8319973: AArch64: Save and restore FPCR in the call stub

Reviewed-by: aph

src/hotspot/cpu/aarch64/assembler_aarch64.hpp

@@ -1088,8 +1088,8 @@ class Assembler : public AbstractAssembler {
 #undef INSN
 
  // we only provide mrs and msr for the special purpose system
- // registers where op1 (instr[20:19]) == 11 and, (currently) only
- // use it for FPSR n.b msr has L (instr[21]) == 0 mrs has L == 1
+ // registers where op1 (instr[20:19]) == 11
+ // n.b msr has L (instr[21]) == 0 mrs has L == 1
 
  void msr(int op1, int CRn, int CRm, int op2, Register rt) {
  starti;

src/hotspot/cpu/aarch64/frame_aarch64.hpp

@@ -93,7 +93,7 @@
  // Entry frames
  // n.b. these values are determined by the layout defined in
  // stubGenerator for the Java call stub
- entry_frame_after_call_words = 27,
+ entry_frame_after_call_words = 29,
  entry_frame_call_wrapper_offset = -8,
 
  // we don't need a save area

src/hotspot/cpu/aarch64/macroAssembler_aarch64.hpp

@@ -570,6 +570,19 @@ class MacroAssembler: public Assembler {
  msr(0b011, 0b0100, 0b0100, 0b001, zr);
  }
 
+ // FPCR : op1 == 011
+ // CRn == 0100
+ // CRm == 0100
+ // op2 == 000
+
+ inline void get_fpcr(Register reg) {
+ mrs(0b11, 0b0100, 0b0100, 0b000, reg);
+ }
+
+ inline void set_fpcr(Register reg) {
+ msr(0b011, 0b0100, 0b0100, 0b000, reg);
+ }
+
  // DCZID_EL0: op1 == 011
  // CRn == 0000
  // CRm == 0000

src/hotspot/cpu/aarch64/stubGenerator_aarch64.cpp

@@ -136,7 +136,8 @@ class StubGenerator: public StubCodeGenerator {
  // [ return_from_Java ] <--- sp
  // [ argument word n ]
  // ...
- // -27 [ argument word 1 ]
+ // -29 [ argument word 1 ]
+ // -28 [ saved Floating-point Control Register ]
  // -26 [ saved v15 ] <--- sp_after_call
  // -25 [ saved v14 ]
  // -24 [ saved v13 ]
@@ -168,8 +169,9 @@ class StubGenerator: public StubCodeGenerator {
 
  // Call stub stack layout word offsets from fp
  enum call_stub_layout {
- sp_after_call_off = -26,
+ sp_after_call_off  = -28,
 
+ fpcr_off = sp_after_call_off,
  d15_off = -26,
  d13_off = -24,
  d11_off = -22,
@@ -199,8 +201,9 @@ class StubGenerator: public StubCodeGenerator {
  StubCodeMark mark(this, "StubRoutines", "call_stub");
  address start = __ pc();
 
- const Address sp_after_call(rfp, sp_after_call_off * wordSize);
+ const Address sp_after_call (rfp, sp_after_call_off * wordSize);
 
+ const Address fpcr_save (rfp, fpcr_off * wordSize);
  const Address call_wrapper (rfp, call_wrapper_off * wordSize);
  const Address result (rfp, result_off * wordSize);
  const Address result_type (rfp, result_type_off * wordSize);
@@ -249,6 +252,14 @@ class StubGenerator: public StubCodeGenerator {
  __ stpd(v13, v12, d13_save);
  __ stpd(v15, v14, d15_save);
 
+ __ get_fpcr(rscratch1);
+ __ str(rscratch1, fpcr_save);
+ // Set FPCR to the state we need. We do want Round to Nearest. We
+ // don't want non-IEEE rounding modes or floating-point traps.
+ __ bfi(rscratch1, zr, 22, 4); // Clear DN, FZ, and Rmode
+ __ bfi(rscratch1, zr, 8, 5); // Clear exception-control bits (8-12)
+ __ set_fpcr(rscratch1);
+
  // install Java thread in global register now we have saved
  // whatever value it held
  __ mov(rthread, c_rarg7);
@@ -362,6 +373,10 @@ class StubGenerator: public StubCodeGenerator {
  __ ldp(r22, r21, r22_save);
  __ ldp(r20, r19, r20_save);
 
+ // restore fpcr
+ __ ldr(rscratch1, fpcr_save);
+ __ set_fpcr(rscratch1);
+
  __ ldp(c_rarg0, c_rarg1, call_wrapper);
  __ ldrw(c_rarg2, result_type);
  __ ldr(c_rarg3, method);