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CodeGen: ConstStructBuilder must verify packed constraints after padding

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Before, ConstStructBuilder::AppendBytes would check packed constraints
prior to padding being added before the field's offset.  However, adding
this padding might force our struct to be packed.  Because we wouldn't
check *after* adding padding, ConstStructBuilder would be in an
inconsistent state leading to a crash.

This fixes PR21300.

llvm-svn: 220153
This commit is contained in:
David Majnemer
2014-10-19 00:03:10 +00:00
parent 090a237f29
commit afefe97e1c
2 changed files with 21 additions and 9 deletions
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19
clang/lib/CodeGen/CGExprConstant.cpp
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@@ -106,15 +106,6 @@ AppendBytes(CharUnits FieldOffsetInChars, llvm::Constant *InitCst) {
CharUnits AlignedNextFieldOffsetInChars =
NextFieldOffsetInChars.RoundUpToAlignment(FieldAlignment);
if (AlignedNextFieldOffsetInChars > FieldOffsetInChars) {
assert(!Packed && "Alignment is wrong even with a packed struct!");
// Convert the struct to a packed struct.
ConvertStructToPacked();
AlignedNextFieldOffsetInChars = NextFieldOffsetInChars;
}
if (AlignedNextFieldOffsetInChars < FieldOffsetInChars) {
// We need to append padding.
AppendPadding(FieldOffsetInChars - NextFieldOffsetInChars);
@@ -122,6 +113,16 @@ AppendBytes(CharUnits FieldOffsetInChars, llvm::Constant *InitCst) {
assert(NextFieldOffsetInChars == FieldOffsetInChars &&
"Did not add enough padding!");
AlignedNextFieldOffsetInChars =
NextFieldOffsetInChars.RoundUpToAlignment(FieldAlignment);
}
if (AlignedNextFieldOffsetInChars > FieldOffsetInChars) {
assert(!Packed && "Alignment is wrong even with a packed struct!");
// Convert the struct to a packed struct.
ConvertStructToPacked();
AlignedNextFieldOffsetInChars = NextFieldOffsetInChars;
}