[PATCH] D59871: [AMDGPU] Avoid mistaking a ds atomic for a load

[Tim Renouf via Phabricator via llvm-commits]

tpr created this revision.
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SIInstrInfo::areLoadsFromSameBasePtr was mistaking a ds atomic for a
load, and then asserting when there was a non-constant operand where it
was expecting to find the load constant offset.

Change-Id: I484b3e240d0a25f34846a8cafbaf2befb37f8c07


Repository:
  rL LLVM

https://reviews.llvm.org/D59871

Files:
  lib/Target/AMDGPU/SIInstrInfo.cpp
  test/CodeGen/AMDGPU/two-ds-atomics.ll


Index: test/CodeGen/AMDGPU/two-ds-atomics.ll
===================================================================
--- /dev/null
+++ test/CodeGen/AMDGPU/two-ds-atomics.ll
@@ -0,0 +1,27 @@
+; RUN: llc -march=amdgcn -mcpu=gfx900 -verify-machineinstrs < %s | FileCheck -check-prefix=GCN %s
+
+; This test case asserted due to SIInstrInfo::areLoadsFromSameBasePtr mistaking
+; an atomic for a load.
+
+; GCN-LABEL: _amdgpu_cs_main:
+; GCN: ds_max_u32
+; GCN: ds_min_u32
+
+ at TileFarZ = external dso_local addrspace(3) global i32, align 16
+ at TileNearZ = external dso_local addrspace(3) global i32, align 16
+
+define amdgpu_cs void @_amdgpu_cs_main() local_unnamed_addr #0 {
+.entry:
+  %tmp = tail call float @llvm.amdgcn.image.load.mip.2d.f32.i32(i32 1, i32 undef, i32 undef, i32 0, <8 x i32> undef, i32 0, i32 0)
+  %tmp1 = bitcast float %tmp to i32
+  %tmp2 = atomicrmw volatile umax i32 addrspace(3)* @TileFarZ, i32 %tmp1 seq_cst
+  %tmp3 = atomicrmw volatile umin i32 addrspace(3)* @TileNearZ, i32 %tmp1 seq_cst
+  unreachable
+}
+
+; Function Attrs: nounwind readonly
+declare float @llvm.amdgcn.image.load.mip.2d.f32.i32(i32 immarg, i32, i32, i32, <8 x i32>, i32 immarg, i32 immarg) #1
+
+attributes #0 = { "target-features" }
+attributes #1 = { nounwind readonly }
+
Index: lib/Target/AMDGPU/SIInstrInfo.cpp
===================================================================
--- lib/Target/AMDGPU/SIInstrInfo.cpp
+++ lib/Target/AMDGPU/SIInstrInfo.cpp
@@ -150,8 +150,9 @@
   unsigned Opc0 = Load0->getMachineOpcode();
   unsigned Opc1 = Load1->getMachineOpcode();
 
-  // Make sure both are actually loads.
-  if (!get(Opc0).mayLoad() || !get(Opc1).mayLoad())
+  // Make sure both are actually loads (not stores or atomics).
+  if (!get(Opc0).mayLoad() || get(Opc0).mayStore() || !get(Opc1).mayLoad() ||
+      get(Opc1).mayStore())
     return false;
 
   if (isDS(Opc0) && isDS(Opc1)) {


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