Mercurial > hg > truffle
changeset 6141:e7715c222897
7174532: jdk/test/java/lang/Math/WorstCaseTests.java failing on x86
Summary: increase precision on x86 for the steps of the computation of exp and pow.
Reviewed-by: kvn
author | roland |
---|---|
date | Tue, 12 Jun 2012 10:02:36 +0200 |
parents | d5dded5d1e0d |
children | 121e5708ae96 |
files | src/cpu/x86/vm/assembler_x86.cpp src/cpu/x86/vm/assembler_x86.hpp |
diffstat | 2 files changed, 23 insertions(+), 0 deletions(-) [+] |
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--- a/src/cpu/x86/vm/assembler_x86.cpp Mon Jun 11 22:38:28 2012 -0700 +++ b/src/cpu/x86/vm/assembler_x86.cpp Tue Jun 12 10:02:36 2012 +0200 @@ -6927,21 +6927,42 @@ addptr(rsp,sizeof(jdouble)); } +void MacroAssembler::increase_precision() { + subptr(rsp, BytesPerWord); + fnstcw(Address(rsp, 0)); + movl(rax, Address(rsp, 0)); + orl(rax, 0x300); + push(rax); + fldcw(Address(rsp, 0)); + pop(rax); +} + +void MacroAssembler::restore_precision() { + fldcw(Address(rsp, 0)); + addptr(rsp, BytesPerWord); +} + void MacroAssembler::fast_pow() { // computes X^Y = 2^(Y * log2(X)) // if fast computation is not possible, result is NaN. Requires // fallback from user of this macro. + // increase precision for intermediate steps of the computation + increase_precision(); fyl2x(); // Stack: (Y*log2(X)) ... pow_exp_core_encoding(); // Stack: exp(X) ... + restore_precision(); } void MacroAssembler::fast_exp() { // computes exp(X) = 2^(X * log2(e)) // if fast computation is not possible, result is NaN. Requires // fallback from user of this macro. + // increase precision for intermediate steps of the computation + increase_precision(); fldl2e(); // Stack: log2(e) X ... fmulp(1); // Stack: (X*log2(e)) ... pow_exp_core_encoding(); // Stack: exp(X) ... + restore_precision(); } void MacroAssembler::pow_or_exp(bool is_exp, int num_fpu_regs_in_use) {
--- a/src/cpu/x86/vm/assembler_x86.hpp Mon Jun 11 22:38:28 2012 -0700 +++ b/src/cpu/x86/vm/assembler_x86.hpp Tue Jun 12 10:02:36 2012 +0200 @@ -2395,6 +2395,8 @@ // runtime call. void fast_pow(); void fast_exp(); + void increase_precision(); + void restore_precision(); // computes exp(x). Fallback to runtime call included. void exp_with_fallback(int num_fpu_regs_in_use) { pow_or_exp(true, num_fpu_regs_in_use); }