JDK-7063628 : Use cbcond on T4
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: hs22
  • Priority: P4
  • Status: Closed
  • Resolution: Fixed
  • OS: generic
  • CPU: sparc
  • Submitted: 2011-07-07
  • Updated: 2011-11-25
  • Resolved: 2011-09-30
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JDK 7 JDK 8 Other
7u2Fixed 8Fixed hs22Fixed
Related Reports
Relates :  
T4 has new short branch instruction without delay slot. Add it to hotspot sparc assembler. I will file separate rfe to use cbcond in C2 generated code.


EVALUATION http://hg.openjdk.java.net/hsx/hotspot-rt/hotspot/rev/3d42f82cd811

PUBLIC COMMENTS Added new MacroAssembler instructions cmp_and_br() and old branch instructions are modified to use cbcond on T4 if distance is small (2K bytes). Most of the rest changes are usage of these new branch instructions in Interpreter and C1. The prototype was done by Tom and I took some of his additional fixes. The formssel.cpp change is a bug fix where the MatchNode equality test wasn't recursing so it would mistakenly return true for complex matches. Added a fake label for branches generated in temp buffer by MachNode::emit_size(), added assert into .ad files to check label. There was problem in is_in_wdisp16_range() (and in initial implementation of use_cbc()) which calls target(L) before emitting branch. Non-bound (forward branch) labels record current pc() as a branch address and later try to patch instruction (which could be 'cmp') at that address. Removed unused code in check_klass_subtype_fast_path(). Modified vm_version string: has_ prefix is removed and only v8 or v9 will be printed as well only niagara_plus or niagara.

EVALUATION http://hg.openjdk.java.net/hsx/hotspot-comp/hotspot/rev/3d42f82cd811