fallback: legalize: G_INSERT_VECTOR_ELT <4 x s32>,s32,s64

Run:main-04ca53e65f-20261014-113325
Kind:fallback
Category:legalize: G_INSERT_VECTOR_ELT <4 x s32>,s32,s64 NEW
Occurrences:3 in 2 configs, 2 test files
Snippet from:mul.70ebe807b2.ll (mutant of mul.ll) @muli64_m4352 via llvm-extract
Config:-mtriple=riscv64 -mattr=+m -verify-machineinstrs
Local check:reproduces at 04ca53e65f
Compiler Explorer:not uploaded (over --godbolt-limit or disabled)

Snippet:

@G.1 = external global <4 x i32>

; Function Attrs: nounwind
define i64 @muli64_m4352(i64 %a) #0 {
  %LGV = load <4 x i32>, ptr @G.1, align 16
  %I = insertelement <4 x i32> %LGV, i32 -1, i64 %a
  %1 = mul i64 %a, -4352
  store <4 x i32> %I, ptr @G.1, align 16
  ret i64 %1
}

attributes #0 = { nounwind }

Reproduce:

llc -mtriple=riscv64 -mattr=+m -verify-machineinstrs -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel.* snippet.ll -o -
llc -mtriple=riscv64 -mattr=+m -verify-machineinstrs -global-isel=0 snippet.ll -o -

Local llc output:

remark: <unknown>:0:0: unable to legalize instruction: %3:_(<4 x s32>) = G_INSERT_VECTOR_ELT %1:_, %4:_(s32), %0:_(s64) (in function: muli64_m4352)
warning: Instruction selection used fallback path for muli64_m4352

Occurrences (3):

InputFunctionConfig
mul.70ebe807b2.ll (mutant of mul.ll)muli64_m4352-mtriple=riscv64 -mattr=+m -verify-machineinstrs
mul.7694056409.ll (mutant of mul.ll)muli64_m4352-mtriple=riscv64 -verify-machineinstrs
reduction-formation.3eb68d4638.ll (mutant of reduction-formation.ll)reduce_sum_4xi32-mtriple=riscv64 -verify-machineinstrs

Generated 2026-10-15 08:05 UTC.