[PATCH] D53540: [COFF, ARM64] Implement support for SEH extensions __try/__except/__finally

[Reid Kleckner via Phabricator via llvm-commits]

rnk added inline comments.


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Comment at: Target/AArch64/AArch64AsmPrinter.cpp:680
+    const MCExpr *Expr = Sym->getVariableValue();
+    assert(isa<MCConstantExpr>(Expr) &&
+             "Frame alloc symbol should be a constant");
----------------
efriedma wrote:
> rnk wrote:
> > I think this assertion will fail if you use localrecover before localescape. I would make a test case for that. Is there really not some pseudo instruction we can use so that the materialization can be relaxed by the assembler?
> > 
> > Otherwise, there's no point to using this MCSymbol hack. We might as well have a simpler side table if we retain the requirement that localescape be code generated first.
> > Is there really not some pseudo instruction we can use
> 
> The AArch64 assembler currently doesn't have any useful support for this sort of construct. Maybe it could be extended. (Is the value an arbitrary 64-bit integer, or is there some restriction on the possible values?)
These values are offsets from the FP (or SP) to a stack object, so they are typically small. If there are implementation limits on the size of an aarch64 stack frame, we can definitely use that to guide isel here.


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  https://reviews.llvm.org/D53540/new/

https://reviews.llvm.org/D53540