fallback: legalize: G

fallback: legalize: G_CLMUL s64

Run:	explore-bc8218b282-20261015-075519
Kind:	fallback
Category:	legalize: G_CLMUL s64
Occurrences:	85 in 11 configs, 5 test files
Snippet from:	rv32zbc-intrinsic.ll @llvm_clmulr_i32 via llvm-extract
Config:	`-mtriple=riscv32 -mattr=+zbc -verify-machineinstrs`
Local check:	reproduces at bc8218b282
Compiler Explorer:	not uploaded (over --godbolt-limit or disabled)

Snippet:

; Function Attrs: nounwind
define i32 @llvm_clmulr_i32(i32 %a, i32 %b) #0 {
  %tmp1 = zext i32 %a to i64
  %tmp2 = zext i32 %b to i64
  %tmp3 = call i64 @llvm.clmul.i64(i64 %tmp1, i64 %tmp2)
  %tmp4 = lshr i64 %tmp3, 31
  %tmp5 = trunc i64 %tmp4 to i32
  ret i32 %tmp5
}

; Function Attrs: nocallback nocreateundeforpoison nofree nosync nounwind speculatable willreturn memory(none)
declare i64 @llvm.clmul.i64(i64, i64) #1

attributes #0 = { nounwind }
attributes #1 = { nocallback nocreateundeforpoison nofree nosync nounwind speculatable willreturn memory(none) }

Reproduce:

llc -mtriple=riscv32 -mattr=+zbc -verify-machineinstrs -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel.* snippet.ll -o -
llc -mtriple=riscv32 -mattr=+zbc -verify-machineinstrs -global-isel=0 snippet.ll -o -

Local llc output:

remark: <unknown>:0:0: unable to legalize instruction: %4:_(s64) = G_CLMUL %2:_, %3:_ (in function: llvm_clmulr_i32)
warning: Instruction selection used fallback path for llvm_clmulr_i32

Occurrences (85) (first 50):

