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Type:
Enhancement
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Resolution: Fixed
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Priority:
P4
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Affects Version/s: 22
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Component/s: hotspot
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b07
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riscv
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linux
| Issue | Fix Version | Assignee | Priority | Status | Resolution | Resolved In Build |
|---|---|---|---|---|---|---|
| JDK-8312389 | 21.0.1 | Vladimir Kempik | P4 | Resolved | Fixed | b04 |
| JDK-8312219 | 17.0.9 | Vladimir Kempik | P4 | Resolved | Fixed | b01 |
We sometimes emit this code in risc-v backend:
slli Rd, Rs, 0
(for example we do this in String.IndexOf intrinsic)
it's an equivalent of addi Rd, Rs, 0 ( a synonym for mv Rd, Rs)
addi with 0 has higher chances to be just a register renaming in decoder and not utilise ALU.
We observed some positive effect of replacing slli by 0 with addi on hifive.
slli Rd, Rs, 0
(for example we do this in String.IndexOf intrinsic)
it's an equivalent of addi Rd, Rs, 0 ( a synonym for mv Rd, Rs)
addi with 0 has higher chances to be just a register renaming in decoder and not utilise ALU.
We observed some positive effect of replacing slli by 0 with addi on hifive.
- backported by
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JDK-8312219 RISC-V: small improvements to shift immediate instructions
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- Resolved
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- Resolved
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- links to
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Commit
openjdk/jdk17u-dev/d79c2ef1
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Commit
openjdk/jdk21u/1776b3d2
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Commit
openjdk/jdk/f3b96f69
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Review
openjdk/jdk17u-dev/1584
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Review
openjdk/jdk21u/10
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Review
openjdk/jdk/14823
(3 links to)