[PowerPC] Remove extra nop after notoc call

[stefanp]

Summary

Calls that are marked as @notoc do not require the extra nop after the call for the TOC restore.

[sfertile]

LGTM.

llvm/lib/Target/PowerPC/PPCInstr64Bit.td

def BLA8_NOP : IForm_and_DForm_4_zero<18, 1, 1, 24,
                              (outs), (ins abscalltarget:$func),
                              "bla $func\n\tnop", IIC_BrB,
                              [(PPCcall_nop (i64 imm:$func))]>;
     let Predicates = [PCRelativeMemops] in {
       // BL8_NOTOC means that the caller does not use the TOC pointer and if
       // it does use R2 then it is just a caller saved register. Therefore it is
       // safe to emit only the bl and not the nop for this instruction. The
       // linker will not try to restore R2 after the call.
-      def BL8_NOTOC : IForm_and_DForm_4_zero<18, 0, 1, 24, (outs),
-                                             (ins calltarget:$func),
-                                             "bl $func", IIC_BrB, []>;
+      def BL8_NOTOC : IForm<18, 0, 1, (outs),
     }
   }
   let Uses = [CTR8, RM] in {
     let isPredicable = 1 in
       def BCTRL8 : XLForm_2_ext<19, 528, 20, 0, 1, (outs), (ins),
                                 "bctrl", IIC_BrB, [(PPCbctrl)]>,
                    Requires<[In64BitMode]>;
 

llvm/test/CodeGen/PowerPC/pcrel-call-linkage-simple.ll

 define dso_local void @ExternalSymbol(i8* nocapture %out, i8* nocapture readonly %in, i64 %num) local_unnamed_addr {
 entry:
   tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 1 %out, i8* align 1 %in, i64 %num, i1 false)
   ret void
 }
 
 declare void @llvm.memcpy.p0i8.p0i8.i64(i8* noalias nocapture writeonly, i8* noalias nocapture readonly, i64, i1 immarg)
 
+
+; CHECK-S-LABEL: callerNoTail
+; CHECK-S:     bl callee@notoc
+; CHECK-S-NOT: nop
+; CHECK-S:     bl callee@notoc
+; CHECK-S-NOT: nop
+; CHECK-S:     blr
+
+; CHECK-O-LABEL: callerNoTail
+; CHECK-O:      bl
+; CHECK-O-NEXT: R_PPC64_REL24_NOTOC callee
+; CHECK-O-NOT:  nop
+; CHECK-O:      bl
+; CHECK-O-NEXT: R_PPC64_REL24_NOTOC callee
+; CHECK-O-NOT:  nop
+; CHECK-O:      blr
+define dso_local signext i32 @callerNoTail() local_unnamed_addr {
+entry:
+  %call1 = tail call signext i32 bitcast (i32 (...)* @callee to i32 ()*)()
+  %call2 = tail call signext i32 bitcast (i32 (...)* @callee to i32 ()*)()
+  %add = add i32 %call1, %call2
+  ret i32 %add
+}
+