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Matthias Krüger
12c102ec53
Support reg_addr register class in s390x inline assembly In s390x, `r0` cannot be used as an address register (it is evaluated as zero in an address context). Therefore, currently, in assemblies involving memory accesses, `r0` must be [marked as clobbered](https://github.com/taiki-e/atomic-maybe-uninit/blob/1a1155653a26667396c805954ab61c8cbb14de8c/src/arch/s390x.rs#L58) or [explicitly used to a non-address](https://github.com/taiki-e/atomic-maybe-uninit/blob/1a1155653a26667396c805954ab61c8cbb14de8c/src/arch/s390x.rs#L135) or explicitly use an address register to prevent `r0` from being allocated to a register for the address. This patch adds a register class for allocating general-purpose registers, except `r0`, to make it easier to use address registers. (powerpc already has a register class (reg_nonzero) for a similar purpose.) This is identical to the `a` constraint in LLVM and GCC: https://llvm.org/docs/LangRef.html#supported-constraint-code-list > a: A 32, 64, or 128-bit integer address register (excludes R0, which in an address context evaluates as zero). https://gcc.gnu.org/onlinedocs/gcc/Machine-Constraints.html > a > Address register (general purpose register except r0) cc ``@uweigand`` r? ``@Amanieu``
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