[gem5-dev] Change in gem5/gem5[develop]: arch-x86: Move the step division helper out of the ISA desc.

[Gabe Black (Gerrit) via gem5-dev]

Gabe Black has uploaded this change for review. (  
https://gem5-review.googlesource.com/c/public/gem5/+/42362 )

Change subject: arch-x86: Move the step division helper out of the ISA desc.
......................................................................

arch-x86: Move the step division helper out of the ISA desc.

Change-Id: I3c5714d6485c3b000561bdaa478c9393bc844bca
---
M src/arch/x86/insts/static_inst.cc
M src/arch/x86/insts/static_inst.hh
M src/arch/x86/isa/microops/regop.isa
3 files changed, 35 insertions(+), 37 deletions(-)



diff --git a/src/arch/x86/insts/static_inst.cc  
b/src/arch/x86/insts/static_inst.cc
index 59c0089..2bd6b3d 100644
--- a/src/arch/x86/insts/static_inst.cc
+++ b/src/arch/x86/insts/static_inst.cc
@@ -120,6 +120,36 @@
 }

 void
+X86StaticInst::divideStep(uint64_t dividend, uint64_t divisor,
+        uint64_t &quotient, uint64_t &remainder)
+{
+    // Check for divide by zero.
+    assert(divisor != 0);
+    // If the divisor is bigger than the dividend, don't do anything.
+    if (divisor <= dividend) {
+        // Shift the divisor so it's msb lines up with the dividend.
+        int dividendMsb = findMsbSet(dividend);
+        int divisorMsb = findMsbSet(divisor);
+        int shift = dividendMsb - divisorMsb;
+        divisor <<= shift;
+        // Compute what we'll add to the quotient if the divisor isn't
+        // now larger than the dividend.
+        uint64_t quotientBit = 1;
+        quotientBit <<= shift;
+        // If we need to step back a bit (no pun intended) because the
+        // divisor got too to large, do that here. This is the "or two"
+        // part of one or two bit division.
+        if (divisor > dividend) {
+            quotientBit >>= 1;
+            divisor >>= 1;
+        }
+        // Decrement the remainder and increment the quotient.
+        quotient += quotientBit;
+        remainder -= divisor;
+    }
+}
+
+void
 X86StaticInst::printReg(std::ostream &os, RegId reg, int size)
 {
     assert(size == 1 || size == 2 || size == 4 || size == 8);
diff --git a/src/arch/x86/insts/static_inst.hh  
b/src/arch/x86/insts/static_inst.hh
index 8c70d05..ea9c249 100644
--- a/src/arch/x86/insts/static_inst.hh
+++ b/src/arch/x86/insts/static_inst.hh
@@ -119,6 +119,9 @@
     void printSrcReg(std::ostream &os, int reg, int size) const;
     void printDestReg(std::ostream &os, int reg, int size) const;

+    static void divideStep(uint64_t divident, uint64_t divisor,
+            uint64_t &quotient, uint64_t &remainder);
+
     static inline uint64_t
     merge(uint64_t into, RegIndex index, uint64_t val, int size)
     {
diff --git a/src/arch/x86/isa/microops/regop.isa  
b/src/arch/x86/isa/microops/regop.isa
index f83ec84..7e79b35 100644
--- a/src/arch/x86/isa/microops/regop.isa
+++ b/src/arch/x86/isa/microops/regop.isa
@@ -133,9 +133,6 @@
 }};

 output header {{
-    void divide(uint64_t dividend, uint64_t divisor,
-            uint64_t &quotient, uint64_t &remainder);
-
     enum SegmentSelectorCheck
     {
         SegNoCheck,
@@ -163,38 +160,6 @@
     };
 }};

-output decoder {{
-    void
-    divide(uint64_t dividend, uint64_t divisor,
-            uint64_t &quotient, uint64_t &remainder)
-    {
-        //Check for divide by zero.
-        assert(divisor != 0);
-        //If the divisor is bigger than the dividend, don't do anything.
-        if (divisor <= dividend) {
-            //Shift the divisor so it's msb lines up with the dividend.
-            int dividendMsb = findMsbSet(dividend);
-            int divisorMsb = findMsbSet(divisor);
-            int shift = dividendMsb - divisorMsb;
-            divisor <<= shift;
-            //Compute what we'll add to the quotient if the divisor isn't
-            //now larger than the dividend.
-            uint64_t quotientBit = 1;
-            quotientBit <<= shift;
-            //If we need to step back a bit (no pun intended) because the
-            //divisor got too to large, do that here. This is the "or two"
-            //part of one or two bit division.
-            if (divisor > dividend) {
-                quotientBit >>= 1;
-                divisor >>= 1;
-            }
-            //Decrement the remainder and increment the quotient.
-            quotient += quotientBit;
-            remainder -= divisor;
-        }
-    }
-}};
-
 let {{
     # Make these empty strings so that concatenating onto
     # them will always work.
@@ -681,7 +646,7 @@
             if (divisor == 0) {
                 fault = std::make_shared<DivideError>();
             } else {
-                divide(dividend, divisor, quotient, remainder);
+                divideStep(dividend, divisor, quotient, remainder);
                 //Record the final results.
                 Remainder = remainder;
                 Quotient = quotient;
@@ -736,7 +701,7 @@
                     }
                     remainder = dividend;
                     //Do the division.
-                    divide(dividend, divisor, quotient, remainder);
+                    divideStep(dividend, divisor, quotient, remainder);
                 }
             }
             //Keep track of how many bits there are still to pull in.

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Gerrit-Project: public/gem5
Gerrit-Branch: develop
Gerrit-Change-Id: I3c5714d6485c3b000561bdaa478c9393bc844bca
Gerrit-Change-Number: 42362
Gerrit-PatchSet: 1
Gerrit-Owner: Gabe Black <gabe.bl...@gmail.com>
Gerrit-MessageType: newchange
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