main: add -print-allocs flag that lets you print all heap allocations

This flag, if set, is a regexp for function names. If there are heap
allocations in the matching function names, these heap allocations will
be printed with an explanation why the heap allocation exists (and why
the object can't be stack allocated).

main.go

@@ -13,6 +13,7 @@ import (
 	"os/exec"
 	"os/signal"
 	"path/filepath"
+	"regexp"
 	"runtime"
 	"strings"
 	"sync/atomic"
@@ -901,6 +902,7 @@ func main() {
 	target := flag.String("target", "", "LLVM target | .json file with TargetSpec")
 	printSize := flag.String("size", "", "print sizes (none, short, full)")
 	printStacks := flag.Bool("print-stacks", false, "print stack sizes of goroutines")
+	printAllocsString := flag.String("print-allocs", "", "regular expression of functions for which heap allocations should be printed")
 	printCommands := flag.Bool("x", false, "Print commands")
 	nodebug := flag.Bool("no-debug", false, "disable DWARF debug symbol generation")
 	ocdOutput := flag.Bool("ocd-output", false, "print OCD daemon output during debug")
@@ -941,6 +943,14 @@ func main() {
 		fmt.Fprintln(os.Stderr, err)
 		os.Exit(1)
 	}
+	var printAllocs *regexp.Regexp
+	if *printAllocsString != "" {
+		printAllocs, err = regexp.Compile(*printAllocsString)
+		if err != nil {
+			fmt.Fprintln(os.Stderr, err)
+			os.Exit(1)
+		}
+	}
 	options := &compileopts.Options{
 		Target:        *target,
 		Opt:           *opt,
@@ -953,6 +963,7 @@ func main() {
 		Debug:         !*nodebug,
 		PrintSizes:    *printSize,
 		PrintStacks:   *printStacks,
+		PrintAllocs:   printAllocs,
 		PrintCommands: *printCommands,
 		Tags:          *tags,
 		GlobalValues:  globalVarValues,