[llvm] [PowerPC] Add special handling for arguments that are smaller than pointer size. (PR #119003)

[via llvm-commits]

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@@ -7291,7 +7294,23 @@ SDValue PPCTargetLowering::LowerFormalArguments_AIX(
       SDValue FIN = DAG.getFrameIndex(FI, PtrVT);
       SDValue ArgValue =
           DAG.getLoad(ValVT, dl, Chain, FIN, MachinePointerInfo());
-      InVals.push_back(ArgValue);
+
+      // While the ABI specifies the the higher bits of the load should be
+      // zeroed out this is not always the case. For safety this code will zero
+      // extend the loaded value if the size of the argument type is smaller
+      // then the load.
+      if (!ArgVT.isVector() && !ValVT.isVector() && ArgVT.isInteger() &&
+          ValVT.isInteger() &&
+          ArgVT.getScalarSizeInBits() < ValVT.getScalarSizeInBits()) {
+        SDValue ArgValueTrunc = DAG.getNode(ISD::TRUNCATE, dl, ArgVT, ArgValue);
+        //    DAG.getLoad(ArgVT, dl, Chain, FIN, MachinePointerInfo());
+        SDValue ArgValueExt =
+            ArgSignExt ? DAG.getSExtOrTrunc(ArgValueTrunc, dl, ValVT)
+                       : DAG.getZExtOrTrunc(ArgValueTrunc, dl, ValVT);
+        InVals.push_back(ArgValueExt);
+      } else {
+        InVals.push_back(ArgValue);
+      }
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RolandF77 wrote:

braces not needed here

https://github.com/llvm/llvm-project/pull/119003