[PowerPC]: Don't allow r0 as a target for LD_GOT_TPREL_L/32

Summary:
The linker is free to relax this (relocation R_PPC_GOT_TPREL16) against
R_PPC_TLS, if it sees fit (initial exec to local exec).  If r0 is used,
this can generate execution-invalid code (converts to 'addi %rX, %r0,
FOO, which translates in PPC-lingo to li %rX, FOO).  Forbid this
instead.

This fixes static binaries using locales on FreeBSD/powerpc
(tested on FreeBSD/powerpcspe).

Reviewed By: nemanjai
Differential Revision: https://reviews.llvm.org/D76662

Author: Justin Hibbits

llvm/lib/Target/PowerPC/PPCInstr64Bit.td

@@ -1127,7 +1127,7 @@ def ADDISgotTprelHA: PPCEmitTimePseudo<(outs g8rc:$rD), (ins g8rc_nox0:$reg, s16
                            (PPCaddisGotTprelHA i64:$reg,
                                                tglobaltlsaddr:$disp))]>,
                   isPPC64;
-def LDgotTprelL: PPCEmitTimePseudo<(outs g8rc:$rD), (ins s16imm64:$disp, g8rc_nox0:$reg),
+def LDgotTprelL: PPCEmitTimePseudo<(outs g8rc_nox0:$rD), (ins s16imm64:$disp, g8rc_nox0:$reg),
                         "#LDgotTprelL",
                         [(set i64:$rD,
                           (PPCldGotTprelL tglobaltlsaddr:$disp, i64:$reg))]>,

llvm/lib/Target/PowerPC/PPCInstrInfo.td

@@ -3213,7 +3213,7 @@ def PPC32GOT: PPCEmitTimePseudo<(outs gprc:$rD), (ins), "#PPC32GOT",
 def PPC32PICGOT: PPCEmitTimePseudo<(outs gprc:$rD, gprc:$rT), (ins), "#PPC32PICGOT", 
                 []>, NoEncode<"$rT">;
 
-def LDgotTprelL32: PPCEmitTimePseudo<(outs gprc:$rD), (ins s16imm:$disp, gprc_nor0:$reg),
+def LDgotTprelL32: PPCEmitTimePseudo<(outs gprc_nor0:$rD), (ins s16imm:$disp, gprc_nor0:$reg),
                            "#LDgotTprelL32",
                            [(set i32:$rD,
                              (PPCldGotTprelL tglobaltlsaddr:$disp, i32:$reg))]>;

llvm/test/CodeGen/PowerPC/tls.ll

@@ -11,11 +11,11 @@
 ;OPT1-LABEL:          localexec:
 define i32 @localexec() nounwind {
 entry:
-;OPT0:          addis [[REG1:[0-9]+]], 13, a@tprel@ha
-;OPT0-NEXT:     addi [[REG2:[0-9]+]], [[REG1]], a@tprel@l
+;OPT0:          addis [[REG1:[1-9][0-9]*]], 13, a@tprel@ha
+;OPT0-NEXT:     addi [[REG2:[1-9][0-9]*]], [[REG1]], a@tprel@l
 ;OPT0-NEXT:     li [[REG3:[0-9]+]], 42
 ;OPT0:          stw [[REG3]], 0([[REG2]])
-;OPT1:          addis [[REG1:[0-9]+]], 13, a@tprel@ha
+;OPT1:          addis [[REG1:[1-9][0-9]*]], 13, a@tprel@ha
 ;OPT1-NEXT:     li [[REG3:[0-9]+]], 42
 ;OPT1:     stw [[REG3]], a@tprel@l([[REG1]])
   store i32 42, i32* @a, align 4
@@ -36,19 +36,19 @@ entry:
 }
 
 ; OPT1-LABEL: main2:
-; OPT1: addis [[REG1:[0-9]+]], 2, a2@got@tprel@ha
+; OPT1: addis [[REG1:[1-9][0-9]*]], 2, a2@got@tprel@ha
 ; OPT1: ld [[REG2:[0-9]+]], a2@got@tprel@l([[REG1]])
 ; OPT1: add {{[0-9]+}}, [[REG2]], a2@tls
 
 ;OPT0-PPC32-LABEL:    main2:
-;OPT0-PPC32:       li [[REG1:[0-9]+]], _GLOBAL_OFFSET_TABLE_@l
+;OPT0-PPC32:       li [[REG1:[1-9][0-9]*]], _GLOBAL_OFFSET_TABLE_@l
 ;OPT0-PPC32:       addis [[REG1]], [[REG1]], _GLOBAL_OFFSET_TABLE_@ha
-;OPT0-PPC32:       lwz [[REG2:[0-9]+]], a2@got@tprel([[REG1]])
+;OPT0-PPC32:       lwz [[REG2:[1-9][0-9]*]], a2@got@tprel([[REG1]])
 ;OPT0-PPC32:       add 3, [[REG2]], a2@tls
 
 ;OPT0-PPC32-PIC-LABEL:  main2:
 ;OPT0-PPC32-PIC:        .long _GLOBAL_OFFSET_TABLE_-{{.*}}
 ;OPT0-PPC32-PIC-NOT:    li {{[0-9]+}}, _GLOBAL_OFFSET_TABLE_@l
-;OPT0-PPC32-PIC-NOT:    addis {{[0-9]+}}, {{[0-9+]}}, _GLOBAL_OFFSET_TABLE_@ha
+;OPT0-PPC32-PIC-NOT:    addis {{[0-9]+}}, {{[1-9][0-9*]}}, _GLOBAL_OFFSET_TABLE_@ha
 ;OPT0-PPC32-PIC-NOT:    bl __tls_get_addr(a2@tlsgd)@PLT
-;OPT0-PPC32-PIC:        lwz {{[0-9]+}}, a2@got@tprel({{[0-9]+}})
+;OPT0-PPC32-PIC:        lwz {{[0-9]+}}, a2@got@tprel({{[1-9][0-9]*}})