MIPS64: [turbofan] Implemented the TruncateFloat32ToUint64 TurboFan operator.

Port 68cc0be2

Original commit message:
The TruncateFloat32ToUint64 operator converts a float32 to an uint64 using
round-to-zero rounding mode. If the input value is outside uint64 range, then
the result depends on the architecture. I provide an implementation for x64 and
arm64.

BUG=

Review URL: https://codereview.chromium.org/1481093003

Cr-Commit-Position: refs/heads/master@{#32383}

src/compiler/mips64/code-generator-mips64.cc

@@ -1035,6 +1035,12 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       __ Trunc_uw_d(i.InputDoubleRegister(0), i.OutputRegister(), scratch);
       break;
     }
+    case kMips64TruncUlS: {
+      FPURegister scratch = kScratchDoubleReg;
+      // TODO(plind): Fix wrong param order of Trunc_ul_s() macro-asm function.
+      __ Trunc_ul_s(i.InputDoubleRegister(0), i.OutputRegister(), scratch);
+      break;
+    }
     case kMips64TruncUlD: {
       FPURegister scratch = kScratchDoubleReg;
       // TODO(plind): Fix wrong param order of Trunc_ul_d() macro-asm function.

src/compiler/mips64/instruction-codes-mips64.h

@@ -82,6 +82,7 @@ namespace compiler {
   V(Mips64TruncLS)                  \
   V(Mips64TruncLD)                  \
   V(Mips64TruncUwD)                 \
+  V(Mips64TruncUlS)                 \
   V(Mips64TruncUlD)                 \
   V(Mips64CvtDW)                    \
   V(Mips64CvtSL)                    \

src/compiler/mips64/instruction-selector-mips64.cc

@@ -742,7 +742,7 @@ void InstructionSelector::VisitTruncateFloat64ToInt64(Node* node) {
 
 
 void InstructionSelector::VisitTruncateFloat32ToUint64(Node* node) {
-  UNIMPLEMENTED();
+  VisitRR(this, kMips64TruncUlS, node);
 }
 
 

src/mips64/macro-assembler-mips64.cc

@@ -1628,6 +1628,13 @@ void MacroAssembler::Trunc_ul_d(FPURegister fd, FPURegister fs,
 }
 
 
+void MacroAssembler::Trunc_ul_s(FPURegister fd, FPURegister fs,
+                                FPURegister scratch) {
+  Trunc_ul_s(fs, t8, scratch);
+  dmtc1(t8, fd);
+}
+
+
 void MacroAssembler::Trunc_w_d(FPURegister fd, FPURegister fs) {
   trunc_w_d(fd, fs);
 }
@@ -1686,7 +1693,7 @@ void MacroAssembler::Trunc_ul_d(FPURegister fd, Register rs,
   DCHECK(!fd.is(scratch));
   DCHECK(!rs.is(at));
 
-  // Load 2^63 into scratch as its float representation.
+  // Load 2^63 into scratch as its double representation.
   li(at, 0x43e0000000000000);
   dmtc1(at, scratch);
 
@@ -1712,6 +1719,37 @@ void MacroAssembler::Trunc_ul_d(FPURegister fd, Register rs,
 }
 
 
+void MacroAssembler::Trunc_ul_s(FPURegister fd, Register rs,
+                                FPURegister scratch) {
+  DCHECK(!fd.is(scratch));
+  DCHECK(!rs.is(at));
+
+  // Load 2^63 into scratch as its float representation.
+  li(at, 0x5f000000);
+  dmtc1(at, scratch);
+
+  // Test if scratch > fd.
+  // If fd < 2^63 we can convert it normally.
+  Label simple_convert, done;
+  BranchF32(&simple_convert, NULL, lt, fd, scratch);
+
+  // First we subtract 2^63 from fd, then trunc it to rs
+  // and add 2^63 to rs.
+  sub_s(scratch, fd, scratch);
+  trunc_l_s(scratch, scratch);
+  dmfc1(rs, scratch);
+  Or(rs, rs, Operand(1UL << 63));
+  Branch(&done);
+
+  // Simple conversion.
+  bind(&simple_convert);
+  trunc_l_s(scratch, fd);
+  dmfc1(rs, scratch);
+
+  bind(&done);
+}
+
+
 void MacroAssembler::Madd_d(FPURegister fd, FPURegister fr, FPURegister fs,
     FPURegister ft, FPURegister scratch) {
   if (0) {  // TODO(plind): find reasonable arch-variant symbol names.

src/mips64/macro-assembler-mips64.h

@@ -839,6 +839,10 @@ class MacroAssembler: public Assembler {
   void Trunc_ul_d(FPURegister fd, FPURegister fs, FPURegister scratch);
   void Trunc_ul_d(FPURegister fd, Register rs, FPURegister scratch);
 
+  // Convert single to unsigned long.
+  void Trunc_ul_s(FPURegister fd, FPURegister fs, FPURegister scratch);
+  void Trunc_ul_s(FPURegister fd, Register rs, FPURegister scratch);
+
   void Trunc_w_d(FPURegister fd, FPURegister fs);
   void Round_w_d(FPURegister fd, FPURegister fs);
   void Floor_w_d(FPURegister fd, FPURegister fs);