Changeset 50531 in webkit for trunk/JavaScriptCore/assembler/MacroAssemblerX86Common.h

Timestamp:

Nov 4, 2009, 3:59:14 PM (16 years ago)

Author:

[email protected]

Message:

​https://bugs.webkit.org/show_bug.cgi?id=31104
Refactor x86-specific behaviour out of the JIT.

Patch by Gavin Barraclough <​[email protected]> on 2009-11-04
Reviewed by Oliver Hunt.

• Add explicit double branch conditions for ordered and unordered comparisons (presently the brehaviour is a mix).
• Refactor double to int conversion out into the MacroAssembler.
• Remove broken double to int conversion for !JSVALUE32_64 builds - this code was broken and slowing us down, fixing it showed it not to be an improvement.
• Remove exclusion of double to int conversion from (1 % X) cases in JSVALUE32_64 builds - if this was of benefit this is no longer the case; simplify.

• assembler/MacroAssemblerARM.h:

(JSC::MacroAssemblerARM::):

• assembler/MacroAssemblerARMv7.h:

(JSC::MacroAssemblerARMv7::):

• assembler/MacroAssemblerX86Common.h:

(JSC::MacroAssemblerX86Common::):
(JSC::MacroAssemblerX86Common::convertInt32ToDouble):
(JSC::MacroAssemblerX86Common::branchDouble):
(JSC::MacroAssemblerX86Common::branchConvertDoubleToInt32):

• jit/JITArithmetic.cpp:

(JSC::JIT::emitBinaryDoubleOp):
(JSC::JIT::emit_op_div):
(JSC::JIT::emitSlow_op_jnless):
(JSC::JIT::emitSlow_op_jnlesseq):

• jit/JITOpcodes.cpp:

(JSC::JIT::emit_op_jfalse):

File:

• trunk/JavaScriptCore/assembler/MacroAssemblerX86Common.h (modified) (6 diffs)

trunk/JavaScriptCore/assembler/MacroAssemblerX86Common.h

@@ -37 +37 @@
 
 class MacroAssemblerX86Common : public AbstractMacroAssembler<X86Assembler> {
+    static const int DoubleConditionBitInvert = 0x10;
+    static const int DoubleConditionBitSpecial = 0x20;
+    static const int DoubleConditionBits = DoubleConditionBitInvert | DoubleConditionBitSpecial;
+
 public:
 
@@ -57 +61 @@
 
     enum DoubleCondition {
-        DoubleEqual = X86Assembler::ConditionE,
+        // These conditions will only evaluate to true if the comparison is ordered - i.e. neither operand is NaN.
+        DoubleEqual = X86Assembler::ConditionE | DoubleConditionBitSpecial,
         DoubleNotEqual = X86Assembler::ConditionNE,
         DoubleGreaterThan = X86Assembler::ConditionA,
         DoubleGreaterThanOrEqual = X86Assembler::ConditionAE,
-        DoubleLessThan = X86Assembler::ConditionB,
-        DoubleLessThanOrEqual = X86Assembler::ConditionBE,
+        DoubleLessThan = X86Assembler::ConditionA | DoubleConditionBitInvert,
+        DoubleLessThanOrEqual = X86Assembler::ConditionAE | DoubleConditionBitInvert,
+        // If either operand is NaN, these conditions always evaluate to true.
+        DoubleEqualOrUnordered = X86Assembler::ConditionE,
+        DoubleNotEqualOrUnordered = X86Assembler::ConditionNE | DoubleConditionBitSpecial,
+        DoubleGreaterThanOrUnordered = X86Assembler::ConditionB | DoubleConditionBitInvert,
+        DoubleGreaterThanOrEqualOrUnordered = X86Assembler::ConditionBE | DoubleConditionBitInvert,
+        DoubleLessThanOrUnordered = X86Assembler::ConditionB,
+        DoubleLessThanOrEqualOrUnordered = X86Assembler::ConditionBE,
     };
+    COMPILE_ASSERT(
+        !((X86Assembler::ConditionE | X86Assembler::ConditionNE | X86Assembler::ConditionA | X86Assembler::ConditionAE | X86Assembler::ConditionB | X86Assembler::ConditionBE) & DoubleConditionBits),
+        DoubleConditionBits_should_not_interfere_with_X86Assembler_Condition_codes);
 
     static const RegisterID stackPointerRegister = X86Registers::esp;
@@ -417 +432 @@
     void convertInt32ToDouble(Address src, FPRegisterID dest)
     {
+        ASSERT(isSSE2Present());
         m_assembler.cvtsi2sd_mr(src.offset, src.base, dest);
     }
@@ -423 +439 @@
     {
         ASSERT(isSSE2Present());
-        m_assembler.ucomisd_rr(right, left);
-        return Jump(m_assembler.jCC(x86Condition(cond)));
-    }
-
-    Jump branchDouble(DoubleCondition cond, FPRegisterID left, Address right)
-    {
-        m_assembler.ucomisd_mr(right.offset, right.base, left);
-        return Jump(m_assembler.jCC(x86Condition(cond)));
+
+        if (cond & DoubleConditionBitInvert)
+            m_assembler.ucomisd_rr(left, right);
+        else
+            m_assembler.ucomisd_rr(right, left);
+
+        if (cond == DoubleEqual) {
+            Jump isUnordered(m_assembler.jp());
+            Jump result = Jump(m_assembler.je());
+            isUnordered.link(this);
+            return result;
+        } else if (cond == DoubleNotEqualOrUnordered) {
+            Jump isUnordered(m_assembler.jp());
+            Jump isEqual(m_assembler.je());
+            isUnordered.link(this);
+            Jump result = jump();
+            isEqual.link(this);
+            return result;
+        }
+
+        ASSERT(!(cond & DoubleConditionBitSpecial));
+        return Jump(m_assembler.jCC(static_cast<X86Assembler::Condition>(cond & ~DoubleConditionBits)));
     }
 
@@ -442 +472 @@
         m_assembler.cvttsd2si_rr(src, dest);
         return branch32(Equal, dest, Imm32(0x80000000));
+    }
+
+    // Convert 'src' to an integer, and places the resulting 'dest'.
+    // If the result is not representable as a 32 bit value, branch.
+    // May also branch for some values that are representable in 32 bits
+    // (specifically, in this case, 0).
+    void branchConvertDoubleToInt32(FPRegisterID src, RegisterID dest, JumpList& failureCases, FPRegisterID fpTemp)
+    {
+        ASSERT(isSSE2Present());
+        m_assembler.cvttsd2si_rr(src, dest);
+
+        // If the result is zero, it might have been -0.0, and the double comparison won't catch this!
+        failureCases.append(branchTest32(Zero, dest));
+
+        // Convert the integer result back to float & compare to the original value - if not equal or unordered (NaN) then jump.
+        convertInt32ToDouble(dest, fpTemp);
+        m_assembler.ucomisd_rr(fpTemp, src);
+        failureCases.append(m_assembler.jp());
+        failureCases.append(m_assembler.jne());
     }
 
@@ -886 +935 @@
 protected:
     X86Assembler::Condition x86Condition(Condition cond)
-    {
-        return static_cast<X86Assembler::Condition>(cond);
-    }
-
-    X86Assembler::Condition x86Condition(DoubleCondition cond)
     {
         return static_cast<X86Assembler::Condition>(cond);