Bug 516348 - nanojit: add findSpecificRegForUnallocated(). r=edwsmith.

--HG--
extra : convert_revision : 0e40a8977b80a96f9233488878589afcdfc8d800

js/src/nanojit/Assembler.cpp

@@ -417,6 +417,30 @@ namespace nanojit
         return r;
     }
 
+    // Like findSpecificRegFor(), but only for when 'r' is known to be free
+    // and 'ins' is known to not already have a register allocated.  Updates
+    // the register state (maintaining the invariants) but does not generate
+    // any code.  The return value is redundant, always being 'r', but it's
+    // sometimes useful to have it there for assignments.
+    Register Assembler::findSpecificRegForUnallocated(LIns* ins, Register r)
+    {
+        if (ins->isop(LIR_alloc)) {
+            // never allocate a reg for this w/out stack space too
+            findMemFor(ins);
+        }
+
+        NanoAssert(ins->isUnusedOrHasUnknownReg());
+        NanoAssert(_allocator.free & rmask(r));
+
+        if (!ins->isUsed())
+            ins->markAsUsed();
+        ins->setReg(r);
+        _allocator.removeFree(r);
+        _allocator.addActive(r, ins);
+
+        return r;
+    }
+ 
     int Assembler::findMemFor(LIns *ins)
     {
         if (!ins->isUsed())
@@ -1379,7 +1403,7 @@ namespace nanojit
         for (int i=0, n = NumSavedRegs; i < n; i++) {
             LIns *p = b->savedRegs[i];
             if (p)
-                findSpecificRegFor(p, savedRegs[p->paramArg()]);
+                findSpecificRegForUnallocated(p, savedRegs[p->paramArg()]);
         }
     }
 
@@ -1398,10 +1422,10 @@ namespace nanojit
     {
         LInsp state = _thisfrag->lirbuf->state;
         if (state)
-            findSpecificRegFor(state, argRegs[state->paramArg()]);
+            findSpecificRegForUnallocated(state, argRegs[state->paramArg()]);
         LInsp param1 = _thisfrag->lirbuf->param1;
         if (param1)
-            findSpecificRegFor(param1, argRegs[param1->paramArg()]);
+            findSpecificRegForUnallocated(param1, argRegs[param1->paramArg()]);
     }
 
     void Assembler::handleLoopCarriedExprs(InsList& pending_lives)

js/src/nanojit/Assembler.h

@@ -229,7 +229,8 @@ namespace nanojit
             Register    findRegFor(LIns* i, RegisterMask allow);
             void        findRegFor2(RegisterMask allow, LIns* ia, Reservation* &resva, LIns *ib, Reservation* &resvb);
             void        findRegFor2b(RegisterMask allow, LIns* ia, Register &ra, LIns *ib, Register &rb);
-            Register    findSpecificRegFor(LIns* i, Register w);
+            Register    findSpecificRegFor(LIns* i, Register r);
+            Register    findSpecificRegForUnallocated(LIns* i, Register r);
             Register    prepResultReg(LIns *i, RegisterMask allow);
             void        freeRsrcOf(LIns *i, bool pop);
             void        evictIfActive(Register r);

js/src/nanojit/Nativei386.cpp

@@ -870,7 +870,7 @@ namespace nanojit
         // if this is last use of lhs in reg, we can re-use result reg
         // else, lhs already has a register assigned.
         Register ra = ( lhs->isUnusedOrHasUnknownReg()
-                      ? findSpecificRegFor(lhs, rr)
+                      ? findSpecificRegForUnallocated(lhs, rr)
                       : lhs->getReg() );
 
         if (forceReg)
@@ -996,7 +996,7 @@ namespace nanojit
         // if this is last use of lhs in reg, we can re-use result reg
         // else, lhs already has a register assigned.
         Register ra = ( lhs->isUnusedOrHasUnknownReg()
-                      ? findSpecificRegFor(lhs, rr)
+                      ? findSpecificRegForUnallocated(lhs, rr)
                       : lhs->getReg() );
 
         if (op == LIR_not)
@@ -1048,12 +1048,12 @@ namespace nanojit
              * @todo -- If LHS is const, we could eliminate a register use.
              */
             Register rleft = ( lhs->isUnusedOrHasUnknownReg()
-                             ? findSpecificRegFor(lhs, rr)
+                             ? findSpecificRegForUnallocated(lhs, rr)
                              : lhs->getReg() );
 
