JDK-8154943 : AArch64: redundant address computation instructions with vectorization
- Type: Bug
- Component: hotspot
- Sub-Component: compiler
- Affected Version: 9
- Priority: P4
- Status: Resolved
- Resolution: Fixed
- CPU: aarch64
- Submitted: 2016-04-22
- Updated: 2019-09-16
- Resolved: 2016-05-04
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| JDK 9 |
|---|
9 b120Fixed  |
Related Reports
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Relates :
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Description
Example generated code:
;; B106: # B106 B107 <- B105 B106 Loop: B106-B106 inner main of N612 Freq: 293550
0x000003ffa9275650: sbfiz x0, x4, #3, #32
0x000003ffa9275654: add x3, x5, x0
0x000003ffa9275658: sbfiz x7, x4, #3, #32
0x000003ffa927565c: ldr q19, [x3,#16]
0x000003ffa9275660: add x19, x5, x7
0x000003ffa9275664: ldr q20, [x19,#32] ;*daload {reexecute=0 rethrow=0 return_oop=0}
; - jnt.scimark2.LU::factor@237 (line 235)
both sbfiz and add are strictly indentical and so fully redundant. The redundant instructions are caused by 2 ConvI2L nodes that are identical except for their type:
1984 ConvI2L _ 1683 [ 1987 ] debug_idx = 33701984 type = long: dump_spec = #long:minint..maxint-1:www
1678 ConvI2L _ 1683 [ 1672 ] bci = 49 debug_orig = dump_spec = #long:0..maxint-1:www debug_idx = 30401678 line = 183 type = long:
The type doesn't help code generation on arm so it could be widened and duplicated instructions could then be removed.