all: fix some comments

Change-Id: Ic196f7a97e423708d0a86ff8da99871e966dc2fc
Reviewed-on: https://go-review.googlesource.com/c/arch/+/466000
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: David Chase <drchase@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

ppc64/ppc64asm/field.go

@@ -80,7 +80,7 @@ func (bs BitFields) Parse(i [2]uint32) uint64 {
 	return u
 }
 
-// Parse extracts the bitfields from i, concatenate them and return the result
+// ParseSigned extracts the bitfields from i, concatenate them and return the result
 // as a signed integer. Parse will panic if any bitfield in b is invalid.
 func (bs BitFields) ParseSigned(i [2]uint32) int64 {
 	u, l := bs.parse(i)

x86/x86asm/decode.go

@@ -1550,7 +1550,7 @@ var addr16 = [8]Mem{
 	{Base: BX},
 }
 
-// baseReg returns the base register for a given register size in bits.
+// baseRegForBits returns the base register for a given register size in bits.
 func baseRegForBits(bits int) Reg {
 	switch bits {
 	case 8: