cmd/compile: Avoid and filter out zero-length location-lists.
This change avoids creating zero length location lists by
repairing an overly aggressive change in CL146718
and by explicitly checking for and filtering out any
zero-length lists that are detected (building
compiler+runtime creates a single one).
Updates #28486.
Change-Id: I01c571fee2376474c7f3038e801bd58fd9e0b820
Reviewed-on: https://go-review.googlesource.com/c/150097
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
diff --git a/src/cmd/compile/internal/ssa/debug.go b/src/cmd/compile/internal/ssa/debug.go
index 7407a75..c2736d8 100644
--- a/src/cmd/compile/internal/ssa/debug.go
+++ b/src/cmd/compile/internal/ssa/debug.go
@@ -881,12 +881,11 @@
for _, b := range state.f.Blocks {
state.mergePredecessors(b, blockLocs, prevBlock)
- // Handle any differences among predecessor blocks and previous block (perhaps not a predecessor)
- for _, varID := range state.changedVars.contents() {
- state.updateVar(VarID(varID), b, BlockStart)
- }
-
if !blockLocs[b.ID].relevant {
+ // Handle any differences among predecessor blocks and previous block (perhaps not a predecessor)
+ for _, varID := range state.changedVars.contents() {
+ state.updateVar(VarID(varID), b, BlockStart)
+ }
continue
}
@@ -1019,6 +1018,14 @@
// they get incomplete debug info on 32-bit platforms.
return
}
+ if start == end {
+ if state.loggingEnabled {
+ // Printf not logf so not gated by GOSSAFUNC; this should fire very rarely.
+ fmt.Printf("Skipping empty location list for %v in %s\n", state.vars[varID], state.f.Name)
+ }
+ return
+ }
+
list := state.lists[varID]
list = appendPtr(state.ctxt, list, start)
list = appendPtr(state.ctxt, list, end)
