cmd/internal/obj/arm64: add checks for incorrect use of REGTMP register

The current assembler uses REGTMP as a temporary destination register,
when optimizing one instruction into a multi-instruction sequence. But
in some cases, when the source register is REGTMP, this behavior is
incorrect.

For example:
  ADD	$0x1234567, R27, R3

The current assembler encodes it into
  MOVD	$17767, R27
  MOVK	$(291<<16), R27
  ADD	R27, R27, R3

It is illegal to overwrite R27. This CL adds the related checks.

Add test cases.

Change-Id: I0af373d9fd23d8f067c093778dd4cc76748faf38
Reviewed-on: https://go-review.googlesource.com/c/go/+/344689
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: fannie zhang <Fannie.Zhang@arm.com>

2 files changed, 35 insertions, 7 deletions

diff --git a/src/cmd/asm/internal/asm/testdata/arm64error.s b/src/cmd/asm/internal/asm/testdata/arm64error.s
index 8b12b16680..7b006432c0 100644
--- a/src/cmd/asm/internal/asm/testdata/arm64error.s
+++ b/src/cmd/asm/internal/asm/testdata/arm64error.s
@@ -406,12 +406,12 @@ TEXT errors(SB),$0
 	VBIF	V0.D2, V1.D2, V2.D2                              // ERROR "invalid arrangement"
 	VUADDW	V9.B8, V12.H8, V14.B8                            // ERROR "invalid arrangement"
 	VUADDW2	V9.B8, V12.S4, V14.S4                            // ERROR "operand mismatch"
-	VUMAX   V1.D2, V2.D2, V3.D2                              // ERROR "invalid arrangement"
-	VUMIN   V1.D2, V2.D2, V3.D2                              // ERROR "invalid arrangement"
+	VUMAX	V1.D2, V2.D2, V3.D2                              // ERROR "invalid arrangement"
+	VUMIN	V1.D2, V2.D2, V3.D2                              // ERROR "invalid arrangement"
 	VUMAX	V1.B8, V2.B8, V3.B16                             // ERROR "operand mismatch"
 	VUMIN	V1.H4, V2.S4, V3.H4                              // ERROR "operand mismatch"
 	VSLI	$64, V7.D2, V8.D2                                // ERROR "shift out of range"
-	VUSRA   $0, V7.D2, V8.D2                                 // ERROR "shift out of range"
+	VUSRA	$0, V7.D2, V8.D2                                 // ERROR "shift out of range"
 	CASPD	(R3, R4), (R2), (R8, R9)                         // ERROR "source register pair must start from even register"
 	CASPD	(R2, R3), (R2), (R9, R10)                        // ERROR "destination register pair must start from even register"
 	CASPD	(R2, R4), (R2), (R8, R9)                         // ERROR "source register pair must be contiguous"
@@ -419,8 +419,15 @@ TEXT errors(SB),$0
 	ADD	R1>>2, RSP, R3                                   // ERROR "illegal combination"
 	ADDS	R2<<3, R3, RSP                                   // ERROR "unexpected SP reference"
 	CMP	R1<<5, RSP                                       // ERROR "the left shift amount out of range 0 to 4"
-	MOVD.P  y+8(FP), R1                                      // ERROR "illegal combination"
-	MOVD.W  x-8(SP), R1                                      // ERROR "illegal combination"
-	LDP.P   x+8(FP), (R0, R1)                                // ERROR "illegal combination"
-	LDP.W   x+8(SP), (R0, R1)                                // ERROR "illegal combination"
+	MOVD.P	y+8(FP), R1                                      // ERROR "illegal combination"
+	MOVD.W	x-8(SP), R1                                      // ERROR "illegal combination"
+	LDP.P	x+8(FP), (R0, R1)                                // ERROR "illegal combination"
+	LDP.W	x+8(SP), (R0, R1)                                // ERROR "illegal combination"
+	ADD	$0x1234567, R27, R3                              // ERROR "cannot use REGTMP as source"
+	ADD	$0x3fffffffc000, R27, R5                         // ERROR "cannot use REGTMP as source"
+	AND	$0x22220000, R27, R4                             // ERROR "cannot use REGTMP as source"
+	ANDW	$0x6006000060060, R27, R5                        // ERROR "cannot use REGTMP as source"
+	STP	(R3, R4), 0x1234567(R27)                         // ERROR "REGTMP used in large offset store"
+	LDP	0x1234567(R27), (R3, R4)                         // ERROR "REGTMP used in large offset load"
+	STP	(R26, R27), 700(R2)                              // ERROR "cannot use REGTMP as source"
 	RET
diff --git a/src/cmd/internal/obj/arm64/asm7.go b/src/cmd/internal/obj/arm64/asm7.go
index 8db25cf967..5d6caaed5f 100644
--- a/src/cmd/internal/obj/arm64/asm7.go
+++ b/src/cmd/internal/obj/arm64/asm7.go
@@ -3407,6 +3407,9 @@ func (c *ctxt7) asmout(p *obj.Prog, o *Optab, out []uint32) {
 		o4 = os[3]
 
