fallback: legalize: G_BITCAST s32,<4 x s8>

Run:explore-bc8218b282-20261015-075519
Kind:fallback
Category:legalize: G_BITCAST s32,<4 x s8>
Occurrences:12 in 2 configs, 3 test files
Snippet from:rvp-bitcast-const-fold.ll @pnot_v4i8 via llvm-extract
Config:-mtriple=riscv32 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
Local check:reproduces at bc8218b282
Compiler Explorer:not uploaded (over --godbolt-limit or disabled)

Snippet:

define i32 @pnot_v4i8(i32 %a) {
  %bc = bitcast i32 %a to <4 x i8>
  %not = xor <4 x i8> %bc, splat (i8 -1)
  %res = bitcast <4 x i8> %not to i32
  ret i32 %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: %5:_(s32) = G_BITCAST %4:_(<4 x s8>) (in function: pnot_v4i8)
warning: Instruction selection used fallback path for pnot_v4i8

Occurrences (12):

InputFunctionConfig
rvp-bitcast-const-fold.llpnot_v4i8-mtriple=riscv32 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-bitcast-const-fold.llpnot_v4i8-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-narrowing-shift-trunc.lltrunc_lshr_v4i16_to_v4i8-mtriple=riscv32 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-narrowing-shift-trunc.lltrunc_lshr_v4i16_to_v4i8-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-zip.lltest_punzipe_v4i8_coerce-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-zip.lltest_punzipo_v4i8_coerce-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-bitcast-const-fold.4f260f0c9a.ll (mutant of rvp-bitcast-const-fold.ll)pnot_v4i8-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-bitcast-const-fold.8eddcf349b.ll (mutant of rvp-bitcast-const-fold.ll)pnot_v4i8-mtriple=riscv32 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-narrowing-shift-trunc.c5799ec1c2.ll (mutant of rvp-narrowing-shift-trunc.ll)trunc_lshr_v4i16_to_v4i8-mtriple=riscv32 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-narrowing-shift-trunc.c8219937e3.ll (mutant of rvp-narrowing-shift-trunc.ll)trunc_lshr_v4i16_to_v4i8-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-zip.14d6f1ac8b.ll (mutant of rvp-zip.ll)test_punzipe_v4i8_coerce-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-zip.14d6f1ac8b.ll (mutant of rvp-zip.ll)test_punzipo_v4i8_coerce-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs

Generated 2026-10-15 08:05 UTC.