cmd/internal/obj/ppc64: generate big uint32 values in register

When using "MOVD $const, Rx", any 32b constant can be generated in
register quickly. Avoid transforming big uint32 values into a load.

And, fix the instance in runtime.usleep where I discovered this.

Change-Id: I46e156d7edf200f85b5b61162f00223c0ad81fe2
Reviewed-on: https://go-review.googlesource.com/c/go/+/444815
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Paul Murphy <murp@ibm.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>

src/cmd/asm/internal/asm/testdata/ppc64.s

@@ -28,6 +28,11 @@ TEXT asmtest(SB),DUPOK|NOSPLIT,$0
 	MOVW $-32767, R5                // 38a08001
 	MOVW $-32768, R6                // 38c08000
 	MOVW $1234567, R5               // 6405001260a5d687
+	// Hex constant 0x80000001
+	MOVW $2147483649, R5            // 6405800060a50001
+	MOVD $2147483649, R5            // 6405800060a50001
+	// Hex constant 0xFFFFFFFF80000001
+	MOVD $-2147483647, R5    	// 3ca0800060a50001
 	MOVD 8(R3), R4                  // e8830008
 	MOVD (R3)(R4), R5               // 7ca4182a
 	MOVD (R3)(R0), R5               // 7ca0182a

src/cmd/internal/obj/ppc64/obj9.go

@@ -78,9 +78,12 @@ func progedit(ctxt *obj.Link, p *obj.Prog, newprog obj.ProgAlloc) {
 			}
 		}
 
-		// Put >32-bit constants in memory and load them
 	case AMOVD:
-		if p.From.Type == obj.TYPE_CONST && p.From.Name == obj.NAME_NONE && p.From.Reg == 0 && int64(int32(p.From.Offset)) != p.From.Offset {
+		// 32b constants (signed and unsigned) can be generated via 1 or 2 instructions.
+		// All others must be placed in memory and loaded.
+		isS32 := int64(int32(p.From.Offset)) == p.From.Offset
+		isU32 := uint64(uint32(p.From.Offset)) == uint64(p.From.Offset)
+		if p.From.Type == obj.TYPE_CONST && p.From.Name == obj.NAME_NONE && p.From.Reg == 0 && !isS32 && !isU32 {
 			p.From.Type = obj.TYPE_MEM
 			p.From.Sym = ctxt.Int64Sym(p.From.Offset)
 			p.From.Name = obj.NAME_EXTERN

src/runtime/sys_linux_ppc64x.s

@@ -112,8 +112,7 @@ TEXT runtime·usleep(SB),NOSPLIT,$16-4
 
 	// Use magic constant 0x8637bd06 and shift right 51
 	// to perform usec/1000000.
-	ORIS	$0x8637, R0, R4	// Note, R0 always contains 0 here.
-	OR	$0xbd06, R4, R4
+	MOVD	$0x8637bd06, R4
 	MULLD	R3, R4, R4	// Convert usec to S.
 	SRD	$51, R4, R4
 	MOVD	R4, 8(R1)	// Store to tv_sec