[clang] [PowerPC] Support local-dynamic TLS relocation on AIX (PR #66316)

[Amy Kwan via cfe-commits]

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@@ -145,9 +163,88 @@ namespace {
                                                               .addImm(0);
 
         if (IsAIX) {
-          // The variable offset and region handle are copied in r4 and r3. The
-          // copies are followed by GETtlsADDR32AIX/GETtlsADDR64AIX.
-          if (!IsTLSTPRelMI) {
+          if (IsTLSLDAIXMI) {
+            // It is better to put TLSLDAIX node before LoadOffsetToc node,
+            // because LoadOffsetToc node can use clobbers r4/r5. Search for the
+            // first paired LoadOffsetToc node within the same BB.
+            unsigned LDTocOp =
+                Is64Bit ? (IsLargeModel ? PPC::LDtocL : PPC::LDtoc)
+                        : (IsLargeModel ? PPC::LWZtocL : PPC::LWZtoc);
+            MachineBasicBlock::iterator Anchor = I;
+            if (!RegInfo.use_empty(OutReg)) {
+              std::set<MachineInstr *> Uses;
+              // Collect all instructions that use OutReg
+              for (MachineOperand &MO : RegInfo.use_operands(OutReg)) {
+                if (Uses.count(MO.getParent()))
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amy-kwan wrote:

Pull out the `MO.getParent()` calls, and end the comment on 176 with a period.

https://github.com/llvm/llvm-project/pull/66316