[CIR] Lower signext and zeroext attributes (#1473)

CIR is currently ignoring the `signext` and `zeroext` for function
arguments and return types produced by CallConvLowering.

This PR lowers them to LLVM IR.

Author: AdUhTkJm

clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp

@@ -2212,6 +2212,34 @@ mlir::LogicalResult CIRToLLVMFuncOpLowering::matchAndRewrite(
       Loc, op.getName(), llvmFnTy, linkage, isDsoLocal, cconv,
       mlir::SymbolRefAttr(), attributes);
 
+  // Lower CIR attributes for arguments.
+  for (unsigned index = 0; index < fnType.getNumInputs(); index++) {
+    mlir::DictionaryAttr cirAttrs = op.getArgAttrDict(index);
+    if (cirAttrs) {
+      if (cirAttrs.get(cir::CIRDialect::getZExtAttrName()))
+        fn.setArgAttr(index, mlir::LLVM::LLVMDialect::getZExtAttrName(),
+                      rewriter.getUnitAttr());
+      if (cirAttrs.get(cir::CIRDialect::getSExtAttrName()))
+        fn.setArgAttr(index, mlir::LLVM::LLVMDialect::getSExtAttrName(),
+                      rewriter.getUnitAttr());
+    }
+  }
+
+  // Lower CIR attributes for return value.
+  // Each function has no more than one result in CIR, so no need for a loop.
+  assert(op.getNumResults() <= 1);
+  if (op.getNumResults() > 0) {
+    mlir::DictionaryAttr resultAttrs = op.getResultAttrDict(0);
+    if (resultAttrs) {
+      if (resultAttrs.get(cir::CIRDialect::getZExtAttrName()))
+        fn.setResultAttr(0, mlir::LLVM::LLVMDialect::getZExtAttrName(),
+                         rewriter.getUnitAttr());
+      if (resultAttrs.get(cir::CIRDialect::getSExtAttrName()))
+        fn.setResultAttr(0, mlir::LLVM::LLVMDialect::getSExtAttrName(),
+                         rewriter.getUnitAttr());
+    }
+  }
+
   fn.setVisibility_Attr(mlir::LLVM::VisibilityAttr::get(
       getContext(), lowerCIRVisibilityToLLVMVisibility(
                         op.getGlobalVisibilityAttr().getValue())));

clang/test/CIR/Lowering/attribute-lowering.cir

@@ -1,11 +1,23 @@
 // RUN: cir-translate %s -cir-to-llvmir --disable-cc-lowering -o -  | FileCheck %s -check-prefix=LLVM
 
 !s32i = !cir.int<s, 32>
+!s8i = !cir.int<u, 8>
+!u8i = !cir.int<u, 8>
 
 module {
   cir.global "private" internal @const_array = #cir.const_array<[#cir.int<1> : !s32i]> : !cir.array<!s32i x 1> {section = ".abc"}
   // LLVM: @const_array = internal global [1 x i32] [i32 1], section ".abc"
 
   cir.global "private" internal @const_struct = #cir.const_struct<{#cir.int<1> : !s32i}> : !cir.struct<struct {!s32i}> {section = ".abc"}
   // LLVM: @const_struct = internal global { i32 } { i32 1 }, section ".abc"
+
+  cir.func @func_zeroext(%arg0: !u8i {cir.zeroext}) -> (!u8i {cir.zeroext}) {
+    cir.return %arg0 : !u8i
+  }
+  // LLVM: define zeroext i8 @func_zeroext(i8 zeroext %0) 
+
+  cir.func @func_signext(%arg0: !s8i {cir.signext}) -> (!s8i {cir.signext}) {
+    cir.return %arg0 : !s8i
+  }
+  // LLVM: define signext i8 @func_signext(i8 signext %0) 
 }