 	case 13: /* addop $vcon, [R], R (64 bit literal); cmp $lcon,R -> addop $lcon,R, ZR */
+		if p.Reg == REGTMP {
+			c.ctxt.Diag("cannot use REGTMP as source: %v\n", p)
+		}
 		if p.To.Reg == REG_RSP && isADDSop(p.As) {
 			c.ctxt.Diag("illegal destination register: %v\n", p)
 		}
@@ -3724,6 +3727,9 @@ func (c *ctxt7) asmout(p *obj.Prog, o *Optab, out []uint32) {
 		o1 |= (uint32(r&31) << 5) | uint32(rt&31)
 
 	case 28: /* logop $vcon, [R], R (64 bit literal) */
+		if p.Reg == REGTMP {
+			c.ctxt.Diag("cannot use REGTMP as source: %v\n", p)
+		}
 		o := uint32(0)
 		num := uint8(0)
 		cls := oclass(&p.From)
@@ -4354,6 +4360,9 @@ func (c *ctxt7) asmout(p *obj.Prog, o *Optab, out []uint32) {
 
 		/* reloc ops */
 	case 64: /* movT R,addr -> adrp + add + movT R, (REGTMP) */
+		if p.From.Reg == REGTMP {
+			c.ctxt.Diag("cannot use REGTMP as source: %v\n", p)
+		}
 		o1 = ADR(1, 0, REGTMP)
 		o2 = c.opirr(p, AADD) | REGTMP&31<<5 | REGTMP&31
 		rel := obj.Addrel(c.cursym)
@@ -4585,6 +4594,9 @@ func (c *ctxt7) asmout(p *obj.Prog, o *Optab, out []uint32) {
 		//	add Rtmp, R, Rtmp
 		//	ldp (Rtmp), (R1, R2)
 		r := int(p.From.Reg)
+		if r == REGTMP {
+			c.ctxt.Diag("REGTMP used in large offset load: %v", p)
+		}
 		if r == obj.REG_NONE {
 			r = int(o.param)
 		}
@@ -4601,6 +4613,9 @@ func (c *ctxt7) asmout(p *obj.Prog, o *Optab, out []uint32) {
 	case 76:
 		//	add $O, R, Rtmp or sub $O, R, Rtmp
 		//	stp (R1, R2), (Rtmp)
+		if p.From.Reg == REGTMP || p.From.Offset == REGTMP {
+			c.ctxt.Diag("cannot use REGTMP as source: %v", p)
+		}
 		r := int(p.To.Reg)
 		if r == obj.REG_NONE {
 			r = int(o.param)
@@ -4628,6 +4643,9 @@ func (c *ctxt7) asmout(p *obj.Prog, o *Optab, out []uint32) {
 		//	add Rtmp, R, Rtmp
 		//	stp (R1, R2), (Rtmp)
 		r := int(p.To.Reg)
+		if r == REGTMP || p.From.Reg == REGTMP || p.From.Offset == REGTMP {
+			c.ctxt.Diag("REGTMP used in large offset store: %v", p)
+		}
 		if r == obj.REG_NONE {
 			r = int(o.param)
 		}
@@ -4933,6 +4951,9 @@ func (c *ctxt7) asmout(p *obj.Prog, o *Optab, out []uint32) {
 		o1 |= (uint32(Q&1) << 30) | (uint32((r>>5)&7) << 16) | (uint32(r&0x1f) << 5) | uint32(rt&31)
 
 	case 87: /* stp (r,r), addr(SB) -> adrp + add + stp */
+		if p.From.Reg == REGTMP || p.From.Offset == REGTMP {
+			c.ctxt.Diag("cannot use REGTMP as source: %v", p)
+		}
 		o1 = ADR(1, 0, REGTMP)
 		o2 = c.opirr(p, AADD) | REGTMP&31<<5 | REGTMP&31
 		rel := obj.Addrel(c.cursym)