MIPS: port ARM: Fix context save/restore for VFP registers.

src/mips/macro-assembler-mips.cc

Index: src/mips/macro-assembler-mips.cc
diff --git a/src/mips/macro-assembler-mips.cc b/src/mips/macro-assembler-mips.cc
index c7f727bef604e1e0eff71ff0987b00b57f5d2c56..606b41db28fd42850fa9cb7cc3d371b4a490b0e1 100644
--- a/src/mips/macro-assembler-mips.cc
+++ b/src/mips/macro-assembler-mips.cc
@@ -752,6 +752,64 @@ void MacroAssembler::MultiPopReversed(RegList regs) {
 }
 
 
+void MacroAssembler::MultiPushFPU(RegList regs) {
+  CpuFeatures::Scope scope(FPU);
+  int16_t NumSaved = 0;
+  int16_t NumToPush = NumberOfBitsSet(regs);
+
+  addiu(sp, sp, -8 * NumToPush);
+  for (int16_t i = kNumRegisters; i > 0; i--) {
+    if ((regs & (1 << i)) != 0) {
+      sdc1(FPURegister::from_code(i),
+           MemOperand(sp, 8 * (NumToPush - ++NumSaved)));
+    }
+  }

[Yang, 2011/08/31 12:38:44]

Consider - for readability - introducing a stack_offset variable to keep track
where to store the next register. For example:

int16_t NumToPush = NumberOfBitsSet(regs);
int16_t stack_offset = NumToPush * 8;

addiu(sp, sp, -8 * NumToPush);
for (int16_t i = kNumRegisters; i > 0; i--) {
  if ((regs & (1 << i)) != 0) {
    stack_offset -= 8;
    sdc1(FPURegister::from_code(i),
         MemOperand(sp, stack_offset));
  }
}

Also consider using kDoubleSize instead of the constant 8.

Maybe those non-FPU MultiPush and MultiPop commands can be refactored as well?

[Paul Lind, 2011/09/01 06:50:27]

Nice suggestion, the code looks much cleaner now. I updated all the Multi's ...

BTW, mips does not have a subiu instruction. The addiu takes a signed 16-bit
immediate, so it can be used for subtract. I changed to use the Subu()
macro-instruction, which emits addiu with negative immediate value, to make it
more obvious in the code we are subtracting (more obvious than - sign.)

+}
+
+
+void MacroAssembler::MultiPushReversedFPU(RegList regs) {
+  CpuFeatures::Scope scope(FPU);
+  int16_t NumSaved = 0;
+  int16_t NumToPush = NumberOfBitsSet(regs);
+
+  addiu(sp, sp, -8 * NumToPush);
+  for (int16_t i = 0; i < kNumRegisters; i++) {
+    if ((regs & (1 << i)) != 0) {
+      sdc1(FPURegister::from_code(i),
+           MemOperand(sp, 8 * (NumToPush - ++NumSaved)));
+    }
+  }
+}
+
+
+void MacroAssembler::MultiPopFPU(RegList regs) {
+  CpuFeatures::Scope scope(FPU);
+  int16_t NumSaved = 0;
+
+  for (int16_t i = 0; i < kNumRegisters; i++) {
+    if ((regs & (1 << i)) != 0) {
+      ldc1(FPURegister::from_code(i),
+           MemOperand(sp, 8 * (NumSaved++)));
+    }
+  }
+  addiu(sp, sp, 8 * NumSaved);
+}
+
+
+void MacroAssembler::MultiPopReversedFPU(RegList regs) {
+  CpuFeatures::Scope scope(FPU);
+  int16_t NumSaved = 0;
+
+  for (int16_t i = kNumRegisters; i > 0; i--) {
+    if ((regs & (1 << i)) != 0) {
+      ldc1(FPURegister::from_code(i),
+           MemOperand(sp, 8 * (NumSaved++)));
+    }
+  }
+  addiu(sp, sp, 8 * NumSaved);
+}
+
+
 void MacroAssembler::Ext(Register rt,
                          Register rs,
                          uint16_t pos,