Changeset 154207 in webkit for trunk/Source/JavaScriptCore/assembler/MacroAssemblerX86Common.h

Timestamp:

Aug 16, 2013, 4:34:21 PM (12 years ago)

Author:

[email protected]

Message:

[JSC] x86: improve code generation for xxxTest32
​https://bugs.webkit.org/show_bug.cgi?id=119876

Reviewed by Geoffrey Garen.

Try to use testb whenever possible when testing for an immediate value.

When the input is an address and an offset, we can tweak the mask
and offset to be able to generate testb for any byte of the mask.

When the input is a register, we can use testb if we are only interested
in testing the low bits.

• assembler/MacroAssemblerX86Common.h:

(JSC::MacroAssemblerX86Common::branchTest32):
(JSC::MacroAssemblerX86Common::test32):
(JSC::MacroAssemblerX86Common::generateTest32):

File:

• trunk/Source/JavaScriptCore/assembler/MacroAssemblerX86Common.h (modified) (4 diffs)

trunk/Source/JavaScriptCore/assembler/MacroAssemblerX86Common.h

@@ -1139 +1139 @@
     Jump branchTest32(ResultCondition cond, RegisterID reg, TrustedImm32 mask = TrustedImm32(-1))
     {
-        // if we are only interested in the low seven bits, this can be tested with a testb
         if (mask.m_value == -1)
             m_assembler.testl_rr(reg, reg);
+        else if (!(mask.m_value & ~0xff))
+            m_assembler.testb_i8r(mask.m_value, reg);
         else
             m_assembler.testl_i32r(mask.m_value, reg);
@@ -1149 +1150 @@
     Jump branchTest32(ResultCondition cond, Address address, TrustedImm32 mask = TrustedImm32(-1))
     {
-        if (mask.m_value == -1)
-            m_assembler.cmpl_im(0, address.offset, address.base);
-        else
-            m_assembler.testl_i32m(mask.m_value, address.offset, address.base);
+        generateTest32(address, mask);
         return Jump(m_assembler.jCC(x86Condition(cond)));
     }
@@ -1420 +1418 @@
     void test32(ResultCondition cond, Address address, TrustedImm32 mask, RegisterID dest)
     {
-        if (mask.m_value == -1)
-            m_assembler.cmpl_im(0, address.offset, address.base);
-        else
-            m_assembler.testl_i32m(mask.m_value, address.offset, address.base);
+        generateTest32(address, mask);
         set32(x86Condition(cond), dest);
     }
@@ -1504 +1499 @@
     // x86_64, and clients & subclasses of MacroAssembler should be using 'supportsFloatingPoint()'.
     friend class MacroAssemblerX86;
+
+    ALWAYS_INLINE void generateTest32(Address address, TrustedImm32 mask = TrustedImm32(-1))
+    {
+        if (mask.m_value == -1)
+            m_assembler.cmpl_im(0, address.offset, address.base);
+        else if (!(mask.m_value & ~0xff))
+            m_assembler.testb_im(mask.m_value, address.offset, address.base);
+        else if (!(mask.m_value & ~0xff00))
+            m_assembler.testb_im(mask.m_value >> 8, address.offset + 1, address.base);
+        else if (!(mask.m_value & ~0xff0000))
+            m_assembler.testb_im(mask.m_value >> 16, address.offset + 2, address.base);
+        else if (!(mask.m_value & ~0xff000000))
+            m_assembler.testb_im(mask.m_value >> 24, address.offset + 3, address.base);
+        else
+            m_assembler.testl_i32m(mask.m_value, address.offset, address.base);
+    }
 
 #if CPU(X86)