[dev.ssa] cmd/internal/ssa: implement global variables

Fix a few compilation errors due to previous merge from tip.

Change-Id: I826ad5a9d602a8f8be2762ad00b030dea6f41bcc
Reviewed-on: https://go-review.googlesource.com/9967Reviewed-by: Alan Donovan <adonovan@google.com>

src/cmd/internal/gc/ssa.go

@@ -153,12 +153,16 @@ func (s *ssaState) stmt(n *Node) {
 
 			// TODO(khr): nil check
 			s.vars[".mem"] = s.curBlock.NewValue3(ssa.OpStore, n.Right.Type, nil, addr, val, s.mem())
-		} else if n.Left.Addable == 0 {
+		} else if !n.Left.Addable {
 			// TODO
 			log.Fatalf("assignment to non-addable value")
 		} else if n.Left.Class&PHEAP != 0 {
 			// TODO
 			log.Fatalf("assignment to heap value")
+		} else if n.Left.Class == PEXTERN {
+			// assign to global variable
+			addr := s.f.Entry.NewValue(ssa.OpGlobal, Ptrto(n.Left.Type), n.Left.Sym)
+			s.vars[".mem"] = s.curBlock.NewValue3(ssa.OpStore, ssa.TypeMem, nil, addr, val, s.mem())
 		} else if n.Left.Class == PPARAMOUT {
 			// store to parameter slot
 			addr := s.f.Entry.NewValue(ssa.OpFPAddr, Ptrto(n.Right.Type), n.Left.Xoffset)
@@ -254,7 +258,12 @@ func (s *ssaState) expr(n *Node) *ssa.Value {
 	}
 	switch n.Op {
 	case ONAME:
-		// remember offsets for PPARAM names
+		// TODO: remember offsets for PPARAM names
+		if n.Class == PEXTERN {
+			// global variable
+			addr := s.f.Entry.NewValue(ssa.OpGlobal, Ptrto(n.Type), n.Sym)
+			return s.curBlock.NewValue2(ssa.OpLoad, n.Type, nil, addr, s.mem())
+		}
 		s.argOffsets[n.Sym.Name] = n.Xoffset
 		return s.variable(n.Sym.Name, n.Type)
 		// binary ops

src/cmd/internal/gc/type.go

@@ -56,7 +56,3 @@ func (t *Type) PtrTo() ssa.Type {
 
 func (t *Type) IsMemory() bool { return false }
 func (t *Type) IsFlags() bool  { return false }
-
-func (t *Type) String() string {
-	return typefmt(t, 0)
-}

src/cmd/internal/ssa/lowerAmd64.go

@@ -333,6 +333,26 @@ func lowerAmd64(v *Value) bool {
 		}
 		goto end3d8628a6536350a123be81240b8a1376
 	end3d8628a6536350a123be81240b8a1376:
+		;
+		// match: (MOVQload [off] (Global [sym]) mem)
+		// cond:
+		// result: (MOVQloadglobal [GlobalOffset{sym,off.(int64)}] mem)
+		{
+			off := v.Aux
+			if v.Args[0].Op != OpGlobal {
+				goto end20693899317f3f8d1b47fefa64087654
+			}
+			sym := v.Args[0].Aux
+			mem := v.Args[1]
+			v.Op = OpMOVQloadglobal
+			v.Aux = nil
+			v.resetArgs()
+			v.Aux = GlobalOffset{sym, off.(int64)}
+			v.AddArg(mem)
+			return true
+		}
+		goto end20693899317f3f8d1b47fefa64087654
+	end20693899317f3f8d1b47fefa64087654:
 		;
 		// match: (MOVQload [off1] (ADDCQ [off2] ptr) mem)
 		// cond:
@@ -424,6 +444,28 @@ func lowerAmd64(v *Value) bool {
 		}
 		goto end1cb5b7e766f018270fa434c6f46f607f
 	end1cb5b7e766f018270fa434c6f46f607f:
+		;
+		// match: (MOVQstore [off] (Global [sym]) val mem)
+		// cond:
+		// result: (MOVQstoreglobal [GlobalOffset{sym,off.(int64)}] val mem)
+		{
+			off := v.Aux
+			if v.Args[0].Op != OpGlobal {
+				goto end657d07e37c720a8fbb108a31bb48090d
+			}
+			sym := v.Args[0].Aux
+			val := v.Args[1]
+			mem := v.Args[2]
+			v.Op = OpMOVQstoreglobal
+			v.Aux = nil
+			v.resetArgs()
+			v.Aux = GlobalOffset{sym, off.(int64)}
+			v.AddArg(val)
+			v.AddArg(mem)
+			return true
+		}
+		goto end657d07e37c720a8fbb108a31bb48090d
+	end657d07e37c720a8fbb108a31bb48090d:
 		;
 		// match: (MOVQstore [off1] (ADDCQ [off2] ptr) val mem)
 		// cond:

