[llgo] set debuglocs for calls in synthetic functions

Synthesized functions do not have valid locations,
and so we were not setting a debug location. Recent
changes to DI require that function call instructions
within a function having DI must have a location set.
We just set the debug location to line=0, col=0.

Reviewers: pcc

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D22905

llvm-svn: 288772

Author: axw

llgo/debug/debug.go

@@ -154,9 +154,6 @@ func (d *DIBuilder) Value(b llvm.Builder, v ssa.Value, llv llvm.Value, paramInde
 
 // SetLocation sets the current debug location.
 func (d *DIBuilder) SetLocation(b llvm.Builder, pos token.Pos) {
-	if !pos.IsValid() {
-		return
-	}
 	position := d.fset.Position(pos)
 	d.lb = llvm.Metadata{}
 	if position.Filename != d.fnFile && position.Filename != "" {

llgo/irgen/ssa.go

@@ -327,7 +327,7 @@ func (u *unit) defineFunction(f *ssa.Function) {
 	fr.addCommonFunctionAttrs(fr.function)
 	fr.function.SetLinkage(linkage)
 
-	fr.logf("Define function: %s", f.String())
+	fr.logf("Define function: %s @ %s", f.String(), fr.pkg.Prog.Fset.Position(f.Pos()))
 	fti := u.llvmtypes.getSignatureInfo(f.Signature)
 	delete(u.undefinedFuncs, f)
 	fr.retInf = fti.retInf