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  1. JDK
  2. JDK-8294492

RISC-V: Use li instead of patchable movptr at non-patchable callsites

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    • Enhancement
    • Resolution: Fixed
    • P4
    • 20
    • 19, 20
    • hotspot
    • 19
    • b18
    • riscv
    • linux

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      Description

        A cleanup which can also reduce some code size. The main purpose is to separate mixed movptr usages: movptr's semantics allow it to be used for fixed-length patchable addresses. In the backend several places which are not patchable use movptr (6 instructions) as well, but that's unnecessary for we can use li(1~6 instructions) to substitute them.

        Originally some non-patchable callsites:
        ```
        ;; 0x401ab1dc40
        0x000000401372b324: lui t0,0x201
        0x000000401372b328: addi t0,t0,-680 # 0x0000000000200d58
        0x000000401372b32c: slli t0,t0,0xb
        0x000000401372b32e: addi t0,t0,1905
        0x000000401372b332: slli t0,t0,0x6
        0x000000401372b334: jalr t0
        ```
        Now:
        ```
        0x000000401b2bd9f4: lui t0,0x4003
        0x000000401b2bd9f8: addiw t0,t0,-1275
        0x000000401b2bd9fc: slli t0,t0,0xc
        0x000000401b2bda00: jalr 1080(t0) # 0x0000000004003438
        ```

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                xlinzheng Xiaolin Zheng
                xlinzheng Xiaolin Zheng
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                  Updated:
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