[llvm] [llvm][RISCV] Handle fpround and fpextend for zvfbfa without zvfbfmin (PR #164366)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-risc-v

Author: Brandon Wu (4vtomat)

<details>
<summary>Changes</summary>

Add codegen support for fpround and fpextend for zvfbfa.


---
Full diff: https://github.com/llvm/llvm-project/pull/164366.diff


2 Files Affected:

- (modified) llvm/lib/Target/RISCV/RISCVInstrInfoZvfbf.td (+34) 
- (added) llvm/test/CodeGen/RISCV/rvv/issue-164324.ll (+22) 


``````````diff
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfoZvfbf.td b/llvm/lib/Target/RISCV/RISCVInstrInfoZvfbf.td
index f7d1a099c69d9..b9c5b75983b1f 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfoZvfbf.td
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfoZvfbf.td
@@ -668,4 +668,38 @@ foreach vti = NoGroupBF16Vectors in {
   def : Pat<(vti.Scalar (extractelt (vti.Vector vti.RegClass:$rs2), 0)),
             (vfmv_f_s_inst vti.RegClass:$rs2, vti.Log2SEW)>;
 }
+
+let Predicates = [HasStdExtZvfbfa] in {
+  foreach fvtiToFWti = AllWidenableBF16ToFloatVectors in {
+    defvar fvti = fvtiToFWti.Vti;
+    defvar fwti = fvtiToFWti.Wti;
+    def : Pat<(fwti.Vector (any_riscv_fpextend_vl
+                               (fvti.Vector fvti.RegClass:$rs1),
+                               (fvti.Mask VMV0:$vm),
+                               VLOpFrag)),
+              (!cast<Instruction>("PseudoVFWCVT_F_F_ALT_V_"#fvti.LMul.MX#"_E"#fvti.SEW#"_MASK")
+                  (fwti.Vector (IMPLICIT_DEF)), fvti.RegClass:$rs1,
+                  (fvti.Mask VMV0:$vm),
+                  GPR:$vl, fvti.Log2SEW, TA_MA)>;
+
+    def : Pat<(fvti.Vector (any_riscv_fpround_vl
+                               (fwti.Vector fwti.RegClass:$rs1),
+                               (fwti.Mask VMV0:$vm), VLOpFrag)),
+              (!cast<Instruction>("PseudoVFNCVT_F_F_ALT_W_"#fvti.LMul.MX#"_E"#fvti.SEW#"_MASK")
+                  (fvti.Vector (IMPLICIT_DEF)), fwti.RegClass:$rs1,
+                  (fwti.Mask VMV0:$vm),
+                  // Value to indicate no rounding mode change in
+                  // RISCVInsertReadWriteCSR
+                  FRM_DYN,
+                  GPR:$vl, fvti.Log2SEW, TA_MA)>;
+    def : Pat<(fvti.Vector (fpround (fwti.Vector fwti.RegClass:$rs1))),
+              (!cast<Instruction>("PseudoVFNCVT_F_F_ALT_W_"#fvti.LMul.MX#"_E"#fvti.SEW)
+                  (fvti.Vector (IMPLICIT_DEF)),
+                  fwti.RegClass:$rs1,
+                  // Value to indicate no rounding mode change in
+                  // RISCVInsertReadWriteCSR
+                  FRM_DYN,
+                  fvti.AVL, fvti.Log2SEW, TA_MA)>;
+  }
+}
 } // Predicates = [HasStdExtZvfbfa]
diff --git a/llvm/test/CodeGen/RISCV/rvv/issue-164324.ll b/llvm/test/CodeGen/RISCV/rvv/issue-164324.ll
new file mode 100644
index 0000000000000..5bdcf907cc5fc
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/rvv/issue-164324.ll
@@ -0,0 +1,22 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: sed 's/iXLen/i32/g' %s | llc -mtriple=riscv32 -mattr=+v,+zvfh,+experimental-zvfbfa \
+; RUN:   -verify-machineinstrs -target-abi=ilp32d | FileCheck %s
+; RUN: sed 's/iXLen/i64/g' %s | llc -mtriple=riscv64 -mattr=+v,+zvfh,+experimental-zvfbfa \
+; RUN:   -verify-machineinstrs -target-abi=lp64d | FileCheck %s
+
+define <vscale x 8 x bfloat> @intrinsic_vfadd_vv_nxv1bf16_nxv1bf16_nxv1bf16(<vscale x 8 x bfloat> %0, <vscale x 8 x bfloat> %1) nounwind {
+; CHECK-LABEL: intrinsic_vfadd_vv_nxv1bf16_nxv1bf16_nxv1bf16:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    vsetvli a0, zero, e16alt, m2, ta, ma
+; CHECK-NEXT:    vfwcvt.f.f.v v12, v10
+; CHECK-NEXT:    vfwcvt.f.f.v v16, v8
+; CHECK-NEXT:    vsetvli zero, zero, e32, m4, ta, ma
+; CHECK-NEXT:    vfadd.vv v12, v16, v12
+; CHECK-NEXT:    vsetvli zero, zero, e16alt, m2, ta, ma
+; CHECK-NEXT:    vfncvt.f.f.w v8, v12
+; CHECK-NEXT:    ret
+entry:
+  %a = fadd <vscale x 8 x bfloat> %0, %1
+
+  ret <vscale x 8 x bfloat> %a
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/164366