src/cmd/internal/ssa/op.go

@@ -37,7 +37,7 @@ const (
 	OpConst
 
 	OpArg    // address of a function parameter/result.  Memory input is an arg called ".mem".
-	OpGlobal // address of a global variable
+	OpGlobal // address of a global variable (aux is a *gc.Sym)
 	OpFunc   // entry address of a function
 	OpCopy   // output = input
 	OpPhi    // select an input based on which predecessor we came from
@@ -121,6 +121,10 @@ const (
 	OpMOVQload8  // (ptr,idx,mem): loads from ptr+idx*8+aux.(int64)
 	OpMOVQstore8 // (ptr,idx,val,mem): stores to ptr+idx*8+aux.(int64), returns mem
 
+	// load/store from global.  aux = GlobalOffset
+	OpMOVQloadglobal  // (mem) -> value
+	OpMOVQstoreglobal // (val, mem) -> mem
+
 	// load/store 8-byte integer register from stack slot.
 	OpMOVQloadFP
 	OpMOVQloadSP
@@ -133,6 +137,12 @@ const (
 	OpMax // sentinel
 )
 
+// GlobalOffset represents a fixed offset within a global variable
+type GlobalOffset struct {
+	Global interface{} // holds a *cmd/internal/gc.Sym
+	Offset int64
+}
+
 //go:generate stringer -type=Op
 
 type OpInfo struct {
@@ -203,6 +213,8 @@ var gpload = [2][]regMask{{gp, 0}, {gp}}
 var gploadX = [2][]regMask{{gp, gp, 0}, {gp}} // indexed loads
 var gpstore = [2][]regMask{{gp, gp, 0}, {0}}
 var gpstoreX = [2][]regMask{{gp, gp, gp, 0}, {0}} // indexed stores
+var gploadglobal = [2][]regMask{{0}, {gp}}
+var gpstoreglobal = [2][]regMask{{gp, 0}, {0}}
 
 var gpload_stack = [2][]regMask{{0}, {gp}}
 var gpstore_stack = [2][]regMask{{gp, 0}, {0}}
@@ -292,6 +304,9 @@ var amd64Table = [...]OpInfo{
 	OpMOVQload8:  {asm: "MOVQ\t%A(%I0)(%I1*8),%O0", reg: gploadX},
 	OpMOVQstore8: {asm: "MOVQ\t%I2,%A(%I0)(%I1*8)", reg: gpstoreX},
 
+	OpMOVQloadglobal:  {reg: gploadglobal},
+	OpMOVQstoreglobal: {reg: gpstoreglobal},
+
 	OpMOVQconst: {asm: "MOVQ\t$%A,%O0", reg: gp01},
 
 	OpStaticCall: {asm: "CALL\t%A(SB)"},

src/cmd/internal/ssa/op_string.go

@@ -4,9 +4,9 @@ package ssa
 
 import "fmt"
 
