backend: de-virtualize regalloc

internal/engine/wazevo/backend/compiler_lower.go

@@ -9,7 +9,7 @@ import (
 func (c *compiler) Lower() {
 	c.assignVirtualRegisters()
 	c.mach.SetCurrentABI(c.GetFunctionABI(c.ssaBuilder.Signature()))
-	c.mach.ExecutableContext().StartLoweringFunction(c.ssaBuilder.BlockIDMax())
+	c.mach.StartLoweringFunction(c.ssaBuilder.BlockIDMax())
 	c.lowerBlocks()
 }
 
@@ -20,21 +20,19 @@ func (c *compiler) lowerBlocks() {
 		c.lowerBlock(blk)
 	}
 
-	ectx := c.mach.ExecutableContext()
 	// After lowering all blocks, we need to link adjacent blocks to layout one single instruction list.
 	var prev ssa.BasicBlock
 	for next := builder.BlockIteratorReversePostOrderBegin(); next != nil; next = builder.BlockIteratorReversePostOrderNext() {
 		if prev != nil {
-			ectx.LinkAdjacentBlocks(prev, next)
+			c.mach.LinkAdjacentBlocks(prev, next)
 		}
 		prev = next
 	}
 }
 
 func (c *compiler) lowerBlock(blk ssa.BasicBlock) {
 	mach := c.mach
-	ectx := mach.ExecutableContext()
-	ectx.StartBlock(blk)
+	mach.StartBlock(blk)
 
 	// We traverse the instructions in reverse order because we might want to lower multiple
 	// instructions together.
@@ -76,15 +74,15 @@ func (c *compiler) lowerBlock(blk ssa.BasicBlock) {
 		default:
 			mach.LowerInstr(cur)
 		}
-		ectx.FlushPendingInstructions()
+		mach.FlushPendingInstructions()
 	}
 
 	// Finally, if this is the entry block, we have to insert copies of arguments from the real location to the VReg.
 	if blk.EntryBlock() {
 		c.lowerFunctionArguments(blk)
 	}
 
-	ectx.EndBlock()
+	mach.EndBlock()
 }
 
 // lowerBranches is called right after StartBlock and before any LowerInstr call if
@@ -93,15 +91,15 @@ func (c *compiler) lowerBlock(blk ssa.BasicBlock) {
 //
 // See ssa.Instruction IsBranching, and the comment on ssa.BasicBlock.
 func (c *compiler) lowerBranches(br0, br1 *ssa.Instruction) {
-	ectx := c.mach.ExecutableContext()
+	mach := c.mach
 
 	c.setCurrentGroupID(br0.GroupID())
 	c.mach.LowerSingleBranch(br0)
-	ectx.FlushPendingInstructions()
+	mach.FlushPendingInstructions()
 	if br1 != nil {
 		c.setCurrentGroupID(br1.GroupID())
 		c.mach.LowerConditionalBranch(br1)
-		ectx.FlushPendingInstructions()
+		mach.FlushPendingInstructions()
 	}
 
 	if br0.Opcode() == ssa.OpcodeJump {
@@ -119,11 +117,11 @@ func (c *compiler) lowerBranches(br0, br1 *ssa.Instruction) {
 			c.lowerBlockArguments(args, target)
 		}
 	}
-	ectx.FlushPendingInstructions()
+	mach.FlushPendingInstructions()
 }
 
 func (c *compiler) lowerFunctionArguments(entry ssa.BasicBlock) {
-	ectx := c.mach.ExecutableContext()
+	mach := c.mach
 
 	c.tmpVals = c.tmpVals[:0]
 	for i := 0; i < entry.Params(); i++ {
@@ -135,8 +133,8 @@ func (c *compiler) lowerFunctionArguments(entry ssa.BasicBlock) {
 			c.tmpVals = append(c.tmpVals, ssa.ValueInvalid)
 		}
 	}
-	c.mach.LowerParams(c.tmpVals)
-	ectx.FlushPendingInstructions()
+	mach.LowerParams(c.tmpVals)
+	mach.FlushPendingInstructions()
 }
 
 // lowerBlockArguments lowers how to pass arguments to the given successor block.

internal/engine/wazevo/backend/isa/amd64/abi_entry_preamble_test.go

@@ -307,7 +307,7 @@ func TestMachineCompileEntryPreamble(t *testing.T) {
 	} {
 		t.Run(tc.name, func(t *testing.T) {
 			_, _, m := newSetupWithMockContext()
-			m.ectx.RootInstr = m.compileEntryPreamble(tc.sig)
+			m.rootInstr = m.compileEntryPreamble(tc.sig)
 			require.Equal(t, tc.exp, m.Format())
 		})
 	}

internal/engine/wazevo/backend/isa/amd64/abi_go_call.go

@@ -14,7 +14,6 @@ var calleeSavedVRegs = []regalloc.VReg{
 
 // CompileGoFunctionTrampoline implements backend.Machine.
 func (m *machine) CompileGoFunctionTrampoline(exitCode wazevoapi.ExitCode, sig *ssa.Signature, needModuleContextPtr bool) []byte {
-	ectx := m.ectx
 	argBegin := 1 // Skips exec context by default.
 	if needModuleContextPtr {
 		argBegin++
@@ -25,7 +24,7 @@ func (m *machine) CompileGoFunctionTrampoline(exitCode wazevoapi.ExitCode, sig *
 	m.currentABI = abi
 
 	cur := m.allocateNop()
-	ectx.RootInstr = cur
+	m.rootInstr = cur
 
 	// Execution context is always the first argument.
 	execCtrPtr := raxVReg
@@ -272,7 +271,7 @@ func (m *machine) CompileGoFunctionTrampoline(exitCode wazevoapi.ExitCode, sig *
 	cur = m.revertRBPRSP(cur)
 	linkInstr(cur, m.allocateInstr().asRet())
 
-	m.encodeWithoutSSA(ectx.RootInstr)
+	m.encodeWithoutSSA(m.rootInstr)
 	return m.c.Buf()
 }
 
@@ -347,10 +346,8 @@ var stackGrowSaveVRegs = []regalloc.VReg{
 
 // CompileStackGrowCallSequence implements backend.Machine.
 func (m *machine) CompileStackGrowCallSequence() []byte {
-	ectx := m.ectx
-
 	cur := m.allocateNop()
-	ectx.RootInstr = cur
+	m.rootInstr = cur
 
 	cur = m.setupRBPRSP(cur)
 
@@ -379,7 +376,7 @@ func (m *machine) CompileStackGrowCallSequence() []byte {
 	cur = m.revertRBPRSP(cur)
 	linkInstr(cur, m.allocateInstr().asRet())
 
-	m.encodeWithoutSSA(ectx.RootInstr)
+	m.encodeWithoutSSA(m.rootInstr)
 	return m.c.Buf()
 }