Input	Function	Config
clmul.ll	clmul_i64	`-mtriple=riscv32 -mattr=+m -verify-machineinstrs`
clmul.ll	clmul_i64_zext	`-mtriple=riscv32 -mattr=+m -verify-machineinstrs`
clmul.ll	clmul_i64	`-mtriple=riscv32 -mattr=+m,+zbc -verify-machineinstrs`
clmul.ll	clmul_i64_zext	`-mtriple=riscv32 -mattr=+m,+zbc -verify-machineinstrs`
clmul.ll	clmul_i64	`-mtriple=riscv32 -mattr=+m,+zbs -verify-machineinstrs`
clmul.ll	clmul_i64_zext	`-mtriple=riscv32 -mattr=+m,+zbs -verify-machineinstrs`
clmul.ll	clmul_i64	`-mtriple=riscv32 -mattr=+m,+zvbc -verify-machineinstrs`
clmul.ll	clmul_i64_zext	`-mtriple=riscv32 -mattr=+m,+zvbc -verify-machineinstrs`
clmul.ll	clmul_i64	`-mtriple=riscv32 -verify-machineinstrs`
clmul.ll	clmul_i64_zext	`-mtriple=riscv32 -verify-machineinstrs`
clmul.ll	clmul_i64	`-mtriple=riscv64 -mattr=+m -verify-machineinstrs`
clmul.ll	clmul_i64_zext	`-mtriple=riscv64 -mattr=+m -verify-machineinstrs`
clmul.ll	clmul_i64	`-mtriple=riscv64 -mattr=+m,+zbs -verify-machineinstrs`
clmul.ll	clmul_i64_zext	`-mtriple=riscv64 -mattr=+m,+zbs -verify-machineinstrs`
clmul.ll	clmul_i64	`-mtriple=riscv64 -mattr=+m,+zvbc -verify-machineinstrs`
clmul.ll	clmul_i64_zext	`-mtriple=riscv64 -mattr=+m,+zvbc -verify-machineinstrs`
clmul.ll	clmul_i64	`-mtriple=riscv64 -verify-machineinstrs`
clmul.ll	clmul_i64_zext	`-mtriple=riscv64 -verify-machineinstrs`
clmulh.ll	clmulh_i32	`-mtriple=riscv32 -mattr=+m -verify-machineinstrs`
clmulh.ll	clmulh_i32	`-mtriple=riscv32 -mattr=+m,+zbc -verify-machineinstrs`
clmulh.ll	clmulh_i32	`-mtriple=riscv32 -mattr=+m,+zbs -verify-machineinstrs`
clmulh.ll	clmulh_i32	`-mtriple=riscv32 -mattr=+m,+zvbc -verify-machineinstrs`
clmulh.ll	clmulh_i32	`-mtriple=riscv32 -verify-machineinstrs`
clmulh.ll	clmulh_i32	`-mtriple=riscv64 -mattr=+m -verify-machineinstrs`
clmulh.ll	clmulh_i32	`-mtriple=riscv64 -mattr=+m,+zbs -verify-machineinstrs`
clmulh.ll	clmulh_i32	`-mtriple=riscv64 -mattr=+m,+zvbc -verify-machineinstrs`
clmulh.ll	clmulh_i32	`-mtriple=riscv64 -verify-machineinstrs`
clmulr.ll	clmulr_i32	`-mtriple=riscv32 -mattr=+m -verify-machineinstrs`
clmulr.ll	clmulr_i32	`-mtriple=riscv32 -mattr=+m,+zbc -verify-machineinstrs`
clmulr.ll	clmulr_i32	`-mtriple=riscv32 -mattr=+m,+zbs -verify-machineinstrs`
clmulr.ll	clmulr_i32	`-mtriple=riscv32 -verify-machineinstrs`
clmulr.ll	clmulr_i32	`-mtriple=riscv64 -mattr=+m -verify-machineinstrs`
clmulr.ll	clmulr_i32	`-mtriple=riscv64 -mattr=+m,+zbs -verify-machineinstrs`
clmulr.ll	clmulr_i32	`-mtriple=riscv64 -verify-machineinstrs`
rv32zbc-intrinsic.ll	llvm_clmulr_i32	`-mtriple=riscv32 -mattr=+zbc -verify-machineinstrs`
rv32zbc-zbkc-intrinsic.ll	llvm_clmulh_i32	`-mtriple=riscv32 -mattr=+zbc -verify-machineinstrs`
rv32zbc-zbkc-intrinsic.ll	llvm_clmulh_i32	`-mtriple=riscv32 -mattr=+zbkc -verify-machineinstrs`
clmul.0416b79ff7.ll (mutant of clmul.ll)	clmul_i64	`-mtriple=riscv32 -mattr=+m,+zbs -verify-machineinstrs`
clmul.0480d57012.ll (mutant of clmul.ll)	clmul_i64	`-mtriple=riscv32 -mattr=+m,+zvbc -verify-machineinstrs`
clmul.0496fa590c.ll (mutant of clmul.ll)	clmul_i64_zext	`-mtriple=riscv32 -mattr=+m,+zbs -verify-machineinstrs`
clmul.0f5735b99f.ll (mutant of clmul.ll)	clmul_i64_zext	`-mtriple=riscv64 -verify-machineinstrs`
clmul.12fd06213b.ll (mutant of clmul.ll)	clmul_i64	`-mtriple=riscv32 -verify-machineinstrs`
clmul.1824459440.ll (mutant of clmul.ll)	clmul_i64_zext	`-mtriple=riscv64 -mattr=+m,+zbs -verify-machineinstrs`
clmul.1aab5cbcdd.ll (mutant of clmul.ll)	clmul_i64_zext	`-mtriple=riscv32 -verify-machineinstrs`
clmul.1c0684c19c.ll (mutant of clmul.ll)	clmul_i64_zext	`-mtriple=riscv64 -mattr=+m,+zvbc -verify-machineinstrs`
clmul.22b9179d93.ll (mutant of clmul.ll)	clmul_i64	`-mtriple=riscv32 -mattr=+m,+zbc -verify-machineinstrs`
clmul.233000f046.ll (mutant of clmul.ll)	clmul_i64_zext	`-mtriple=riscv64 -mattr=+m -verify-machineinstrs`
clmul.3692010aca.ll (mutant of clmul.ll)	clmul_i64_zext	`-mtriple=riscv64 -mattr=+m,+zvbc -verify-machineinstrs`
clmul.47cebd0107.ll (mutant of clmul.ll)	clmul_i64_zext	`-mtriple=riscv32 -mattr=+m,+zbs -verify-machineinstrs`
clmul.4a55d7fa5f.ll (mutant of clmul.ll)	clmul_i64	`-mtriple=riscv64 -verify-machineinstrs`

Generated 2026-10-15 08:05 UTC.