src/cmd/compile/internal/ssa/regalloc_test.go

// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

import (
	"cmd/compile/internal/types"
	"cmd/internal/src"
	"testing"
)

func TestLiveControlOps(t *testing.T) {
	c := testConfig(t)
	f := c.Fun("entry",
		Bloc("entry",
			Valu("mem", OpInitMem, types.TypeMem, 0, nil),
			Valu("x", OpAMD64MOVLconst, c.config.Types.Int8, 1, nil),
			Valu("y", OpAMD64MOVLconst, c.config.Types.Int8, 2, nil),
			Valu("a", OpAMD64TESTB, types.TypeFlags, 0, nil, "x", "y"),
			Valu("b", OpAMD64TESTB, types.TypeFlags, 0, nil, "y", "x"),
			Eq("a", "if", "exit"),
		),
		Bloc("if",
			Eq("b", "plain", "exit"),
		),
		Bloc("plain",
			Goto("exit"),
		),
		Bloc("exit",
			Exit("mem"),
		),
	)
	flagalloc(f.f)
	regalloc(f.f)
	checkFunc(f.f)
}

// Test to make sure G register is never reloaded from spill (spill of G is okay)
// See #25504
func TestNoGetgLoadReg(t *testing.T) {
	/*
		Original:
		func fff3(i int) *g {
			gee := getg()
			if i == 0 {
				fff()
			}
			return gee // here
		}
	*/
	c := testConfigARM64(t)
	f := c.Fun("b1",
		Bloc("b1",
			Valu("v1", OpInitMem, types.TypeMem, 0, nil),
			Valu("v6", OpArg, c.config.Types.Int64, 0, c.Frontend().Auto(src.NoXPos, c.config.Types.Int64)),
			Valu("v8", OpGetG, c.config.Types.Int64.PtrTo(), 0, nil, "v1"),
			Valu("v11", OpARM64CMPconst, types.TypeFlags, 0, nil, "v6"),
			Eq("v11", "b2", "b4"),
		),
		Bloc("b4",
			Goto("b3"),
		),
		Bloc("b3",
			Valu("v14", OpPhi, types.TypeMem, 0, nil, "v1", "v12"),
			Valu("sb", OpSB, c.config.Types.Uintptr, 0, nil),
			Valu("v16", OpARM64MOVDstore, types.TypeMem, 0, nil, "v8", "sb", "v14"),
			Exit("v16"),
		),
		Bloc("b2",
			Valu("v12", OpARM64CALLstatic, types.TypeMem, 0, AuxCallLSym("_"), "v1"),
			Goto("b3"),
		),
	)
	regalloc(f.f)
	checkFunc(f.f)
	// Double-check that we never restore to the G register. Regalloc should catch it, but check again anyway.
	r := f.f.RegAlloc
	for _, b := range f.blocks {
		for _, v := range b.Values {
			if v.Op == OpLoadReg && r[v.ID].String() == "g" {
				t.Errorf("Saw OpLoadReg targeting g register: %s", v.LongString())
			}
		}
	}
}

// Test to make sure we don't push spills into loops.
// See issue #19595.
func TestSpillWithLoop(t *testing.T) {
	c := testConfig(t)
	f := c.Fun("entry",
		Bloc("entry",
			Valu("mem", OpInitMem, types.TypeMem, 0, nil),
			Valu("ptr", OpArg, c.config.Types.Int64.PtrTo(), 0, c.Frontend().Auto(src.NoXPos, c.config.Types.Int64)),
			Valu("cond", OpArg, c.config.Types.Bool, 0, c.Frontend().Auto(src.NoXPos, c.config.Types.Bool)),
			Valu("ld", OpAMD64MOVQload, c.config.Types.Int64, 0, nil, "ptr", "mem"), // this value needs a spill
			Goto("loop"),
		),
		Bloc("loop",
			Valu("memphi", OpPhi, types.TypeMem, 0, nil, "mem", "call"),
			Valu("call", OpAMD64CALLstatic, types.TypeMem, 0, AuxCallLSym("_"), "memphi"),
			Valu("test", OpAMD64CMPBconst, types.TypeFlags, 0, nil, "cond"),
			Eq("test", "next", "exit"),
		),
		Bloc("next",
			Goto("loop"),
		),
		Bloc("exit",
			Valu("store", OpAMD64MOVQstore, types.TypeMem, 0, nil, "ptr", "ld", "call"),
			Exit("store"),
		),
	)
	regalloc(f.f)
	checkFunc(f.f)
	for _, v := range f.blocks["loop"].Values {
		if v.Op == OpStoreReg {
			t.Errorf("spill inside loop %s", v.LongString())
		}
	}
}

