fallback: legalize: G_SMULH s64

Run:explore-04ca53e65f-20261014-114124
Kind:fallback
Category:legalize: G_SMULH s64
Occurrences:9 in 1 configs, 2 test files
Snippet from:smulh.ll @smulh_i64 via llvm-extract
Config:-mtriple=riscv32
Local check:reproduces at 04ca53e65f
Compiler Explorer:not uploaded (over --godbolt-limit or disabled)

Snippet:

; Function Attrs: nounwind
define i64 @smulh_i64(i64 %x, i64 %y) #0 {
  %r = call i64 @llvm.smulh.i64(i64 %x, i64 %y)
  ret i64 %r
}

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

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

Reproduce:

llc -mtriple=riscv32 -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel.* snippet.ll -o -
llc -mtriple=riscv32 -global-isel=0 snippet.ll -o -

Local llc output:

remark: <unknown>:0:0: unable to legalize instruction: %6:_(s64) = G_SMULH %0:_, %1:_ (in function: smulh_i64)
warning: Instruction selection used fallback path for smulh_i64

Occurrences (9):

InputFunctionConfig
overflow-intrinsic-optimizations.llno__mulodi4-mtriple=riscv32
smulh.llsmulh_i64-mtriple=riscv32
smulh.llsmulh_v1i64-mtriple=riscv32
overflow-intrinsic-optimizations.6c348a1ba4.ll (mutant of overflow-intrinsic-optimizations.ll)no__mulodi4-mtriple=riscv32
overflow-intrinsic-optimizations.87b54fa49d.ll (mutant of overflow-intrinsic-optimizations.ll)no__mulodi4-mtriple=riscv32
overflow-intrinsic-optimizations.e4ef18ae05.ll (mutant of overflow-intrinsic-optimizations.ll)no__mulodi4-mtriple=riscv32
overflow-intrinsic-optimizations.eb91736a38.ll (mutant of overflow-intrinsic-optimizations.ll)no__mulodi4-mtriple=riscv32
smulh.4db6869591.ll (mutant of smulh.ll)smulh_v1i64-mtriple=riscv32
smulh.5110d83f7b.ll (mutant of smulh.ll)smulh_v1i64-mtriple=riscv32

Generated 2026-10-15 08:05 UTC.