cmd/compile: implement constant rotates on arm64

Explicit constant rotates work, but constant arguments to
bits.RotateLeft* needed the additional rule.

Fixes #48465

Change-Id: Ia7544f21d0e7587b6b6506f72421459cd769aea6
Reviewed-on: https://go-review.googlesource.com/c/go/+/350909
Trust: Keith Randall <[email protected]>
Trust: Josh Bleecher Snyder <[email protected]>
Run-TryBot: Keith Randall <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Josh Bleecher Snyder <[email protected]>

Author: randall77

src/cmd/compile/internal/ssa/gen/ARM.rules

@@ -508,6 +508,8 @@
 (TST x (MOVWconst [c])) => (TSTconst [c] x)
 (TEQ x (MOVWconst [c])) => (TEQconst [c] x)
 
+(SRR x (MOVWconst [c])) => (SRRconst x [c&31])
+
 // Canonicalize the order of arguments to comparisons - helps with CSE.
 (CMP x y) && canonLessThan(x,y) => (InvertFlags (CMP y x))
 
@@ -1136,7 +1138,6 @@
 ( ORshiftRL [c] (SLLconst x [32-c]) x) => (SRRconst [   c] x)
 (XORshiftRL [c] (SLLconst x [32-c]) x) => (SRRconst [   c] x)
 
-(RotateLeft32 x (MOVWconst [c])) => (SRRconst [-c&31] x)
 (RotateLeft16 <t> x (MOVWconst [c])) => (Or16 (Lsh16x32 <t> x (MOVWconst [c&15])) (Rsh16Ux32 <t> x (MOVWconst [-c&15])))
 (RotateLeft8 <t> x (MOVWconst [c])) => (Or8 (Lsh8x32 <t> x (MOVWconst [c&7])) (Rsh8Ux32 <t> x (MOVWconst [-c&7])))
 (RotateLeft32 x y) => (SRR x (RSBconst [0] <y.Type> y))

src/cmd/compile/internal/ssa/gen/ARM64.rules

@@ -1175,6 +1175,9 @@
 (CMPW x (MOVDconst [c])) => (CMPWconst [int32(c)] x)
 (CMPW (MOVDconst [c]) x) => (InvertFlags (CMPWconst [int32(c)] x))
 
+(ROR x (MOVDconst [c])) => (RORconst x [c&63])
+(RORW x (MOVDconst [c])) => (RORWconst x [c&31])
+
 // Canonicalize the order of arguments to comparisons - helps with CSE.
 ((CMP|CMPW) x y) && canonLessThan(x,y) => (InvertFlags ((CMP|CMPW) y x))
 

src/cmd/compile/internal/ssa/rewriteARM.go

@@ -34,8 +34,15 @@ func rot64(x uint64) uint64 {
 	// ppc64le:"ROTL\t[$]9"
 	a += x<<9 ^ x>>55
 
-	// s390x:"RISBGZ\t[$]0, [$]63, [$]7, "
+	// amd64:"ROLQ\t[$]10"
+	// arm64:"ROR\t[$]54"
+	// s390x:"RISBGZ\t[$]0, [$]63, [$]10, "
+	// ppc64:"ROTL\t[$]10"
+	// ppc64le:"ROTL\t[$]10"
 	// arm64:"ROR\t[$]57" // TODO this is not great line numbering, but then again, the instruction did appear
+	// s390x:"RISBGZ\t[$]0, [$]63, [$]7, " // TODO ditto
+	a += bits.RotateLeft64(x, 10)
+
 	return a
 }
 
@@ -64,8 +71,16 @@ func rot32(x uint32) uint32 {
 	// ppc64le:"ROTLW\t[$]9"
 	a += x<<9 ^ x>>23
 
-	// s390x:"RLL\t[$]7"
+	// amd64:"ROLL\t[$]10"
+	// arm:"MOVW\tR\\d+@>22"
+	// arm64:"RORW\t[$]22"
+	// s390x:"RLL\t[$]10"
+	// ppc64:"ROTLW\t[$]10"
+	// ppc64le:"ROTLW\t[$]10"
 	// arm64:"RORW\t[$]25" // TODO this is not great line numbering, but then again, the instruction did appear
+	// s390x:"RLL\t[$]7" // TODO ditto
+	a += bits.RotateLeft32(x, 10)
+
 	return a
 }