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comparison src/cpu/x86/vm/assembler_x86.cpp @ 6141:e7715c222897

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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 e2961d14584b
children 8c92982cbbc4
comparison
equal deleted inserted replaced
6140:d5dded5d1e0d 6141:e7715c222897
6925 movl(Address(rsp,0),0); 6925 movl(Address(rsp,0),0);
6926 fmul_d(Address(rsp,0)); // Stack: 2^X ... 6926 fmul_d(Address(rsp,0)); // Stack: 2^X ...
6927 addptr(rsp,sizeof(jdouble)); 6927 addptr(rsp,sizeof(jdouble));
6928 } 6928 }
6929 6929
6930 void MacroAssembler::increase_precision() {
6931 subptr(rsp, BytesPerWord);
6932 fnstcw(Address(rsp, 0));
6933 movl(rax, Address(rsp, 0));
6934 orl(rax, 0x300);
6935 push(rax);
6936 fldcw(Address(rsp, 0));
6937 pop(rax);
6938 }
6939
6940 void MacroAssembler::restore_precision() {
6941 fldcw(Address(rsp, 0));
6942 addptr(rsp, BytesPerWord);
6943 }
6944
6930 void MacroAssembler::fast_pow() { 6945 void MacroAssembler::fast_pow() {
6931 // computes X^Y = 2^(Y * log2(X)) 6946 // computes X^Y = 2^(Y * log2(X))
6932 // if fast computation is not possible, result is NaN. Requires 6947 // if fast computation is not possible, result is NaN. Requires
6933 // fallback from user of this macro. 6948 // fallback from user of this macro.
6949 // increase precision for intermediate steps of the computation
6950 increase_precision();
6934 fyl2x(); // Stack: (Y*log2(X)) ... 6951 fyl2x(); // Stack: (Y*log2(X)) ...
6935 pow_exp_core_encoding(); // Stack: exp(X) ... 6952 pow_exp_core_encoding(); // Stack: exp(X) ...
6953 restore_precision();
6936 } 6954 }
6937 6955
6938 void MacroAssembler::fast_exp() { 6956 void MacroAssembler::fast_exp() {
6939 // computes exp(X) = 2^(X * log2(e)) 6957 // computes exp(X) = 2^(X * log2(e))
6940 // if fast computation is not possible, result is NaN. Requires 6958 // if fast computation is not possible, result is NaN. Requires
6941 // fallback from user of this macro. 6959 // fallback from user of this macro.
6960 // increase precision for intermediate steps of the computation
6961 increase_precision();
6942 fldl2e(); // Stack: log2(e) X ... 6962 fldl2e(); // Stack: log2(e) X ...
6943 fmulp(1); // Stack: (X*log2(e)) ... 6963 fmulp(1); // Stack: (X*log2(e)) ...
6944 pow_exp_core_encoding(); // Stack: exp(X) ... 6964 pow_exp_core_encoding(); // Stack: exp(X) ...
6965 restore_precision();
6945 } 6966 }
6946 6967
6947 void MacroAssembler::pow_or_exp(bool is_exp, int num_fpu_regs_in_use) { 6968 void MacroAssembler::pow_or_exp(bool is_exp, int num_fpu_regs_in_use) {
6948 // kills rax, rcx, rdx 6969 // kills rax, rcx, rdx
6949 // pow and exp needs 2 extra registers on the fpu stack. 6970 // pow and exp needs 2 extra registers on the fpu stack.