Mercurial > jdk8-mips64-public > hotspot / file comparison
comparison: src/cpu/x86/vm/vm_version_x86.cpp
src/cpu/x86/vm/vm_version_x86.cpp
- changeset 7269
- e48395e6a91b
- parent 7152
- 166d744df0de
- child 7535
- 7ae4e26cb1e0
- child 8307
- daaf806995b3
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| 7268:af6ff94a005d | 7269:e48395e6a91b |
|---|---|
| 871 | 871 |
| 872 // Use count trailing zeros instruction if available | 872 // Use count trailing zeros instruction if available |
| 873 if (supports_bmi1()) { | 873 if (supports_bmi1()) { |
| 874 // tzcnt does not require VEX prefix | 874 // tzcnt does not require VEX prefix |
| 875 if (FLAG_IS_DEFAULT(UseCountTrailingZerosInstruction)) { | 875 if (FLAG_IS_DEFAULT(UseCountTrailingZerosInstruction)) { |
| 876 UseCountTrailingZerosInstruction = true; | 876 if (!UseBMI1Instructions && !FLAG_IS_DEFAULT(UseBMI1Instructions)) { |
| 877 // Don't use tzcnt if BMI1 is switched off on command line. | |
| 878 UseCountTrailingZerosInstruction = false; | |
| 879 } else { | |
| 880 UseCountTrailingZerosInstruction = true; | |
| 881 } | |
| 877 } | 882 } |
| 878 } else if (UseCountTrailingZerosInstruction) { | 883 } else if (UseCountTrailingZerosInstruction) { |
| 879 warning("tzcnt instruction is not available on this CPU"); | 884 warning("tzcnt instruction is not available on this CPU"); |
| 880 FLAG_SET_DEFAULT(UseCountTrailingZerosInstruction, false); | 885 FLAG_SET_DEFAULT(UseCountTrailingZerosInstruction, false); |
| 881 } | 886 } |
| 882 | 887 |
| 883 // BMI instructions use an encoding with VEX prefix. | 888 // BMI instructions (except tzcnt) use an encoding with VEX prefix. |
| 884 // VEX prefix is generated only when AVX > 0. | 889 // VEX prefix is generated only when AVX > 0. |
| 885 if (supports_bmi1() && supports_avx()) { | 890 if (supports_bmi1() && supports_avx()) { |
| 886 if (FLAG_IS_DEFAULT(UseBMI1Instructions)) { | 891 if (FLAG_IS_DEFAULT(UseBMI1Instructions)) { |
| 887 UseBMI1Instructions = true; | 892 UseBMI1Instructions = true; |
| 888 } | 893 } |
