Changeset 154158 in webkit for trunk/Source/JavaScriptCore/assembler

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):

Location:

trunk/Source/JavaScriptCore/assembler

Files:

• MacroAssemblerX86Common.h (modified) (2 diffs)
• MacroAssemblerX86_64.h (modified) (2 diffs)
• X86Assembler.h (modified) (1 diff)

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);
     }
     

trunk/Source/JavaScriptCore/assembler/MacroAssemblerX86_64.h

@@ -184 +184 @@
     void add64(TrustedImm32 imm, RegisterID srcDest)
     {
-        m_assembler.addq_ir(imm.m_value, srcDest);
+        if (imm.m_value == 1)
+            m_assembler.incq_r(srcDest);
+        else
+            m_assembler.addq_ir(imm.m_value, srcDest);
     }
 
     void add64(TrustedImm64 imm, RegisterID dest)
     {
-        move(imm, scratchRegister);
-        add64(scratchRegister, dest);
+        if (imm.m_value == 1)
+            m_assembler.incq_r(dest);
+        else {
+            move(imm, scratchRegister);
+            add64(scratchRegister, dest);
+        }
     }
 
@@ -270 +277 @@
     void sub64(TrustedImm32 imm, RegisterID dest)
     {
-        m_assembler.subq_ir(imm.m_value, dest);
+        if (imm.m_value == 1)
+            m_assembler.decq_r(dest);
+        else
+            m_assembler.subq_ir(imm.m_value, dest);
     }
     
     void sub64(TrustedImm64 imm, RegisterID dest)
     {
-        move(imm, scratchRegister);
-        sub64(scratchRegister, dest);
+        if (imm.m_value == 1)
+            m_assembler.decq_r(dest);
+        else {
+            move(imm, scratchRegister);
+            sub64(scratchRegister, dest);
+        }
     }
 

trunk/Source/JavaScriptCore/assembler/X86Assembler.h

@@ -501 +501 @@
 #endif
 
+    void dec_r(RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_GROUP5_Ev, GROUP1_OP_OR, dst);
+    }
+
+    void decq_r(RegisterID dst)
+    {
+        m_formatter.oneByteOp64(OP_GROUP5_Ev, GROUP1_OP_OR, dst);
+    }
+
+    void inc_r(RegisterID dst)
+    {
+        m_formatter.oneByteOp(OP_GROUP5_Ev, GROUP1_OP_ADD, dst);
+    }
+
+    void incq_r(RegisterID dst)
+    {
+        m_formatter.oneByteOp64(OP_GROUP5_Ev, GROUP1_OP_ADD, dst);
+    }
+
     void negl_r(RegisterID dst)
     {