fallback: legalize: G_ATOMICRMW_ADD s8,p0

Run:explore-04ca53e65f-20261014-114124
Kind:fallback
Category:legalize: G_ATOMICRMW_ADD s8,p0
Occurrences:4 in 4 configs, 1 test files
Snippet from:forced-atomics.ll @rmw8 via llvm-extract
Config:-mtriple=riscv32 -mattr=+forced-atomics
Local check:reproduces at 04ca53e65f
Compiler Explorer:not uploaded (over --godbolt-limit or disabled)

Snippet:

; Function Attrs: nounwind
define i8 @rmw8(ptr %p) #0 {
  %v = atomicrmw add ptr %p, i8 1 seq_cst, align 1
  ret i8 %v
}

attributes #0 = { nounwind }

Reproduce:

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

Local llc output:

remark: <unknown>:0:0: unable to legalize instruction: %1:_(s8) = G_ATOMICRMW_ADD %0:_(p0), %2:_ :: (load store seq_cst (s8) on %ir.p) (in function: rmw8)
warning: Instruction selection used fallback path for rmw8

Occurrences (4):

InputFunctionConfig
forced-atomics.llrmw8-mtriple=riscv32 -mattr=+forced-atomics
forced-atomics.llrmw8-mtriple=riscv32 -mattr=+forced-atomics,+no-trailing-seq-cst-fence
forced-atomics.llrmw8-mtriple=riscv64 -mattr=+forced-atomics
forced-atomics.llrmw8-mtriple=riscv64 -mattr=+forced-atomics,+no-trailing-seq-cst-fence

Generated 2026-10-15 08:05 UTC.