[RISCV] Add test case showing fli being hoisted out of a loop and creating extra copies/spills.

[craig.topper]

Summary

Test case for D146314.

[reames]

LGTM

llvm/test/CodeGen/RISCV/fli-licm.ll

+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 2
+; RUN: llc < %s -mtriple=riscv32 -target-abi=ilp32f -mattr=+experimental-zfa \
+; RUN:   | FileCheck %s --check-prefix=RV32
+; RUN: llc < %s -mtriple=riscv64 -target-abi=lp64f -mattr=+experimental-zfa \
+; RUN:   | FileCheck %s --check-prefix=RV64
+
+; The purpose of this test is to check that an FLI instruction that
+; materializes an immediate is not MachineLICM'd out of a loop.
+
+%struct.Node = type { ptr, i8* }
+
+define void @process_nodes(ptr %0) nounwind {
+; RV32-LABEL: process_nodes:
+; RV32:       # %bb.0: # %entry
+; RV32-NEXT:    addi sp, sp, -16
+; RV32-NEXT:    sw ra, 12(sp) # 4-byte Folded Spill
+; RV32-NEXT:    sw s0, 8(sp) # 4-byte Folded Spill
+; RV32-NEXT:    fsw fs0, 4(sp) # 4-byte Folded Spill
+; RV32-NEXT:    beqz a0, .LBB0_3
+; RV32-NEXT:  # %bb.1: # %loop.preheader
+; RV32-NEXT:    mv s0, a0
+; RV32-NEXT:    fli.s fs0, 1.0
+; RV32-NEXT:  .LBB0_2: # %loop
+; RV32-NEXT:    # =>This Inner Loop Header: Depth=1
+; RV32-NEXT:    fmv.s fa0, fs0
+; RV32-NEXT:    mv a0, s0
+; RV32-NEXT:    call do_it@plt
+; RV32-NEXT:    lw s0, 0(s0)
+; RV32-NEXT:    bnez s0, .LBB0_2
+; RV32-NEXT:  .LBB0_3: # %exit
+; RV32-NEXT:    lw ra, 12(sp) # 4-byte Folded Reload
+; RV32-NEXT:    lw s0, 8(sp) # 4-byte Folded Reload
+; RV32-NEXT:    flw fs0, 4(sp) # 4-byte Folded Reload
+; RV32-NEXT:    addi sp, sp, 16
+; RV32-NEXT:    ret
+;
+; RV64-LABEL: process_nodes:
+; RV64:       # %bb.0: # %entry
+; RV64-NEXT:    addi sp, sp, -32
+; RV64-NEXT:    sd ra, 24(sp) # 8-byte Folded Spill
+; RV64-NEXT:    sd s0, 16(sp) # 8-byte Folded Spill
+; RV64-NEXT:    fsw fs0, 12(sp) # 4-byte Folded Spill
+; RV64-NEXT:    beqz a0, .LBB0_3
+; RV64-NEXT:  # %bb.1: # %loop.preheader
+; RV64-NEXT:    mv s0, a0
+; RV64-NEXT:    fli.s fs0, 1.0
+; RV64-NEXT:  .LBB0_2: # %loop
+; RV64-NEXT:    # =>This Inner Loop Header: Depth=1
+; RV64-NEXT:    fmv.s fa0, fs0
+; RV64-NEXT:    mv a0, s0
+; RV64-NEXT:    call do_it@plt
+; RV64-NEXT:    ld s0, 0(s0)
+; RV64-NEXT:    bnez s0, .LBB0_2
+; RV64-NEXT:  .LBB0_3: # %exit
+; RV64-NEXT:    ld ra, 24(sp) # 8-byte Folded Reload
+; RV64-NEXT:    ld s0, 16(sp) # 8-byte Folded Reload
+; RV64-NEXT:    flw fs0, 12(sp) # 4-byte Folded Reload
+; RV64-NEXT:    addi sp, sp, 32
+; RV64-NEXT:    ret
+entry:
+  %1 = icmp eq ptr %0, null
+  br i1 %1, label %exit, label %loop
+
+loop:
+  %2 = phi %struct.Node* [ %4, %loop ], [ %0, %entry ]
+  tail call void @do_it(float 1.000000e+00, ptr nonnull %2)
+  %3 = getelementptr inbounds %struct.Node, ptr %2, i64 0, i32 0
+  %4 = load ptr, ptr %3, align 8
+  %5 = icmp eq ptr %4, null
+  br i1 %5, label %exit, label %loop
+
+exit:
+  ret void
+}
+
+declare void @do_it(float, ptr)