[llvm] [X86] Align f128 and i128 to 16 bytes when passing on x86-32 (PR #138092)

[Trevor Gross via llvm-commits]

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@@ -374,5 +374,37 @@ static bool CC_X86_64_I128(unsigned &ValNo, MVT &ValVT, MVT &LocVT,
   return true;
 }
 
+/// Special handling for i128 and fp128: on x86-32, i128 and fp128 get legalized
+/// as four i32s, but fp128 must be passed on the stack with 16-byte alignment.
+/// Technically only fp128 has a specified ABI, but it makes sense to handle
+/// i128 the same until we hear differently.
+static bool CC_X86_32_I128_FP128(unsigned &ValNo, MVT &ValVT, MVT &LocVT,
+                                 CCValAssign::LocInfo &LocInfo,
+                                 ISD::ArgFlagsTy &ArgFlags, CCState &State) {
+  assert(ValVT == MVT::i32 && "Should have i32 parts");
+  SmallVectorImpl<CCValAssign> &PendingMembers = State.getPendingLocs();
+  PendingMembers.push_back(
+      CCValAssign::getPending(ValNo, ValVT, LocVT, LocInfo));
+
+  if (!ArgFlags.isInConsecutiveRegsLast())
+    return true;
+
+  unsigned NumRegs = PendingMembers.size();
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tgross35 wrote:

It looks like somebody got this already https://github.com/llvm/llvm-project/commit/fe1941967267e472

https://github.com/llvm/llvm-project/pull/138092