X86: Distinguish between the rep and repe prefixes.

STOS and MOVS only accept the rep prefix which always loops until rcx becomes
0. The other string instructions accept repe (same encoding as rep) and repne
which also check the condition code flags each iteration.

--HG--
extra : convert_revision : 544149f640302070810fb53e53bfeb0e87160ffc

4 files changed, 33 insertions, 41 deletions

diff --git a/src/arch/x86/isa/decoder/one_byte_opcodes.isa b/src/arch/x86/isa/decoder/one_byte_opcodes.isa
index 0816eb175..f76912f06 100644
--- a/src/arch/x86/isa/decoder/one_byte_opcodes.isa
+++ b/src/arch/x86/isa/decoder/one_byte_opcodes.isa
@@ -332,8 +332,8 @@
             0x3: mov_Ov_rAX();
             0x4: StringInst::MOVS(Yb,Xb);
             0x5: StringInst::MOVS(Yv,Xv);
-            0x6: StringInst::CMPS(Yb,Xb);
-            0x7: StringInst::CMPS(Yv,Xv);
+            0x6: StringTestInst::CMPS(Yb,Xb);
+            0x7: StringTestInst::CMPS(Yv,Xv);
         }
         0x15: decode OPCODE_OP_BOTTOM3 {
             0x0: Inst::TEST(rAb,Ib);
@@ -342,8 +342,8 @@
             0x3: StringInst::STOS(Yv);
             0x4: lods_Al_Xb();
             0x5: lods_rAX_Xv();
-            0x6: StringInst::SCAS(Yb);
-            0x7: StringInst::SCAS(Yv);
+            0x6: StringTestInst::SCAS(Yb);
+            0x7: StringTestInst::SCAS(Yv);
         }
         format Inst {
             0x16: MOV(Bb,Ib);
diff --git a/src/arch/x86/isa/formats/string.isa b/src/arch/x86/isa/formats/string.isa
index cd182ff62..b1d3c4bbe 100644
--- a/src/arch/x86/isa/formats/string.isa
+++ b/src/arch/x86/isa/formats/string.isa
@@ -61,7 +61,7 @@
 //
 //////////////////////////////////////////////////////////////////////////
 
-def format StringInst(*opTypeSet) {{
+def format StringTestInst(*opTypeSet) {{
     allBlocks = OutputBlocks()
 
     regBlocks = specializeInst(Name, list(opTypeSet), EmulEnv())
@@ -86,3 +86,29 @@ def format StringInst(*opTypeSet) {{
     (header_output, decoder_output,
      decode_block, exec_output) = allBlocks.makeList()
 }};
+
+def format StringInst(*opTypeSet) {{
+    allBlocks = OutputBlocks()
+
+    regBlocks = specializeInst(Name, list(opTypeSet), EmulEnv())
+    eBlocks = specializeInst(Name + "_E", list(opTypeSet), EmulEnv())
+
+    for blocks in (regBlocks, eBlocks):
+        allBlocks.header_output += blocks.header_output
+        allBlocks.decoder_output += blocks.decoder_output
+        allBlocks.exec_output += blocks.exec_output
+
+    allBlocks.decode_block = '''
+        if (LEGACY_REP) {
+            %s
+        } else if (LEGACY_REPNE) {
+            // The repne prefix is illegal
+            return new MicroFault(machInst, "illprefix", new InvalidOpcode);
+        } else {
+            %s
+        }
+    ''' % (eBlocks.decode_block, regBlocks.decode_block)
+
+    (header_output, decoder_output,
+     decode_block, exec_output) = allBlocks.makeList()
+}};
diff --git a/src/arch/x86/isa/insts/general_purpose/string/move_string.py b/src/arch/x86/isa/insts/general_purpose/string/move_string.py
index 6a78a2cd4..b64acfdc2 100644
--- a/src/arch/x86/isa/insts/general_purpose/string/move_string.py
+++ b/src/arch/x86/isa/insts/general_purpose/string/move_string.py
@@ -82,25 +82,7 @@ topOfLoop:
     subi rcx, rcx, 1, flags=(EZF,), dataSize=asz
     add rdi, rdi, t3, dataSize=asz
     add rsi, rsi, t3, dataSize=asz
-    bri t0, label("topOfLoop"), flags=(CSTRZnEZF,)
-    fault "NoFault"
-};
-
-def macroop MOVS_N_M_M {
-    # Find the constant we need to either add or subtract from rdi
-    ruflag t0, 10
-    movi t3, t3, dsz, flags=(CEZF,), dataSize=asz
-    subi t4, t0, dsz, dataSize=asz
-    mov t3, t3, t4, flags=(nCEZF,), dataSize=asz
-
-topOfLoop:
-    ld t1, seg, [1, t0, rsi]
-    st t1, es, [1, t0, rdi]
-
-    subi rcx, rcx, 1, flags=(EZF,), dataSize=asz
-    add rdi, rdi, t3, dataSize=asz
-    add rsi, rsi, t3, dataSize=asz
-    bri t0, label("topOfLoop"), flags=(CSTRnZnEZF,)
+    bri t0, label("topOfLoop"), flags=(nCEZF,)
     fault "NoFault"
 };
 '''
diff --git a/src/arch/x86/isa/insts/general_purpose/string/store_string.py b/src/arch/x86/isa/insts/general_purpose/string/store_string.py
index a8655cf96..a8d558929 100644
--- a/src/arch/x86/isa/insts/general_purpose/string/store_string.py
+++ b/src/arch/x86/isa/insts/general_purpose/string/store_string.py
@@ -78,23 +78,7 @@ topOfLoop:
 
     subi rcx, rcx, 1, flags=(EZF,), dataSize=asz
     add rdi, rdi, t3, dataSize=asz
-    bri t0, label("topOfLoop"), flags=(CSTRZnEZF,)
-    fault "NoFault"
-};
-
-def macroop STOS_N_M {
-    # Find the constant we need to either add or subtract from rdi
-    ruflag t0, 10
-    movi t3, t3, dsz, flags=(CEZF,), dataSize=asz
-    subi t4, t0, dsz, dataSize=asz
-    mov t3, t3, t4, flags=(nCEZF,), dataSize=asz
-
-topOfLoop:
-    st rax, es, [1, t0, rdi]
-
-    subi rcx, rcx, 1, flags=(EZF,), dataSize=asz
-    add rdi, rdi, t3, dataSize=asz
-    bri t0, label("topOfLoop"), flags=(CSTRnZnEZF,)
+    bri t0, label("topOfLoop"), flags=(nCEZF,)
     fault "NoFault"
 };
 '''