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Fix a Mach-O assembler segfault for a subtraction expression with an undefined symbol.

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In a Mach-O object file a relocatable expression of the form
SymbolA - SymbolB + constant is allowed when both symbols are
defined in a section.  But when either symbol is undefined it
is an error.

The code was crashing when it had an undefined symbol in this case.
And should have printed a error message using the location information
in the relocation entry.

rdar://18678402


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220599 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Kevin Enderby
2014-10-24 22:39:40 +00:00
parent ab08da75d7
commit 44ccedc273
3 changed files with 19 additions and 4 deletions
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lib/Target/X86/MCTargetDesc/X86MachObjectWriter.cpp
+7 -4
View File
@@ -179,11 +179,14 @@ void X86MachObjectWriter::RecordX86_64Relocation(MachObjectWriter *Writer,
if (A_Base == B_Base && A_Base)
report_fatal_error("unsupported relocation with identical base", false);
// A subtraction expression where both symbols are undefined is a
// A subtraction expression where either symbol is undefined is a
// non-relocatable expression.
if (A->isUndefined() && B->isUndefined())
report_fatal_error("unsupported relocation with subtraction expression",
false);
if (A->isUndefined() || B->isUndefined()) {
StringRef Name = A->isUndefined() ? A->getName() : B->getName();
Asm.getContext().FatalError(Fixup.getLoc(),
"unsupported relocation with subtraction expression, symbol '" +
Name + "' can not be undefined in a subtraction expression");
}
Value += Writer->getSymbolAddress(&A_SD, Layout) -
(!A_Base ? 0 : Writer->getSymbolAddress(A_Base, Layout));