Dead calls with convergence token uses are not deleted

[arsenm]

Calls with convergencectrl bundles appear to never be deleted when unused:

; RUN:  opt -S -mtriple=amdgcn-amd-amdhsa -O3 %s

; The calls should be deleted
define void @dead_readfirstlane_convergencetoken(<2 x i32> %src) convergent {
  %t = call token @llvm.experimental.convergence.entry()
  %vec = call <2 x i32> @llvm.amdgcn.readfirstlane.v2i32(<2 x i32> %src) [ "convergencectrl"(token %t) ]
  ret void
}

In this example, every pass is a no-op. I would expect instcombine or any of the DCE passes to erase the entry token and readfirstlane call

[llvmbot]

@llvm/issue-subscribers-backend-amdgpu

Author: Matt Arsenault (arsenm)

Calls with convergencectrl bundles appear to never be deleted when unused:

; RUN:  opt -S -mtriple=amdgcn-amd-amdhsa -O3 %s

; The calls should be deleted
define void @<!-- -->dead_readfirstlane_convergencetoken(&lt;2 x i32&gt; %src) convergent {
  %t = call token @<!-- -->llvm.experimental.convergence.entry()
  %vec = call &lt;2 x i32&gt; @<!-- -->llvm.amdgcn.readfirstlane.v2i32(&lt;2 x i32&gt; %src) [ "convergencectrl"(token %t) ]
  ret void
}

In this example, every pass is a no-op. I would expect instcombine or any of the DCE passes to erase the entry token and readfirstlane call