fallback: legalize: G_BITCAST s64,<4 x s16>

Run:explore-04ca53e65f-20261014-114124
Kind:fallback
Category:legalize: G_BITCAST s64,<4 x s16>
Occurrences:13 in 3 configs, 3 test files
Snippet from:rvp-bitcast-const-fold.ll @pnot_v4i16 via llvm-extract
Config:-mtriple=riscv32 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
Local check:reproduces at 04ca53e65f
Compiler Explorer:not uploaded (over --godbolt-limit or disabled)

Snippet:

define i64 @pnot_v4i16(i64 %a) {
  %bc = bitcast i64 %a to <4 x i16>
  %not = xor <4 x i16> %bc, splat (i16 -1)
  %res = bitcast <4 x i16> %not to i64
  ret i64 %res
}

Reproduce:

llc -mtriple=riscv32 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel.* snippet.ll -o -
llc -mtriple=riscv32 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs -global-isel=0 snippet.ll -o -

Local llc output:

remark: <unknown>:0:0: unable to legalize instruction: %7:_(s64) = G_BITCAST %6:_(<4 x s16>) (in function: pnot_v4i16)
warning: Instruction selection used fallback path for pnot_v4i16

Occurrences (13):

InputFunctionConfig
rvp-bitcast-const-fold.llpnot_v4i16-mtriple=riscv32 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-bitcast-const-fold.llpnot_v4i16-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-bitcast-paired.lladd_v4i16_via_bitcast-mtriple=riscv32 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-bitcast-paired.lladd_v4i16_via_bitcast-mtriple=riscv32 -mattr=+experimental-p,+m,+zbb,+d -verify-machineinstrs
rvp-bitcast-paired.lladd_v4i16_via_bitcast-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-ppaireo-w.llinsert_lo_v4i16-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-bitcast-const-fold.23693da188.ll (mutant of rvp-bitcast-const-fold.ll)pnot_v4i16-mtriple=riscv32 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-bitcast-const-fold.c8133aab26.ll (mutant of rvp-bitcast-const-fold.ll)pnot_v4i16-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-bitcast-paired.2c193fb556.ll (mutant of rvp-bitcast-paired.ll)add_v4i16_via_bitcast-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-bitcast-paired.84de9f6546.ll (mutant of rvp-bitcast-paired.ll)add_v4i16_via_bitcast-mtriple=riscv32 -mattr=+experimental-p,+m,+zbb,+d -verify-machineinstrs
rvp-bitcast-paired.d975ab3551.ll (mutant of rvp-bitcast-paired.ll)add_v4i16_via_bitcast-mtriple=riscv32 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-ppaireo-w.9b69117a89.ll (mutant of rvp-ppaireo-w.ll)insert_lo_v4i16-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-ppaireo-w.a7a5d26441.ll (mutant of rvp-ppaireo-w.ll)insert_lo_v4i16-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs

Generated 2026-10-15 08:05 UTC.