fallback: legalize: G_CTLZ_ZERO_POISON s32,s256
| Run: | explore-bc8218b282-20261015-075519 |
| Kind: | fallback |
| Category: | legalize: G_CTLZ_ZERO_POISON s32,s256 NEW |
| Occurrences: | 1 in 1 configs, 1 test files |
| Snippet from: | wide-scalar-shift-by-byte-multiple-legalization.46b1d74a8f.ll (mutant of wide-scalar-shift-by-byte-multiple-legalization.ll) @lshr_32bytes via llvm-extract |
| Config: | -mtriple=riscv32 -verify-machineinstrs |
| Local check: | reproduces at bc8218b282 |
| Compiler Explorer: | not uploaded (over --godbolt-limit or disabled) |
Snippet:
@G.2 = external global i256
@G.3 = external global i256
; Function Attrs: nounwind
define void @lshr_32bytes(ptr %src.ptr, ptr %byteOff.ptr, ptr %dst) #0 {
%LGV = load i256, ptr @G.2, align 4
%src = load i256, ptr %src.ptr, align 1
%byteOff = load i256, ptr %byteOff.ptr, align 1
%B = udiv i256 %src, %LGV
%bitOff = shl i256 %byteOff, 3
%res = lshr i256 %src, %bitOff
store i256 %res, ptr %dst, align 1
store i256 %B, ptr @G.3, align 4
ret void
}
attributes #0 = { nounwind }
Reproduce:
llc -mtriple=riscv32 -verify-machineinstrs -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel.* snippet.ll -o -
llc -mtriple=riscv32 -verify-machineinstrs -global-isel=0 snippet.ll -o -
Local llc output:
remark: <unknown>:0:0: unable to legalize instruction: %3126:_(s32) = G_CTLZ_ZERO_POISON %8:_(s256) (in function: lshr_32bytes)
warning: Instruction selection used fallback path for lshr_32bytes
Occurrences (1):
Generated 2026-10-15 08:05 UTC.