             /* Does RHS have a register yet? If not, try to re-use the result reg. */
             Register rright = ( rr != rleft && rhs->isUnusedOrHasUnknownReg()
-                              ? findSpecificRegFor(rhs, rr)
+                              ? findSpecificRegForUnallocated(rhs, rr)
                               : findRegFor(rhs, GpRegs & ~(rmask(rleft))) );
 
             if (op == LIR_ldcb)
@@ -1268,7 +1268,7 @@ namespace nanojit
             // if this is last use of lhs in reg, we can re-use result reg
             // else, lhs already has a register assigned.
             if (lhs->isUnusedOrHasUnknownReg()) {
-                ra = findSpecificRegFor(lhs, rr);
+                ra = findSpecificRegForUnallocated(lhs, rr);
             } else {
                 ra = lhs->getReg();
                 if ((rmask(ra) & XmmRegs) == 0) {
@@ -1296,7 +1296,7 @@ namespace nanojit
             // if this is last use of lhs in reg, we can re-use result reg
             // else, lhs already has a different reg assigned
             if (lhs->isUnusedOrHasUnknownReg())
-                findSpecificRegFor(lhs, rr);
+                findSpecificRegForUnallocated(lhs, rr);
 
             NanoAssert(lhs->getReg()==FST0);
             // assume that the lhs is in ST(0) and rhs is on stack
@@ -1457,7 +1457,7 @@ namespace nanojit
 
             // if this is last use of lhs in reg, we can re-use result reg
             if (lhs->isUnusedOrHasUnknownReg()) {
-                ra = findSpecificRegFor(lhs, rr);
+                ra = findSpecificRegForUnallocated(lhs, rr);
             } else if ((rmask(lhs->getReg()) & XmmRegs) == 0) {
                 // We need this case on AMD64, because it's possible that
                 // an earlier instruction has done a quadword load and reserved a
@@ -1499,7 +1499,7 @@ namespace nanojit
             // last use of lhs in reg, can reuse rr
             // else, lhs already has a different reg assigned
             if (lhs->isUnusedOrHasUnknownReg())
-                findSpecificRegFor(lhs, rr);
+                findSpecificRegForUnallocated(lhs, rr);
 
             NanoAssert(lhs->getReg()==FST0);
             // assume that the lhs is in ST(0) and rhs is on stack
@@ -1747,7 +1747,7 @@ namespace nanojit
                 // compare two different numbers
                 int d = findMemFor(rhs);
                 int pop = lhs->isUnusedOrHasUnknownReg();
-                findSpecificRegFor(lhs, FST0);
+                findSpecificRegForUnallocated(lhs, FST0);
                 // lhs is in ST(0) and rhs is on stack
                 FCOM(pop, d, FP);
             }
@@ -1755,7 +1755,7 @@ namespace nanojit
             {
                 // compare n to itself, this is a NaN test.
                 int pop = lhs->isUnusedOrHasUnknownReg();
-                findSpecificRegFor(lhs, FST0);
+                findSpecificRegForUnallocated(lhs, FST0);
                 // value in ST(0)
                 if (pop)
                     FCOMPP();

js/src/nanojit/RegAlloc.h

@@ -74,6 +74,12 @@ namespace nanojit
             free |= rmask(r);
         }
 
+        void removeFree(Register r)
+        {
+            NanoAssert(isFree(r));
+            free &= ~rmask(r);
+        }
+
         void addActive(Register r, LIns* v)
         {
             //  Count++;