X87: [wasm] Use the Float64Max/Min machine operators to implement F64Max/Min.

src/compiler/x87/code-generator-x87.cc

Index: src/compiler/x87/code-generator-x87.cc
diff --git a/src/compiler/x87/code-generator-x87.cc b/src/compiler/x87/code-generator-x87.cc
index 9b8b823be33beb2d5f76a603c40436a2251e0671..fa11dfcac21cf6459e7a187cbabadd32b91618bd 100644
--- a/src/compiler/x87/code-generator-x87.cc
+++ b/src/compiler/x87/code-generator-x87.cc
@@ -191,25 +191,47 @@ class OutOfLineLoadInteger final : public OutOfLineCode {
   Register const result_;
 };
 
-class OutOfLineLoadNaN final : public OutOfLineCode {
+class OutOfLineLoadFloat32NaN final : public OutOfLineCode {
  public:
-  OutOfLineLoadNaN(CodeGenerator* gen, X87Register result)
+  OutOfLineLoadFloat32NaN(CodeGenerator* gen, X87Register result)
       : OutOfLineCode(gen), result_(result) {}
 
   void Generate() final {
     DCHECK(result_.code() == 0);
     USE(result_);
     __ fstp(0);
-    __ push(Immediate(0xffffffff));

[ahaas, 2016/08/11 06:39:00]

I think you could also just push the default NaN instead of calculating it. The
default NaN for float64 is 0xfff8000000000000. For float32 it is 0xffc00000.

-    __ push(Immediate(0x7fffffff));
-    __ fld_d(MemOperand(esp, 0));
-    __ lea(esp, Operand(esp, kDoubleSize));
+    __ fldz();
+    __ fldz();
+    __ fdiv(1);
+    __ fstp(0);
+    __ lea(esp, Operand(esp, -kFloatSize));
+    __ fstp_s(MemOperand(esp, 0));
+    __ fld_s(MemOperand(esp, 0));
+    __ lea(esp, Operand(esp, kFloatSize));
   }
 
  private:
   X87Register const result_;
 };
 
+class OutOfLineLoadFloat64NaN final : public OutOfLineCode {
+ public:
+  OutOfLineLoadFloat64NaN(CodeGenerator* gen, X87Register result)
+      : OutOfLineCode(gen), result_(result) {}
+
+  void Generate() final {
+    DCHECK(result_.code() == 0);
+    USE(result_);
+    __ fstp(0);
+    __ fldz();
+    __ fldz();
+    __ fdiv(1);
+    __ fstp(0);
+  }
+
+ private:
+  X87Register const result_;
+};
 
 class OutOfLineTruncateDoubleToI final : public OutOfLineCode {
  public:
@@ -271,7 +293,7 @@ class OutOfLineRecordWrite final : public OutOfLineCode {
 
 }  // namespace
 
-#define ASSEMBLE_CHECKED_LOAD_FLOAT(asm_instr)                        \
+#define ASSEMBLE_CHECKED_LOAD_FLOAT(asm_instr, OutOfLineLoadNaN)      \
   do {                                                                \
     auto result = i.OutputDoubleRegister();                           \
     auto offset = i.InputRegister(0);                                 \
@@ -1295,7 +1317,8 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
       __ fld(1);
       __ FCmp();
 
-      auto ool = new (zone()) OutOfLineLoadNaN(this, i.OutputDoubleRegister());
+      auto ool =
+          new (zone()) OutOfLineLoadFloat64NaN(this, i.OutputDoubleRegister());
       __ j(parity_even, ool->entry());
       __ j(below, &done_compare, Label::kNear);
       __ j(above, &compare_swap, Label::kNear);
@@ -1330,7 +1353,8 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
       __ fld(1);
       __ FCmp();
 
-      auto ool = new (zone()) OutOfLineLoadNaN(this, i.OutputDoubleRegister());
+      auto ool =
+          new (zone()) OutOfLineLoadFloat64NaN(this, i.OutputDoubleRegister());
       __ j(parity_even, ool->entry());
       __ j(above, &done_compare, Label::kNear);
       __ j(below, &compare_swap, Label::kNear);
@@ -1898,10 +1922,10 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
       ASSEMBLE_CHECKED_LOAD_INTEGER(mov);
       break;
     case kCheckedLoadFloat32:
-      ASSEMBLE_CHECKED_LOAD_FLOAT(fld_s);
+      ASSEMBLE_CHECKED_LOAD_FLOAT(fld_s, OutOfLineLoadFloat32NaN);
       break;
     case kCheckedLoadFloat64:
-      ASSEMBLE_CHECKED_LOAD_FLOAT(fld_d);
+      ASSEMBLE_CHECKED_LOAD_FLOAT(fld_d, OutOfLineLoadFloat64NaN);
       break;
     case kCheckedStoreWord8:
       ASSEMBLE_CHECKED_STORE_INTEGER(mov_b);