[PATCH] D58964: [AMDGPU] Allow MIMG with no uses in adjustWritemask in isel

[David Stuttard via Phabricator via llvm-commits]

dstuttard updated this revision to Diff 189716.
dstuttard added a comment.

Modified test in line with review comments


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D58964/new/

https://reviews.llvm.org/D58964

Files:
  lib/Target/AMDGPU/SIISelLowering.cpp
  test/CodeGen/AMDGPU/img-nouse-adjust.ll


Index: test/CodeGen/AMDGPU/img-nouse-adjust.ll
===================================================================
--- /dev/null
+++ test/CodeGen/AMDGPU/img-nouse-adjust.ll
@@ -0,0 +1,22 @@
+; RUN: llc -march=amdgcn -mcpu=gfx900 -start-before=amdgpu-isel -stop-after=amdgpu-isel -verify-machineinstrs < %s | FileCheck %s --check-prefix=GCN
+
+; We're really just checking for no crashes
+; The feature we're testing for in AdjustWriteMask leaves the image_load as an instruction just post amdgpu-isel
+; In reality, it's hard to get an image intrinsic into AdjustWriteMask with no uses as it will usually get removed
+; first, but it can happen, hence the fix associated with this test
+
+; GCN-LABEL: name: _amdgpu_cs_main
+; GCN-LABEL: bb.0
+; GCN: IMAGE_LOAD_V4_V2
+define amdgpu_cs void @_amdgpu_cs_main(i32 %dummy) local_unnamed_addr #0 {
+.entry:
+  %unused.result = tail call <4 x float> @llvm.amdgcn.image.load.2d.v4f32.i32(i32 15, i32 undef, i32 undef, <8 x i32> undef, i32 0, i32 0) #3
+  call void asm sideeffect ";", "" () #0
+  ret void
+}
+
+; Function Attrs: nounwind readonly
+declare <4 x float> @llvm.amdgcn.image.load.2d.v4f32.i32(i32, i32, i32, <8 x i32>, i32, i32) #1
+  
+attributes #0 = { nounwind }
+attributes #1 = { nounwind readonly  }
Index: lib/Target/AMDGPU/SIISelLowering.cpp
===================================================================
--- lib/Target/AMDGPU/SIISelLowering.cpp
+++ lib/Target/AMDGPU/SIISelLowering.cpp
@@ -9163,6 +9163,10 @@
   // Don't allow 0 dmask, as hardware assumes one channel enabled.
   bool NoChannels = !NewDmask;
   if (NoChannels) {
+    if (!UsesTFC) {
+      // No uses of the result and not using TFC. Then do nothing.
+      return Node;
+    }
     // If the original dmask has one channel - then nothing to do
     if (OldBitsSet == 1)
       return Node;


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