From: Josh Bleecher Snyder <josharian@gmail.com>
Date: Mon, 2 Mar 2020 21:51:20 +0000 (-0800)
Subject: cmd/compile: simplify converted SSA form for 'if false'
X-Git-Tag: go1.15beta1~947
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=7b0b6c2f7e9d925763a2e1d2ba10682019827a9b;p=gostls13.git

cmd/compile: simplify converted SSA form for 'if false'

The goal here is to make it easier for a human to
examine the SSA when a function contains lots of dead code.

No significant compiler metric or generated code differences.

Change-Id: I81915fa4639bc8820cc9a5e45e526687d0d1f57a
Reviewed-on: https://go-review.googlesource.com/c/go/+/221791
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
---

diff --git a/src/cmd/compile/internal/gc/ssa.go b/src/cmd/compile/internal/gc/ssa.go
index f2a472bde6..34adeabae1 100644
--- a/src/cmd/compile/internal/gc/ssa.go
+++ b/src/cmd/compile/internal/gc/ssa.go
@@ -1274,6 +1274,16 @@ func (s *state) stmt(n *Node) {
 		s.assign(n.Left, r, deref, skip)
 
 	case OIF:
+		if Isconst(n.Left, CTBOOL) {
+			s.stmtList(n.Left.Ninit)
+			if n.Left.Bool() {
+				s.stmtList(n.Nbody)
+			} else {
+				s.stmtList(n.Rlist)
+			}
+			break
+		}
+
 		bEnd := s.f.NewBlock(ssa.BlockPlain)
 		var likely int8
 		if n.Likely() {