[llvm-branch-commits] [llvm] [AMDGPU][SILoadStoreOptimizer] Include constrained buffer load variants (PR #101619)

[Matt Arsenault via llvm-branch-commits]

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@@ -1735,8 +1735,10 @@ unsigned SILoadStoreOptimizer::getNewOpcode(const CombineInfo &CI,
   case UNKNOWN:
     llvm_unreachable("Unknown instruction class");
   case S_BUFFER_LOAD_IMM: {
+    // If XNACK is enabled, use the constrained opcodes when the first load is
+    // under-aligned.
     const MachineMemOperand *MMO = *CI.I->memoperands_begin();
-    bool NeedsConstrainedOpc = needsConstraintedOpcode(*STM, MMO, Width);
+    bool NeedsConstrainedOpc = MMO && needsConstrainedOpcode(*STM, MMO, Width);
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arsenm wrote:

This is an invalid way of checking for no mmo. This is dereferencing the end iterator. 

https://github.com/llvm/llvm-project/pull/101619