[llvm] [RISCV] Implement foward inserting save/restore FRM instructions. (PR #77744)

[Yeting Kuo via llvm-commits]

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@@ -0,0 +1,217 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 4
+; RUN: llc -mtriple=riscv64 -mattr=+v -verify-machineinstrs -target-abi=lp64d < %s | FileCheck %s
+
+declare <vscale x 1 x float> @llvm.riscv.vfadd.nxv1f32.nxv1f32(
+  <vscale x 1 x float>,
+  <vscale x 1 x float>,
+  <vscale x 1 x float>,
+  i64, i64);
+
+; Test only save/restore frm once.
+define <vscale x 1 x float> @test(<vscale x 1 x float> %0, <vscale x 1 x float> %1, i64 %2) nounwind {
+; CHECK-LABEL: test:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    vsetvli zero, a0, e32, mf2, ta, ma
+; CHECK-NEXT:    fsrmi a0, 0
+; CHECK-NEXT:    vfadd.vv v8, v8, v9
+; CHECK-NEXT:    vfadd.vv v8, v8, v8
+; CHECK-NEXT:    fsrm a0
+; CHECK-NEXT:    ret
+entry:
+  %a = call <vscale x 1 x float> @llvm.riscv.vfadd.nxv1f32.nxv1f32(
+    <vscale x 1 x float> undef,
+    <vscale x 1 x float> %0,
+    <vscale x 1 x float> %1,
+    i64 0, i64 %2)
+  %b = call <vscale x 1 x float> @llvm.riscv.vfadd.nxv1f32.nxv1f32(
+    <vscale x 1 x float> undef,
+    <vscale x 1 x float> %a,
+    <vscale x 1 x float> %a,
+    i64 0, i64 %2)
+  ret <vscale x 1 x float> %b
+}
+
+; Test only restore frm once.
+define <vscale x 1 x float> @test2(<vscale x 1 x float> %0, <vscale x 1 x float> %1, i64 %2) nounwind {
+; CHECK-LABEL: test2:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    vsetvli zero, a0, e32, mf2, ta, ma
+; CHECK-NEXT:    fsrmi a0, 0
+; CHECK-NEXT:    vfadd.vv v8, v8, v9
+; CHECK-NEXT:    fsrmi 1
+; CHECK-NEXT:    vfadd.vv v8, v8, v8
+; CHECK-NEXT:    fsrm a0
+; CHECK-NEXT:    ret
+entry:
+  %a = call <vscale x 1 x float> @llvm.riscv.vfadd.nxv1f32.nxv1f32(
+    <vscale x 1 x float> undef,
+    <vscale x 1 x float> %0,
+    <vscale x 1 x float> %1,
+    i64 0, i64 %2)
+  %b = call <vscale x 1 x float> @llvm.riscv.vfadd.nxv1f32.nxv1f32(
+    <vscale x 1 x float> undef,
+    <vscale x 1 x float> %a,
+    <vscale x 1 x float> %a,
+    i64 1, i64 %2)
+  ret <vscale x 1 x float> %b
+}
+
+; Test restoring frm before function call and doing nothing with folling dynamic
+; rounding mode operations.
+declare void @foo()
+define <vscale x 1 x float> @test3(<vscale x 1 x float> %0, <vscale x 1 x float> %1, i64 %2) nounwind {
+; CHECK-LABEL: test3:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    addi sp, sp, -32
+; CHECK-NEXT:    sd ra, 24(sp) # 8-byte Folded Spill
+; CHECK-NEXT:    sd s0, 16(sp) # 8-byte Folded Spill
+; CHECK-NEXT:    csrr a1, vlenb
+; CHECK-NEXT:    slli a1, a1, 1
+; CHECK-NEXT:    sub sp, sp, a1
+; CHECK-NEXT:    mv s0, a0
+; CHECK-NEXT:    vsetvli zero, a0, e32, mf2, ta, ma
+; CHECK-NEXT:    fsrmi a0, 0
+; CHECK-NEXT:    vfadd.vv v8, v8, v9
+; CHECK-NEXT:    addi a1, sp, 16
+; CHECK-NEXT:    vs1r.v v8, (a1) # Unknown-size Folded Spill
+; CHECK-NEXT:    fsrm a0
+; CHECK-NEXT:    call foo
+; CHECK-NEXT:    vsetvli zero, s0, e32, mf2, ta, ma
+; CHECK-NEXT:    addi a0, sp, 16
+; CHECK-NEXT:    vl1r.v v8, (a0) # Unknown-size Folded Reload
+; CHECK-NEXT:    vfadd.vv v8, v8, v8
+; CHECK-NEXT:    csrr a0, vlenb
+; CHECK-NEXT:    slli a0, a0, 1
+; CHECK-NEXT:    add sp, sp, a0
+; CHECK-NEXT:    ld ra, 24(sp) # 8-byte Folded Reload
+; CHECK-NEXT:    ld s0, 16(sp) # 8-byte Folded Reload
+; CHECK-NEXT:    addi sp, sp, 32
+; CHECK-NEXT:    ret
+entry:
+  %a = call <vscale x 1 x float> @llvm.riscv.vfadd.nxv1f32.nxv1f32(
+    <vscale x 1 x float> undef,
+    <vscale x 1 x float> %0,
+    <vscale x 1 x float> %1,
+    i64 0, i64 %2)
+  call void @foo()
+  %b = call <vscale x 1 x float> @llvm.riscv.vfadd.nxv1f32.nxv1f32(
+    <vscale x 1 x float> undef,
+    <vscale x 1 x float> %a,
+    <vscale x 1 x float> %a,
+    i64 7, i64 %2)
+  ret <vscale x 1 x float> %b
+}
+
+; Test restoring frm before inline asm and doing nothing with folling dynamic
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yetingk wrote:

Done.

https://github.com/llvm/llvm-project/pull/77744