diff -r 7a963b8b0b30 -r 68578047307f src/arch/x86/isa/decoder/two_byte_opcodes.isa
--- a/src/arch/x86/isa/decoder/two_byte_opcodes.isa	Thu Mar 17 15:59:49 2011 -0700
+++ b/src/arch/x86/isa/decoder/two_byte_opcodes.isa	Tue Nov 03 16:55:16 2009 -0500
@@ -680,7 +680,7 @@
                     }
                     // repne (0xF2)
                     0x8: decode OPCODE_OP_BOTTOM3 {
-                        0x4: WarnUnimpl::haddps_Vo_Wo();
+                        0x4: HADDPS(Vo,Wo);
                         0x5: WarnUnimpl::hsubps_Vo_Wo();
                         default: UD2();
                     }
diff -r 7a963b8b0b30 -r 68578047307f src/arch/x86/isa/insts/simd128/floating_point/arithmetic/horizontal_addition.py
--- a/src/arch/x86/isa/insts/simd128/floating_point/arithmetic/horizontal_addition.py	Thu Mar 17 15:59:49 2011 -0700
+++ b/src/arch/x86/isa/insts/simd128/floating_point/arithmetic/horizontal_addition.py	Tue Nov 03 16:55:16 2009 -0500
@@ -36,7 +36,90 @@
 # Authors: Gabe Black
 
 microcode = '''
-# HADDPS
+def macroop HADDPS_XMM_XMM {
+    movfp ufp1, xmmh
+    msrli ufp1, ufp1, 32, size=8, ext=0
+    movfp ufp2, xmmh
+    maddf ufp3, ufp1, ufp2, size=4, ext=1
+    mslli ufp3, ufp3, 32, size=8, ext=0
+
+    movfp ufp1, xmml
+    msrli ufp1, ufp1, 32, size=8, ext=0
+    movfp ufp2, xmml
+    maddf ufp3, ufp1, ufp2, size=4, ext=1
+
+    movfp ufp1, xmmhm
+    msrli ufp1, ufp1, 32, size=8, ext=0
+    movfp ufp2, xmmhm
+    maddf ufp4, ufp1, ufp2, size=4, ext=1
+    mslli ufp4, ufp4, 32, size=8, ext=0
+
+    movfp ufp1, xmmlm
+    msrli ufp1, ufp1, 32, size=8, ext=0
+    movfp ufp2, xmmlm
+    maddf ufp4, ufp1, ufp2, size=4, ext=1
+
+    movfp xmml, ufp3
+    movfp xmmh, ufp4
+};
+
+def macroop HADDPS_XMM_M {
+    movfp ufp1, xmmh
+    msrli ufp1, ufp1, 32, size=8, ext=0
+    movfp ufp2, xmmh
+    maddf ufp3, ufp1, ufp2, size=4, ext=1
+    mslli ufp3, ufp3, 32, size=8, ext=0
+
+    movfp ufp1, xmml
+    msrli ufp1, ufp1, 32, size=8, ext=0
+    movfp ufp2, xmml
+    maddf ufp3, ufp1, ufp2, size=4, ext=1
+
+    movfp xmml, ufp3
+
+    ldfp ufp1, seg, sib, "DISPLACEMENT+8", dataSize=8
+    movfp ufp2, ufp1
+    msrli ufp1, ufp1, 32, size=8, ext=0
+    maddf ufp3, ufp1, ufp2, size=4, ext=1
+    mslli ufp3, ufp3, 32, size=8, ext=0
+
+    ldfp ufp1, seg, sib, disp, dataSize=8
+    movfp ufp2, ufp1
+    msrli ufp1, ufp1, 32, size=8, ext=0
+    maddf ufp3, ufp1, ufp2, size=4, ext=1
+
+    movfp xmmh, ufp3
+};
+
+def macroop HADDPS_XMM_P {
+    rdip t7
+
+    movfp ufp1, xmmh
+    msrli ufp1, ufp1, 32, size=8, ext=0
+    movfp ufp2, xmmh
+    maddf ufp3, ufp1, ufp2, size=4, ext=1
+    mslli ufp3, ufp3, 32, size=8, ext=0
+
+    movfp ufp1, xmml
+    msrli ufp1, ufp1, 32, size=8, ext=0
+    movfp ufp2, xmml
+    maddf ufp3, ufp1, ufp2, size=4, ext=1
+
+    movfp xmml, ufp3
+
+    ldfp ufp1, seg, riprel, "DISPLACEMENT+8", dataSize=8
+    movfp ufp2, ufp1
+    msrli ufp1, ufp1, 32, size=8, ext=0
+    maddf ufp3, ufp1, ufp2, size=4, ext=1
+    mslli ufp3, ufp3, 32, size=8, ext=0
+
+    ldfp ufp1, seg, riprel, disp, dataSize=8
+    movfp ufp2, ufp1
+    msrli ufp1, ufp1, 32, size=8, ext=0
+    maddf ufp3, ufp1, ufp2, size=4, ext=1
+
+    movfp xmmh, ufp3
+};
 
 def macroop HADDPD_XMM_XMM {
     maddf ufp1, xmmh , xmml, size=8, ext=Scalar