fallback: legalize: G_PHI <4 x s32>

Run:explore-bc8218b282-20261015-075519
Kind:fallback
Category:legalize: G_PHI <4 x s32> NEW
Occurrences:15 in 15 configs, 10 test files
Snippet from:push-pop-opt-crash.2c1ddae79e.ll (mutant of push-pop-opt-crash.ll) @f0 via llvm-extract + llvm-reduce
Config:-mattr=+zcmp -verify-machineinstrs -mtriple=riscv32 -target-abi=ilp32
Local check:reproduces at bc8218b282
Compiler Explorer:https://godbolt.org/z/e39brYjjo (llc-assertions-trunk, checked 2026-10-15 08:05 UTC): G reproduces

Snippet:

define <4 x i32> @f0(i1 %c) {
entry:
  br i1 %c, label %if.T, label %if.F

if.T:                                             ; preds = %entry
  br label %if.F

if.F:                                             ; preds = %if.T, %entry
  %0 = phi <4 x i32> [ zeroinitializer, %if.T ], [ splat (i32 1), %entry ]
  ret <4 x i32> %0
}

Compiler Explorer panes:

PaneOptionsExitInstsstderr
GlobalISel-mattr=+zcmp -verify-machineinstrs -mtriple=riscv32 -target-abi=ilp32 -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel.*010remark: <unknown>:0:0: unable to legalize instruction: %3:_(<4 x s32>) = G_PHI %4:_(<4 x s32>), %bb.2, %6:_(<4 x s32>), %bb.1 (in function: f0)
warning: Instruction selection used fallback path for f0
SelectionDAG (control)-mattr=+zcmp -verify-machineinstrs -mtriple=riscv32 -target-abi=ilp32 -global-isel=0010-

Reproduce:

llc -mattr=+zcmp -verify-machineinstrs -mtriple=riscv32 -target-abi=ilp32 -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel.* snippet.ll -o -
llc -mattr=+zcmp -verify-machineinstrs -mtriple=riscv32 -target-abi=ilp32 -global-isel=0 snippet.ll -o -

Local llc output:

remark: <unknown>:0:0: unable to legalize instruction: %3:_(<4 x s32>) = G_PHI %4:_(<4 x s32>), %bb.2, %6:_(<4 x s32>), %bb.1 (in function: f0)
warning: Instruction selection used fallback path for f0

Occurrences (15):

InputFunctionConfig
fli-licm.9f51e0d570.ll (mutant of fli-licm.ll)process_nodes-mtriple=riscv64 -target-abi=lp64f -mattr=+zfa
fli-licm.bc6a5e5cf6.ll (mutant of fli-licm.ll)process_nodes-mtriple=riscv32 -target-abi=ilp32f -mattr=+zfa
loop-strength-reduce-add-cheaper-than-mul.5f6159907e.ll (mutant of loop-strength-reduce-add-cheaper-than-mul.ll)test-mtriple=riscv32 -verify-machineinstrs -mattr=+m
loop-strength-reduce-add-cheaper-than-mul.7c519fc765.ll (mutant of loop-strength-reduce-add-cheaper-than-mul.ll)test-mtriple=riscv64 -verify-machineinstrs -mattr=+m
loop-strength-reduce-loop-invar.7d3dddfadb.ll (mutant of loop-strength-reduce-loop-invar.ll)test-mtriple=riscv64 -verify-machineinstrs
loop-strength-reduce-loop-invar.d098449f2a.ll (mutant of loop-strength-reduce-loop-invar.ll)test-mtriple=riscv32 -verify-machineinstrs
machine-cse.0b48be9a4a.ll (mutant of machine-cse.ll)commute_fnmadd_f32-mtriple=riscv32 -mattr=+f,+d,+zfh -target-abi=ilp32d
machine-cse.d68532baf4.ll (mutant of machine-cse.ll)commute_fnmadd_f32-mtriple=riscv64 -mattr=+f,+d,+zfh -target-abi=lp64d
pr101786.1a020a8e93.ll (mutant of pr101786.ll)test--mtriple=riscv64
pr51206.d17a3d15d5.ll (mutant of pr51206.ll)wobble-mtriple=riscv64-unknown-linux-gnu -mattr=+m
push-pop-opt-crash.2c1ddae79e.ll (mutant of push-pop-opt-crash.ll)f0-mattr=+zcmp -verify-machineinstrs -mtriple=riscv32 -target-abi=ilp32
push-pop-opt-crash.344c071ea3.ll (mutant of push-pop-opt-crash.ll)f0-mattr=+zcmp -verify-machineinstrs -mtriple=riscv64 -target-abi=lp64
shrinkwrap-save-restore-fixed-reg.e9cb573578.ll (mutant of shrinkwrap-save-restore-fixed-reg.ll)shrinkwrap_entry_no_preds-mtriple=riscv64 -mattr=+save-restore,+reserve-x5 -verify-machineinstrs
stack-protector-vector-clobber.19ac8ffc7b.ll (mutant of stack-protector-vector-clobber.ll)test_stack_protector_with_vector_clobber-mtriple=riscv64 -mattr=+v
trunc-free.7fe7ba479e.ll (mutant of trunc-free.ll)foo-mtriple=riscv64

Generated 2026-10-15 08:05 UTC.