func TestSpillMove1(t *testing.T) {
	c := testConfig(t)
	f := c.Fun("entry",
		Bloc("entry",
			Valu("mem", OpInitMem, types.TypeMem, 0, nil),
			Valu("x", OpArg, c.config.Types.Int64, 0, c.Frontend().Auto(src.NoXPos, c.config.Types.Int64)),
			Valu("p", OpArg, c.config.Types.Int64.PtrTo(), 0, c.Frontend().Auto(src.NoXPos, c.config.Types.Int64.PtrTo())),
			Valu("a", OpAMD64TESTQ, types.TypeFlags, 0, nil, "x", "x"),
			Goto("loop1"),
		),
		Bloc("loop1",
			Valu("y", OpAMD64MULQ, c.config.Types.Int64, 0, nil, "x", "x"),
			Eq("a", "loop2", "exit1"),
		),
		Bloc("loop2",
			Eq("a", "loop1", "exit2"),
		),
		Bloc("exit1",
			// store before call, y is available in a register
			Valu("mem2", OpAMD64MOVQstore, types.TypeMem, 0, nil, "p", "y", "mem"),
			Valu("mem3", OpAMD64CALLstatic, types.TypeMem, 0, AuxCallLSym("_"), "mem2"),
			Exit("mem3"),
		),
		Bloc("exit2",
			// store after call, y must be loaded from a spill location
			Valu("mem4", OpAMD64CALLstatic, types.TypeMem, 0, AuxCallLSym("_"), "mem"),
			Valu("mem5", OpAMD64MOVQstore, types.TypeMem, 0, nil, "p", "y", "mem4"),
			Exit("mem5"),
		),
	)
	flagalloc(f.f)
	regalloc(f.f)
	checkFunc(f.f)
	// Spill should be moved to exit2.
	if numSpills(f.blocks["loop1"]) != 0 {
		t.Errorf("spill present from loop1")
	}
	if numSpills(f.blocks["loop2"]) != 0 {
		t.Errorf("spill present in loop2")
	}
	if numSpills(f.blocks["exit1"]) != 0 {
		t.Errorf("spill present in exit1")
	}
	if numSpills(f.blocks["exit2"]) != 1 {
		t.Errorf("spill missing in exit2")
	}

}

func TestSpillMove2(t *testing.T) {
	c := testConfig(t)
	f := c.Fun("entry",
		Bloc("entry",
			Valu("mem", OpInitMem, types.TypeMem, 0, nil),
			Valu("x", OpArg, c.config.Types.Int64, 0, c.Frontend().Auto(src.NoXPos, c.config.Types.Int64)),
			Valu("p", OpArg, c.config.Types.Int64.PtrTo(), 0, c.Frontend().Auto(src.NoXPos, c.config.Types.Int64.PtrTo())),
			Valu("a", OpAMD64TESTQ, types.TypeFlags, 0, nil, "x", "x"),
			Goto("loop1"),
		),
		Bloc("loop1",
			Valu("y", OpAMD64MULQ, c.config.Types.Int64, 0, nil, "x", "x"),
			Eq("a", "loop2", "exit1"),
		),
		Bloc("loop2",
			Eq("a", "loop1", "exit2"),
		),
		Bloc("exit1",
			// store after call, y must be loaded from a spill location
			Valu("mem2", OpAMD64CALLstatic, types.TypeMem, 0, AuxCallLSym("_"), "mem"),
			Valu("mem3", OpAMD64MOVQstore, types.TypeMem, 0, nil, "p", "y", "mem2"),
			Exit("mem3"),
		),
		Bloc("exit2",
			// store after call, y must be loaded from a spill location
			Valu("mem4", OpAMD64CALLstatic, types.TypeMem, 0, AuxCallLSym("_"), "mem"),
			Valu("mem5", OpAMD64MOVQstore, types.TypeMem, 0, nil, "p", "y", "mem4"),
			Exit("mem5"),
		),
	)
	flagalloc(f.f)
	regalloc(f.f)
	checkFunc(f.f)
	// There should be a spill in loop1, and nowhere else.
	// TODO: resurrect moving spills out of loops? We could put spills at the start of both exit1 and exit2.
	if numSpills(f.blocks["loop1"]) != 1 {
		t.Errorf("spill missing from loop1")
	}
	if numSpills(f.blocks["loop2"]) != 0 {
		t.Errorf("spill present in loop2")
	}
	if numSpills(f.blocks["exit1"]) != 0 {
		t.Errorf("spill present in exit1")
	}
	if numSpills(f.blocks["exit2"]) != 0 {
		t.Errorf("spill present in exit2")
	}

}

func numSpills(b *Block) int {
	n := 0
	for _, v := range b.Values {
		if v.Op == OpStoreReg {
			n++
		}
	}
	return n
}