feat: implement llgo.stackSave

ssa/eh.go

@@ -91,6 +91,16 @@ func (p Program) tySiglongjmp() *types.Signature {
 	return p.sigljmpTy
 }
 
+// func() uintptr
+func (p Program) tyStacksave() *types.Signature {
+	if p.stackSaveTy == nil {
+		paramPtr := types.NewParam(token.NoPos, nil, "", p.VoidPtr().raw.Type)
+		params := types.NewTuple(paramPtr)
+		p.stackSaveTy = types.NewSignatureType(nil, nil, nil, nil, params, false)
+	}
+	return p.stackSaveTy
+}
+
 func (b Builder) AllocaSigjmpBuf() Expr {
 	prog := b.Prog
 	n := unsafe.Sizeof(sigjmpbuf{})
@@ -98,6 +108,12 @@ func (b Builder) AllocaSigjmpBuf() Expr {
 	return b.Alloca(size)
 }
 
+// declare ptr @llvm.stacksave.p0()
+func (b Builder) StackSave() Expr {
+	fn := b.Pkg.cFunc("llvm.stacksave", b.Prog.tyStacksave())
+	return b.InlineCall(fn)
+}
+
 func (b Builder) Sigsetjmp(jb, savemask Expr) Expr {
 	if b.Prog.target.GOARCH == "wasm" {
 		return b.Setjmp(jb)

ssa/package.go

@@ -195,6 +195,7 @@ type aProgram struct {
 	mallocTy       *types.Signature
 	freeTy         *types.Signature
 	memsetInlineTy *types.Signature
+	stackSaveTy    *types.Signature
 
 	createKeyTy *types.Signature
 	getSpecTy   *types.Signature