[llvm] [RISCV][GISel] Add calling convention support for half (PR #94110)

[Yingwei Zheng via llvm-commits]

================
@@ -0,0 +1,136 @@
+; NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 5
+; RUN: llc -mtriple=riscv32 -global-isel -stop-after=irtranslator \
+; RUN:    -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefix=RV32I %s
+; RUN: llc -mtriple=riscv32 -mattr=+zfh -target-abi ilp32f \
+; RUN:    -global-isel -stop-after=irtranslator -verify-machineinstrs < %s \
+; RUN:   | FileCheck -check-prefix=RV32IZFH %s
+
+define half @callee_half_in_regs(half %x) nounwind {
+  ; RV32I-LABEL: name: callee_half_in_regs
+  ; RV32I: bb.1 (%ir-block.0):
+  ; RV32I-NEXT:   liveins: $x10
+  ; RV32I-NEXT: {{  $}}
+  ; RV32I-NEXT:   [[COPY:%[0-9]+]]:_(s32) = COPY $x10
+  ; RV32I-NEXT:   [[TRUNC:%[0-9]+]]:_(s16) = G_TRUNC [[COPY]](s32)
----------------
dtcxzyw wrote:

I am wondering that whether we should handle nan-boxing here.
See https://dtcxzyw.github.io/riscv-isa-manual-host/unpriv-isa-asciidoc.html#nanboxing


https://github.com/llvm/llvm-project/pull/94110