From a9c33665ea9ba27e79bcb19e256e754209de9acb Mon Sep 17 00:00:00 2001
From: arti <arti@localhost>
Date: Wed, 11 Nov 2026 16:50:00 +0000
Subject: [PATCH] tms34010: accept the optimizer's returned argument attribute

---
 llvm/lib/Target/TMS34010/TMS34010ISelLowering.cpp | 10 +++++++---
 llvm/test/CodeGen/TMS34010/m2-reject-sret.ll      |  2 +-
 llvm/test/CodeGen/TMS34010/m2-returned.ll         | 15 +++++++++++++++
 3 files changed, 23 insertions(+), 4 deletions(-)
 create mode 100644 llvm/test/CodeGen/TMS34010/m2-returned.ll

diff --git a/llvm/lib/Target/TMS34010/TMS34010ISelLowering.cpp b/llvm/lib/Target/TMS34010/TMS34010ISelLowering.cpp
index 8ca048b630d3..c5e7d2b43ff1 100644
--- a/llvm/lib/Target/TMS34010/TMS34010ISelLowering.cpp
+++ b/llvm/lib/Target/TMS34010/TMS34010ISelLowering.cpp
@@ -70,11 +70,15 @@ SDValue TMS34010TargetLowering::LowerFormalArguments(
   // elimination).
   for (unsigned i = 0, e = Ins.size(); i != e; ++i) {
     const ISD::InputArg &In = Ins[i];
+    // `returned` is an optimization hint, not an ABI feature: the argument is
+    // still passed in its normal stack slot, and the callee already returns
+    // through the ABI's A8.  The optimizer infers it for ordinary C such as
+    // `int first(int a, int b) { return a; }`, so rejecting it made valid -O2
+    // input uncompilable.  The ABI-affecting flags stay rejected.
     if (In.Flags.isSRet() || In.Flags.isByVal() || In.Flags.isInReg() ||
-        In.Flags.isNest() || In.Flags.isReturned())
+        In.Flags.isNest())
       report_fatal_error(
-          "M2 supports only plain arguments "
-          "(no sret/byval/inreg/nest/returned)",
+          "M2 supports only plain arguments (no sret/byval/inreg/nest)",
           false);
     if (In.VT != MVT::i32)
       report_fatal_error("M2 supports only i32 and pointer arguments", false);
diff --git a/llvm/test/CodeGen/TMS34010/m2-reject-sret.ll b/llvm/test/CodeGen/TMS34010/m2-reject-sret.ll
index de8f55bf2287..8c132aeecb8f 100644
--- a/llvm/test/CodeGen/TMS34010/m2-reject-sret.ll
+++ b/llvm/test/CodeGen/TMS34010/m2-reject-sret.ll
@@ -3,7 +3,7 @@
 ;
 ; M2 has no sret convention.  The pointer attribute must be rejected even
 ; though its legalized type is a plain i32.
-; CHECK: M2 supports only plain arguments (no sret/byval/inreg/nest/returned)
+; CHECK: M2 supports only plain arguments (no sret/byval/inreg/nest)
 define void @sret_arg(ptr sret(i32) %out) {
 entry:
   store i32 0, ptr %out
diff --git a/llvm/test/CodeGen/TMS34010/m2-returned.ll b/llvm/test/CodeGen/TMS34010/m2-returned.ll
new file mode 100644
index 000000000000..1e81c0f626a8
--- /dev/null
+++ b/llvm/test/CodeGen/TMS34010/m2-returned.ll
@@ -0,0 +1,15 @@
+; RUN: llc -march=tms34010 -O0 -filetype=asm < %s | FileCheck %s
+; RUN: llc -march=tms34010 -O2 -filetype=asm < %s | FileCheck %s
+;
+; `returned` is an optimizer hint, not an ABI convention: the optimizer infers
+; it for `return a`, and the argument still lives in its normal FP-relative
+; stack slot.  It must not be rejected.
+define i32 @first(i32 returned %a, i32 %b) {
+entry:
+  ret i32 %a
+}
+; CHECK-LABEL: _first:
+; CHECK: MOVE A13, -*SP, 1
+; CHECK: ADDI -32, A{{[0-9]+}}
+; CHECK: MOVE {{A[0-9]+}}, A8
+; CHECK: RETS 2