Don't remove trap instructions from the generated code.

They are semantically meaningful. In the cases where we expect recovery,
e.g. when handling an exception, the caller should make sure to exit the
thread before reaching the trap.

Author: maleadt

src/precompile.jl

@@ -52,7 +52,6 @@ end
 function _precompile_()
     ccall(:jl_generating_output, Cint, ()) == 1 || return nothing
     @assert precompile(Tuple{typeof(GPUCompiler.assign_args!),Expr,Vector{Any}})
-    @assert precompile(Tuple{typeof(GPUCompiler.lower_trap!),LLVM.Module})
     @assert precompile(Tuple{typeof(GPUCompiler.lower_unreachable!),LLVM.Function})
     @assert precompile(Tuple{typeof(GPUCompiler.lower_gc_frame!),LLVM.Function})
     @assert precompile(Tuple{typeof(GPUCompiler.lower_throw!),LLVM.Module})

src/ptx.jl

@@ -187,7 +187,6 @@ end
 
 function finish_ir!(@nospecialize(job::CompilerJob{PTXCompilerTarget}),
                     mod::LLVM.Module, entry::LLVM.Function)
-    lower_trap!(mod)
     for f in functions(mod)
         lower_unreachable!(f)
     end
@@ -246,36 +245,6 @@ end
 
 ## LLVM passes
 
-# replace calls to `trap` with inline assembly calling `exit`, which isn't fatal
-function lower_trap!(mod::LLVM.Module)
-    job = current_job::CompilerJob
-    changed = false
-    @timeit_debug to "lower trap" begin
-
-    if haskey(functions(mod), "llvm.trap")
-        trap = functions(mod)["llvm.trap"]
-
-        # inline assembly to exit a thread
-        exit_ft = LLVM.FunctionType(LLVM.VoidType())
-        exit = InlineAsm(exit_ft, "exit;", "", true)
-
-        for use in uses(trap)
-            val = user(use)
-            if isa(val, LLVM.CallInst)
-                @dispose builder=IRBuilder() begin
-                    position!(builder, val)
-                    call!(builder, exit_ft, exit)
-                end
-                unsafe_delete!(LLVM.parent(val), val)
-                changed = true
-            end
-        end
-    end
-
-    end
-    return changed
-end
-
 # lower `unreachable` to `exit` so that the emitted PTX has correct control flow
 #
 # During back-end compilation, `ptxas` inserts instructions to manage the harware's