cmd/compile: mark R12 clobbered for special calls

In external linking mode the external linker may insert
trampolines, which use R12 as a scratch register. So a call could
potentially clobber R12 if the target is laid out too far. Mark
R12 clobbered.

Also, we will use R12 for trampolines in the Go linker as well.

CL 310731 updated the generated rewrite files so imports are
grouped, but the generator was not updated to do so. Grouped
imports are nice. But as those are generated files, for
simplicity and my laziness, just regenerate with the current
generator (which makes imports not grouped).

Change-Id: Iddb741ff7314a291ade5fbffc7d315f555808409
Reviewed-on: https://go-review.googlesource.com/c/go/+/314453
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>

10 files changed, 31 insertions, 46 deletions

diff --git a/src/cmd/compile/internal/ssa/gen/ARMOps.go b/src/cmd/compile/internal/ssa/gen/ARMOps.go
index 253ff573ec..d1f86039a3 100644
--- a/src/cmd/compile/internal/ssa/gen/ARMOps.go
+++ b/src/cmd/compile/internal/ssa/gen/ARMOps.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build ignore
 // +build ignore
 
 package main
@@ -156,7 +157,7 @@ func init() {
 			reg: regInfo{
 				inputs:   []regMask{buildReg("R1"), buildReg("R0")},
 				outputs:  []regMask{buildReg("R0"), buildReg("R1")},
-				clobbers: buildReg("R2 R3 R14"),
+				clobbers: buildReg("R2 R3 R12 R14"), // R14 is LR, R12 is linker trampoline scratch register
 			},
 			clobberFlags: true,
 			typ:          "(UInt32,UInt32)",
@@ -459,7 +460,7 @@ func init() {
 			argLength: 3,
 			reg: regInfo{
 				inputs:   []regMask{buildReg("R1"), buildReg("R0")},
-				clobbers: buildReg("R1 R14"),
+				clobbers: buildReg("R1 R12 R14"), // R14 is LR, R12 is linker trampoline scratch register
 			},
 			faultOnNilArg0: true,
 		},
@@ -476,7 +477,7 @@ func init() {
 			argLength: 3,
 			reg: regInfo{
 				inputs:   []regMask{buildReg("R2"), buildReg("R1")},
-				clobbers: buildReg("R0 R1 R2 R14"),
+				clobbers: buildReg("R0 R1 R2 R12 R14"), // R14 is LR, R12 is linker trampoline scratch register
 			},
 			faultOnNilArg0: true,
 			faultOnNilArg1: true,
@@ -564,8 +565,8 @@ func init() {
 
 		// LoweredWB invokes runtime.gcWriteBarrier. arg0=destptr, arg1=srcptr, arg2=mem, aux=runtime.gcWriteBarrier
 		// It saves all GP registers if necessary,
-		// but clobbers R14 (LR) because it's a call.
-		{name: "LoweredWB", argLength: 3, reg: regInfo{inputs: []regMask{buildReg("R2"), buildReg("R3")}, clobbers: (callerSave &^ gpg) | buildReg("R14")}, clobberFlags: true, aux: "Sym", symEffect: "None"},
+		// but clobbers R14 (LR) because it's a call, and R12 which is linker trampoline scratch register.
+		{name: "LoweredWB", argLength: 3, reg: regInfo{inputs: []regMask{buildReg("R2"), buildReg("R3")}, clobbers: (callerSave &^ gpg) | buildReg("R12 R14")}, clobberFlags: true, aux: "Sym", symEffect: "None"},
 	}
 
 	blocks := []blockData{
diff --git a/src/cmd/compile/internal/ssa/opGen.go b/src/cmd/compile/internal/ssa/opGen.go
index 2f56625397..51cb0881b8 100644
--- a/src/cmd/compile/internal/ssa/opGen.go
+++ b/src/cmd/compile/internal/ssa/opGen.go
@@ -13879,7 +13879,7 @@ var opcodeTable = [...]opInfo{
 				{0, 2}, // R1
 				{1, 1}, // R0
 			},
-			clobbers: 16396, // R2 R3 R14
+			clobbers: 20492, // R2 R3 R12 R14
 			outputs: []outputInfo{
 				{0, 1}, // R0
 				{1, 2}, // R1
@@ -17228,7 +17228,7 @@ var opcodeTable = [...]opInfo{
 				{0, 2}, // R1
 				{1, 1}, // R0
 			},
-			clobbers: 16386, // R1 R14
+			clobbers: 20482, // R1 R12 R14
 		},
 	},
 	{
@@ -17242,7 +17242,7 @@ var opcodeTable = [...]opInfo{
 				{0, 4}, // R2
 				{1, 2}, // R1
 			},
-			clobbers: 16391, // R0 R1 R2 R14
+			clobbers: 20487, // R0 R1 R2 R12 R14
 		},
 	},
 	{
@@ -17403,7 +17403,7 @@ var opcodeTable = [...]opInfo{
 				{0, 4}, // R2
 				{1, 8}, // R3
 			},
-			clobbers: 4294918144, // R14 F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15
+			clobbers: 4294922240, // R12 R14 F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15
 		},
 	},
 
