47fd32f81c
Proof: https://alive2.llvm.org/ce/z/J7GBMU Same as https://github.com/llvm/llvm-project/pull/92753, the types of LHS and RHS in shift nodes may differ. + When VT is smaller than ShiftVT, it is safe to use trunc. + When VT is larger than ShiftVT, it is safe to use zext iff `is_zero_poison` is true (i.e., `opcode == ISD::CTTZ_ZERO_UNDEF`). See also the counterexample `src_shl_cttz2 -> tgt_shl_cttz2` in the alive2 proofs. Fixes issue https://github.com/llvm/llvm-project/pull/85066#issuecomment-2142553617.
46 lines
1.2 KiB
LLVM
46 lines
1.2 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
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; RUN: llc -mtriple=powerpc64le < %s | FileCheck %s
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; Tests from pr85066
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define i64 @test_shl_zext_cttz(i16 %x) {
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; CHECK-LABEL: test_shl_zext_cttz:
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; CHECK: # %bb.0: # %entry
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; CHECK-NEXT: oris 3, 3, 1
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; CHECK-NEXT: neg 4, 3
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; CHECK-NEXT: and 3, 3, 4
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; CHECK-NEXT: clrldi 3, 3, 32
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; CHECK-NEXT: blr
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entry:
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%cttz = tail call i16 @llvm.cttz.i16(i16 %x, i1 false)
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%zext = zext i16 %cttz to i64
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%res = shl i64 1, %zext
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ret i64 %res
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}
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define i64 @test_shl_zext_cttz_zero_is_poison(i16 %x) {
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; CHECK-LABEL: test_shl_zext_cttz_zero_is_poison:
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; CHECK: # %bb.0: # %entry
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; CHECK-NEXT: neg 4, 3
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; CHECK-NEXT: and 3, 3, 4
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; CHECK-NEXT: clrldi 3, 3, 32
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; CHECK-NEXT: blr
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entry:
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%cttz = tail call i16 @llvm.cttz.i16(i16 %x, i1 true)
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%zext = zext i16 %cttz to i64
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%res = shl i64 1, %zext
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ret i64 %res
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}
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define i16 @test_shl_trunc_cttz(i32 %x) {
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; CHECK-LABEL: test_shl_trunc_cttz:
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; CHECK: # %bb.0: # %entry
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; CHECK-NEXT: neg 4, 3
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; CHECK-NEXT: and 3, 3, 4
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; CHECK-NEXT: blr
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entry:
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%cttz = tail call i32 @llvm.cttz.i32(i32 %x, i1 false)
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%trunc = trunc i32 %cttz to i16
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%res = shl i16 1, %trunc
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ret i16 %res
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}
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