fallback: legalize: G_SUB <2 x s32>

Run:main-04ca53e65f-20261014-113325
Kind:fallback
Category:legalize: G_SUB <2 x s32>
Occurrences:10 in 2 configs, 3 test files
Snippet from:rvp-simd-32.ll @test_pwsub_h via llvm-extract
Config:-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
Local check:reproduces at 04ca53e65f
Compiler Explorer:not uploaded (over --godbolt-limit or disabled)

Snippet:

define <2 x i32> @test_pwsub_h(<2 x i16> %a, <2 x i16> %b) {
  %a_ext = sext <2 x i16> %a to <2 x i32>
  %b_ext = sext <2 x i16> %b to <2 x i32>
  %res = sub <2 x i32> %a_ext, %b_ext
  ret <2 x i32> %res
}

Reproduce:

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

Local llc output:

remark: <unknown>:0:0: unable to legalize instruction: %8:_(<2 x s32>) = G_SUB %6:_, %7:_ (in function: test_pwsub_h)
warning: Instruction selection used fallback path for test_pwsub_h

Occurrences (10):

InputFunctionConfig
rvp-simd-32.lltest_pwsub_h-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-simd-32.lltest_pwsubu_h-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-simd-64.lltest_pdif_w-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-simd-64.lltest_pdifu_w-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-simd-64.lltest_psub_w-mtriple=riscv64 -mattr=+experimental-p,+m,+zbb -verify-machineinstrs
rvp-widening-sub-acc.lltest_pwsuba_v2i16-mtriple=riscv64 -mattr=+experimental-p -verify-machineinstrs
rvp-widening-sub-acc.lltest_pwsubau_v2i16-mtriple=riscv64 -mattr=+experimental-p -verify-machineinstrs
rvp-widening-sub-acc.3ba4fff81a.ll (mutant of rvp-widening-sub-acc.ll)test_pwsuba_v2i16-mtriple=riscv64 -mattr=+experimental-p -verify-machineinstrs
rvp-widening-sub-acc.3ba4fff81a.ll (mutant of rvp-widening-sub-acc.ll)test_pwsubau_v2i16-mtriple=riscv64 -mattr=+experimental-p -verify-machineinstrs
rvp-widening-sub-acc.77f1199aa7.ll (mutant of rvp-widening-sub-acc.ll)test_pwsuba_v2i16-mtriple=riscv64 -mattr=+experimental-p -verify-machineinstrs

Generated 2026-10-15 08:05 UTC.