cmd/compile: try harder to not use an empty src.XPos for a bogus line
The fix for #35652 did not guarantee that it was using a non-empty
src position to replace an empty one. The new code checks again
and falls back to a more certain position. (The input in question
compiles to a single empty infinite loop, and none of the actual instructions
had any source position at all. That is a bug, but given the pathology
of this input, not one worth dealing with this late in the release cycle,
if ever.)
Literally:
00000 (5) TEXT "".f(SB), ABIInternal
00001 (5) PCDATA $0, $-2
00002 (5) PCDATA $1, $-2
00003 (5) FUNCDATA $0, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
00004 (5) FUNCDATA $1, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
00005 (5) FUNCDATA $2, gclocals·33cdeccccebe80329f1fdbee7f5874cb(SB)
b2
00006 (?) XCHGL AX, AX
b6
00007 (+1048575) JMP 6
00008 (?) END
TODO: Add runtime.InfiniteLoop(), replace infinite loops with a call to
that, and use an eco-friendly runtime.gopark instead. (This was Cherry's
excellent idea.)
Updates #35652
Fixes #35695
Change-Id: I4b9a841142ee4df0f6b10863cfa0721a7e13b437
Reviewed-on: https://go-review.googlesource.com/c/go/+/207964
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
diff --git a/src/cmd/compile/internal/gc/ssa.go b/src/cmd/compile/internal/gc/ssa.go
index 96fbddb..bda170e 100644
--- a/src/cmd/compile/internal/gc/ssa.go
+++ b/src/cmd/compile/internal/gc/ssa.go
@@ -6043,6 +6043,9 @@
p.Pos = p.Pos.WithIsStmt()
if b.Pos == src.NoXPos {
b.Pos = p.Pos // It needs a file, otherwise a no-file non-zero line causes confusion. See #35652.
+ if b.Pos == src.NoXPos {
+ b.Pos = pp.Text.Pos // Sometimes p.Pos is empty. See #35695.
+ }
}
b.Pos = b.Pos.WithBogusLine() // Debuggers are not good about infinite loops, force a change in line number
}
diff --git a/test/fixedbugs/issue35652.go b/test/fixedbugs/issue35652.go
index 1ae4069..178a84d 100644
--- a/test/fixedbugs/issue35652.go
+++ b/test/fixedbugs/issue35652.go
@@ -6,10 +6,23 @@
package p
-func f() {
+func e() {
for true {
if true {
continue
}
}
}
+
+func g() {}
+
+func f() {
+ i := 0
+ if true {
+ i++
+ }
+ for true {
+ continue
+ g()
+ }
+}
