Changeset 154158 in webkit for trunk/Source/JavaScriptCore/assembler/MacroAssemblerX86Common.h

Timestamp:

Aug 15, 2013, 7:35:31 PM (12 years ago)

Author:

[email protected]

Message:

[JSC] x86: Use inc and dec when possible
​https://bugs.webkit.org/show_bug.cgi?id=119831

Reviewed by Geoffrey Garen.

When incrementing or decrementing by an immediate of 1, use the insctructions
inc and dec instead of add and sub.
The instructions have good timing and their encoding is smaller.

• assembler/MacroAssemblerX86Common.h:

(JSC::MacroAssemblerX86_64::add32):
(JSC::MacroAssemblerX86_64::sub32):

• assembler/MacroAssemblerX86_64.h:

(JSC::MacroAssemblerX86_64::add64):
(JSC::MacroAssemblerX86_64::sub64):

• assembler/X86Assembler.h:

(JSC::X86Assembler::dec_r):
(JSC::X86Assembler::decq_r):
(JSC::X86Assembler::inc_r):
(JSC::X86Assembler::incq_r):

File:

• trunk/Source/JavaScriptCore/assembler/MacroAssemblerX86Common.h (modified) (2 diffs)

trunk/Source/JavaScriptCore/assembler/MacroAssemblerX86Common.h

@@ -128 +128 @@
     void add32(TrustedImm32 imm, RegisterID dest)
     {
-        m_assembler.addl_ir(imm.m_value, dest);
+        if (imm.m_value == 1)
+            m_assembler.inc_r(dest);
+        else
+            m_assembler.addl_ir(imm.m_value, dest);
     }
     
@@ -375 +378 @@
     void sub32(TrustedImm32 imm, RegisterID dest)
     {
-        m_assembler.subl_ir(imm.m_value, dest);
+        if (imm.m_value == 1)
+            m_assembler.dec_r(dest);
+        else
+            m_assembler.subl_ir(imm.m_value, dest);
     }