[llvm] [PowerPC] 32-bit large code-model support for toc-data (PR #85129)

[Zaara Syeda via llvm-commits]

================
@@ -6144,23 +6142,44 @@ void PPCDAGToDAGISel::Select(SDNode *N) {
            " ELF/AIX or 32-bit AIX in the following.");
 
     // Transforms the ISD::TOC_ENTRY node for 32-bit AIX large code model mode
-    // or 64-bit medium (ELF-only) or large (ELF and AIX) code model code. We
-    // generate two instructions as described below. The first source operand
-    // is a symbol reference. If it must be toc-referenced according to
+    // or 64-bit medium (ELF-only) or large (ELF and AIX) code model code non
+    // toc-data symbols.
+    // We generate two instructions as described below. The first source
+    // operand is a symbol reference. If it must be toc-referenced according to
     // Subtarget, we generate:
     // [32-bit AIX]
     //   LWZtocL(@sym, ADDIStocHA(%r2, @sym))
     // [64-bit ELF/AIX]
     //   LDtocL(@sym, ADDIStocHA8(%x2, @sym))
     // Otherwise we generate:
     //   ADDItocL8(ADDIStocHA8(%x2, @sym), @sym)
+
+    // For large code model toc-data symbols we generate:
+    // [32-bit AIX]
+    //   ADDItocL(ADDIStocHA(%x2, @sym), @sym)
+    // [64-bit AIX]
+    //   ADDItocL8(ADDIStocHA8(%x2, @sym), @sym)
+
     SDValue GA = N->getOperand(0);
     SDValue TOCbase = N->getOperand(1);
 
     EVT VT = isPPC64 ? MVT::i64 : MVT::i32;
     SDNode *Tmp = CurDAG->getMachineNode(
         isPPC64 ? PPC::ADDIStocHA8 : PPC::ADDIStocHA, dl, VT, TOCbase, GA);
 
+    // On AIX if the symbol has the toc-data attribute it will be defined
+    // in the TOC entry, so we use an ADDItocL similar to the medium code
+    // model ELF abi.
+    if (isAIXABI && hasTocDataAttr(GA)) {
+      if (isPPC64)
+        report_fatal_error(
+            "64-bit large code model toc-data not yet supported");
+
+      ReplaceNode(N, CurDAG->getMachineNode(PPC::ADDItocL, dl, VT,
+                                            SDValue(Tmp, 0), GA));
+      return;
+    }
+
----------------
syzaara wrote:

Line 6195 is handling the Linux medium code model path. For tocdata 64-bit with large code model, I will have a follow up patch to use ADDItocL8 (with the appropriate enhancements made in PPCAsmPrinter.cpp). ADDItocL8 will then be used on line 6175 above.
I plan to post the 64-bit support next once this 32-bit patch is approved and merged.

https://github.com/llvm/llvm-project/pull/85129