llvm/llvm-project

AMDGPU GlobalISel fails on select of G_UBSANTRAP

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#131,740 opened on Mar 18, 2025

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backend:AMDGPUgood first issuellvm:globalisel

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Description

https://godbolt.org/z/6PzeExK4f

; RUN: llc -mtriple=amdgcn-amd-amdhsa -global-isel < %s
; LLVM ERROR: cannot select: G_UBSANTRAP 0 (in function: ubsan_trap)

define void @ubsan_trap() {
  call void @llvm.ubsantrap(i8 0)
  ret void
}

We already handle G_TRAP and G_DEBUGTRAP. ubsan isn't particularly special and should be able to follow

Contributor guide

Research direction
Examine the existing implementation for G TRAP and G DEBUGTRAP in the AMDGPU GlobalISel backend (likely in AMDGPUInstructionSelector or similar). Add a new case for G UBSANTRAP that handles it similarly. The test case in the issue can be used to verify the fix.
Tech stack
cpp
Domain
compilers
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
C++LLVM
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40