diff --git a/src/cmd/compile/internal/ssa/rewrite386.go b/src/cmd/compile/internal/ssa/rewrite386.go
index 93b258afac..1ec2d26f75 100644
--- a/src/cmd/compile/internal/ssa/rewrite386.go
+++ b/src/cmd/compile/internal/ssa/rewrite386.go
@@ -3,10 +3,8 @@
 
 package ssa
 
-import (
-	"cmd/compile/internal/types"
-	"math"
-)
+import "math"
+import "cmd/compile/internal/types"
 
 func rewriteValue386(v *Value) bool {
 	switch v.Op {
diff --git a/src/cmd/compile/internal/ssa/rewriteAMD64.go b/src/cmd/compile/internal/ssa/rewriteAMD64.go
index dd92b41c20..0b98b9ddf6 100644
--- a/src/cmd/compile/internal/ssa/rewriteAMD64.go
+++ b/src/cmd/compile/internal/ssa/rewriteAMD64.go
@@ -3,12 +3,10 @@
 
 package ssa
 
-import (
-	"cmd/compile/internal/types"
-	"cmd/internal/obj"
-	"internal/buildcfg"
-	"math"
-)
+import "internal/buildcfg"
+import "math"
+import "cmd/internal/obj"
+import "cmd/compile/internal/types"
 
 func rewriteValueAMD64(v *Value) bool {
 	switch v.Op {
diff --git a/src/cmd/compile/internal/ssa/rewriteARM.go b/src/cmd/compile/internal/ssa/rewriteARM.go
index 25db5b9fba..febb5566e3 100644
--- a/src/cmd/compile/internal/ssa/rewriteARM.go
+++ b/src/cmd/compile/internal/ssa/rewriteARM.go
@@ -3,10 +3,8 @@
 
 package ssa
 
-import (
-	"cmd/compile/internal/types"
-	"internal/buildcfg"
-)
+import "internal/buildcfg"
+import "cmd/compile/internal/types"
 
 func rewriteValueARM(v *Value) bool {
 	switch v.Op {
diff --git a/src/cmd/compile/internal/ssa/rewritePPC64.go b/src/cmd/compile/internal/ssa/rewritePPC64.go
index fe7620c218..96dee0bd21 100644
--- a/src/cmd/compile/internal/ssa/rewritePPC64.go
+++ b/src/cmd/compile/internal/ssa/rewritePPC64.go
@@ -3,11 +3,9 @@
 
 package ssa
 
-import (
-	"cmd/compile/internal/types"
-	"internal/buildcfg"
-	"math"
-)
+import "internal/buildcfg"
+import "math"
+import "cmd/compile/internal/types"
 
 func rewriteValuePPC64(v *Value) bool {
 	switch v.Op {
diff --git a/src/cmd/compile/internal/ssa/rewriteRISCV64.go b/src/cmd/compile/internal/ssa/rewriteRISCV64.go
index bc4b18e0cd..431fb1aaf6 100644
--- a/src/cmd/compile/internal/ssa/rewriteRISCV64.go
+++ b/src/cmd/compile/internal/ssa/rewriteRISCV64.go
@@ -3,10 +3,8 @@
 
 package ssa
 
-import (
-	"cmd/compile/internal/types"
-	"math"
-)
+import "math"
+import "cmd/compile/internal/types"
 
 func rewriteValueRISCV64(v *Value) bool {
 	switch v.Op {
diff --git a/src/cmd/compile/internal/ssa/rewriteS390X.go b/src/cmd/compile/internal/ssa/rewriteS390X.go
index 49c5898704..8b41d62c31 100644
--- a/src/cmd/compile/internal/ssa/rewriteS390X.go
+++ b/src/cmd/compile/internal/ssa/rewriteS390X.go
@@ -3,11 +3,9 @@
 
 package ssa
 
-import (
-	"cmd/compile/internal/types"
-	"cmd/internal/obj/s390x"
-	"math"
-)
+import "math"
+import "cmd/compile/internal/types"
+import "cmd/internal/obj/s390x"
 
 func rewriteValueS390X(v *Value) bool {
 	switch v.Op {
diff --git a/src/cmd/compile/internal/ssa/rewriteWasm.go b/src/cmd/compile/internal/ssa/rewriteWasm.go
index ed23ae032a..5dab09f85b 100644
--- a/src/cmd/compile/internal/ssa/rewriteWasm.go
+++ b/src/cmd/compile/internal/ssa/rewriteWasm.go
@@ -3,11 +3,9 @@
 
 package ssa
 
-import (
-	"cmd/compile/internal/types"
-	"internal/buildcfg"
-	"math"
-)
+import "internal/buildcfg"
+import "math"
+import "cmd/compile/internal/types"
 
 func rewriteValueWasm(v *Value) bool {
 	switch v.Op {
diff --git a/src/cmd/compile/internal/ssa/rewritegeneric.go b/src/cmd/compile/internal/ssa/rewritegeneric.go
index 0e5f49491e..52258201ca 100644
--- a/src/cmd/compile/internal/ssa/rewritegeneric.go
+++ b/src/cmd/compile/internal/ssa/rewritegeneric.go
@@ -3,10 +3,8 @@
 
 package ssa
 
-import (
-	"cmd/compile/internal/types"
-	"math"
-)
+import "math"
+import "cmd/compile/internal/types"
 
 func rewriteValuegeneric(v *Value) bool {
 	switch v.Op {