From: Cherry Mui <cherryyz@google.com>
Date: Wed, 19 May 2021 22:13:45 +0000 (-0400)
Subject: [dev.typeparams] cmd/compile, runtime: do not zero X15 on Plan 9
X-Git-Tag: go1.18beta1~1818^2^2~522
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=02117775d1;p=gostls13.git

[dev.typeparams] cmd/compile, runtime: do not zero X15 on Plan 9

On Plan 9, we cannot use SSE registers in note handlers, so we
don't use X15 for zeroing (MOVOstorezero and DUFFZERO). Do not
zero X15 on Plan 9.

Change-Id: I2b083b01b27965611cb83d19afd66b383dc77846
Reviewed-on: https://go-review.googlesource.com/c/go/+/321329
Trust: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
---

diff --git a/src/cmd/compile/internal/amd64/ssa.go b/src/cmd/compile/internal/amd64/ssa.go
index ca5f36e775..7e2dc41928 100644
--- a/src/cmd/compile/internal/amd64/ssa.go
+++ b/src/cmd/compile/internal/amd64/ssa.go
@@ -1005,14 +1005,18 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
 	case ssa.OpAMD64CALLstatic:
 		if buildcfg.Experiment.RegabiG && s.ABI == obj.ABI0 && v.Aux.(*ssa.AuxCall).Fn.ABI() == obj.ABIInternal {
 			// zeroing X15 when entering ABIInternal from ABI0
-			opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
+			if buildcfg.GOOS != "plan9" { // do not use SSE on Plan 9
+				opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
+			}
 			// set G register from TLS
 			getgFromTLS(s, x86.REG_R14)
 		}
 		s.Call(v)
 		if buildcfg.Experiment.RegabiG && s.ABI == obj.ABIInternal && v.Aux.(*ssa.AuxCall).Fn.ABI() == obj.ABI0 {
 			// zeroing X15 when entering ABIInternal from ABI0
-			opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
+			if buildcfg.GOOS != "plan9" { // do not use SSE on Plan 9
+				opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
+			}
 			// set G register from TLS
 			getgFromTLS(s, x86.REG_R14)
 		}
@@ -1306,7 +1310,9 @@ func ssaGenBlock(s *ssagen.State, b, next *ssa.Block) {
 	case ssa.BlockRetJmp:
 		if buildcfg.Experiment.RegabiG && s.ABI == obj.ABI0 && b.Aux.(*obj.LSym).ABI() == obj.ABIInternal {
 			// zeroing X15 when entering ABIInternal from ABI0
-			opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
+			if buildcfg.GOOS != "plan9" { // do not use SSE on Plan 9
+				opregreg(s, x86.AXORPS, x86.REG_X15, x86.REG_X15)
+			}
 			// set G register from TLS
 			getgFromTLS(s, x86.REG_R14)
 		}
diff --git a/src/runtime/asm_amd64.s b/src/runtime/asm_amd64.s
index 14f29e1964..5990ce54c8 100644
--- a/src/runtime/asm_amd64.s
+++ b/src/runtime/asm_amd64.s
@@ -1600,7 +1600,9 @@ TEXT ·sigpanic0<ABIInternal>(SB),NOSPLIT,$0-0
 #ifdef GOEXPERIMENT_regabig
 	get_tls(R14)
 	MOVQ	g(R14), R14
+#ifndef GOOS_plan9
 	XORPS	X15, X15
+#endif
 #endif
 	JMP	·sigpanic<ABIInternal>(SB)