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MC: Improve error reporting for equated symbols and undefined labels

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Currently, the code path is likely only reachable with super edge-case scenario,
but will be more reachable with the upcoming parseAssignmentExpression improvement
to address a pile of hacks.
This commit is contained in:
Fangrui Song
2025-05-26 13:05:20 -07:00
parent 73c4929322
commit 27b6ba449b
3 changed files with 8 additions and 6 deletions
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8
llvm/lib/MC/MCAssembler.cpp
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@@ -415,8 +415,8 @@ static bool getLabelOffset(const MCAssembler &Asm, const MCSymbol &S,
bool ReportError, uint64_t &Val) {
if (!S.getFragment()) {
if (ReportError)
report_fatal_error("unable to evaluate offset to undefined symbol '" +
S.getName() + "'");
reportFatalUsageError("cannot evaluate undefined symbol '" + S.getName() +
"'");
return false;
}
Val = Asm.getFragmentOffset(*S.getFragment()) + S.getOffset();
@@ -431,8 +431,8 @@ static bool getSymbolOffsetImpl(const MCAssembler &Asm, const MCSymbol &S,
// If SD is a variable, evaluate it.
MCValue Target;
if (!S.getVariableValue()->evaluateAsValue(Target, Asm))
report_fatal_error("unable to evaluate offset for variable '" +
S.getName() + "'");
reportFatalUsageError("cannot evaluate equated symbol '" + S.getName() +
"'");
uint64_t Offset = Target.getConstant();

2
llvm/lib/MC/MCExpr.cpp
View File

@@ -538,6 +538,8 @@ bool MCExpr::evaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm,
// Allows aliases with zero offset.
if (Res.getConstant() == 0 && (!A || !B))
return true;
} else {
return false;
}
}

4
llvm/test/MC/MachO/variable-errors.s
View File

@@ -1,8 +1,8 @@
// RUN: not --crash llvm-mc -triple x86_64-apple-darwin10 %s -filetype=obj -o %t.o 2> %t.err
// RUN: not llvm-mc -triple x86_64-apple-darwin10 %s -filetype=obj -o %t.o 2> %t.err
// RUN: FileCheck < %t.err %s
.data
t0_a:
t0_x = t0_a - t0_b
// CHECK: unable to evaluate offset to undefined symbol 't0_b'
// CHECK: cannot evaluate undefined symbol 't0_b'
.long t0_x