified: llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp?rev=362286&r1=362285&r2=362286&view=diff
--- llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp (original)
+++ llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp Fri May 31 21:51:26 2019
@@ -842,7 +842,7 @@ RuntimeDyldImpl::emitSection(const Objec
       // Align DataSize to stub alignment if we have any stubs (PaddingSize will
       // have been increased above to account for this).
       if (StubBufSize > 0)
-        DataSize &= ~(getStubAlignment() - 1);
+        DataSize &= -(uint64_t)getStubAlignment();
     LLVM_DEBUG(dbgs() << "emitSection SectionID: " << SectionID << " Name: "

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