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6823354: Add intrinsics for {Integer,Long}.{numberOfLeadingZeros,numberOfTrailingZeros}()

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These methods can be instrinsified by using bit scan, bit test, and population count instructions.

Reviewed-by: kvn, never
This commit is contained in:
Christian Thalinger 2009-05-06 00:27:52 -07:00
parent 716c78f080
commit 6a270f9f19
15 changed files with 997 additions and 17 deletions
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10
hotspot/src/cpu/x86/vm/vm_version_x86.cpp
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@ -284,7 +284,7 @@ void VM_Version::get_processor_features() {
}
char buf[256];
jio_snprintf(buf, sizeof(buf), "(%u cores per cpu, %u threads per core) family %d model %d stepping %d%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s",
jio_snprintf(buf, sizeof(buf), "(%u cores per cpu, %u threads per core) family %d model %d stepping %d%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s",
cores_per_cpu(), threads_per_core(),
cpu_family(), _model, _stepping,
(supports_cmov() ? ", cmov" : ""),
@ -301,6 +301,7 @@ void VM_Version::get_processor_features() {
(supports_mmx_ext() ? ", mmxext" : ""),
(supports_3dnow() ? ", 3dnow" : ""),
(supports_3dnow2() ? ", 3dnowext" : ""),
(supports_lzcnt() ? ", lzcnt": ""),
(supports_sse4a() ? ", sse4a": ""),
(supports_ht() ? ", ht": ""));
_features_str = strdup(buf);
@ -364,6 +365,13 @@ void VM_Version::get_processor_features() {
UseXmmI2D = false;
}
}
// Use count leading zeros count instruction if available.
if (supports_lzcnt()) {
if (FLAG_IS_DEFAULT(UseCountLeadingZerosInstruction)) {
UseCountLeadingZerosInstruction = true;
}
}
}
if( is_intel() ) { // Intel cpus specific settings