================
@@ -1938,6 +1938,27 @@ mlir::LogicalResult
CIRToLLVMPtrStrideOpLowering::matchAndRewrite(
return mlir::success();
}
+mlir::LogicalResult CIRToLLVMPtrMaskOpLowering::matchAndRewrite(
+ cir::PtrMaskOp op, OpAdaptor adaptor,
+ mlir::ConversionPatternRewriter &rewriter) const {
+ const mlir::Type resultTy = getTypeConverter()->convertType(op.getType());
+
+ // llvm.ptrmask requires the mask to be exactly the pointer index width, so
+ // resize it.
+ std::optional<uint64_t> indexWidth =
+ dataLayout.getTypeIndexBitwidth(adaptor.getPtr().getType());
+ assert(indexWidth && "!llvm.ptr always has an index width");
+
+ auto cirMaskTy = mlir::cast<cir::IntType>(op.getMask().getType());
+ mlir::Value mask = getLLVMIntCast(
----------------
adams381 wrote:
The quantity `llvm.ptrmask` is verified against is the pointer index width
rather than the pointer size, and CIR keeps those apart already:
`PointerType::getIndexBitwidth` returns the spec's index and falls back to the
size only when the index is unspecified. They differ for `__ptr32` on x86-64,
which is the address-space-271 module in the lowering test.
A verifier could get at that, since CIRGen attaches a DLTI spec and the
verifier could walk up to the module. What puts me off is that op validity
would then depend on a module attribute, so the same `cir.ptr_mask` would
verify or not depending on whether a layout is attached. Plenty of
hand-written CIR has none, including the round-trip test in this PR.
On the cost/benefit: for the producer this exists for, the resize never fires.
Classic builds the mask at `IntPtrTy` in `emitRoundPointerUpToAlignment`, the
x86-64 `va_arg` expansion will do the same, and `getLLVMIntCast` hands back the
operand untouched when the widths already match. So it costs three lines and
buys correct IR rather than a verifier failure if a later producer does not
know the target's index width. `cir.ptr_stride` also takes any fundamental
integer and resizes it through `convertToIndexTy`, so tightening `ptr_mask`
alone would make it the stricter of the two.
That is reasoning rather than strong conviction. If you would rather the op
demanded the mask at index width, I would put the check in the lowering as an
`errorNYI` instead of the verifier, for the module-attribute reason. Do you
think the tighter contract is worth making every producer know the target's
index width?
https://github.com/llvm/llvm-project/pull/224143
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