[AIX][AsmPrinter] Print Symbol in comments for TOC load

[jsji]

Summary

We are using TOCEntry symbols like LC..0 in TOC loads,
this is hard to read , at least requiring an additional step to figure
out the loaded symbols.

We should print out the name in comments.

[jsji]

Update update_llc_test tests as well.

[shchenz]

Like this improvement. It will make the assembly be more clear. LGTM

llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp

case PPC::LWZtoc: {
     // references into the toc section. The displacement value will be generated
     // relative to the toc-base.
     if (IsAIX) {
       assert(
           TM.getCodeModel() == CodeModel::Small &&
           "This pseudo should only be selected for 32-bit small code model.");
       Exp = getTOCEntryLoadingExprForXCOFF(MOSymbol, Exp, VK);
       TmpInst.getOperand(1) = MCOperand::createExpr(Exp);
+
+      // Print MO for better readability
+      if (isVerbose())
+        OutStreamer->GetCommentOS() << MO << '\n';
       EmitToStreamer(*OutStreamer, TmpInst);
       return;
     }
 
     // Create an explicit subtract expression between the local symbol and
     // '.LTOC' to manifest the toc-relative offset.
     const MCExpr *PB = MCSymbolRefExpr::create(
         OutContext.getOrCreateSymbol(Twine(".LTOC")), OutContext);
case PPC::LDtoc: {
     // synthesize later.
     MCSymbol *TOCEntry = lookUpOrCreateTOCEntry(MOSymbol, VK);
 
     MCSymbolRefExpr::VariantKind VKExpr =
         IsAIX ? MCSymbolRefExpr::VK_None : MCSymbolRefExpr::VK_PPC_TOC;
     const MCExpr *Exp = MCSymbolRefExpr::create(TOCEntry, VKExpr, OutContext);
     TmpInst.getOperand(1) = MCOperand::createExpr(
         IsAIX ? getTOCEntryLoadingExprForXCOFF(MOSymbol, Exp, VK) : Exp);
+
+    // Print MO for better readability
+    if (isVerbose() && IsAIX)
+      OutStreamer->GetCommentOS() << MO << '\n';
     EmitToStreamer(*OutStreamer, TmpInst);
     return;
   }
   case PPC::ADDIStocHA: {
     assert((IsAIX && !IsPPC64 && TM.getCodeModel() == CodeModel::Large) &&
            "This pseudo should only be selected for 32-bit large code model on"
            " AIX.");
 

llvm/test/CodeGen/PowerPC/aix-overflow-toc.py

 print("define void @foo() {")
 print("entry:")
 for x in range(0, numentries):
     print("store i32 1, i32* @a%d, align 4" % (x))
 print("ret void")
 print("}")
 
 # 32-bit assembly check
-# ASM32:  lwz 4, L..C0(2)
-# ASM32:  lwz 4, L..C1(2)
+# ASM32:  lwz 4, L..C0(2) # @a0
+# ASM32:  lwz 4, L..C1(2) # @a1
 
-# ASM32:  lwz 4, L..C8191(2)
-# ASM32:  lwz 4, L..C8192-65536(2)
-# ASM32:  lwz 4, L..C8193-65536(2)
+# ASM32:  lwz 4, L..C8191(2) # @a8191
+# ASM32:  lwz 4, L..C8192-65536(2) # @a8192
+# ASM32:  lwz 4, L..C8193-65536(2) # @a8193
 
-# ASM32:  lwz 4, L..C12288-65536(2)
-# ASM32:  lwz 4, L..C12289-65536(2)
+# ASM32:  lwz 4, L..C12288-65536(2) # @a12288
+# ASM32:  lwz 4, L..C12289-65536(2) # @a12289
 
 # 64-bit assembly check
-# ASM64:  ld 4, L..C0(2)
-# ASM64:  ld 4, L..C1(2)
+# ASM64:  ld 4, L..C0(2) # @a0
+# ASM64:  ld 4, L..C1(2) # @a1
 
-# ASM64:  ld 4, L..C4095(2)
-# ASM64:  ld 4, L..C4096-65536(2)
-# ASM64:  ld 4, L..C4097-65536(2)
-
-# ASM64:  ld 4, L..C12287-65536(2)
-# ASM64:  ld 4, L..C12288-131072(2)
-# ASM64:  ld 4, L..C12289-131072(2)
+# ASM64:  ld 4, L..C4095(2) # @a4095
+# ASM64:  ld 4, L..C4096-65536(2) # @a4096
+# ASM64:  ld 4, L..C4097-65536(2) # @a4097
+
+# ASM64:  ld 4, L..C12287-65536(2) # @a12287
+# ASM64:  ld 4, L..C12288-131072(2) # @a12288
+# ASM64:  ld 4, L..C12289-131072(2) # @a12289
 
 # DIS32:   0: 80 82 00 00   lwz 4, 0(2)
 # DIS32:  00000002:  R_TOC  (idx: 24591) a0[TC]
 # DIS32:   c: 80 82 00 04   lwz 4, 4(2)
 # DIS32:  0000000e:  R_TOC  (idx: 24593) a1[TC]
 
 # DIS32:    fffc: 80 82 7f fc   lwz 4, 32764(2)
 # DIS32:      0000fffe:  R_TOC  (idx: 40973) a8191[TC]

llvm/test/tools/UpdateTestChecks/update_llc_test_checks/Inputs/ppc_generated_funcs.ll.generated.expected

 ; AIX-NEXT:    addi 1, 1, 48
 ; AIX-NEXT:    lwz 31, -4(1)
 ; AIX-NEXT:    blr
 ;
 ; AIX-LABEL: main:
 ; AIX:       # %bb.0:
 ; AIX-NEXT:    stw 31, -4(1)
 ; AIX-NEXT:    stwu 1, -48(1)
-; AIX-NEXT:    lwz 4, L..C0(2)
+; AIX-NEXT:    lwz 4, L..C0(2) # @x
 ; AIX-NEXT:    mr 31, 1
 ; AIX-NEXT:    li 3, 0
 ; AIX-NEXT:    stw 3, 40(31)
 ; AIX-NEXT:    li 3, 1
 ; AIX-NEXT:    li 5, 2
 ; AIX-NEXT:    li 6, 3
 ; AIX-NEXT:    li 7, 4
 ; AIX-NEXT:    stw 3, 36(31)

llvm/test/tools/UpdateTestChecks/update_llc_test_checks/Inputs/ppc_generated_funcs.ll.nogenerated.expected

 ; CHECK-NEXT:    lwz 31, 28(1)
 ; CHECK-NEXT:    addi 1, 1, 32
 ; CHECK-NEXT:    blr
 ;
 ; AIX-LABEL: main:
 ; AIX:       # %bb.0:
 ; AIX-NEXT:    stw 31, -4(1)
 ; AIX-NEXT:    stwu 1, -48(1)
-; AIX-NEXT:    lwz 4, L..C0(2)
+; AIX-NEXT:    lwz 4, L..C0(2) # @x
 ; AIX-NEXT:    mr 31, 1
 ; AIX-NEXT:    li 3, 0
 ; AIX-NEXT:    stw 3, 40(31)
 ; AIX-NEXT:    li 3, 1
 ; AIX-NEXT:    li 5, 2
 ; AIX-NEXT:    li 6, 3
 ; AIX-NEXT:    li 7, 4
 ; AIX-NEXT:    stw 3, 36(31)