From: Keith Randall <khr@golang.org>
Date: Thu, 16 Feb 2023 00:11:37 +0000 (-0800)
Subject: cmd/compile: ensure InitMem comes after Args
X-Git-Tag: go1.21rc1~1549
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=518889b35cb07f3e71963f2ccfc0f96ee26a51ce;p=gostls13.git

cmd/compile: ensure InitMem comes after Args

The debug info generation currently depends on this invariant.

A small update to CL 468455.

Update #58482

Change-Id: Ica305d360d9af04036c604b6a65b683f7cb6e212
Reviewed-on: https://go-review.googlesource.com/c/go/+/468695
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: David Chase <drchase@google.com>
---

diff --git a/src/cmd/compile/internal/ssa/schedule.go b/src/cmd/compile/internal/ssa/schedule.go
index 679d1487d0..49bad25765 100644
--- a/src/cmd/compile/internal/ssa/schedule.go
+++ b/src/cmd/compile/internal/ssa/schedule.go
@@ -15,6 +15,7 @@ import (
 const (
 	ScorePhi       = iota // towards top of block
 	ScoreArg              // must occur at the top of the entry block
+	ScoreInitMem          // after the args - used as mark by debug info generation
 	ScoreReadTuple        // must occur immediately after tuple-generating insn (or call)
 	ScoreNilCheck
 	ScoreMemory
@@ -162,9 +163,12 @@ func schedule(f *Func) {
 					f.Fatalf("%s appeared outside of entry block, b=%s", v.Op, b.String())
 				}
 				score[v.ID] = ScorePhi
-			case v.Op == OpArg || v.Op == OpSP || v.Op == OpSB || v.Op == OpInitMem:
+			case v.Op == OpArg || v.Op == OpSP || v.Op == OpSB:
 				// We want all the args as early as possible, for better debugging.
 				score[v.ID] = ScoreArg
+			case v.Op == OpInitMem:
+				// Early, but after args. See debug.go:buildLocationLists
+				score[v.ID] = ScoreInitMem
 			case v.Type.IsMemory():
 				// Schedule stores as early as possible. This tends to
 				// reduce register pressure.