7dbf2e7b57
The existing redundant copy elimination required a virtual register source, but the same logic works for any physreg where we don't have to worry about clobbers. On RISCV, this helps eliminate redundant CSR reads from VLENB. Differential Revision: https://reviews.llvm.org/D125564
95 lines
2.5 KiB
LLVM
95 lines
2.5 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
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; RUN: llc -O3 < %s -mtriple=riscv32 | FileCheck %s
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; These tests demonstrate optimizations involving copies from VLENB.
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define void @unused_copy_is_dead() {
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; CHECK-LABEL: unused_copy_is_dead:
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; CHECK: # %bb.0: # %entry
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; CHECK-NEXT: ret
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entry:
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call i32 @llvm.read_register.i32(metadata !0)
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ret void
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}
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define i32 @simple_cse() {
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; CHECK-LABEL: simple_cse:
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; CHECK: # %bb.0: # %entry
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; CHECK-NEXT: csrr a0, vlenb
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; CHECK-NEXT: sub a0, a0, a0
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; CHECK-NEXT: ret
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entry:
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%v1 = call i32 @llvm.read_register.i32(metadata !0)
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%v2 = call i32 @llvm.read_register.i32(metadata !0)
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%sub = sub i32 %v1, %v2
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ret i32 %sub
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}
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define i32 @sink_to_use_branch(i1 %c) {
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; CHECK-LABEL: sink_to_use_branch:
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; CHECK: # %bb.0: # %entry
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; CHECK-NEXT: andi a0, a0, 1
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; CHECK-NEXT: beqz a0, .LBB2_2
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; CHECK-NEXT: # %bb.1: # %used
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; CHECK-NEXT: csrr a0, vlenb
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; CHECK-NEXT: .LBB2_2: # %unused
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; CHECK-NEXT: ret
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entry:
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%v1 = call i32 @llvm.read_register.i32(metadata !0)
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br i1 %c, label %used, label %unused
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used:
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ret i32 %v1
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unused:
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ret i32 0
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}
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define i32 @sink_to_use_call() {
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; CHECK-LABEL: sink_to_use_call:
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; CHECK: # %bb.0: # %entry
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; CHECK-NEXT: addi sp, sp, -16
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; CHECK-NEXT: .cfi_def_cfa_offset 16
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; CHECK-NEXT: sw ra, 12(sp) # 4-byte Folded Spill
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; CHECK-NEXT: sw s0, 8(sp) # 4-byte Folded Spill
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; CHECK-NEXT: .cfi_offset ra, -4
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; CHECK-NEXT: .cfi_offset s0, -8
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; CHECK-NEXT: csrr s0, vlenb
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; CHECK-NEXT: call unknown@plt
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; CHECK-NEXT: mv a0, s0
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; CHECK-NEXT: lw ra, 12(sp) # 4-byte Folded Reload
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; CHECK-NEXT: lw s0, 8(sp) # 4-byte Folded Reload
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; CHECK-NEXT: addi sp, sp, 16
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; CHECK-NEXT: ret
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entry:
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%v1 = call i32 @llvm.read_register.i32(metadata !0)
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call void @unknown() ; maythrow
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ret i32 %v1
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}
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define void @machine_licm() {
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; CHECK-LABEL: machine_licm:
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; CHECK: # %bb.0: # %entry
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; CHECK-NEXT: addi sp, sp, -16
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; CHECK-NEXT: .cfi_def_cfa_offset 16
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; CHECK-NEXT: sw ra, 12(sp) # 4-byte Folded Spill
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; CHECK-NEXT: .cfi_offset ra, -4
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; CHECK-NEXT: .LBB4_1: # %loop
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; CHECK-NEXT: # =>This Inner Loop Header: Depth=1
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; CHECK-NEXT: csrr a0, vlenb
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; CHECK-NEXT: call use@plt
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; CHECK-NEXT: j .LBB4_1
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entry:
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br label %loop
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loop:
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%v1 = call i32 @llvm.read_register.i32(metadata !0)
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call void @use(i32 %v1)
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br label %loop
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}
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declare i32 @llvm.read_register.i32(metadata) nounwind
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declare void @unknown()
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declare void @use(i32)
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!0 = !{!"vlenb"}
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