RFR: 8339741: RISC-V: C ABI breakage for integer on stack [v2]

[Robbin Ehn]

> Hi please review,
> 
> When calling a native function using integers smaller than 64,
> they must be loaded from a Java stack slot and widen to 64-bit, sign-extended.
> In the interpreter case we only store 32-bit, which means the top 32-bit are 'random'.
> In the compiler case we do an ld and grab random top 32-bit.
> These should be loaded with a lw from Java stack, thus proper sign extended and then stored with sd into the native stack.
> 
> I found the intrepter bug first, wrote a test case for it, which found the compiler bug.
> 
> Here you can see the difference, both are legal todo from a compiler:
> https://godbolt.org/z/85aMhja5f
> Relevant specs:
> https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-cc.adoc
>> integer scalars narrower than XLEN bits are widened according to the sign of their type up to 32 bits, then sign-extended to XLEN bits.
> 
> I checked floats also, they seems fine, but please go ahead and do a check regarding floats.
> 
> Passes ./test/hotspot/jtreg/compiler/calls/, runnnig t1.

Robbin Ehn has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Added comment
 - Merge branch 'master' into c_abi_error
 - Fixed

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/20912/files
  - new: https://git.openjdk.org/jdk/pull/20912/files/3afd24d9..6e738aa5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=20912&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=20912&range=00-01

  Stats: 1281 lines in 67 files changed: 769 ins; 235 del; 277 mod
  Patch: https://git.openjdk.org/jdk/pull/20912.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20912/head:pull/20912

PR: https://git.openjdk.org/jdk/pull/20912