cmd/internal/obj/mips: added support for GOARCH=mips64{,le}

MIPS64 has 32 general purpose 64-bit integer registers (R0-R31), 32
64-bit floating point registers (F0-F31). Instructions are fixed-width,
and are 32-bit wide. Instructions are all in standard 1-, 2-, 3-operand
forms.

MIPS64-specific relocations are added. For this reason, test data of
cmd/newlink are regenerated.

No other changes are made to portable structures.

Branch delay slots are current filled with NOP instructions. The function
for instruction scheduling (try to fill the delay slot with a useful
instruction) is implemented but disabled for now.

Change-Id: Ic364999c7a33245260c1381fc26a2fa8972d38b3
Reviewed-on: https://go-review.googlesource.com/14442
Reviewed-by: Minux Ma <minux@golang.org>

src/cmd/internal/obj/link.go

@@ -411,12 +411,18 @@ const (
 	// low 16 bits into that of the second instruction.
 	R_ADDRPOWER
 	R_ADDRARM64
+	// R_ADDRMIPS (only used on mips64) resolves to a 32-bit external address,
+	// by loading the address into a register with two instructions (lui, ori).
+	R_ADDRMIPS
 	R_SIZE
 	R_CALL
 	R_CALLARM
 	R_CALLARM64
 	R_CALLIND
 	R_CALLPOWER
+	// R_CALLMIPS (only used on mips64) resolves to non-PC-relative target address
+	// of a CALL (JAL) instruction, by encoding the address into the instruction.
+	R_CALLMIPS
 	R_CONST
 	R_PCREL
 	// R_TLS_LE, used on 386, amd64, and ARM, resolves to the offset of the
@@ -437,6 +443,10 @@ const (
 	R_USEFIELD
 	R_POWER_TOC
 	R_GOTPCREL
+	// R_JMPMIPS (only used on mips64) resolves to non-PC-relative target address
+	// of a JMP instruction, by encoding the address into the instruction.
+	// The stack nosplit check ignores this since it is not a function call.
+	R_JMPMIPS
 
 	// Platform dependent relocations. Architectures with fixed width instructions
 	// have the inherent issue that a 32-bit (or 64-bit!) displacement cannot be