X86: Make not taken conditional moves leave the destination alone. Adjust CMOVcc.

The manuals from both AMD and Intel say that when writing to a 32 bit
destination in 64 bit mode, the upper 32 bits of the register are filled with
zeros. They also both say that the CMOV instructions leave their destination
alone when their condition fails. Unfortunately, it seems that CMOV will zero
extend its destination register whether or not it was supposed to actually do
a move on both platforms. This seems to be the only case where this happens,
but it would be hard to say for sure.

2 files changed, 49 insertions, 1 deletions

diff --git a/src/arch/x86/isa/insts/general_purpose/data_transfer/conditional_move.py b/src/arch/x86/isa/insts/general_purpose/data_transfer/conditional_move.py
index 8a036ef58..264bbe370 100644
--- a/src/arch/x86/isa/insts/general_purpose/data_transfer/conditional_move.py
+++ b/src/arch/x86/isa/insts/general_purpose/data_transfer/conditional_move.py
@@ -56,12 +56,14 @@
 microcode = '''
 def macroop CMOVZ_R_R
 {
+    mov reg, reg, reg, flags=(nCZF,)
     mov reg, reg, regm, flags=(CZF,)
 };
 
 def macroop CMOVZ_R_M
 {
     ld t1, seg, sib, disp
+    mov reg, reg, reg, flags=(nCZF,)
     mov reg, reg, t1, flags=(CZF,)
 };
 
@@ -69,17 +71,20 @@ def macroop CMOVZ_R_P
 {
     rdip t7
     ld t1, seg, riprel, disp
+    mov reg, reg, reg, flags=(nCZF,)
     mov reg, reg, t1, flags=(CZF,)
 };
 
 def macroop CMOVNZ_R_R
 {
+    mov reg, reg, reg, flags=(CZF,)
     mov reg, reg, regm, flags=(nCZF,)
 };
 
 def macroop CMOVNZ_R_M
 {
     ld t1, seg, sib, disp
+    mov reg, reg, reg, flags=(CZF,)
     mov reg, reg, t1, flags=(nCZF,)
 };
 
@@ -87,17 +92,20 @@ def macroop CMOVNZ_R_P
 {
     rdip t7
     ld t1, seg, riprel, disp
+    mov reg, reg, reg, flags=(CZF,)
     mov reg, reg, t1, flags=(nCZF,)
 };
 
 def macroop CMOVB_R_R
 {
+    mov reg, reg, reg, flags=(nCCF,)
     mov reg, reg, regm, flags=(CCF,)
 };
 
 def macroop CMOVB_R_M
 {
     ld t1, seg, sib, disp
+    mov reg, reg, reg, flags=(nCCF,)
     mov reg, reg, t1, flags=(CCF,)
 };
 
@@ -105,17 +113,20 @@ def macroop CMOVB_R_P
 {
     rdip t7
     ld t1, seg, riprel, disp
+    mov reg, reg, reg, flags=(nCCF,)
     mov reg, reg, t1, flags=(CCF,)
 };
 
 def macroop CMOVNB_R_R
 {
+    mov reg, reg, reg, flags=(CCF,)
     mov reg, reg, regm, flags=(nCCF,)
 };
 
 def macroop CMOVNB_R_M
 {
     ld t1, seg, sib, disp
+    mov reg, reg, reg, flags=(CCF,)
     mov reg, reg, t1, flags=(nCCF,)
 };
 
@@ -123,17 +134,20 @@ def macroop CMOVNB_R_P
 {
     rdip t7
     ld t1, seg, riprel, disp
+    mov reg, reg, reg, flags=(CCF,)
     mov reg, reg, t1, flags=(nCCF,)
 };
 
 def macroop CMOVBE_R_R
 {
+    mov reg, reg, reg, flags=(nCCvZF,)
     mov reg, reg, regm, flags=(CCvZF,)
 };
 
 def macroop CMOVBE_R_M
 {
     ld t1, seg, sib, disp
+    mov reg, reg, reg, flags=(nCCvZF,)
     mov reg, reg, t1, flags=(CCvZF,)
 };
 
@@ -141,17 +155,20 @@ def macroop CMOVBE_R_P
 {
     rdip t7
     ld t1, seg, riprel, disp
+    mov reg, reg, reg, flags=(nCCvZF,)
     mov reg, reg, t1, flags=(CCvZF,)
 };
 
 def macroop CMOVNBE_R_R
 {
+    mov reg, reg, reg, flags=(CCvZF,)
     mov reg, reg, regm, flags=(nCCvZF,)
 };
 
 def macroop CMOVNBE_R_M
 {
     ld t1, seg, sib, disp
+    mov reg, reg, reg, flags=(CCvZF,)
     mov reg, reg, t1, flags=(nCCvZF,)
 };
 
@@ -159,17 +176,20 @@ def macroop CMOVNBE_R_P
 {
     rdip t7
     ld t1, seg, riprel, disp
+    mov reg, reg, reg, flags=(CCvZF,)
     mov reg, reg, t1, flags=(nCCvZF,)
 };
 
 def macroop CMOVS_R_R
 {
+    mov reg, reg, reg, flags=(nCSF,)
     mov reg, reg, regm, flags=(CSF,)
 };
 
 def macroop CMOVS_R_M
 {
     ld t1, seg, sib, disp
+    mov reg, reg, reg, flags=(nCSF,)
     mov reg, reg, t1, flags=(CSF,)
 };
 
@@ -177,17 +197,20 @@ def macroop CMOVS_R_P
 {
     rdip t7
     ld t1, seg, riprel, disp
+    mov reg, reg, reg, flags=(nCSF,)
     mov reg, reg, t1, flags=(CSF,)
 };
 
 def macroop CMOVNS_R_R
 {
+    mov reg, reg, reg, flags=(CSF,)
     mov reg, reg, regm, flags=(nCSF,)
 };
 
 def macroop CMOVNS_R_M
 {
     ld t1, seg, sib, disp
+    mov reg, reg, reg, flags=(CSF,)
     mov reg, reg, t1, flags=(nCSF,)
 };
 
@@ -195,17 +218,20 @@ def macroop CMOVNS_R_P
 {
     rdip t7
     ld t1, seg, riprel, disp
+    mov reg, reg, reg, flags=(CSF,)
     mov reg, reg, t1, flags=(nCSF,)
 };
 
 def macroop CMOVP_R_R
 {
+    mov reg, reg, reg, flags=(nCPF,)
     mov reg, reg, regm, flags=(CPF,)
 };
 
 def macroop CMOVP_R_M
 {
     ld t1, seg, sib, disp
+    mov reg, reg, reg, flags=(nCPF,)
     mov reg, reg, t1, flags=(CPF,)
 };
 
@@ -213,17 +239,20 @@ def macroop CMOVP_R_P
 {
     rdip t7
     ld t1, seg, riprel, disp
+    mov reg, reg, reg, flags=(nCPF,)
     mov reg, reg, t1, flags=(CPF,)
 };
 
 def macroop CMOVNP_R_R
 {
+    mov reg, reg, reg, flags=(CPF,)
     mov reg, reg, regm, flags=(nCPF,)
 };
 
 def macroop CMOVNP_R_M
 {
     ld t1, seg, sib, disp
+    mov reg, reg, reg, flags=(CPF,)
     mov reg, reg, t1, flags=(nCPF,)
 };
 
@@ -231,17 +260,20 @@ def macroop CMOVNP_R_P
 {
     rdip t7
     ld t1, seg, riprel, disp
+    mov reg, reg, reg, flags=(CPF,)
     mov reg, reg, t1, flags=(nCPF,)
 };
 
 def macroop CMOVL_R_R
 {
+    mov reg, reg, reg, flags=(nCSxOF,)
     mov reg, reg, regm, flags=(CSxOF,)
 };
 
 def macroop CMOVL_R_M
 {
     ld t1, seg, sib, disp
+    mov reg, reg, reg, flags=(nCSxOF,)
     mov reg, reg, t1, flags=(CSxOF,)
 };
 
@@ -249,17 +281,20 @@ def macroop CMOVL_R_P
 {
     rdip t7
     ld t1, seg, riprel, disp
+    mov reg, reg, reg, flags=(nCSxOF,)
     mov reg, reg, t1, flags=(CSxOF,)
 };
 
 def macroop CMOVNL_R_R
 {
+    mov reg, reg, reg, flags=(CSxOF,)
     mov reg, reg, regm, flags=(nCSxOF,)
 };
 
 def macroop CMOVNL_R_M
 {
     ld t1, seg, sib, disp
+    mov reg, reg, reg, flags=(CSxOF,)
     mov reg, reg, t1, flags=(nCSxOF,)
 };
 
@@ -267,17 +302,20 @@ def macroop CMOVNL_R_P
 {
     rdip t7
     ld t1, seg, riprel, disp
+    mov reg, reg, reg, flags=(CSxOF,)
     mov reg, reg, t1, flags=(nCSxOF,)
 };
 
 def macroop CMOVLE_R_R
 {
+    mov reg, reg, reg, flags=(nCSxOvZF,)
     mov reg, reg, regm, flags=(CSxOvZF,)
 };
 
 def macroop CMOVLE_R_M
 {
     ld t1, seg, sib, disp
+    mov reg, reg, reg, flags=(nCSxOvZF,)
     mov reg, reg, t1, flags=(CSxOvZF,)
 };
 
@@ -285,17 +323,20 @@ def macroop CMOVLE_R_P
 {
     rdip t7
     ld t1, seg, riprel, disp
+    mov reg, reg, reg, flags=(nCSxOvZF,)
     mov reg, reg, t1, flags=(CSxOvZF,)
 };
 
 def macroop CMOVNLE_R_R
 {
+    mov reg, reg, reg, flags=(CSxOvZF,)
     mov reg, reg, regm, flags=(nCSxOvZF,)
 };
 
 def macroop CMOVNLE_R_M
 {
     ld t1, seg, sib, disp
+    mov reg, reg, reg, flags=(CSxOvZF,)
     mov reg, reg, t1, flags=(nCSxOvZF,)
 };
 
@@ -303,17 +344,20 @@ def macroop CMOVNLE_R_P
 {
     rdip t7
     ld t1, seg, riprel, disp
+    mov reg, reg, reg, flags=(CSxOvZF,)
     mov reg, reg, t1, flags=(nCSxOvZF,)
 };
 
 def macroop CMOVO_R_R
 {
+    mov reg, reg, reg, flags=(nCOF,)
     mov reg, reg, regm, flags=(COF,)
 };
 
 def macroop CMOVO_R_M
 {
     ld t1, seg, sib, disp
+    mov reg, reg, reg, flags=(nCOF,)
     mov reg, reg, t1, flags=(COF,)
 };
 
@@ -321,17 +365,20 @@ def macroop CMOVO_R_P
 {
     rdip t7
     ld t1, seg, riprel, disp
+    mov reg, reg, reg, flags=(nCOF,)
     mov reg, reg, t1, flags=(COF,)
 };
 
 def macroop CMOVNO_R_R
 {
+    mov reg, reg, reg, flags=(COF,)
     mov reg, reg, regm, flags=(nCOF,)
 };
 
 def macroop CMOVNO_R_M
 {
     ld t1, seg, sib, disp
+    mov reg, reg, reg, flags=(COF,)
     mov reg, reg, t1, flags=(nCOF,)
 };
 
@@ -339,6 +386,7 @@ def macroop CMOVNO_R_P
 {
     rdip t7
     ld t1, seg, riprel, disp
+    mov reg, reg, reg, flags=(COF,)
     mov reg, reg, t1, flags=(nCOF,)
 };
 '''
diff --git a/src/arch/x86/isa/microops/regop.isa b/src/arch/x86/isa/microops/regop.isa
index 017ac49e4..a4cb6f4cc 100644
--- a/src/arch/x86/isa/microops/regop.isa
+++ b/src/arch/x86/isa/microops/regop.isa
@@ -639,7 +639,7 @@ let {{
 
     class Mov(CondRegOp):
         code = 'DestReg = merge(SrcReg1, op2, dataSize)'
-        else_code = 'DestReg = merge(DestReg, DestReg, dataSize);'
+        else_code = 'DestReg = DestReg;'
 
     # Shift instructions