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|
package compiler
import (
"errors"
"github.com/tinygo-org/tinygo/transform"
"tinygo.org/x/go-llvm"
)
// Run the LLVM optimizer over the module.
// The inliner can be disabled (if necessary) by passing 0 to the inlinerThreshold.
func (c *Compiler) Optimize(optLevel, sizeLevel int, inlinerThreshold uint) error {
builder := llvm.NewPassManagerBuilder()
defer builder.Dispose()
builder.SetOptLevel(optLevel)
builder.SetSizeLevel(sizeLevel)
if inlinerThreshold != 0 {
builder.UseInlinerWithThreshold(inlinerThreshold)
}
builder.AddCoroutinePassesToExtensionPoints()
if c.PanicStrategy() == "trap" {
c.replacePanicsWithTrap() // -panic=trap
}
// run a check of all of our code
if c.VerifyIR() {
err := c.checkModule()
if err != nil {
return err
}
}
// Run function passes for each function.
funcPasses := llvm.NewFunctionPassManagerForModule(c.mod)
defer funcPasses.Dispose()
builder.PopulateFunc(funcPasses)
funcPasses.InitializeFunc()
for fn := c.mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
funcPasses.RunFunc(fn)
}
funcPasses.FinalizeFunc()
if optLevel > 0 {
// Run some preparatory passes for the Go optimizer.
goPasses := llvm.NewPassManager()
defer goPasses.Dispose()
goPasses.AddGlobalOptimizerPass()
goPasses.AddConstantPropagationPass()
goPasses.AddAggressiveDCEPass()
goPasses.AddFunctionAttrsPass()
goPasses.Run(c.mod)
// Run Go-specific optimization passes.
transform.OptimizeMaps(c.mod)
transform.OptimizeStringToBytes(c.mod)
transform.OptimizeAllocs(c.mod)
c.LowerInterfaces()
c.LowerFuncValues()
// After interfaces are lowered, there are many more opportunities for
// interprocedural optimizations. To get them to work, function
// attributes have to be updated first.
goPasses.Run(c.mod)
// Run TinyGo-specific interprocedural optimizations.
transform.OptimizeAllocs(c.mod)
transform.OptimizeStringToBytes(c.mod)
// Lower runtime.isnil calls to regular nil comparisons.
isnil := c.mod.NamedFunction("runtime.isnil")
if !isnil.IsNil() {
for _, use := range getUses(isnil) {
c.builder.SetInsertPointBefore(use)
ptr := use.Operand(0)
if !ptr.IsABitCastInst().IsNil() {
ptr = ptr.Operand(0)
}
nilptr := llvm.ConstPointerNull(ptr.Type())
icmp := c.builder.CreateICmp(llvm.IntEQ, ptr, nilptr, "")
use.ReplaceAllUsesWith(icmp)
use.EraseFromParentAsInstruction()
}
}
err := c.LowerGoroutines()
if err != nil {
return err
}
} else {
// Must be run at any optimization level.
c.LowerInterfaces()
c.LowerFuncValues()
err := c.LowerGoroutines()
if err != nil {
return err
}
}
if c.VerifyIR() {
if err := c.checkModule(); err != nil {
return err
}
}
if err := c.Verify(); err != nil {
return errors.New("optimizations caused a verification failure")
}
if sizeLevel >= 2 {
// Set the "optsize" attribute to make slightly smaller binaries at the
// cost of some performance.
kind := llvm.AttributeKindID("optsize")
attr := c.ctx.CreateEnumAttribute(kind, 0)
for fn := c.mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
fn.AddFunctionAttr(attr)
}
}
// After TinyGo-specific transforms have finished, undo exporting these functions.
for _, name := range c.getFunctionsUsedInTransforms() {
fn := c.mod.NamedFunction(name)
if fn.IsNil() {
continue
}
fn.SetLinkage(llvm.InternalLinkage)
}
// Run function passes again, because without it, llvm.coro.size.i32()
// doesn't get lowered.
for fn := c.mod.FirstFunction(); !fn.IsNil(); fn = llvm.NextFunction(fn) {
funcPasses.RunFunc(fn)
}
funcPasses.FinalizeFunc()
// Run module passes.
modPasses := llvm.NewPassManager()
defer modPasses.Dispose()
builder.Populate(modPasses)
modPasses.Run(c.mod)
hasGCPass := c.addGlobalsBitmap()
hasGCPass = c.makeGCStackSlots() || hasGCPass
if hasGCPass {
if err := c.Verify(); err != nil {
return errors.New("GC pass caused a verification failure")
}
}
return nil
}
// Replace panic calls with calls to llvm.trap, to reduce code size. This is the
// -panic=trap intrinsic.
func (c *Compiler) replacePanicsWithTrap() {
trap := c.mod.NamedFunction("llvm.trap")
for _, name := range []string{"runtime._panic", "runtime.runtimePanic"} {
fn := c.mod.NamedFunction(name)
if fn.IsNil() {
continue
}
for _, use := range getUses(fn) {
if use.IsACallInst().IsNil() || use.CalledValue() != fn {
panic("expected use of a panic function to be a call")
}
c.builder.SetInsertPointBefore(use)
c.builder.CreateCall(trap, nil, "")
}
}
}
|