-const _Op_name = "OpUnknownOpNopOpFwdRefOpAddOpSubOpMulOpLessOpConstOpArgOpGlobalOpFuncOpCopyOpPhiOpSliceMakeOpSlicePtrOpSliceLenOpSliceCapOpStringMakeOpStringPtrOpStringLenOpSliceIndexOpSliceIndexAddrOpLoadOpStoreOpCheckNilOpCheckBoundOpCallOpStaticCallOpConvertOpConvNopOpFPAddrOpSPAddrOpStoreReg8OpLoadReg8OpADDQOpSUBQOpADDCQOpSUBCQOpMULQOpMULCQOpSHLQOpSHLCQOpNEGQOpCMPQOpCMPCQOpADDLOpTESTQOpSETEQOpSETNEOpSETLOpSETGEOpSETBOpInvertFlagsOpLEAQOpLEAQ2OpLEAQ4OpLEAQ8OpMOVQloadOpMOVQstoreOpMOVQload8OpMOVQstore8OpMOVQloadFPOpMOVQloadSPOpMOVQstoreFPOpMOVQstoreSPOpMOVQconstOpMax"
+const _Op_name = "OpUnknownOpNopOpFwdRefOpAddOpSubOpMulOpLessOpConstOpArgOpGlobalOpFuncOpCopyOpPhiOpSliceMakeOpSlicePtrOpSliceLenOpSliceCapOpStringMakeOpStringPtrOpStringLenOpSliceIndexOpSliceIndexAddrOpLoadOpStoreOpCheckNilOpCheckBoundOpCallOpStaticCallOpConvertOpConvNopOpFPAddrOpSPAddrOpStoreReg8OpLoadReg8OpADDQOpSUBQOpADDCQOpSUBCQOpMULQOpMULCQOpSHLQOpSHLCQOpNEGQOpCMPQOpCMPCQOpADDLOpTESTQOpSETEQOpSETNEOpSETLOpSETGEOpSETBOpInvertFlagsOpLEAQOpLEAQ2OpLEAQ4OpLEAQ8OpMOVQloadOpMOVQstoreOpMOVQload8OpMOVQstore8OpMOVQloadglobalOpMOVQstoreglobalOpMOVQloadFPOpMOVQloadSPOpMOVQstoreFPOpMOVQstoreSPOpMOVQconstOpMax"
 
-var _Op_index = [...]uint16{0, 9, 14, 22, 27, 32, 37, 43, 50, 55, 63, 69, 75, 80, 91, 101, 111, 121, 133, 144, 155, 167, 183, 189, 196, 206, 218, 224, 236, 245, 254, 262, 270, 281, 291, 297, 303, 310, 317, 323, 330, 336, 343, 349, 355, 362, 368, 375, 382, 389, 395, 402, 408, 421, 427, 434, 441, 448, 458, 469, 480, 492, 504, 516, 529, 542, 553, 558}
+var _Op_index = [...]uint16{0, 9, 14, 22, 27, 32, 37, 43, 50, 55, 63, 69, 75, 80, 91, 101, 111, 121, 133, 144, 155, 167, 183, 189, 196, 206, 218, 224, 236, 245, 254, 262, 270, 281, 291, 297, 303, 310, 317, 323, 330, 336, 343, 349, 355, 362, 368, 375, 382, 389, 395, 402, 408, 421, 427, 434, 441, 448, 458, 469, 480, 492, 508, 525, 537, 549, 562, 575, 586, 591}
 
 func (i Op) String() string {
 	if i < 0 || i+1 >= Op(len(_Op_index)) {

src/cmd/internal/ssa/rulegen/lower_amd64.rules

@@ -46,6 +46,10 @@
 (MOVQstore [off1] (FPAddr [off2]) val mem) -> (MOVQstoreFP [off1.(int64)+off2.(int64)] val mem)
 (MOVQstore [off1] (SPAddr [off2]) val mem) -> (MOVQstoreSP [off1.(int64)+off2.(int64)] val mem)
 
+// global loads/stores
+(MOVQload [off] (Global [sym]) mem) -> (MOVQloadglobal [GlobalOffset{sym,off.(int64)}] mem)
+(MOVQstore [off] (Global [sym]) val mem) -> (MOVQstoreglobal [GlobalOffset{sym,off.(int64)}] val mem)
+
 // fold constants into instructions
 (ADDQ x (Const [c])) -> (ADDCQ [c] x) // TODO: restrict c to int32 range?
 (ADDQ (Const [c]) x) -> (ADDCQ [c] x)