[release-branch.go1.21] Revert "cmd/compile: omit redundant sign/unsign extension on arm64"

This reverts CL 427454.

Reason for revert: causes incorrect generated code in some rare cases

We'll fix-forward at tip, so the revert just needs to be done for 1.21.

Fixes golang#62143

Change-Id: Id242230481ff4d4ba5f58236c6d8237729fc3b80
Reviewed-on: https://go-review.googlesource.com/c/go/+/520976
Run-TryBot: Keith Randall <[email protected]>
Reviewed-by: Ruinan Sun <[email protected]>
Reviewed-by: Keith Randall <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>

Author: randall77

src/cmd/compile/internal/ssa/_gen/ARM64Ops.go

@@ -13,7 +13,6 @@ import "strings"
 //  - *const instructions may use a constant larger than the instruction can encode.
 //    In this case the assembler expands to multiple instructions and uses tmp
 //    register (R27).
-//  - All 32-bit Ops will zero the upper 32 bits of the destination register.
 
 // Suffixes encode the bit width of various instructions.
 // D (double word) = 64 bit

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

@@ -1290,10 +1290,6 @@ func zeroUpper32Bits(x *Value, depth int) bool {
 		OpAMD64SHRL, OpAMD64SHRLconst, OpAMD64SARL, OpAMD64SARLconst,
 		OpAMD64SHLL, OpAMD64SHLLconst:
 		return true
-	case OpARM64REV16W, OpARM64REVW, OpARM64RBITW, OpARM64CLZW, OpARM64EXTRWconst,
-		OpARM64MULW, OpARM64MNEGW, OpARM64UDIVW, OpARM64DIVW, OpARM64UMODW,
-		OpARM64MADDW, OpARM64MSUBW, OpARM64RORW, OpARM64RORWconst:
-		return true
 	case OpArg:
 		return x.Type.Size() == 4
 	case OpPhi, OpSelect0, OpSelect1: