cmd/compile: insert instrumentation more carefully in racewalk

Be more careful about inserting instrumentation in racewalk.
If the node being instrumented is an OAS, and it has a non-
empty Ninit, then append instrumentation to the Ninit list
rather than letting it be inserted before the OAS (and the
compilation of its init list).  This deals with the case that
the Ninit list defines a variable used in the RHS of the OAS.

Fixes #15091.

Change-Id: Iac91696d9104d07f0bf1bd3499bbf56b2e1ef073
Reviewed-on: https://go-review.googlesource.com/21771
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: David Chase <drchase@google.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/src/cmd/compile/internal/ssa/regalloc.go b/src/cmd/compile/internal/ssa/regalloc.go
index 22b9d12c19..aec23a1368 100644
--- a/src/cmd/compile/internal/ssa/regalloc.go
+++ b/src/cmd/compile/internal/ssa/regalloc.go
@@ -417,7 +417,7 @@ func (s *regAllocState) allocValToReg(v *Value, mask regMask, nospill bool, line
 		// Load v from its spill location.
 		case vi.spill != nil:
 			if s.f.pass.debug > logSpills {
-				s.f.Config.Warnl(vi.spill.Line, "load spill")
+				s.f.Config.Warnl(vi.spill.Line, "load spill for %v from %v", v, vi.spill)
 			}
 			c = s.curBlock.NewValue1(line, OpLoadReg, v.Type, vi.spill)
 			vi.spillUsed = true
@@ -1078,7 +1078,7 @@ func (s *regAllocState) regalloc(f *Func) {
 		vi := s.values[i]
 		if vi.spillUsed {
 			if s.f.pass.debug > logSpills {
-				s.f.Config.Warnl(vi.spill.Line, "spilled value")
+				s.f.Config.Warnl(vi.spill.Line, "spilled value at %v remains", vi.spill)
 			}
 			continue
 		}